# My car audio test rig (and computer sound) project:



## Grinder (Dec 18, 2016)

This thing started out with a pair of Polk Audio DB651s (and the Skar Audio IX-8). I originally built it to test some of my ideas for a car audio boombox. (See my boombox project at)

http://www.diymobileaudio.com/forum...sion/318938-my-car-audio-boombox-project.html

Once the boombox project was more or less completed, I installed a pair of Rockford Fosgate PPS4-8s (shown in the picture below):

https://www.amazon.com/Rockford-Fos...ie=UTF8&qid=1484506335&sr=1-1&keywords=PPS4-8

…and two PP8-T tweeters: 

https://www.amazon.com/Rockford-Fosgate-PP8-T-Punch-Tweeter/dp/B007AQ2XBQ

…and two PP4-X crossovers:

https://www.amazon.com/Rockford-Fos...&qid=1484506405&sr=1-1-catcorr&keywords=PP4-X

…to test my weird concept of a car audio derived PA/mobile DJ/home stereo system (see details of this project in my “T/S parameters for R F PPS4-8?” thread at):

http://www.diymobileaudio.com/forum...ssion/317762-t-s-parameters-r-f-pps4-8-a.html (I apologize in advance for the rather convoluted nature of the first page of that thread)

...As seen in the picture below, an R400-4D provides amplification for the mids and tweets (front channels), while the IX-8 D2 is on the bridged rear channels. 12 Volt power via an EVGA 700B computer power supply (just like my boombox project).

This test rig (as seen in the pictures below) presently serves as my computer sound.

Soon I’ll be removing the R400-4D and hooking up a P400X2 and an R500X1D (with another EVGA 700B) for further testing of my car audio derived PA-mobile DJ/home stereo system concept.


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## Grinder (Dec 18, 2016)

On behalf of anyone who might otherwise be misled by the juxtaposition of these "pro audio" (SPL) spec mids and tweets, with this little ol' Skar Audio IX-8 entry-level sub, I'll just say that the term "mismatch" would be a major understatement. 

They actually work fine together at low-to-moderate volume levels, but this little sub is nowhere near capable of reaching the kind of high SPL these mids and tweets are designed for. 

Rockford Fosgate markets these 8" mids as "midbass" drivers, but they aren't really very effective below about 200Hz or so (this is just my sort of educated guess from listening to test tones and music through them). Lucky for me, this little sub (in a sealed enclosure, such as this one), unlike many other subs, has a frequency response that extends well into the low end of these so called "midbass" (midrange) drivers.

Also, in a sealed enclosure this sub only gets down as low as 40-50Hz, which means you would probably need more than several of these (and sufficient additional amplifier power) AND at least one or more larger subs (depending on how very large and/or powerful they are) to cover the range from 50-60Hz down to 20Hz (or even lower).

I just figured some due diligence on my part was needed here, lest anyone be misled by this admittedly very odd project/work-in-progress.

If I am wrong in any of this, I welcome correction (lest I further mislead anyone).

Any comments or suggestions?


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## lurch (Jan 20, 2014)

thanks for this and your other posts Grinder. 
i have on order a pair of the rf 8's to replace a pair of dayton reference 8's that 
i " thought " were blown. turns out the amp had a dirty switch and the the
daytons are just fine. 
i am still going to try the rf in my doors if the weather ever clears up around here but
i fear i am making a big mistake. 
been reading your posts with interest to get an idea of how these will perform although
our applications are very different. 
reviews online are pointless because they all say basically the same thing :
" these rock ". 
none of the reveiwers tell us how they actually SOUND. 
rf doesn't tell us much about them either, like you said, i can't find a frequency response
graph anywhere. 

so thanks for all the input !


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## Grinder (Dec 18, 2016)

> thanks for this and your other posts Grinder.
> i have on order a pair of the rf 8's to replace a pair of dayton reference 8's that
> i " thought " were blown. turns out the amp had a dirty switch and the the
> daytons are just fine.
> ...


You're welcome, lurch. Thank you for your feedback!

I will be very interested to know how well they work for you, and how they stack up against your Dayton Reference 8s. 

I assume your doors aren't sealed. If that's the case, perhaps you'll get more midbass from them in IB (I'm under the impression that unsealed doors are classified as "infinite baffle") than I'm getting from them in my sealed enclosures (but perhaps I am completely mistaken in thinking that either environment might support more midbass than the other).

I have no idea how their SQ might compare to your Daytons, but I suspect the biggest difference will be their relative flatness (the PPSs seem rather peaky in the high mids) rather than distortion or cleanness (for what it's worth, the PPSs sound pretty clean to me, though I haven't yet given them any more than 10-20 Watts).

I know exactly what you mean about the pointless reviews (and R F's lack of useful specs) lol! Also, perhaps I'm missing something, but it seems to me that these shouldn't be marketed by R F as "midbass" drivers. I could be wrong, but I'm pretty sure one would need to add some sort of woofers to bridge the gap between these and proper subs.

Please don't let my potentially flawed feedback discourage you. At least you can delay your disappointment until you listen to them yourself; because for all we really know, they might actually work really great for you!

Thanks again, lurch! I look forward to hearing from you.


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## lurch (Jan 20, 2014)

yup, i will definitely be giving a review once i have taken a listen. 
will be a few weeks before they are installed, we are expecting 6 inches of snow
tomorrow and i don't have a garage. 

the daytons aren't giving me a whole lot of mid bass, but they do shine throughout
the mid range. 
we will see how the rf's compare. 

keep up with your impressions, i'm interested.


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## Grinder (Dec 18, 2016)

> will be a few weeks before they are installed, we are expecting 6 inches of snow
> tomorrow and i don't have a garage.


Ahhhh... life in the north! (empathy from northeast US)


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## lurch (Jan 20, 2014)

took FOREVER for the rf's to get here, finally arrived last week. 
I haven't had a chance to install them yet, the weather still blows here but i
wanted to ask :
now that you have had some play time what are your impressions / recommendations, if
any ??

i was shocked at the size of the motors on these things, and woven tinsel leads. 
these look and feel very high in quality. 
fingers crossed for performance in regards to my application.


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## Grinder (Dec 18, 2016)

lurch said:


> took FOREVER for the rf's to get here, finally arrived last week.
> I haven't had a chance to install them yet, the weather still blows here but i
> wanted to ask :
> now that you have had some play time what are your impressions / recommendations, if
> ...


Good to hear from you, Lurch. I’ve been likewise wondering what your impressions might be. Winter’s not done here either (got over a foot of snow here last night), but sadly that’s been the least of my problems…

So, I’m still using my funky test rig for computer sound (in lieu of my yet-to-be-built stereo cabinets). But I did finally get around to replacing the R400-4D (too noisy) with the (more powerful and clean) P400X2, and an R500X1D for the sub (note that both amps are being powered by just one power supply, which works fine for now; but when my system is complete, each amp will have its own power supply), and it seems that the PPSs have finally broken in. While their mid-bass response has definitely improved, they still seem too bright - but I believe this is mostly due to the PPTs being overmatched to the PPSs, despite the lowest (-6 dB) tweeter attenuation setting of the PPXs.

In the meantime I tried out my test rig on my mom's Onkyo TX-8160 receiver (running the PPSs and PPTs via the PPXs, with the R500X1D still powering the sub) and was pleasantly surprised by how nicely balanced it all sounded with the bass set to +4-6/10 and the treble set to -2-4/10 (depending on the song and/or type of music).

I was likewise quite impressed by the high-quality look and feel of these drivers, and in my opinion their overall SQ lives up to their appearance. It’s just that these PP8-T tweeters (at 105 dB/Wm) are 10.5 dB more efficient than the PPS4-8s (at “only” 94.5 dB/Wm), and these PPS4-8s seem a bit bright to me (and a bit weak in the lower end of their range). But this seems to be easily fixed with a bit of EQ (or simply bass and treble?). However, I really have no idea how they’d sound in your application, but I’ll be surprised if you aren’t able to get them nicely dialed-in with a bit of EQ/DSP.

Are you familiar with my “Can SPL drivers + DSP = SQ?” thread? (if not, check it out - though I apologize that it is rather long and convoluted). If so, you’ll know that I’m planning to build two car audio-based home systems, one for my “computer sound,” and another system for my mom (for modest HT and music duty). Well, I’ve finally built Mom’s cabinets (and managed to wrap one of them in some kind of reasonably-nice-looking Naugahyde stuff, which quickly began to unstick from the cabinet in spots - and look like ****). So, any day now I’ll be getting a delivery from PE, including black “speaker carpet” (for mine and Mom’s speakers) and a Crown XLS 1002 amp (for Mom’s 4 Skar IX-8 subs). 

Within a few weeks I hope to begin building my computer sound speaker cabinets.

These are pictures of Mom’s cabinets as of today (exterior dimensions: 9"w x 15"d x 33.5"h), and an updated picture of my test rig's ugly guts. With any luck these will be done by this weekend. 

I’ll follow up soon with more pictures and impressions. I am very much looking forward to finally hearing these drivers at a decent height, AND WITH SEVERAL FEET OF STEREO SEPARATION!


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## Grinder (Dec 18, 2016)

lurch said:


> thanks for this and your other posts Grinder.
> i have on order a pair of the rf 8's to replace a pair of dayton reference 8's that
> i " thought " were blown. turns out the amp had a dirty switch and the the
> daytons are just fine.
> ...


On second thought…

I didn’t have any idea what “Dayton Reference 8s” are, so I looked them up, and comparing their specs I can tell you that they are nothing at all like PPS4-8s:

Dayton Audio RS225-4 8" Reference Woofer 4 Ohm
http://www.rockfordfosgate.com/supp...er/std_adp.php?p_faqid=1194&p_li=&p_topview=1

It seems to me that, given enough EQ or DSP, the RFs could be made to produce decent SQ (clean and flat), at the cost of reduced SPL potential (due to distortion), but I wouldn’t bother with any of that if I didn’t have to.

I was pretty much clueless of all this when I bought my RFs, and in hindsight I would (comparing their respective specs) MUCH rather have the Daytons.

I hope this helps.


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## lurch (Jan 20, 2014)

oh yes, they are two TOTALLY different beasties ! LOL !

the driver's side dayton definitely has a rattle, that's from me being an animal
with the volume and the loudness and the low xover point i experimented with
a few weeks back. 
so the RFs are going to get a try. 
i've just realized that the mounting holes differ, the dayton is a 6 point and the
RF is an eight point mount, looks like i have some modding to do to my adapter
rings. ( AAAUURGH ). 
weather is clearing up now, so pretty soon and i will give my impressions, most likely 
this week sometime. 

wish me luck …


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## Grinder (Dec 18, 2016)

lurch said:


> oh yes, they are two TOTALLY different beasties ! LOL !
> 
> the driver's side dayton definitely has a rattle, that's from me being an animal
> with the volume and the loudness and the low xover point i experimented with
> ...


I'm guessing that you've been happy enough with the Daytons, but given the rattle and sudden need for replacement, you decided to opt for drivers with higher sensitivity and power handling (for considerably higher SPL, you animal, LOL). And the RFs would seem to fit the bill. However, your mention of "the low x-over point" (how low, I wonder), and given the meager 1mm x-max and inherently weak bass/midbass response of the RFs, compared to the killer 6mm x-max and (very likely) much stronger bass/midbass response of the Daytons (and you're "being an animal with the volume") leads me to increasingly suspect that you'll be unsatisfied with the RFs (while you might be able to force enough bass/midbass from them, you won't nearly make the most of their clean SPL potential).

It seems to me that the natural/inherent frequency response of the RF is much more akin to what one would expect from a 4" or 5" midrange than a from an 8" midbass, and that the natural/inherent frequency response of the Dayton is akin to what one would expect from an 8" - 12" woofer (or kickass midbass).

In any case, I look forward to your feedback. And I wish you luck.


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## Grinder (Dec 18, 2016)

Finally finished Mom’s (living room) computer sound system today (bi-amped, 2.2 for HT and music). Still have a lot more critical listening and "stratoblasting" to do (and perhaps a bit more tweaking of the Crown), but so far, I’m very happy with the sound quality (and dynamic impact) of the system.

Onkyo TX-8160 receiver (Bass knob 0/10, Treble knob -6/10): 
(2) Rockford Fosgate PPS4-8 midbass (0.7 net cu. ft. sealed, fiberglass batting).
(2) Rockford Fosgate PP8-T tweeter.
(2) Rockford Fosgate PP4-X crossover (“-6dB ATT” setting).

Crown XLS 1002 amp (30Hz – 500Hz Bandpass setting, Gain 8/10):
(4) Skar Audio IX-8 D2 (each in 0.48 net cu. ft. sealed, fiberglass batting), with modified Kicker GR80 grill covers.
Wired in series for 8 Ohms/channel, then paralleled at 4 Ohms to bridged amp 

¾” MDF cabinets (9”W x 15”D x 33.25H) finished in Parts Express # 260-768 Speaker Cabinet Carpet (with 3M Super 77 Multipurpose Adhesive).
Dayton Audio Heavy Duty Binding Posts.
Sewell Silverback Performance Banana Plugs.
C&E 12AWG High Performance Speaker Wire.

I’ve been planning to build myself a pair of speakers just like these, but with another IX-8 on the bottom (for three IX-8s each), in a ported section of each enclosure (for my “computer sound”), but I’ll probably end up using the six IX-8s to build as many as three more car audio-based boomboxes - see: http://www.diymobileaudio.com/forum...sion/318938-my-car-audio-boombox-project.html - (and use one of these for my computer sound instead), with two IX-8s each (instead of just one), and save my other set of PPS4-8s, PP8-Ts and PP4-Xs to use as the top-end of a pair of PA/Mobile DJ speakers with 12” pro woofers, a pair of 15” ported sub cabs to go with them, and a couple Behringer iNukes (I keep dreaming…).


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## lurch (Jan 20, 2014)

those rockford horns are HUGE !!
any more progress with the tweaking ?
i would try the bass drivers in stereo, you may be surprised at how much separation 
there is in the freqs you are feeding them, like mid drum hits etc. 
( just a thought ...). 
i built a set similar to yours years ago except with 2 x 12's in each enclosure and
ported. LOVED THEM. ( so did the cops ....)
attached a pic. 

"I'm guessing that you've been happy enough with the Daytons, but given the rattle and sudden need for replacement, you decided to opt for drivers with higher sensitivity and power handling (for considerably higher SPL, you animal, LOL). And the RFs would seem to fit the bill. However, your mention of "the low x-over point" (how low, I wonder), and given the meager 1mm x-max and inherently weak bass/midbass response of the RFs, compared to the killer 6mm x-max and (very likely) much stronger bass/midbass response of the Daytons (and you're "being an animal with the volume") leads me to increasingly suspect that you'll be unsatisfied with the RFs (while you might be able to force enough bass/midbass from them, you won't nearly make the most of their clean SPL potential)."

you hit every nail squarely on the head. :laugh:


i did some frequencie generation tests today on that dayton. 
this was after giving the hp/lp switch on the amp a few clicks back & forth, thinking
it could be the issue. 
the dayton didnt miss a single step, even turned up very high at 50 hertz. 
i did find a nasty rear door rattle though, maybe that is fooling me into thinking
the speaker is toast, or that damned switch is acting up. ( likely ). 
as soon as I committed to swapping them out with the RFs it started to rain again so the
daytons stay for now, especially since the rattle seems to have completely vanished.


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## Grinder (Dec 18, 2016)

> those rockford horns are HUGE !!
> any more progress with the tweaking ?
> i would try the bass drivers in stereo, you may be surprised at how much separation
> there is in the freqs you are feeding them, like mid drum hits etc.
> ...


Yeah, they are ludicrously ginormous tweets (weighing in at 3+ lbs. each); they could easily keep up with one or two more PPS 8s per channel! 

Done a bit more listening; turned the treble up one click (-4/10 instead of -6/10). The more I listen, the more I like, particularly the precise detail and realism of the highs and mids; and I seriously doubt many 4" or 5" drivers (re-thinking my earlier comparison) have the kind of punchy attack that I'm hearing from the PPSs. And crossing the IX-8s way up at 500Hz seems to more than adequately make up for the PPS's shortcomings, while the PPSs seemingly add newfound punch and detail to the IXs. The Crown probably deserves a lot of the credit for this - and two coupled pairs of IX-8's are soooo much more powerful (and seemingly effortless) than just one IX-8.

Great suggestion, however the Onkyo has mono sub-out. And one of the main reasons I chose this particular receiver was because it has "Zone 2" outputs (which I was led to believe were pre-outs. Sadly, one man's "pre-out" = another man's "line-out"), and it turns out that their volume is not controlled. So, yeah, I was planning on running the IX's in stereo (and I had no idea I'd be crossing them way up at 500Hz. With one R500X1D per channel, 250Hz would have been the highest setting, and with 8" midbass I thought I might be crossing them as low as 80Hz; and I nonetheless wanted them in stereo. 

Nice speakers (they're monsters!)! Do you still have them? Were both 12s ported (or just one)? I've been too scared to go ported. From the utter lack of consensus in opinions about them, I'm afraid they'll be too peaky/muddy/boomy for me. But as I mentioned in my last post, I'd like to try adding a ported IX-8 to the bottom of a pair of speakers just like my mom's. Any thoughts on that? 




> you hit every nail squarely on the head.


Thanks for that (was hoping I wasn't "talking out of school").




> i did some frequencie generation tests today on that dayton.
> this was after giving the hp/lp switch on the amp a few clicks back & forth, thinking
> it could be the issue.
> the dayton didnt miss a single step, even turned up very high at 50 hertz.
> ...


Great news!! 

And if it turns out that the PPSs aren't right for your car, here's hoping you'll like them well enough to use them for another project (like another pair of towers?? LOL).


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## lurch (Jan 20, 2014)

those monsters were built in the mid 80's, before computers were readily accessible 
and when radio shack was still around ( i miss radio shack ). 
I had built many speakers before these, most turned out ok. 
i was NOT impressed with much on the market that was affordable. 
The best book i ever bought was " the loudspeaker cook book ", i wore it out. 
Anyways, i ran them up untill i had to move , 15 years ago, that's when they went
into storage because i ended up in a building for persons with disabilities. 
Imagine trundling those into a small apartment with old folks around ! ?
Sold them to a pair of young men about 6 months ago for 200 bucks. 
They are painfully missed. 

Your statement about " effortless " sound is definitely true, more cone area rules. 

as for porting :
i say try it !
be sure to choose a pipe size so that caps are availlable for that size. 
if you don't like the results just cap them off from the inside, no one but you will ever
know. 
i would also port the entire enclosure, not just one driver, this will make the target
frequencey easier to hit and all that nice juicy air inside gets used to the full benefit. 

today could be a decent weather day, i may just get out and see if i can install the RFs
without too much modification, if the mods are extensive i'll need to wait for a longer
warmer summer day.


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## Grinder (Dec 18, 2016)

Wondering how your Monsters' foam surrounds held up. I’ve never seen any that lasted more than 20 yrs., but I’ll still buy them. Finally got around to replacing the one in my ‘96 PS-1200 last year (it disintegrated in about 18 years). It's why those cloth surrounds on the PPSs seemed so attractive, but in hindsight I might rather have foam surrounds (with decent x-max, etc.). 

Speaking of the PPSs (and the PP-Ts), having done a bit more critical listening, the honeymoon is over. The fact is, these will never be quite right without DSP (or the like). Precise detail is very nice, but the lack of tonal balance can sound cold (PPS) and harsh (PPT). And the IXs have their own problems without having to make up for the PPS lack of midbass. What these (and the IXs) need is to have their response peaks brought down, rather than adding bass knob and/or raising the IXs LP, and turning down the treble knob (duh!). However, I just realized (duh again!), since the audio signal is coming from the PC (HDMI to TV to optical to receiver), I should use a PC-based DSP, like “VST Host” and “Plug-ins” (I need to go back and study my http://www.diymobileaudio.com/forum...2482-need-little-help-diy-computer-sound.html thread! I’m still on the bottom of a very steep learning curve). Speaking of books, I recently purchased “HI-FI Loudspeakers and Enclosures,” by Abraham B. Cohen, on high recommendation (though I’ve yet to read more than a few pages).

I’ve always been fascinated with speakers. As a kid, I’d managed to get my hands on a several 2” – 5” drivers from radios and the like, and in my own way I learned quite a bit about IB/free-air speaker placement, and audible effects of series and parallel wiring. But until recently I’ve rarely had the necessary combination of free-time, tools, workspace and resources to pursue my DIY audio inclinations much further than several crude $0.0 salvage-audio projects, and one under-$200-but-bangin’ car stereo in ’87.

And yeah, bummer about Radio Shack (and having to sell your dear old friends). Back in the day, they had all the bits and pieces.... Btw, that’s where I bought my one and only pair of store-bought home speakers in ‘85. They were Realistic (of course), with 12” woofers, and the (3”?) mid. was isolated by a plastic tube that was open to the rear of the cabinet. They weren’t horrible, but pretty boomy, and a couple years later I traded them (plus $50) for a pair of little satellites my Audiophile friend had made (each with two 4” full-range, an 8” passive, and a piezo), following a side-by-side audition. Needed a bit of bass EQ, but I loved them (until their foam surrounds began disintegrating in the early ‘00s), and they remained my mains until ’93, when I purchased the horns I’ve been using ever since (designed and built by that same Audiophile friend, who had built them for his own use in ‘89). Btw, my friend threw some Eminence 12s in those Realistics, and he’s used them for bedroom sound ever since. 

As for porting, my idea (flawed as it might be) was to try and have the best of both worlds (assuming, right or wrong, that there are “two worlds”): tight, punchy bass of small sealed (two IX-8s/channel), with the efficiency and effective low extension of ported (one IX-8/channel). Even so, I’m afraid I’ll end up with boomy bass, when what I want most is tight, crisp bass and drums, with the kick-drum bringing that sharp thump to the chest. Deep bass is very nice, but definitely not at the risk of degrading the rest. And then there’s the number crunching (modeling, tuning frequencies, etc.), of which I’m totally clueless… Of course, I’m certainly open to any ideas and/or assistance. And thanks for the great tip about internal port caps, and “no one will ever know the difference.” I love it! 

Wishing you luck with getting the RFs installed (and hoping you have DSP, or some other means of smoothing their response).


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## lurch (Jan 20, 2014)

hhhmmmmm.......
maybe i'll hold off till the alpine h800 processor is installed. THANKS, you have given
me great and needed info. 

as for the idea of ported mixed with sealed :
the first iteration of the monsters were exactly that, sheeesh, so long ago. 
the bottom 12" was an audiosphere accoustic suspension woofer, so it was in its own
sealed space, the top 12" was an awesome phillips driver that was good for either, so
it got the top portion of the air, ported. 
the sound was remarkably good. 
one day my kids got a hold of my microphone and pointed at a speaker when the amp
was turned up, the surrounds of all the woofers vaporized!!
by the time i got there it was all over. 
OK ..... so i bought four more 12"s, I don't remember what they were. 
opened the lower sealed compartment and retuned. 
i have to say that i was happier with the results, they certainly gained efficiency and
the amp was happier. ( big integrated from yamaha, 200 watt per/ch @ 4 ohms, i still
have that, never letting it go ). 
by running two different alignments on one amp at high power levels the impedance
differences can make an amp run hot, funny things can happen. 
when the ported alignment is fighting with the sealed alignment at resonance the amp
" can " struggle. 
i'm no expert and could be wrong about this though. 
in my case running the same alignment throughout i noticed that the yammy ran
cooler , also seemed to gain a LOT of headroom. 
did quite a few dances and discos with those speakers and amp. 
they could fill a hall, but in a house basement they kicked ass.


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## Grinder (Dec 18, 2016)

Thanks, I'm very happy to help! I rarely have useful feedback to contribute here, so it feels really good to hear that.

And thanks for the additional porting feedback, it makes a lot of sense. 

Which reminds me: It seems to me that I _*might*_ know a very tiny bit about "reactance" (*don't quote me on any of this, as I'm in waaaaaay over my head*), involving (among other things) the reverse flow of current from an AC inductive load, which (in terms of a transducer-amplifier relationship - perhaps) amounts to damping, and (if I'm not once again mistaken) might explain the extra amplifier heat and reduced headroom. Also, it would seem to not only be a lot to ask of an amp to run (and provide damping for?) two different alignments, but there would be no easy way to address the output disparity between those two alignments (though there would have been for that reason, a 2:1 ratio of sealed to ported and a separate amplifier in my case), and there would seem to be no practical way to smooth the response of one alignment without adversely affecting the response of the other.

So, in light of all of this, I'd like to give ported a try (not a sealed-ported hybrid, mind you...). I'd like to start by trying it out on my "car audio test rig" and go from there. I think I might be able to just seal off the amp/HU compartment (to more than adequately increase the .6 cube sub chamber volume to the recommended .75 + port & driver displacement) and add a port. I wonder if it could be tuned to go low enough to prevent decoupling (and the need for some sort of high-pass filter), while not adversely affecting the kind of SQ I desire?

Also, I forgot to mention in my last post that I'll need to go from the PC 3.5mm audio outputs to the amps (no more HDMI to TV, etc.). I'm hoping that the PC DSP software will allow me assign the 3.5mm outputs so that I'll have *separate stereo* outputs for each amp, which would allow me to DSP the subs and the mid-tweets separately, *and* be able to run the subs in stereo. 

Wish me luck, 'cause I think I'm really going to need it.


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## lurch (Jan 20, 2014)

yup to all. 

and you are dealing with a different breed of woofers : long stroke, low efficiency, power
hungry little beasts. 
the back EMF from all that wire in those coils and motor strength will be on a totally
different level. 

as for all the pc 3.5mm to gawd knows what ..... i have NO CLUE .... LoL !!

if you need someone to do a box alignment on winisd just let me know. 
I'll of course need the speakers t/s parameters and box size etc.


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## Grinder (Dec 18, 2016)

"Back EMF..." Had to Google it (goes to show what little I know) LOL. It's a bit overwhelming at times, trying to absorb so much unfamiliar audio terminology, principals, phenomena, etc. It is all very interesting to me, and yet it often seems as if I'll never even learn the basics. I'm getting there, though; thanks to the kindness and patience of folks like yourself.

And thank you so much for offering to help with my cabinet design. 

Here are the driver specs (per Skar Audio IX-8D4 Spec Sheet):

Re 6.4 Ohms
Fs 51.3 Hz
200 W RMS
Qms 4.29
Qes 0.75
Qts 0.64
Xmax 6 mm (one way)
Md 70.4 g
Sens. 83.2 dB
Rms 5.3 Kg/s
Cms 0.14 mm/N
Bl 13.8
Vas 7.8 dm3

"Recommended Enclosure Volume": 

19L sealed (0.67 cu. ft.) 
32L ported (1.13 cu. ft. - not 0.75 cu. ft., as I indicated earlier, per erroneous website specs pertaining to earlier 150/300 Watt version)
No port area or length is listed.

The increased volume of my test rig would be 1.06 cu. ft. (minus .017 cubes driver displacement, and .xx cubes port volume - but for testing purposes, I don't know why I couldn't install the port outside the cabinet, preserving all of the 1.06 gross cubes) 



I'd be just as interested in knowing how the IX-8s in my mom's cabs perform "on paper" in their present configuration/environment (alignment?).

Here are those earlier version's specs (per earlier version Skar Audio IX-8D2 Spec Sheet):

150 W RMS
Re 2*1.8 Ohms
Vas 9.6 L
Fs 45 Hz
Bl 10
Qms 4.8
Qts 0.64
Qes 0.74
n 0.12 %
Sens. 82.6 dB

Just noticed Xmax and a few other specs aren't listed on this spec sheet, but perhaps the ones on their website will fill in those gaps closely enough: https://www.skaraudio.com/products/ix-8?variant=17677557121

In Mom's cabs, they're each in 0.48 net. cu. ft. sealed (0.45 cubes sealed/0.75 ported, recommended per website specs).


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## lurch (Jan 20, 2014)

ok, so mom's cabinettes definitely do NOT get ported, they are already a bit tight. 
buut i will do a graph for you with the specs provided. don't expect it to be too exciting,
it may have a bump ( it WILL have a bump ) through 60-80 hz which i'm sure you can
already hear. nothing wrong with that, makes for punchy sound. 
me thinks an experiment with polyfill is in order ....

the alignment for your test rig is also a little tight, it will require a long wide tube that
will take up a ton of room if you decide to install it inside, which in the end would not
be worth the space, as you already figured out. 
i will model it anyways and also do another with an external port. 
will also do an optimal model, let's see just what they really want. 

by glancing at the specs i would say that these woofers prefer a sealed box anyways.
i could be dead wrong though. 

gimme a couple of days, i have a nutso weekend starting in a few hours. 

UNLESS some one else wants to step in here ?
i do have a computer but it is not online, any graphs i submit will be crappy phone 
pics of my computer screen


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## Grinder (Dec 18, 2016)

Yeah, knew mom's are way too small to port. Besides, she doesn't want or need them any louder or lower (the house is rattling enough already - especially with a 40Hz test tone!). All things considered, I'm quite impressed with how they're performing. But I would like to know how they look on paper, as a reality check (don't be afraid to burst my bubble), and to help guide me in dialing them in with DSP. 

They've each got one layer of R20 fiberglass on the rear panels (7.5" x 8.5" - their volume is 13.5" deep), so they're far from "stuffed. No idea if they'd do better or not with more. Initially had a lot more in the boombox (with the one 200 W version D2 I have). And then I removed most of it and it _seemed_ as if it might have sounded better (at whatever LP it was, and whatever HP for the Polks...); and that was when it was still powered by two bridged channels of the R400-4D. I like it a lot better with the R500X1D, and perhaps it could use a lot more stuffing in its 0.47 net cubes. 

Btw, the PPSs have about 80% of their 0.71 cubes more or less loosely filled with R20 fiberglass

Wondering how you'd compare fiberglass with polyfill.

Got no problem with external port for testing purposes (and for computer sound duty until I build something else). Will be interesting to see what internal and (especially) optimal would look like as well. 

Would ported want or need any fiberglass or polyfill (I assume not, but...)?

Take your time, I'm in no big rush.

I'm sure your screen shots will be fine.

Thanks again, Bro!


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## Grinder (Dec 18, 2016)

Btw, I keep forgetting to mention the ridiculously small push-type speaker terminals on (both pairs of my) PPSs. I had to trim-down 12 gauge speaker wire by more than 50% to make it fit (and I'd be surprised if anything over 18 gauge would fit without trimming)! And they're less than half the size of the ones on PPTs, _which are rated at less than half the power!_ What were they thinking??? For me, it really calls into question RFs design goals and/or commitment to customer satisfaction.


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## lurch (Jan 20, 2014)

ok, we are about to get a bunch of pictur graphs, hang on while i sort this all out.


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## lurch (Jan 20, 2014)

main pic pic ill explain in a few minutes


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## lurch (Jan 20, 2014)

second main pic showing tuning arrangements


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## lurch (Jan 20, 2014)

well, theyre upside down dammit. 

dunno how to fix that ....

ANYWAYS

it turns out that the enclosures used for mom's are as good as it gets. 
this driver dorsnt seem to mind what size sealed it's in, within reason, but
the size you chose is optimal. 

on to ported :
surprising. 
this likes small ported boxes. 
green line is 1 cuft / 3" tube, 9.5" long / tuning = 40 hz. 
red line is .45 cuft ( ! ) / 3" tube , 15.3" long / tuning = 48.6 hz. 

if you want to port your experimental you would have no issues and lots of room
for that port. the FR would look similar to the green trace. 

i chose 3" pipe for all alignments knowing that caps are easily available at any hardware
store. 

i had a much more elegant description of what to see in the graphs but it was 
wiped out when i started to upload the pics, so sorry if im vague at the moment,
my head is tired ......


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## Grinder (Dec 18, 2016)

Wow, thank you so much! 

Still some questions, but they'll wait (and I'll see what I can learn on the interwebs). Might get started reworking the test rig today (very exciting!). That green line looks quite nice, especially if those blue and yellow lines represent sealed. I mean, WOW!!! The difference should be AMAZING (and I probably shouldn't be wondering about tuning them any lower than 40Hz. Thoughts?).

Good to hear about Mom's cabs. Tripled the fiberglass (nearly filled now) while re-wiring them from 8 Ohms/channel (for 4 Ohms at bridged Crown), to 2 Ohms/channel (in preparation for near-future stereo output via PC + "miniDSP 2X4"). Also, crossing them at 75 (instead of 500, LOL), and back to +2 clicks of bass knob on receiver, and it's sounding a bit better - always a tradeoff between adding IX midbass (with accompanying muddy-boomy bass), and tighter, flatter IX response (with too little midbass punch to make up for the RFs), so I'm very much looking forward to DSP (to smooth and stereo the IXs, and to smooth and high-pass the RFs).


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## Grinder (Dec 18, 2016)

Shall I assume that at 3" (3" PVC) I won't need flared ends? And if that were the case, might I opt for a 2" flared port like this? Precision Port 2" Flared Speaker Cabinet Port Tube Kit

According to their calculator Products Menu for a 40Hz tune in a 1 cube box, a 2" dia. port would be 4.8" long, whereas a 3" port would be 10.7" long (including flare length), and shorter would be better for the test rig (and for my next car audio-based boombox project). But might the velocity be too high (or other downsides?)?

Also (FWIW), I could easily add a slot port to the test rig (9" wide x 0.79" (?) x 9.75 long) instead of simply closing off the rear opening of the HU/amp/power supply compartment, by adding wood along each side (and along the bottom edge) of the opening (and fore/aft along the top of the cabinet, all at the theoretical 0.79" dimension), with a panel over the top (and another panel to close off the back), forming a slot port along the top of the cabinet, with its opening at the front (just above the old HU opening).


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## lurch (Jan 20, 2014)

HEY, finally got the time to respond. 

yeah, that green line @ 40hz is as far as you can go without making that graph
start to look ugly, and it has a very steep drop. 
i would recommend aiming for a touch higher, say 42-ish. 
the air space you have there ( approx 1cuft ) turns out to be the sweet spot, as it 
gets larger the graph again starts to get a dip at the mid lows, then a nasty spike
at resonance with a significant group delay. 
the 3" pipe had a low mach number , around 0.06 i seem to recall ?
so a 2" should be more than ok, i can model that tonight if you want. 
can you find a 2.5" tube instead ?
in either case a subsonic or high pass should be used, a good starting point
is probably 35hz. 

personally i like to use tubes. 
i will start off with a longer than modelled pipe and experiment for a while
until i hit the sweet spot. vents are not so forgiving, can be a bit of work
if we get them wrong, but in your case it may not be a big issue since 
there is a lot of wiggle room with the air space you have, and it only makes
the enclosure stronger. 

anyways, it's all worth a try, there is a ton of available output there.


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## Grinder (Dec 18, 2016)

Great stuff!!! Thank you!!!

Tube would be easier to install, and certainly much easier to adjust, though I have no idea how I would fine-tune the length. By ear? If so, I'm wary of my psychoacoustics. Any ideas? And do you start long (how much longer?) and then keep cutting bits off (what length of increments would you advise?) until it's right. And does it need to be tightly sealed (or just a snug slip-fit) each time it's re-installed for a demo? I'm guessing I'll have to buy a full length of some kind (10' or more), in which case I suppose I could cut a number of different lengths within a certain range (at certain increments, like 1/4" or 1/2" or?) and try them all to find which length is best. Considering the purchase of a "UMIK-1" https://www.minidsp.com/products/acoustic-measurement/umik-1 with the miniDSP 2x4 (or 2x4 HD), and I'm wondering if this might also assist in dialing-in port length.

What about flared ports? Would they likely make any worthwhile difference for, 3" or 2.5" or 2" (in terms of port noise, turbulence and/or performance)?

If flares would make no difference with 2.5" PVC (2.47 I.D.), according to that calculator, 1 cube at 42Hz with 2.47" port = 6.51" "flare length port" (and I think a non-flared length would be slightly shorter), which would work perfectly for the test rig, allowing me to install it horizontally in the added chamber, with the opening centered between the sub and the top of the cabinet, with almost 3.5" of clearance between the added rear panel and the inside opening of the port. If you're up for modeling it (I don't mean up all night, but whenever you have the time), that would be great! 

Sorry about all of the questions (what can I say, I'm a hopelessly perfectionist Noob!).


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## lurch (Jan 20, 2014)

that's perfect !

here is my graph :
top yellow line 
mach 0.09
f3 = 35 hz
vent length = 5.37" ( no flare )

i don't see the need for a flare here. 
the velocity is not even close to being a problem so turbulence won't 
be audible. 

what i do for experintation is seal up the pipe as best i can. 
listen, retry ....etc. 
it doesn't have to be loud for you to know if you have found the 
right tune anyways. 

as for the amount to chop off at a time :
it depends on the enclosure, small boxes are more sensitive so small amounts
at a time. 
large boxes are not sensitive to a change in length, so larger chunks can
be hacked off. 
this depends on the size of the pipe in all cases though


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## Grinder (Dec 18, 2016)

Sweet! Thank you!!!


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## lurch (Jan 20, 2014)

added to the last post. 
just wanted to get that pic on there RIGHT SIDE UP ?


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## Grinder (Dec 18, 2016)

Thank you for all that! You're the best!

One more thing: How do you "know if you have found the right tune?" This really is a complete mystery to me.


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## lurch (Jan 20, 2014)

GOOD question. 

it's usually when i come across a song that doesn't sound " right ". 
an expert with the right tools would use an RTA though. 
i used to have that equipment but it's all gone now. 

with music you just " know " , something's not there, or it sounds wrong or
awful etc. 

btw : don't be afraid to cross these woofers another octave higher than 75, they
should be quite happy upwards of 150. 
find their happy place !


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## Grinder (Dec 18, 2016)

Got it!

And I think the miniDSP + UMIK-1 = RTA (more or less. Just googled "RTA," LOL!).

As for crossing the IXs, I know exactly what you mean. It's just that they seem to be rather peaky somewhere in that range (maybe room gain?). But yeah, they're otherwise real good for adding some nice punchy midbass. It will be very interesting to see where the crossing for Mom's IXs and RFs settle out when I get them dialed in with the miniDSP and UMIK-1 (which I have pretty much decided to go ahead and order tomorrow). They're really worth a look if you're not familiar with them. At $105 + $70 (plus $10 for "plug-in" software), it's a very powerful package! https://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4

Thank you so much for all your help!!!!! 

I'll keep updating here as progress would warrant.


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## Grinder (Dec 18, 2016)

BTW, in case anyone's wondering why I'm planning on purchasing a hardware-based solution (miniDSP 2x4) for issues that could be addressed with a free-software-based solution (such as VST host and plugins), the reason is that the Inspiron 3656 (a grossly overpriced, lackluster and disappointing POS, compared to my 1 year newer and only $100 dearer XPS 8700) has headphone output only (not the utterly ubiquitous 5.1 or 7.1 outputs that have been on lots of even lesser PCs for many years), in which case the miniDSP will split that one stereo output into four separately processed outputs (one pair for the subs, and one pair for the mids-highs), whereas my XPS 8700 has 5.1 outputs which (I am led to believe) can be controlled by VST host and plugins, allowing up to five separately processed channels. 

Of course, the 3656s many shortcomings are all my own fault (for having been so clueless as to simply stroll into Best Buy and... well, you get the picture). :blush:


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## Grinder (Dec 18, 2016)

Ordered a miniDSP 2x4, Advanced 2x4 plugin, and UMIK-1 for Mom's system a couple days ago, though I had no idea they'd be coming all the way from Hong Kong, with an expected delivery date of 5/4/17 (#@%!). In the meantime, I'll keep trying to learn what I need to know about VST host and plugins to process my computer sound, but given my efforts so far (and an evident lack of computer savvy), and what little progress I've made, I might soon be buying another miniDSP 2x4.

As you can see in the pictures below, I managed to modify my test rig and get a port installed over the last few days (and it looks so much nicer without the rat’s nest). Because repurposing is good fun, I simply cut off the wider end of a slightly tapered shop-vac extension tube (8.75" long, and 2.315" I.D. at the wide end, and 2.125" I.D. at the narrow end) Now, following a process of trimming and listening a few times it's down to 4.5" (and 2.25" I. D. at the narrow end) though I think I liked it better at 5," but it's really hard to say, partly because of its far from optimal location and listening area - but in any case it doesn't really matter at this point because, due to loud port noise, I'm going to have to try 3" PVC (2.5" PVC would have been too noisy as well) and hope for the best (bearing in mind that the Skar website IX-8 enclosure specs recommend 13 sq. in. port area, which equates to a slightly larger than 4” diameter tube). At its present diameter, I can at times (with lower notes) feel a startlingly strong blast of air from about 6 feet away (very refreshing!).

As for first impressions (so far - haven’t done a whole lot of listening yet), I am very, well… impressed! I had no doubt that there would be a significant increase in efficiency (and SPL), but I am really amazed at the difference. As for SQ (so far), I’m not quite so impressed. It definitely seems to go audibly lower, and that is nice. It also seems much more effortless, and the bass drum has a lot more punch (both of which are very, very nice). On the other hand, newfound (and rather unwelcome) droning boominess overshadows its former reasonably tight midbass. It is now surprisingly punchy and tight near the low end of its range (where the port seems most active), but much of the rest of its range seems to lack definition, as if it's all been overshadowed by a droning resonance, wherein notes of this range seem to sort of blend together, which is all the more surprising and disheartening, given the fact that the R500X1D is set to low pass 50Hz (setting it higher only makes all of this worse). I think it might have sounded somewhat better in this regard while I still had the upper chamber (the added cabinet volume) mostly filled with fiberglass (apart from a clear area between the sub and the port), which I ended up removing early on, due to worries of blowing itchy pink stuff all over the place (having been very surprised at the volume and velocity of air movement). The original sub cabinet volume remains filled with fiberglass, apart from the area between the upper portion of the sub and the port. 

I’m not sure what to make of all this, but I’m certainly not going to give up on ported, though I remain doubtful that I’ll ever like ported as much as sealed (other than for applications in which amp power and cone area are at major odds with design criteria). And lastly, while I expected (and was quite concerned about) decoupling (uncontrolled excursion) at lower frequencies, that hasn’t happened so far (and I wonder why… Could it be a clue of some sort?).

Anyway, I’ll follow-up with impressions after I get a 3” port installed. 

Any comments or suggestions?


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## lurch (Jan 20, 2014)

take ALL the fibreglass out of there, ALL of it !!
before you know it the whole house will be coughing. 
go and buy a bag of sheet poly fill and staple it to the walls, about an
inch thick on each side will help a lot. 
this is the poly that comes rolled up in a sheet, very easy to deal with and
it doesn't come spewing out of the port. every sewing shop sells it. 

WINISD said that a 2" port would be very close to mach 1, that's why i didn't
post or bother with that graph, it was deleted right away. 
the point at which a port gets noisy is .16 mach. 
i'll bring up the 2" inch graph again, just to see where your tuning point
is right now, i have the feeling it's WAAAAY too low, probably down around
30 hz. 

there is nothing wrong with using elbows in ported enclosures if needed. 
i could do a model with a 3" pipe tonight if you want. 
actually, i can do any size you want. 
a three inch doesn't take up a ton of room with the elbow diameters, 
a handy size if space is limited. 

are you using the bass boost on the RF amp ???
turn it off if so. 

you will LOVE the mini dsp. 
worth waiting for, very intuitive interface, nothing head scratching about it. 
you do have to send an email to them to authorize the software, that's the
only thing that stumped me at first.


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## lurch (Jan 20, 2014)

ok
orange graph is where you are now. 
the mach number = .15 !
and you are tuned way down at 37 hz. 

red line is the 3" tube, 9.5" long, tuning freq of 40 hz. 
but i would recommend a higher tune of 42. 
which results in a length of 8.4".


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## Grinder (Dec 18, 2016)

Thanks a lot for the heads-up on the fiberglass; I should know better. :blush:
There's a little sewing shop in town, so on Monday I'll get me some of that poly stuff (for quilts, I suppose).

Thanks for the tuning feedback and research! 

Just to explain myself (not at all to contradict you): I used this port length calculator to figure the length of my shop-vac tube: Port Length Calculator 
vol. 1.04 cu. ft., tuning Hz 42, port dia. 2.25" = port length 4.19" (41Hz = port length 4.48").

Also, in the process of using that calculator, it seems that small variations in box volume have a pretty large affect on port length, and I'm having doubts about how correct my 1.04 volume is (there are some difficult-to-accurately-account-for recesses and protrusions going on in the added space; and then there's the cut-out piece - I don't think I accounted for that added volume, and if I did, it would be too much, as for various reasons I was only able to remove a 6" square portion of the panel's center, possibly contributing to turbulence, and making it all the more potentially problematic to have the inner port opening much more than halfway within the 9" deep added space), and about accounting for varying port displacement (and my own confidence-killing psychoacoustics).

Yeah, *no evil bass boost over here, Boss! *LOL Great tip nonetheless!

Thanks for the feedback on the miniDSP. I can't wait (so to speak)!

And thanks for the new graph! Looks great! I'm really looking forward to trying the 8.4" x 3" tube (I'll probably start a little longer and go down from there). I assume I'll need to keep the port opening at least one port diameter away from interior surfaces. I'll just let the port stick out a few (or several) inches if necessary, in lieu of an elbow (it won't be in the way, and looks aren't an issue with the test rig). 

I'll probably be going ported on my next boombox project (coming soon), as it will be hard to pass up that kind of output and extension from just one IX-8 (versus two of them sealed within the same net volume. Hmmm... that would be a very interesting side-by-side comparison).

Still pretty blown away by Mom's speakers, particularly those four IX-8s (if only I could fit - and power and lift - that many in one of my boomboxes...).


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## Grinder (Dec 18, 2016)

Out of curiosity, I tried to identify present tuning frequency and decoupling propensity by observing excursion while running a 25Hz - 150Hz sweep at moderate volume; and while I was unable to pin down tuning frequency, it seems that I could have quite easily induced uncontrolled excursion somewhere into the 30s. 

Wish I had an inexpensive high pass for the test rig (at least until I can manage to get VST host and plugins or a miniDSP of my own), and for ported boomboxes. Do you think something like this would do the trick (and would 30 Hz be right? And might these adversely affect performance?)? https://www.amazon.com/gp/product/B0006N41CO/ref=s9_dcacsd_dcoop_bw_c_x_5_w

Do you know of any decent cost-effective options? $37 might be a relatively cheap solution, but it seems like a lot to pay for such a tiny (and seemingly incidental) component - and it just so happens that the 30 Hz ones are among the most expensive of their product line?

Picked up 4' of 3" sch. 40 PVC and a 3.5" hole saw, today (but I forgot to get polyfill). I plan to git 'er done tomorrow.


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## lurch (Jan 20, 2014)

download a free frequencey generator app. 
if you have an iphone or tablet i like to use this : AudioSigGen. 
don't get nutso on the volume, sine wave creates lotsa heat. 
( i know you already know this )

and for a high pass or subsonic : the minidsp does that. 
oh.... wait, i thought you had ordered a mini already ?

there are some threads here regarding the FMODs , but i have never used them. 

looking forward to see how this all turns out !


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## Grinder (Dec 18, 2016)

No iPhone or tablet. Used ones from Sonic Electronics on YouTube.
Yeah, thanks! Sine waves are _relentless_.

The miniDSP won't be here for another month, and it's earmarked for Mom's system. I'll have to order another one for me if I can't manage VST blah, blah, blah, but maybe I should just forget VST and order another miniDSP (though I hate to spend any more money than I have to).

Just found FMODs at PE for $26/pair ($12 cheaper). *Does 30 Hz seem right for a 42 Hz tune? * I need something like this for boomboxes.


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## lurch (Jan 20, 2014)

doesn't the 5001D have a sub sonic ??
i can't keep up anymore, LoL !


look up " frequencey generator "
these let you stop at particular frequencies instead of sweeping through. 

heads up : ive only seen the minidsp used with apple. 
not sure if it's compatible with windowz ?


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## Grinder (Dec 18, 2016)

Unfortunately, no, those amps don't; but you can bet that any of my future amps that might be used for ported will have them!

And thanks for the heads-up, but PC is a go.

Nice tip! I'll look for frequency generators.

What Hz SSF would you recommend for 42 Hz tune?


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## Grinder (Dec 18, 2016)

This one is pretty sweet (if anyone else is looking for an online frequency generator): Online Tone Generator - generate pure tones of any frequency


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## lurch (Jan 20, 2014)

general consensus is to SSF at one octave below tuning, but in this case i think that 
is too low. ( 21hz ). 
30 is a good starting point, 35 is probably better. 
the -3db point with this alignment = 35hz, so that's where i would start. 
your ears and eyes will be a better judge though. 

i sure hope this is all helping. 
nobody else seems to be chiming in and i could be wrong on numerous issues in this
thread.


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## Grinder (Dec 18, 2016)

Thanks! Funny, but I was looking for a 35 FMOD, but it seems their choices are only in multiples of ten.

Your feedback throughout this thread has been _extremely_ helpful. Invaluable even, _particularly in the absence of others chiming in on this thread_. Indeed, I'd have been clueless on most of this stuff without your help (and that of other kind folks on this forum). 

I really appreciate your candor, and I completely understand your reticence. Nobody's perfect, but you're doing the best that you can to help, and I very much appreciate that. If I've learned anything about audio over the years, it's that it is as much an art as it is a science, because in the end there is nothing quite like trial and error.


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## Grinder (Dec 18, 2016)

Finally got it done!

I removed the rest of the fiberglass, managed to hole saw a 3.5" hole over the top of the old one, stapled 2" of polyfill on L/R sides and top of the upper cabinet, and very lightly stuffed about as much as would fit in the lower cabinet, while leaving plenty of open space between the sub and port, and then installed a 10" length of 3" PVC (spaced 3.25" off of the rear panel), after adding one wrap of electrical tape to slightly increase the O. D. for a sealed-tight fit.

Then I used the on-line frequency generator (thanks a lot for the tip!!!) at moderate volume, while watching and listening for minimal excursion at peak volume and port action, which seemed to be in the 37Hz - 39Hz range. 

So I cut the port down to 8.5" and repeated the test. Now it seems to be in the 40Hz - 42Hz range (however, I didn't spend a lot of time on these tests, because it seemed to be a lot like guesswork, and I wanted to move on to music, so I'm not at all confident in the accuracy of those numbers). Also, while using the frequency generator, I was not at all surprised to hear some lingering port noise, considering how very bad it was with the 2.3” port. And in the brief time I’ve had with it so far, I've heard a bit of port noise with music, albeit while auditioning a track on the Techmaster P.E.B. “Bass Computer” CD (a cheesy bass-music CD) at moderate volume.

BREAKING NEWS: Doorbell just rang, and it was FedEx, delivering (a month early) the miniDSP 2x4 and UMIK1 I ordered for Mom's system on 3/30 (all the way from Hong Kong in less than a week! Really, I checked the shipping label). Also, I ordered another miniDSP for me (from Amazon/Madisound, to get it a lot sooner - I thought) on 4/4, which is scheduled to be here 4/10 – 4/13. All very exciting! 

I’ll have to wait ‘til I get my miniDSP working (for SSF function, at least) to confidently learn what this ported setup can really do, but so far I am very impressed. Played around with the R500s LPF a bit, and liked it best all the way up at 250Hz (obviously, the PPSs are largely to blame for this; and it's a testament to the vastly lower extension and steeper roll-off of ported).

I am very pleased with the results so far. Overall bass SQ (i.e. tightness, punch, musicality, minimal boominess) seems as good as sealed - with all of the added SPL and efficiency (truly amazing), improved frequency response/extension of ported. Very nice!

Thank you so much for all of your help with this! 

I’ll update soon, when I’ve had more time to form impressions and/or get the miniDSP dialed-in.


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## lurch (Jan 20, 2014)

AAAAAWERSOME !!!

yaaaaaaay !

ok, that's all i have to say .....


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## Grinder (Dec 18, 2016)

Got the miniDSP hooked up to Mom's system, but unfortunately, it’s going to take a while to come to grips with REW (so much for immediate gratification). To begin with, miniDSP tutorial’s “gated measurements” procedure is ludicrous, as it seems to require drivers to be measured individually (how the hell am I going to do that, with passives linking mids and tweets?), and while each is equidistant from the ceiling and floor (oh, lovely! What fun!), and presumably in the absence of any other nearby objects in the room …or, I can simply move everything outside (oh, boy! I can’t wait!). 

Guess I should have done a lot more homework on this, because it’s not exactly what I thought I was signing up for. Makes me wonder how the hell DSP is implemented in an automotive interior.

In any case, before diving head-first into REW (and letting all that processing power go to waste in the meantime), I thought I’d try my hand with the parametric equalizers, and it’s taken me the better part of two days to begin to get the hang of them; and in the process, I’ve managed to get Mom’s speakers sounding vastly better than ever (for the channel splitting, PEQ and crossovers alone, the miniDSP is worth every penny, which makes me all the more eager to hear the results of the whole shebang!).

Thought you might like to see what I’ve come up with so far:


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## lurch (Jan 20, 2014)

awesome !
just think about all that you have learned !
and don't worry too much about measuring, it's your system, make it sound
the way YOU want it to sound. 
there is SO much more to learn, it will take months, so relax and enjoy and learn. 

i certainly don't set my eq's or xovers to any predertimed " curve " , i set things
up so that i myself enjoy the sound. 

once you are comfortable and understand what all these adjustments do the
possibilities are endless. yes the first few days are frustrating because our heads
are overloaded, but it becomes pretty clear after a few sleeps, the puzzle comes
together. 

i say " WELL DONE ". 

wish i was there to see /hear those speakers perform.


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## Grinder (Dec 18, 2016)

Thanks, Bro!
:beerchug:

I really have learned a lot in the last few months, with many thanks to you and a number of other kind individuals on this forum. I tend to be a bit of a slow learner, (and I'm old enough to know better) but I'm still as impatient as ever. So, it's good to stop and look back once in a while, to see how far you've come, especially when you're feeling overwhelmed by how far you've yet to go.

Yeah, I dig what you're saying about setting EQ curves to taste. And I should trust my ears more than I do.

I'm hoping to be able to do time-alignment, and whatever else it takes to get good "imaging" and "soundstage." By way of comparison, I'd love to hear for myself what a good example of these sounds like.

I'll chime in again when I get the other miniDSP PEQ dialed in on the test rig (can't wait to hear what that ported sub can do).

Thanks again!


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## Grinder (Dec 18, 2016)

More amazement at the wonders of ported speakers:

Bought some cheap-o computer speakers from PE https://www.parts-express.com/sound-...-pair--319-128 to help a very elderly friend hear her TV (they'll sit on the table beside her, where she can control their volume as needed) and auditioned them today, out of curiosity, and to make sure they'll do the trick.

I am very impressed. For a $10 pair of powered speakers, they are pretty amazing. They have rear ports that wring considerable bass (particularly when I tried them on the floor, of course) from such small drivers and cabinets. On this frequency generator Online Tone Generator - generate pure tones of any frequency they blew amazingly strong down into the low 50s, with not much more than port noise into the 40s and 30s. F3 was probably up in the 100s, but still... No audible vibrations from their plastic cabinets, but there was some pretty nasty pot-noise while turning their volume knob. SQ isn't great, but it (and SPL) is much better than one would have a right to expect for $10.

Tuned ports are KEWL! 

PS: Got my miniDSP yesterday. Looking forward to manual PEQ tuning my test rig over the next few days.


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## Grinder (Dec 18, 2016)

I forgot to mention a noise issue I've had to contend with, first with Mom's setup, and then with my test rig. 

I'm not sure why, but adding the miniDSP seems to somehow amplify an inherent strange scratchy-static-hiss noise coming from both computers' audio outputs (and made all the more audible by those highly efficient RF drivers). 

Mom's system had been running HDMI from computer to TV, then Toslink from TV to receiver (and receiver mono sub-out to Crown amp). Noise (slight hiss) was quite minimal (especially when considering the efficiency of the RFs). However, when hooking up the miniDSP, I had to ditch the Toslink and go from the computer’s 3.5mm headphone jack, to the stereo RCA inputs of the miniDSP (and then from the four miniDSP output channels, to the receiver and Crown). And then I heard (much louder than the earlier “slight hiss”) that all-too-familiar (from earlier experience with my test rig) “inherent strange scratchy-static-hiss noise.”

I was really bummed for a few minutes, until I got the idea of hooking up a Fiio D3 DAC https://www.amazon.com/Digital-Cove...UTF8&qid=1492918834&sr=8-10&keywords=fiio+dac
that was lying around. Then I was able to ditch the 3.5mm computer headphone-to-RCA cable, and go back to using the Toslink (now from the TV to the DAC, and RCA from the DAC to the miniDSP).
The “inherent strange scratchy-static-hiss noise” is still there, but far less noticeable than it was without the DAC.



And it turned out to to be a very similar situation with my test rig (though I had hoped I’d have less noise, considering my XPS is a much better machine than the over-priced Inspiron I donated to Mom’s system). After I got my miniDSP hooked up, I had to order another DAC. And the results are pretty much the same (though there’s naturally more hiss from the RF amp, than from the Onkyo). 

However, the RF seems to be suffering from low voltage (12.2V from power supply) and/or low input level from computer-TV-DAC-miniDSP, as it takes a rather high (well past 50%) and noisy (excessive low/no-volume hiss) gain setting to get as loud (or maybe a bit louder?) as Mom’s setup (at 125W/channel RMS vs 80W/channel RMS).

On the other hand, that one ported IX-8 amazingly kept pace with those RFs. Very impressive!! Granted, it all depends on the music (if it were hip-hop/rap… fuhgeddaboudit. But for just about anything without particularly strong bass, no worries).

As for DSP on the sub, all I did was set its crossovers to 20Hz HP and 80Hz LP (still tweaking the RFs’ PEQ settings. And I’ve got their LP set at 100Hz, as they seemed to be struggling with the 80Hz setting). Its PEQ is flat for now, as it is much more to my liking as-is than sealed, though that is not to say that I am entirely happy with the sound; it’s just that, in the short time I’ve had to really play with it, I was more focused on getting the RFs dialed in (I was rather surprised by how much different identical RF PEQ settings sounded on my test rig vs Mom’s system – in the same room, and “ballpark” location). I’m pretty confident though, that I’ll be able to PEQ the ported sub to my satisfaction (which I hope to be able to begin to do in the next week or so).


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## lurch (Jan 20, 2014)

UPDATE !

been noticing the left dayton distorting again, particularly on modern jazz tracks. 
one day the " blown coil " sound is there, the next day it is not. like... WTF ?

got fed up with it today and pulled them, the RF's went in. 
turned on the power..... blown coil noise IS STILL THERE !!! 
AAAAAAK. 
ok, investigate :
check all speaker connections and wiggle everything in sight. all AOK
do impedance check on wires with DMM. all AOK. 
check all rca connections .. all AOK. 

give old alpine MRP - F550 a good wack with a pair of pliers. distortion GONE, 
system plays very clean. 
dammit .... looks like my nice old amp is losing the solder joints. ****. 

anyways 
wish i had done the swap a long time ago, my system sounds incredible now. 
the stage burst into life, the clarity is awesome, it all sounds " effortless " .
i didn't touch the output levels or the EQ. 
i DID change the xover points. 
high pass now = 71hz @ 12db. 
low pass = 3k @ 12db. 
they didn't much like being under 70hz, the daytons would go as low as 40 if i asked
politely. this is no biggy anyways cuz my doors weren't doing much below 100hz. 

i am THRILLED with the sound of these RF's. 
they easily keep up with my sub, and are surprisingly smooth. 
my doors are actually producing bass now, something they have not done through
four different sets of woofers installed. 

that 1mm xmax spec'd in the manual certainly doesn't compute, i was watching the
cones in the sunlight and they were moving at least 5mm. 

i was sure i was making a big mistake installing " pro " audio woofers into my vehicle
but now i'm very glad i made the leap. 
these do not sound " shouty " or " too screamin loud " or " honky " in the least !
as a matter of fact they sound better than anything i have heard in this suburban. 
i won't be afraid of pro audio ever again. 

didn't have a great deal of time today and just wanted to get rid of the burnt coil
sound so didn't get time to paint the spacer rings, just wanted to get the swap done ASAP. 

included are a few pics ( woopie dooh daah .... :laugh: )


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## Grinder (Dec 18, 2016)

That's AWESOME!!! Glad to hear it!!!

Now I'm all the more sure that my main problem with the RFs has been those monster tweeters.

It's been a while since I messed with them, but I think Mom's x-over's set at 60 or so, with a 48 dB slope, with the parametric pushing +10 in the 70-80 dB range, with a gradual slope to -10 in the 300s, and then -10 flat the rest of the way, which works pretty well (but still kind of harsh EDIT: in the treble), but if/when I could tame those tweets (and maybe the RF passives are part of the problem) I might go a lot flatter on the EQ.

I've seen some excursion, probably more than 1mm, but not as much as you've seen (are you talking one way?). I'm guessing your doors aren't sealed (?). I'm not sure, but I think I've heard the cones beginning to break up, and imagined that they _might_ have been fighting against the sealed enclosure (though it would seem to be large enough to prevent this, but IDK). Those cones seem very light and flexible, particularly with such a seemingly stiff surround, but IRDK (and I have a vivid imagination).

Anyway, thank you for sharing!!!


Unfortunately my test rig has been in a holding pattern for the last several weeks (and I got kind of burned out on all the DSP stuff - and disappointed and overwhelmed with all of the REW/measurement complexities). But it's main purposes have largely been fulfilled (and then some!), in helping to sort out some of the issues with my boombox projects and Mom's system. Soon I want to try the miniDSP on my horns! I'm looking forward to pushing something like +10-15 dB at 30Hz at them. Those Eminence 15s, being 100 Hz folded horns, have always needed help on the low end (my friend who built them was adding some EQ, but I never have, thus the Paradigm PS-1200 sub - which, BTW, I recently found out, via side-by-side comparison to Mom's system, is -and always was - a Real Piece Of Crap, LOL!!!! Those four sealed IX-8s, given +10 dB at 30Hz, and -10 dB from around 100 on up, are STILL mighty impressive!).


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## Grinder (Dec 18, 2016)

PS: Still looking forward to building my next boombox (ported this time, thank you very much!). Got all the materials, just have to find the time...


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## Grinder (Dec 18, 2016)

PPS: Go ahead and laugh (not that I think you will), but a couple weeks ago I got a wild hair and decided to see what would happen if I added 1.5" dia. ports to the DB651s in my boombox. I started with them at (a ridiculous) 8.5" and worked my way down to about 2.5," which probably "worked" best, though not nearly preferable to sealed (at 0.36 cu. ft.). Nonetheless, it was an interesting experiment.


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## lurch (Jan 20, 2014)

did i notice cone breakup ?
i'm not sure if it was cone break up or just absolute distortion. 
i mean it was HORRIBLE if pushed while the xovers were below 60hz. gaawwd awful 
but get them up higher and all that disappears, they really start to cruise along. 

the doors are kinda semi deadened, basically just open baffle. 
one thing i did notice : most of the door rattles are gone now, most likely because
the excursion is reduced in comparison with the daytons. 

the xmax i saw and mentioned was total excursion, total pistonic movement,
but i swear it was more than 5mm, i didn't want to exaggerate though. 
maybe because they are running open as compared to sealed ?

i think these would do well ported, maybe your next experiment ???

i have many hours and days to set EQ ahead of me. 
a few weeks ago i installed an alpine h800 processor and now have 31 bands eq
per channel to wrap my head around .... FUN. 
pretty sure i can totally screw this up with that much control. 
i'll keep you updated .....

still cannot get over what an improvement these made.
end of frustrations. 
tears of joy.


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## Grinder (Dec 18, 2016)

PPPS: (this is getting ridiculous, but...) I'm surprised that, with the 3" PVC, I'm still hearing port noise (and can feel a breeze from 7+ feet away). I'm wondering:

1) How accurate (underrated) the IX-8 7mm x-max spec might be.

2) If that spec were accurate, and if it were 7mm one way, might the numbers you (so very kindly) provided have been based on a 7mm total x-max?

Any idea what might explain the port noise?


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## lurch (Jan 20, 2014)

yup, i fukked up, the xmax i entered was low and i can't remember why now. 
so sorry. 

there was a reason i wasn't too worried about it but now it escapes me. 
maybe a 4" was going to be too long, that could be it ?
a 3.5" would have been a good compromise but that size is hard to find. 

7+ feet !
that's impressive !


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## Grinder (Dec 18, 2016)

lurch said:


> did i notice cone breakup ?
> i'm not sure if it was cone break up or just absolute distortion.
> i mean it was HORRIBLE if pushed while the xovers were below 60hz. gaawwd awful
> but get them up higher and all that disappears, they really start to cruise along.
> ...



I suppose I might have been hearing Mom's 80W RMS drying up (though they never sounded bad - I'm pretty sensitive to - and very leery of - distortion). In any case, the lower the tune, the lower the dB at which I would begin to hear it (my experiences seem to mirror yours).

YES! I would LOVE to try porting these! In the test rig they've got about o.64 cu. ft. - if you'd care to suggest a tuning frequency and port dia. (assuming that's a large enough cabinet volume).

I look forward to your updates.

I'm so happy for you!!!


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## Grinder (Dec 18, 2016)

lurch said:


> yup, i fukked up, the xmax i entered was low and i can't remember why now.
> so sorry.
> 
> there was a reason i wasn't too worried about it but now it escapes me.
> ...


No worries, Bro!

Yeah, 4" would be too long (that must be it). 3" is almost too long.

And yeah, the air movement seems very impressive to me (but then I have nothing to compare it to - only my lackluster PS-1200). Very refreshing!


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## lurch (Jan 20, 2014)

And yeah, the air movement seems very impressive to me (but then I have nothing to compare it to - only my lackluster PS-1200). Very refreshing![/QUOTE]

LOLOL

isn't that the paradigm model with a 100 watt plate ? gutless. 

and yeah. i'll model a ported enclosure for these RF's. 
now what could be interesting is that 1mm xmax spec .......hhmmmm .....


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## Grinder (Dec 18, 2016)

lurch said:


> And yeah, the air movement seems very impressive to me (but then I have nothing to compare it to - only my lackluster PS-1200). Very refreshing!


LOLOL

isn't that the paradigm model with a 100 watt plate ? gutless. 

and yeah. i'll model a ported enclosure for these RF's. 
now what could be interesting is that 1mm xmax spec .......hhmmmm .....[/QUOTE]

130 watts (I think), but yeah... And no comparison to those four sealed IX-8s! Tested on a tone generator for the first time, and the POS was peaking LIKE CRAZY in the 150 Hz range (50-150 Hz crossover set to 50 Hz), with a very steep drop in output below 50 HZ!

Thanks! Yeah, not sure what to make of that Xmax spec. I'd say just use your best judgement (and know that I'm not averse to experimentation).


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## lurch (Jan 20, 2014)

i suppose it could be an underhung coil design, though the basket design doesn't
reflect this. 
if it is an underhung the xmax spec makes sense :
the coil stays in the gap for +/- 1mm. 
exmech would be a different number, the coil is out of the gap for a few mm but still
has extra space to move, just not as accurately. this is where distortion begins. 

SOOO ... i will design the ported alignment to reflect a 5mm ( total ) xmax. 
mine are having no issues at all moving much more than that and the amp is
approx 125 rms per ch. 

seem fair ?


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## Grinder (Dec 18, 2016)

Sounds good to me.

Thank you!


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## lurch (Jan 20, 2014)

OK, did some modeling this evening. 

turns out that the sealed cabinet cubic volume is WAY too large. 
at 0.63 cubes the rockfords are basically seeing an infinite baffle. 
WINISD suggests a volume of around 0.15 cuft ( ! ). 

ported alignment at 0.64 is also twice the volume that WINISD models for best
response. 
a volume of approx 0.3 tuned to 95hz ( IIRC ) gives the flattest line. 

i inputted your existing box at 0.64 cuft instead of 0.63 but it makes no difference
so i'm not going to correct for that. 

porting can still be done at 0.63, there are still huge output gains to be made although
the frequency graph is a long way from being flat. 

i used 3" tube for all projects and included two sealed and two ported graphs. 

the pic is blurry as hell so if you have questions please ask and i'll give numbers
and whatnots. 

here are the images, let's see if i can gettem right side up …


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## Grinder (Dec 18, 2016)

Thank you!!!

Umm... This is what an RF Tech said when I asked for the ideal enclosure volume (last October): "There is no recommended enclosure size, that speaker is built to work in any application.* If you need a starting point shoot for something around 0.15 - 0.20 cubic feet sealed, you can use our box wizard at the following link to figure out your dimensions."

What can I say... 

It sounded a lot like marketing BS to me. Anyway, I hadn't gotten the best info from them earlier and later (and way before I ever decided to go big).

...and I just couldn't believe that I would get the best sound (punchy "midbass," for example) from such a small enclosure. :blush:

Also, it was my assumption that these are meant for IB applications (unsealed doors), hence the stiff suspension (another assumption), which is mostly why I went so big - so as not to reduce their minimal excursion, and to (hopefully) make the most of their "midbass" response.

It would be great if you could "give the numbers and whatnots" (I'm not at all sure what I'm looking at), particularly if you think I'd likely improve their (both the test rig and, much more importantly, Mom's speakers - whose cabs are larger still, at 0.715 cubes gross) sound with porting.

Edit: My goal would be to somehow alter their enclosure volumes to provide the ideal environment, whether sealed or ported (whichever would be best).


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## lurch (Jan 20, 2014)

YES !

the smaller cabinet volume is the way to go. 

if you can fit a .3 cuft box through a 7" hole it would work out well. 
the port is so short that it should't be a problem, 4.5". 
this works out to approx 95hz tuning freq. 

if you want more models i can try different tube diameters for the .3 box. 
the specified cuft winisd = 3.07 cuft, so 3' is close enough, easily, and whatever
volume the magnet etc. use, i really don't think it's too critical though, close
enough will be fine in this case. 

i'll try to take some clearer pics tomorrow, the graphs speak better than i can, unless you have some specific questions ?


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## Grinder (Dec 18, 2016)

BTW, remember that "Notification" you sent to me, saying you were wondering what my impressions might be, after having had time to hear the ported test rig for a while? Well, I distinctly remember responding with a post (in this thread, I believe), and I even remember thinking afterward that what I'd written was rather vague (and/or not very helpful), and that I ought to follow up with something more useful (after some time with a tone generator, and when I have a better feel for what I'm hearing).

Did you ever see such a post (impressions of the ported sub)?


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## lurch (Jan 20, 2014)

not specifically, no. 
i assumed the post regarding hiss and noise plus all the different dacs/connectors was in response, much of what was over my head, so i just accepted that. 

posts were going missing at around that time, maybe it was a victim?


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## Grinder (Dec 18, 2016)

lurch said:


> YES !
> 
> the smaller cabinet volume is the way to go.
> 
> ...


Perhaps I'm missing something, but I don't know how I might "fit a .3 cuft box through a 7" hole." Any ideas? I assumed I'd have to cram a bunch of wood scraps and such in there to decrease volume, but I'm all ears.

A clearer graph would help; but more than that, I'd like to know what (alignments?) the different colors represent (i.e. sealed, ported, tuning Hz, or whatever).


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## Grinder (Dec 18, 2016)

lurch said:


> not specifically, no.
> i assumed the post regarding hiss and noise plus all the different dacs/connectors was in response, much of what was over my head, so i just accepted that.
> 
> *posts were going missing at around that time, maybe it was a victim*?


That must be it (the missing posts). Sorry about that.

I suppose it's just as well. As I recall, I hadn't really said very much...

I'll follow-up soon (sometime in the next few days).


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## lurch (Jan 20, 2014)

it really is a horrible picture 

aawwrighy, 

the yellow line represents the freq response of your present sealed alignment 
of .63cuft. 
QTC. = 0.46 ( very dry ) 
-3db point = 193hz. 
( mom's will be so similar it's not worth modelling )

red line
sealed cuft = 0.162
QTC. = 0.71 ( near ideal )
-3db = 168hz

blue 
ported cuft = 0.307
tube = 3"w x 4.5"L
port tune = 95.29hz
-3db = 100.76hz !! ( impressive for this driver )

white
ported cuft = 0.63
tube = 3"w x 1.72"L
port tune = 87hz
-3db = 80hz ( see the dip between 150 - 400 ? ) modelled mom's and it
just gets worse. 

hhhmmmm .....
i just modelled a .4cuft. 
this looks GOOD

.4 cuft
tube = 3" x 2.95"L
tuning freq = 95
-3db = 92hz. 
this is the best of the lot. much better than the recommened !

ok... hope that all made sense.


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## Grinder (Dec 18, 2016)

WOW! Thank you!!!

Yes, it all makes sense.

Should I assume that the ports, at 95 Hz, should vent forward (rather than rearward). If so, it would seem best to leave Mom's sealed, as there is no available baffle area (and given the miniDSP, might I just as well leave the cabs at 0.7 cubes? Or might there be advantages beyond those suggested by the red/yellow comparison?).


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## lurch (Jan 20, 2014)

Grinder said:


> WOW! Thank you!!!
> 
> Yes, it all makes sense.
> 
> Should I assume that the ports, at 95 Hz, should vent forward (rather than rearward). If so, it would seem best to leave Mom's sealed, as there is no available baffle area (and given the miniDSP, might I just as well leave the cabs at 0.7 cubes? Or might there be advantages beyond those suggested by the red/yellow comparison?).


good question, given that we are dealing with lower mid freqs i would guess that 
rear ports could have out of phase characteristics that could be irritating, like
an echo ? especially if bouncing off a wall. 
but I don't KNOW, I'm new to this pro audio schtuph. 
we need someone with more experience to answer this. 
can you fit a smaller port or ports ? ( i'll model them if you want )

if this is an audible issue the only fix may be to look at other midranges. 
dayton rs225 comes to mind... LoL !

the red and yellow graphs are pretty close, close enough that a minidsp can handle the differences, I don't think it's worth the effort to modify the cabinets personally. 

on the other hand, porting where doable will make a huge difference in output
below 200hz.


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## Grinder (Dec 18, 2016)

BTW, double checking Mom's miniDSP settings shows that I was way off in my recent reply (oops!). For better or worse, they are: 

High pass 100 Hz, 48 dB slope.

PEQ:


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## Grinder (Dec 18, 2016)

lurch said:


> good question, given that we are dealing with lower mid freqs i would guess that
> rear ports could have out of phase characteristics that could be irritating, like
> an echo ? especially if bouncing off a wall.
> but I don't KNOW, I'm new to this pro audio schtuph.
> ...


Thanks, but unfortunately no room at all for front ports of any size.

On the bright side, we're happy enough (especially Mom) with how they sound now.

...And I'm definitey looking forward to porting the test rig's RFs, where front ports won't be a problem.


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## Grinder (Dec 18, 2016)

Grinder said:


> LOLOL
> 
> isn't that the paradigm model with a 100 watt plate ? gutless.
> 
> ...





> 130 watts (I think), but yeah... And *no comparison to those four sealed IX-8s! Tested on a tone generator for the first time, and the POS was peaking LIKE CRAZY in the 150 Hz range (50-150 Hz crossover set to 50 Hz), with a very steep drop in output below 50 HZ!
> *
> Thanks! Yeah, not sure what to make of that Xmax spec. I'd say just use your best judgement (and know that I'm not averse to experimentation).


Boy, do I feel like an idiot!!!

I had decided to do a quick comparison of my PS-1200 and the IX-8s in Mom’s speakers; and like an idiot, I simply connected the PS-1200’s mono input to Mom’s receiver’s mono sub output. And when I tried a tone generator, I got the results (in bold type) above. It was very surprising, but I didn’t have time to think about it, or explore the issue further, so I just shook my head (saying to myself, “geez, I knew it wasn’t the greatest, but I thought it was a whole lot better than that”) and moved on (bear in mind that it’s been several years since I’ve cranked the thing with any real volume, and it had been many months since I’d used it at all).

So, today I decided to try it again, with the same results. But this time my head was only partially up my ass, and I soon realized that Mom’s receiver gets all of its audio signal via the miniDSP, and the crossover and PEQ settings for the mids-highs (DUH!). 

And when I split the miniDSP input, to feed flat signal to the PS-1200, presto! It played strongly down to about 27 Hz. While it doesn’t sound nearly so nice as the IX-8s, I’m almost certain that it will go louder (but I’m too afraid for Mom’s system to put it to the test). 

So… While the PS-1200 is obviously not the greatest powered sub, I must say that it is definitely NOT a POS (geez… what was I thinking?). :blush:


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## lurch (Jan 20, 2014)

LOL !
that'll learn ya !

yeah, i've owned a few paradigm speakers + subs and they are usually very good. 
my favourites were the large monitor MK sumpinorothers with two 8's, years ago. 
had five of them for hometheater duty, best commercially bought speakers i ever
owned, loved 'em. 
at that time velodyne was coming out strong, so i purchased two of their servo controlled
15' subs to go with the paradigms. beat my house apart with those !


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## Grinder (Dec 18, 2016)

I hope so (but somehow I doubt it)!

Sounds like fun! I'm curious (and a bit surprised) - was that before you had built your own speakers? Do you still have those subs (and how did/do you like them)? And how did those Paradigms compare with those ported monsters you built?

I'd never heard of a servo controlled sub. Fascinating. I've watched in utter amazement the incredibly precise movements created by stepper motors in CNC machines, and I'm imagining a servo controlled sub to be essentially a liner version of more or less the same thing (and that the audio signal would be, by way of comparison, somehow analogous to CNC code).

And BTW, I (finally) began playing around with the test rig's miniDSP subwoofer settings last night. Hopefully I'll be able to move it to the living room tomorrow, where I can hear it properly (and turn it up!) and form impressions. So far, so good.


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## Grinder (Dec 18, 2016)

I've got a bit of a conundrum...

Listening to the test rig today (it's going to take a while to form impressions, but the DSP has helped a lot, by getting rid of considerable boominess - noticed mainly with hip-hop/rap - with a tune similar to Mom's "subs," with less PEQ +/- dB) while considering a few design goals for my next boombox build:

1) I definitely don't want any port noise from my next boombox (I've still got audible port noise - the air movement is astonishing!). 

2) I'd very much like to have lower extension. The test rig starts dropping off at around 35 Hz (high pass is at 20 Hz (!) - not at the 35 Hz you so wisely recommended - and I've got the PEQ adding about 8 Db at 30 Hz (!), so I'm very careful with the volume control), and I am truly impressed …but (surprise, surprise, LOL) I want more - lower extension AND (see #3).

3) Louder.

4) Flatter response (naturally less boomy, with much lower F3).

5) No need for SSF.

6) No need for DSP, EQ, etc.

7) Around 1 cu. ft. net volume or less.

Here’s the conundrum: In my http://www.diymobileaudio.com/forum...-arc-xdi-10-d2-d4-dayton-rss265hf-4-10-a.html thread, the Image Dynamics ID8 (ported) was recommended (as an alternative to a Dayton HF10 or HO10). Back then, when I was looking at the ID8 specs http://docs.wixstatic.com/ugd/d53db0_e453f3cfeea34daebf016a2f1a57f0eb.pdf the 2” I.D. port recommendation meant very little to me. But now, having experienced 2” and 3” ports for my IX8, with its 7mm Xmax, I’m wondering how an ID8, with 15mm Xmax (one way) could get by with a 2” port. I imagined that a driver’s cone area and Xmax would determine the necessary port area - whereas Skar recommends nearly a 4” dia. port for the IX-8, and ID recommends 2” for their ID8. I suppose flared ports might address some of this disparity, but what am I missing?

Anyway… The point is, I’d very strongly consider using a ported ID8 (or an ID10, or some other sub) in my next boombox, if it would allow me to achieve those design goals. Thoughts?


----------



## lurch (Jan 20, 2014)

Grinder said:


> I hope so (but somehow I doubt it)!
> 
> Sounds like fun! I'm curious (and a bit surprised) - was that before you had built your own speakers? Do you still have those subs (and how did/do you like them)? And how did those Paradigms compare with those ported monsters you built?
> 
> ...


the paradigms came a little after, the monsters went to a sound room downstairs and the paradigms did home theater duty. 
hard to compare the two, paradigms = much more refined. 
monsters = loud, efficient and beastly loud .... LOL. 

after an injury and then a divorce i don't have any of that gear now. 

the servo control was an accelerometer mounted in the voil coil former, i think. 
i have ideas of how it worked but they are probably wrong. 

there was a movie we watched one evening, can't remember what movie, a quiet love story i think. 
the main character opens a refrigerator while talking to his girl, must have been wearing the microphone around his neck, when he closed the fridge door every glass in our kitchen cabinets jumped out of the doors !
WHUUMMP !!
scared the crap outta everybody. 
those velodynes had some force behind them. very fun. 
the movie " aliens " was amazzzing with that setup.


----------



## lurch (Jan 20, 2014)

yeah, going with bigger cones is probably the the only answer to getting louder
and lower. and planning the depth of the enclosures accordingly !!!

the reason we couldn't go with 4" ports in the test rig was because of limited depth, right ?
( but it is just a test rig... lessons learned )

i would need to model the ID and daytons to figure out why the port areas recommended
are so different, different qts and vas numbers probably. 
but if louder is what you want bigger is the only way. 

maybe pro audio drivers would be a better choice ??
pioneer makes a pro audio sub that is raved about here, even Victor likes it. 
can't remember the model number, it's a 12" , typical pioneer numbers
" TSW- sumpin sumpin ", sonic sells them, can't gettem here in canada or
i would definitely try one, especially for the price.


----------



## lurch (Jan 20, 2014)

regarding flared ports, take a gander :

vent tuning


----------



## Grinder (Dec 18, 2016)

lurch said:


> the paradigms came a little after, the monsters went to a sound room downstairs and the paradigms did home theater duty.
> hard to compare the two, paradigms = much more refined.
> *monsters = loud, efficient and beastly loud .... LOL*.
> 
> ...


I'm amazed (once again, but forgot to mention it earlier) that those two little mids in your monsters could keep up with four ported 12s!

WHUUMMP!! is right!!! Wonder what those would be like in a basement (or anywhere else, for that matter, LOL)?

Got Aliens queued-up on Netflix (to try out on Mom's system, or was it mostly the surround aspect of the movie, and not so much the sub stuff?).


----------



## lurch (Jan 20, 2014)

it was the sub stuff .... LoL. 

EDIT
there is a scene where the jump ship has an alien in it and eats the pilot. 
as the ship is scattering pieces towards the viewer a crow bar comes at us. 
the surround effect of that is unforgettable, it comes right at you, to the right
and goes past your shoulder. 
yeah, the big paradigms pulled off surround seamlessly, they were impressive. 

if you REALLY wanna watch those woofers wiggle put on predator. 
remember the minigun the big black dude used ???
yup... the raport of that thing was incredible with two 15's. 
made the eyes lose focus.


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## Grinder (Dec 18, 2016)

lurch said:


> yeah, going with bigger cones is probably the the only answer to getting louder
> and lower. and planning the depth of the enclosures accordingly !!!
> 
> *the reason we couldn't go with 4" ports in the test rig was because of limited depth, right* ?
> ...


EDIT: The ID8 has some pretty killer specs. Seems it would go considerably louder and lower. But I've been looking even more at the ID10 (but the ID8 makes for a better comparison to my IX-8 - the quandary).

Yes, a 4" dia. port would have been too long.

That other thread I mentioned was to compare the IRC and Dayton, but here my quandary was regarding the Skar Audio recommended nearly 4" dia. ("13 sq. in.") for my test rig's IX-8, and the ID recommended "2 in. I.D." for their ID8. Am I wrong in my assumption that the ID, with 15mm Xmax, would move a lot more air than my IX-8, with only 7mm Xmax, and that the amount of air movement more or less dictates the port area. I must be missing something, because I'm not suggesting that ID is lying or mistaken, regarding their 2" port recommendation, and I know from experience that Skar's 4" (13 sq. in.) port recommendation would seem to be ideal (given enough room for its length).

Thanks for the tip, I'll try to find the Pioneer. Are we talking about sealed, or ported (at around a cube or less)?


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## Grinder (Dec 18, 2016)

lurch said:


> regarding flared ports, take a gander :
> 
> vent tuning


Definitely gonna study that tomorow. 

Thank you!!!


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## lurch (Jan 20, 2014)

aaaauuurgh... my post got earen when i went looking for this :

https://www.sonicelectronix.com/item_65566_Pioneer-TS-W1200PRO.html

yeah, i'll also do some research on your suggested drivers when i get time.


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## Grinder (Dec 18, 2016)

lurch said:


> it was the sub stuff .... LoL.
> 
> EDIT
> there is a scene where the jump ship has an alien in it and eats the pilot.
> ...


It was nothing like that (well, my front L/R were my horns, but...), but many years ago I had decent 5.1 surround. It was pretty cool, but it was always difficult-to-impossible to integrate into an everyday multi-use environment. In the end, a powerful 2.1 was, for me, a good-enough compromise.

...and Predator too, thank you (and I'm not sure I ever saw it)!


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## Grinder (Dec 18, 2016)

lurch said:


> aaaauuurgh... my post got earen when i went looking for this :
> 
> https://www.sonicelectronix.com/item_65566_Pioneer-TS-W1200PRO.html
> 
> yeah, i'll also do some research on your suggested drivers when i get time.


Wow! Very interesting! Thank you!!

I've already been strongly considering using my RFs in my next boombox (I'm thinking "ultimate boombox from hell" LOL). I'd probably have to go sealed with them though, to keep size & weight down (and to save max room for the sub). Still going to try porting them in my test rig soon - maybe then I'll change my mind about using them (sealed) in a boombox. In any case, I'll plan on using my miniDSP for this project (after all, what good would "the ultimate boombox from hell" be without DSP?).

I'd love to see how one of these would model. I'm guessing it would be best ported, though 1.5 cubes is pretty big for a boombox, but... it might be worth a try. In any case, I'm very intrigued by the idea of creating something unusually small (relatively speaking), capable of making an unusually large sound (again, relatively speaking). I do want LOUD, but definitely not at the expense of LOW. In fact, the ported IX-8 might be just about loud enough that, if it went enough lower, without need of a SSF, I might be completely satisfied (or overjoyed!).

Or, I could get two of these and add the RFs (also ported), to make a killer pair of speakers... but then I already have a killer pair of speakers...


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## lurch (Jan 20, 2014)

at 105db i'm sure that they must be bloody loud !
" boom box from hell " = a suitable name. 
but people here do like them, must be a reason. 

so looked up the idq8 and your IX8. 
they are very different, just take a look at the VAS numbers.


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## Grinder (Dec 18, 2016)

lurch said:


> at 105db i'm sure that they must be bloody loud !
> " boom box from hell " = a suitable name.
> but people here do like them, must be a reason.
> 
> ...


What do their very different VAS numbers suggest? Sorry - I don't even know (yet) what VAS is. :blush:


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## lurch (Jan 20, 2014)

ok, let's see if i can explain vas as it pertains to your situation :

as a volume of air gets smaller the more difficult it becomes to " squeeze " the air. 
i can't remember the exact numbers but
the skar vas = approx 6 liters. 
the ID vas = 25-ish ?

this means that the skar has more force and will work comfortably in a small volume,
while the ID will need more volume to achieve the same output. 
IOW : the ID cannot squeeze the air volume with the same force, thus the port 
doesn't need to be as large. 

far from a technical paper but hopfully that makes sense.


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## Grinder (Dec 18, 2016)

OK, 44 liters vs 8.7 liters. I've read the definition of VAS (again), but what should I understand about it (and the difference between these two numbers)?

EDIT: Never mind. Thank you!


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## Grinder (Dec 18, 2016)

lurch said:


> ok, let's see if i can explain vas as it pertains to your situation :
> 
> as a volume of air gets smaller the more difficult it becomes to " squeeze " the air.
> i can't remember the exact numbers but
> ...


Thank you!! That makes sense, I just can't seem to wrap my head around it. It seems as if the ID's 2x Xmax is pointless/meaningless, if it can't overcome the air volume to utilize it.

Does the smaller port area in any way imply reduced SPL (as compared to a larger port area)?

EDIT: ...(as compared to a NEED for a larger port area)?


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## lurch (Jan 20, 2014)

yeah, it's counterintuitive, it took me a while to wrap my head around " vas ". 
then one day it dawned on me that as an air volume becomes smaller it gets
harder to compress. 
VOILA !
that's when it all made sense to me.


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## lurch (Jan 20, 2014)

wrap my head around it. It seems as if the ID's 2x Xmax is pointless/meaningless, if it can't overcome the air volume to utilize it.
end quote


i looked at the xmax of both, they are the same. 
the IX is listed at 7mm one way. 
the ID is listed as 14mm full stroke. 

the TEN inch ID is 28mm full stroke. maybe this is the mix up ?
BTW : 28mm is impressive, my DC audio 12" is only 23" and it MOVES.


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## Grinder (Dec 18, 2016)

lurch said:


> yeah, it's counterintuitive, it took me a while to wrap my head around " vas ".
> then one day it dawned on me that *as an air volume becomes smaller it gets
> harder to compress.*
> VOILA !
> that's when it all made sense to me.


No, I *totally* get that. But I fail to see how that can make it all make sense.


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## Grinder (Dec 18, 2016)

lurch said:


> wrap my head around it. It seems as if the ID's 2x Xmax is pointless/meaningless, if it can't overcome the air volume to utilize it.
> end quote
> 
> 
> ...


Use the links:

Skar says 7mm, without indication of one-way or not: https://www.skaraudio.com/products/ix-8?variant=17677557121 (click SPECS)

ID says 15mm, "one way linear:" http://docs.wixstatic.com/ugd/d53db0_e453f3cfeea34daebf016a2f1a57f0eb.pdf


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## lurch (Jan 20, 2014)

Grinder said:


> Thank you!! That makes sense, I just can't seem to wrap my head around it. It seems as if the ID's 2x Xmax is pointless/meaningless, if it can't overcome the air volume to utilize it.
> 
> Does the smaller port area in any way imply reduced SPL (as compared to a larger port area)?
> 
> EDIT: ...(as compared to a NEED for a larger port area)?


i donno .....


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## Grinder (Dec 18, 2016)

lurch said:


> wrap my head around it. It seems as if the ID's 2x Xmax is pointless/meaningless, if it can't overcome the air volume to utilize it.
> end quote
> 
> 
> ...


I'm seeing "17mm one way linear" for the ID10 http://docs.wixstatic.com/ugd/d53db0_5458adc52a63457bb2624c19e763eaf5.pdf


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## lurch (Jan 20, 2014)

wow, ok, this one says " peak excursion "

http://docs.wixstatic.com/ugd/d53db0_cf3367427bab4922b0d64543fbd20858.pdf

i don't think a normal ( ( although beefy ) 8" woofer could achieve that kind
of excursion, the surround would need to be HUGE.


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## Grinder (Dec 18, 2016)

lurch said:


> wow, ok, this one says " peak excursion "
> 
> http://docs.wixstatic.com/ugd/d53db0_cf3367427bab4922b0d64543fbd20858.pdf


ID*Q* is a different animal. I've been referring to the "ID" series, not the "IDQ" series.


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## lurch (Jan 20, 2014)

Description
The Skar Audio IX-8 D2 is a high performance, powerful, and responsive 8-inch dual 2-ohm component car subwoofer. The IX series make for a great daily subwoofer, and were engineered to be extremely efficient and reliable. Featuring an advanced air flow cooling design, as well as a high temperature 2-inch copper voice coil, this subwoofer performs at it's rated power levels with ease. Also utilizing a powerful single stack ferrite magnet, competition grade paper cone, and high roll foam surround, this speaker spares no expense. Dual 2-ohm voice coil. Peak Power : 300 Watts, RMS Power : 150 Watts. Sold individually. Fs: 45 Hz, Spl: 82.6 dB, Qts : 0.64. Xmax : 7mm One-Way.


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## Grinder (Dec 18, 2016)

As far as I can tell, the ID8 (at "15mm one way") has at least twice the excursion of the IX-8 (at "7mm").


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## Grinder (Dec 18, 2016)

lurch said:


> Description
> The Skar Audio IX-8 D2 is a high performance, powerful, and responsive 8-inch dual 2-ohm component car subwoofer. The IX series make for a great daily subwoofer, and were engineered to be extremely efficient and reliable. Featuring an advanced air flow cooling design, as well as a high temperature 2-inch copper voice coil, this subwoofer performs at it's rated power levels with ease. Also utilizing a powerful single stack ferrite magnet, competition grade paper cone, and high roll foam surround, this speaker spares no expense. Dual 2-ohm voice coil. Peak Power : 300 Watts, RMS Power : 150 Watts. Sold individually. Fs: 45 Hz, Spl: 82.6 dB, Qts : 0.64. Xmax : 7mm One-Way.


I see, the "One-Way" is in the "Description". Unfortunately, it's not where I was looking - in the "Specs."


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## lurch (Jan 20, 2014)

yeah, hard to know just what to believe. 

anyways, i very much doubt that spec regarding the ID ( i have it open ). 
30mm excursion is just too much to believe.

i would believe it if that was an " exmech " parameter, but not xmax. 
i'm gonna stick with 15mm total stroke.


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## lurch (Jan 20, 2014)

says on this page ( just under the woofer images )
12.5 xmax one way. 
which still seems like too much. 

imagedynamicsusa


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## Grinder (Dec 18, 2016)

lurch said:


> yeah, hard to know just what to believe.
> 
> anyways, i very much doubt that spec regarding the ID ( i have it open ).
> 30mm excursion is just too much to believe.
> ...


Sorry about all the back and forth over Xmax and port area. :worried:

Thank you for your patience.


----------



## lurch (Jan 20, 2014)

OH !
going back a bit :

I modelled the RF's using the 1mm xmax spec instead of 5mm. 
didn't seem right to use my number. 
and i took a closer look today in the sun, at an 80hz xover at 12db i would say
2mm max would be about right.


----------



## lurch (Jan 20, 2014)

Grinder said:


> Sorry about all the back and forth over Xmax and port area. :worried:
> 
> Thank you for your patience.


that's quite awwright.
i've seen others on this forum doing exactly the same thing regarding
ID's xmax specs, now i understand WHY.


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## Grinder (Dec 18, 2016)

lurch said:


> says on this page ( just under the woofer images )
> 12.5 xmax one way.
> which still seems like too much.
> 
> imagedynamicsusa


I take a very dim view of companies that lie about their products. I may never know if ID is lying about Xmax, but it doesn't look good when they list two different specs (15mm and 12.5mm) for the same product.

For evidently being such a pariah on this forum (too many fanboys here?), Skar Audio looks better and better to me all the time.


----------



## Grinder (Dec 18, 2016)

lurch said:


> OH !
> going back a bit :
> 
> I modelled the RF's using the 1mm xmax spec instead of 5mm.
> ...


Oops, I missed this one!

So, what are you thinking?


----------



## lurch (Jan 20, 2014)

nuthin really, just that i'm pretty sure about the graphs and results. 
they are not " scewed " by my opinion, and i'm glad my opinion didn't
alter the results. 
so continue and know that we got it right ....


----------



## Grinder (Dec 18, 2016)

lurch said:


> OH !
> going back a bit :
> 
> I modelled the RF's using the 1mm xmax spec instead of 5mm.
> ...


...and TBO, if my IX-8s are 7mm Xmax, I just couldn't see how the RFs could be moving even half that much (and I was pushing Mom's RFs with NO high pass, AND 4-6 clicks of + bass knob, and I don't think I ever saw anything like that).

EDIT: Never mind.


----------



## Grinder (Dec 18, 2016)

lurch said:


> nuthin really, just that i'm pretty sure about the graphs and results.
> they are not " scewed " by my opinion, and i'm glad my opinion didn't
> alter the results.
> so continue and know that we got it right ....


Aaahhh, I see... I assumed you were saying that you had re-modeled them at 1mm (and that the graphs were representing 5mm).

All good news!!! Thank you!!!


----------



## lurch (Jan 20, 2014)

i have the grills on, so maybe that metal mesh is deceiving me when the
sunlight is shining through them. 
but i'm also pouring some juice to them, the 125wrms figure of my amp
is very conservative. they do boogie !
still very happy with them. 

hhhmmm..... maybe i'll take a video and call it 
" the awesomest sooper doooperest speaker ever " 
( and hide under a psuedo name)


----------



## Grinder (Dec 18, 2016)

lurch said:


> i have the grills on, so maybe that metal mesh is deceiving me when the
> sunlight is shining through them.
> but i'm also pouring some juice to them, the 125wrms figure of my amp
> is very conservative. they do boogie !
> ...


Oh, my! I hope you're wearing ear plugs!!


Do it!!! I'd love to see that!


----------



## Grinder (Dec 18, 2016)

lurch said:


> *i have the grills on, so maybe that metal mesh is deceiving me when the
> sunlight is shining through them*.
> but i'm also pouring some juice to them, the 125wrms figure of my amp
> is very conservative. they do boogie !
> ...


No, man, it's not the sunlight. They're rocking your eyeballs!!! LOL


----------



## lurch (Jan 20, 2014)

K !
will do !
( ear plugs are for pussies who still have their hearing ) 

i need to figure out how to post a video. 
maybe i can make a link to facebook ?


----------



## Grinder (Dec 18, 2016)

lurch said:


> K !
> will do !
> ( ear plugs are for pussies who still have their hearing )
> 
> ...


Just kidding (though I really can't begin to imagine those RFs, in a car, with 125W! I mean, are you actually sitting in the car when it's that loud?).

I got Tinnitus (maybe it's congenital, Mom's had it for many years, and she's been wearing hearing aids for a few) last year - maybe a coincidence, but it started after mowing lawn for 3hrs at a time last summer (very loud, never mowed like that before. Wearing ear plugs this summer). It sucks. 

Don't have a YouTube channel? (Now I'm not kidding, in case you thought I was). It's no biggie at all.


----------



## lurch (Jan 20, 2014)

yoootooob ?

it never dawned on me, i had no idea. 
thanks !
( the internet went racing past me a few years ago )


----------



## Grinder (Dec 18, 2016)

lurch said:


> yoootooob ?
> 
> it never dawned on me, i had no idea.
> thanks !
> ( the internet went racing past me a few years ago )


Call me Captain Obvious. :blush:


And what's _your_ excuse? LOL I was completely off-grid from late '97 thru 2015.


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## Grinder (Dec 18, 2016)

It dawned on me this morning that I've been sending mixed signals with regard to my SQ preferences (for lack of better terminology). Until very recently, I've been saying that, in terms of bass response, what I want most is plenty of tight, punchy bass (think kick drum in the chest), with good musicality, and a lack of boominess.

However, in terms of low bass, all I've ever really heard is my very muddy (and more or less boomy) PS-1200. But now, having heard Mom's IX-8s with DSP (and the ported test rig, with and without DSP) I've gotten a taste for how very much better bass/low bass can sound (than what I've been hearing from the PS-1200, and the sealed IX-8s without DSP), and I'm hooked... Now I want it all, LOL (I *need* the low stuff too!).


Anyway... been reading some posts about those Pioneers. Haven't found a lot of consensus, as folks seem to either love 'em or hate 'em, but I suspect that most of the haters have used them sealed, or in the wrong ported environment, and they're angry because they aren't going nearly low enough. 

I'm interested in giving one a try, if you think I'd have a reasonable expectation of satisfying my new criteria, in under 2 cubes (in as close to 1 cube as possible), for my boombox from hell. 

And I'm assuming that one of these in a boombox would preclude any need for (or advantage of) porting the RFs, which would greatly reduce size and weight (don't worry, I'm still gonna try porting them in the test rig soon). 

Thoughts?

BTW, out of curiosity I also looked around for feedback on the IDs, and came up pretty dry. Anyway, ixnay on the IDixays.


----------



## lurch (Jan 20, 2014)

ok, farted around with youtube for a bit and think ive got it figured out. 

here is a short clip, high pass = 80hz @ 12db's. 
half throttle .....

https://m.youtube.com/watch?v=2gNAC-W9Pj4


----------



## lurch (Jan 20, 2014)

well, if you want the low lows with any authority you are going to have to go BIG. 
there's no getting around it, bigger is gooder, you cant have small and big. 
sorry, too bad so sad. 

i don't have any experience with the pro pioneer, so i would be barking up my own ass
if i tried to sway you one way or the other. 
i would " bet " that they would be more musical in a larger enclosure though, closer
to 1.75 or even 2.5 cuft. 
in a car we have cabin gain working for us, in a home not so much. 

why not join a home speaker forum ? i'm in one called 
" extreme DIY loudspeaker building ".


----------



## Grinder (Dec 18, 2016)

lurch said:


> ok, farted around with youtube for a bit and think ive got it figured out.
> 
> here is a short clip, high pass = 80hz @ 12db's.
> half throttle .....
> ...


Impressive! By "half throttle," do you mean to say that you could turn it up a lot more? 

That seems a fair bit more excursion than I've seen with Mom's RFs. But then they're only getting whatever her Onkyo puts out (supposed to be 80 RMS), minus whatever her tweets and passives are using.

GRACE JONES!!!


----------



## lurch (Jan 20, 2014)

yeah, half throttle = 5 and a half on the dial ... :laugh:

there were people around so didn't wanna disturb them. 

don't know how many watts that would be but i had plenty to go, 
sub was turned off. 
sure sounds horrible through an iphone mic, EEEEYUUUCH


edit
i'll play " planet claire " from The B-52's and take another vid some time. 
that track is LOUD. ( one of my favourites of all time )


----------



## Grinder (Dec 18, 2016)

lurch said:


> well, if you want the low lows with any authority you are going to have to go BIG.
> there's no getting around it, bigger is gooder, you cant have small and big.
> sorry, too bad so sad.
> 
> ...


I'm not sure what "low lows" means. 

As far as lows, I'd be happy with strong to 30 Hz, (without need for SSF?). Are there enough specs for it to be modeled (to find out if it could do this in under 2 cubes)?

I'll check out that forum. Thanks for the tip!!


----------



## Grinder (Dec 18, 2016)

lurch said:


> yeah, half throttle = 5 and a half on the dial ... :laugh:
> 
> there were people around so didn't wanna disturb them.
> 
> ...


WOW! Cones wouldn't break up with distortion, with even more power and excursion?


----------



## Grinder (Dec 18, 2016)

lurch said:


> yeah, half throttle = 5 and a half on the dial ... :laugh:
> 
> there were people around so didn't wanna disturb them.
> 
> ...


Duuuuude!!!! That's one of my all time favorites too!


----------



## lurch (Jan 20, 2014)

would you be willing to try a bandpass ??


----------



## lurch (Jan 20, 2014)

Grinder said:


> Duuuuude!!!! That's one of my all time favorites too!


heee heee heee
that one makes my wind shield wipers jump off the glass.


----------



## Grinder (Dec 18, 2016)

lurch said:


> would you be willing to try a bandpass ??


I'm not sure why not (if it would meet my size and performance criteria).


----------



## lurch (Jan 20, 2014)

Grinder said:


> WOW! Cones wouldn't break up with distortion, with even more power and excursion?


nope, they just keep going. clean and clear !
love these.

looks like i may be able to install the 10" version ( if there is one ....)


----------



## Grinder (Dec 18, 2016)

lurch said:


> would you be willing to try a bandpass ??


I assume I'd want the RFs ported for that (wouldn't a bandpass be fairly limited in effective frequency range?).


----------



## Grinder (Dec 18, 2016)

lurch said:


> nope, they just keep going. clean and clear !
> love these.


HOLY ****!!!


----------



## lurch (Jan 20, 2014)

here ya go, manual for pro 12". 

three boxes drawn, closed, ported, and BP

https://www.manualscat.com/en/pioneer-ts-w1200pro-manual?language=2


----------



## Grinder (Dec 18, 2016)

On another note, check out my http://www.diymobileaudio.com/forum...oking-scary-bass-heavy-music-halloween-2.html thread, posts #36 and #37... Let me know what you think.


----------



## Grinder (Dec 18, 2016)

lurch said:


> here ya go, manual for pro 12".
> 
> three boxes drawn, closed, ported, and BP
> 
> https://www.manualscat.com/en/pioneer-ts-w1200pro-manual?language=2


Thanks!!

BP is definitely too big.

I doubt sealed would go low enough for me (and I think its EBP suggests ported).

So, ported would seem to be the best choice. But I don't see any tuning frequency listed(?).


----------



## lurch (Jan 20, 2014)

YIKES
that bandpass is over 4cuft ..... oops.


----------



## bassfreak85 (Jul 26, 2009)

so what drugs are you guys on?


----------



## lurch (Jan 20, 2014)

yeah, pioneer lists the T/S parameters but info is very sparse regarding their
box designs. 
gimme a night or two and i'll WINISD one up.


----------



## Grinder (Dec 18, 2016)

lurch said:


> yeah, pioneer lists the T/S parameters but info is very sparse regarding their
> box designs.
> gimme a night or two and i'll WINISD one up.


:bowdown:


----------



## Grinder (Dec 18, 2016)

lurch said:


> nope, they just keep going. clean and clear !
> love these.
> 
> looks like i may be able to install the 10" version ( if there is one ....)


You're in luck! PPS4-10 - Punch Pro 10" 4-Ohm Midrange | Rockford Fosgate®

And what an absolute beast it must be!!!!


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## lurch (Jan 20, 2014)

ooohhh boy,
i'm in deep kakaa now ....
i think i'm gonna DO IT .


----------



## Grinder (Dec 18, 2016)

lurch said:


> ooohhh boy,
> i'm in deep kakaa now ....
> i think i'm gonna DO IT .


YEAH!!! :thumbsup:


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## Grinder (Dec 18, 2016)

lurch said:


> well, if you want the low lows with any authority you are going to have to go BIG.
> there's no getting around it, bigger is gooder, you cant have small and big.
> sorry, too bad so sad.
> 
> ...


Oh, no! Not Facebook?! LOL Is there another way to join and participate? 

It's just that I did the whole Facebook thing for a while last year, and ended up deleting my account a few months later (it turned out to be a colossal waste of my time). But I suppose it would be worth doing it again, only for participation in that forum.


----------



## lurch (Jan 20, 2014)

i TOTALLY agree regarding FB. 
full of meme's and other ..... SCHTUPH ....
the loudspeaker page is legit though, tightly regulated i think. 

did those sims last night. 
good news and bad news
- the good news
optimal box size for ported turns out to be 1.3cuft !
tuned to 42hz
very flat freq response here. 
GREEN LINE

- the bad news 
none of the sims get much lower than 45hz before drop off. 


yellow line = sealed box 1.25cft , Qtc. 0.57

orange line = 1.5cuft ported , tuned @ 37
notice the output drop as compared to the green and blue lines, although
it is a smooth drop. 

blue line = 2cuft ported, tuned @ 45 hz. 
hump at 50 hz, but in a car this could be desirable, maybe not in a home. 

the green line is the winner, very flat to 60hz before the minus 3db point of 42.5hz. 
the cabinet is a nice size for the application but doesn't reach down. 
( would be LOUD though )


----------



## Grinder (Dec 18, 2016)

lurch said:


> i TOTALLY agree regarding FB.
> full of meme's and other ..... SCHTUPH ....
> the loudspeaker page is legit though, tightly regulated i think.
> 
> ...


Thank you for that!!!

It's not what I'd hoped for, but I'm not surprised.

I wonder how a pair those 10" RFs would do in a boombox (ported, without a sub). The 8s are rated 80Hz-5kHz (shipping weight 7.75lbs), but the 10s are rated 40Hz-4kHz (shipping weight 22.2lbs!!!)! RF wants $250 apiece, but Amazon's got 'em for $160. I'm not sure if this is a serious question, but it is very intriguing!

EDIT: I realize that these wouldn't likely go as low as those Pioneer "subs," but I'm guessing with DSP they might be forced to do just as well, with a big advantage in reduced overall cabinet size, compared to the 1.3 cubes + the 2x 0.15 cubes (and extra MDF) for 8" RFs. And talk about LOUD! Though I still can't get over that 22lb/ea. weight!!!

After watching your video again today, I played around with Mom's miniDSP settings and got those RFs sounding better than ever. And I'm thinking you must (like Mom's) have some SERIOUS EQ to make them sound like that, particularly with the 12dB slope at 80Hz (which I've adopted for MOM's). And if that song is anything like Pull Up to the Bumper, it's got some serious bump in the mix! Also, I think I've noticed a tendency for these to make a slight unnatural "PUH" sound with kick drum excursion, when they're being pushed hard, and FWIW I could swear I was hearing this from yours as well.

Anyway, for the first time, Mom's RFs are sounding nicely warm and balanced with the sub amp turned off (more or less like yours do), thanks to the wonders of DSP!!! I've been trying to make up for the characteristically thin sound of the RFs with the IX-8(s) for so long now, that I've only just begun (using the miniDSP) to make them sound great on their own, leaving the "subs" to do what they (are being forced to) do best. Thank you for the inspiration!!


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## lurch (Jan 20, 2014)

that "puh " is definitely there, but i think i've narrowed it down to the 100-125 hz area. 
didn't have much time today to play with eq settings as the alpine 117 was removed
and swapped out for my pioneer prs80. HUGE IMPROVEMENT. 

anyways, i'll try to get a better idea of where that " PUH PUH " is and what we can do
about it. 

as for using the RF 10" ........ uuummmm, hhhhmmmm, no. 
i think it would fall on its face as a sub. 
time to look at dayton like others have mentioned. 
just helped a friend of mine with a 15" dayton. we kept it sealed and he is VERY impressed. 
( he is hard to impress ). he raves about it, loves it, wants to marry it.


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## Grinder (Dec 18, 2016)

lurch said:


> that "puh " is definitely there, but i think i've narrowed it down to the 100-125 hz area.
> didn't have much time today to play with eq settings as the alpine 117 was removed
> and swapped out for my pioneer prs80. HUGE IMPROVEMENT.
> 
> ...


Oh, no... not as a sub, but as a two-way woofer and tweeter arrangement (trading sub-bass for kick drum in the chest thump?).

But yeah, I definitely like the Dayton idea.

Boombox with a 15" Dayton... Boombox From Hell, is right!!!! LOL

Seriously though, I wonder how big I _could_ go...? Off to PE!


----------



## lurch (Jan 20, 2014)

ok, now i getcha. 

i was unable to find the specs for the RF 10. 
if you found them shoot them my way.


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## Grinder (Dec 18, 2016)

lurch said:


> ok, now i getcha.
> 
> i was unable to find the specs for the RF 10.
> if you found them shoot them my way.


http://www.rockfordfosgate.com/supp...er/std_adp.php?p_faqid=1194&p_li=&p_topview=1

Click on the 10" owner's manual.


----------



## Grinder (Dec 18, 2016)

> But yeah, I definitely like the Dayton idea.
> 
> Boombox with a 15" Dayton... Boombox From Hell, is right!!!! LOL
> 
> Seriously though, I wonder how big I could go...? Off to PE!


Looks like it's either the RSS265HO-44 10" https://www.parts-express.com/dayton-audio-rss265ho-44-10-reference-ho-dvc-subwoofer--295-463

or the RSS315HO-44 12" https://www.parts-express.com/dayton-audio-rss315ho-44-12-reference-ho-dvc-subwoofer--295-467

...as these are the only two Daytons that do 2 Ohms (and I _need_ that). Funny, but the 10" is 90.5 dB, and the 12" is 84.6 dB, the 10" needs a larger enclosure (0.55 cubes sealed/1.5 ported) than the 12" (0.49 cubes sealed/1.36 ported), the 10" has lower F3 (46Hz sealed/22Hz ported) than the 12" (47Hz sealed/27Hz ported), the 10" weighs 17.2lbs, and the 12" weighs 25.4 lbs.! I'm not sure what to make of all that, but it is nonetheless interesting, LOL.


----------



## Grinder (Dec 18, 2016)

Grinder said:


> Looks like it's either the RSS265HO-44 10" https://www.parts-express.com/dayton-audio-rss265ho-44-10-reference-ho-dvc-subwoofer--295-463
> 
> or the RSS315HO-44 12" https://www.parts-express.com/dayton-audio-rss315ho-44-12-reference-ho-dvc-subwoofer--295-467
> 
> ...as these are the only two Daytons that do 2 Ohms (and I _need_ that). Funny, but the 10" is 90.5 dB, and the 12" is 84.6 dB, the 10" needs a larger enclosure (0.55 cubes sealed/1.5 ported) than the 12" (0.49 cubes sealed/1.36 ported), the 10" has lower F3 (46Hz sealed/22Hz ported) than the 12" (47Hz sealed/27Hz ported), the 10" weighs 17.2lbs, and the 12" weighs 25.4 lbs.! I'm not sure what to make of all that, but it is nonetheless interesting, LOL.


Since I've only got 500W RMS (nominal - less than that at power supply's 12.3V), the 10" might be the best match (with its higher efficiency and lower RMS), and its lower F3s look better too. 

Anyway... it's looking like I might have to choose between sealed or passives, as it seems that ports would likely be be too long and/or eat up too much cabinet volume (and then there's the possibility of port noise); in which case, what about these (2 ea., of 12" or 10", to be mounted 90 degrees from the front baffle on both sides of the cabinet)?
https://www.parts-express.com/dayton-audio-sd270-pr-10-passive-radiator--295-494 for the 10" sub, or 
https://www.parts-express.com/dayton-audio-sd315-pr-12-passive-radiator--295-496 for the 12"

...but I'm worried that the passives might detract too much from tightness, precision and/or musicality (though I really have no idea).


----------



## lurch (Jan 20, 2014)

Grinder said:


> http://www.rockfordfosgate.com/supp...er/std_adp.php?p_faqid=1194&p_li=&p_topview=1
> 
> Click on the 10" owner's manual.



ok, plugged in what there is for specs and came up with this :

green + yellow =
sealed, anywhere from .194 to .25 cuft would be fine. 
.195 qtc = 0.71
.25 qtc = 0.63

red line = 
ported .3 cuft tuned @ 90hz 
tube 3" x 5.5"

orange line =
ported .291cuft tuned @ approx 84hz
tube 3" x 6.9". 

if we go to another setup
.35 cuft ported @ 90 hz 
tube = 3x4.5" 
we get the best output with a clean freq response. 

so a sealed box between .2 and .25 cuft will do well. 
a ported box between .25 and 3.5 will also do well tuned somewhere
in the 82 - 90 hz region.


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## Grinder (Dec 18, 2016)

Thank you!!!

So, they seem pretty similar to our RF 8s (speaking of which, I've just taken a couple screen shots of the latest tuning of Mom's RF 8s and tweets and was getting ready to post them... stay tuned), which kinda rules out my two-way boombox idea.


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## Grinder (Dec 18, 2016)

They're sounding better than ever with this (and I've finally got the tweets under control). They tended to be a bit fatiguing and harsh (mostly due to the tweeters, I believe), and now there's none of that. Very happy!!!!  

Moving the peak from 100Hz to 80Hz seems to have helped with the "PUH" sound, but since I've got them crossed at 80Hz with a 12dB slope (as opposed to the earlier 48Db slope), I think it simply amounts to a lesser peak (even though, come to think of it, that peak is about 5dB higher than before). Anyway, near as I can tell so far, that "PUH" _seems_ to be entirely excursion related, but I really don't know...

Also, I'm wondering how much more volume knob (than they had in your video) your 8s could take, _while playing that same Grace Jones song_ under the same conditions (EQ and whatever). I'm just trying to wrap my head around what you said, juxtaposed with what I saw (and heard, though I realize this is very problematic).


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## Grinder (Dec 18, 2016)

Grinder said:


> Thank you!!!
> 
> So, they seem pretty similar to our RF 8s (speaking of which, I've just taken a couple screen shots of the latest tuning of Mom's RF 8s and tweets and was getting ready to post them... stay tuned), which kinda rules out my two-way boombox idea.


Back to the drawing board...


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## Grinder (Dec 18, 2016)

Grinder said:


> Back to the drawing board...


I'm kinda leaning toward that 10" Dayton - either sealed or with passives.

...or maybe the 12" sealed (it's already heavy without passives, and I'm not sure I want the extra 2" cabinet depth, but if it would significantly outperform the 10," either sealed or with passives, I'd probably just go with it).

Thoughts?


----------



## Grinder (Dec 18, 2016)

Grinder said:


> They're sounding better than ever with this (and I've finally got the tweets under control). They tended to be a bit fatiguing and harsh (mostly due to the tweeters, I believe), and now there's none of that. Very happy!!!!
> 
> Moving the peak from 100Hz to 80Hz seems to have helped with the "PUH" sound, but since I've got them crossed at 80Hz with a 12dB slope (as opposed to the earlier 48Db slope), I think it simply amounts to a lesser peak (even though, come to think of it, that peak is about 5dB higher than before). Anyway, near as I can tell so far, that "PUH" _seems_ to be entirely excursion related, but I really don't know...
> 
> Also, I'm wondering how much more volume knob (than they had in your video) your 8s could take, _while playing that same Grace Jones song_ under the same conditions (EQ and whatever). I'm just trying to wrap my head around what you said, juxtaposed with what I saw (and heard, though I realize this is very problematic).


I wish the pictures weren't so small. Can you see them ok? If not, maybe you can copy them (which is what I usually have do).


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## lurch (Jan 20, 2014)

yeah, too blury to see the numbers in the xover/eq fields,even if i open the pics 
in a separate window. 
but it looks to me that the 8's are not bandpassed ?
oh wait, the woofer/tweeters are joined with passives, forgot about that. 

is that a 20db rise i see @ 80hz ?
the highest i can go is + / - 12 db and IIRC my 80hz band is up maybe 4db ?
brought 100hz down a notch , same with 125. ( they seem to excite in this region )
i'll take a closer look when i get out to the vehicle today. 

i took video of the passenger side with the same song playing, except from from the
drivers seat and none of that noise is there. 
i'll post it and send the link. 
same song, same level.

EDIT
here it is , and im going out the door, won't be back till this evening

https://m.youtube.com/watch?v=MSgbDUMfBec


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## Grinder (Dec 18, 2016)

Yeah, very nearly 20dB(!)

Of course, I'm nearly on-axis... And could it be that you're getting a ton of nice midbass resonance from your doors (versus Mom's smaller - and much more solid - cabinets).


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## Grinder (Dec 18, 2016)

lurch said:


> yeah, too blury to see the numbers in the xover/eq fields,even if i open the pics
> in a separate window.
> but it looks to me that the 8's are not bandpassed ?
> oh wait, the woofer/tweeters are joined with passives, forgot about that.
> ...




I see. Thank you! 

And that's practically on-axis!!!! I'd like to know how you're getting so much midbass from them, with so little EQ. I'm pretty sure that the recording is part of it (but GEEEEEEEEEEZZZZZZ!). 

As I said earlier, maybe it's your doors too (?). And cabin gain? And when _you_ listen to the video, does it sound as if there's more midbass than there really is?

Thoughts?


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## lurch (Jan 20, 2014)

that video was taken maybe 5 seconds after the first ?
i just aimed the phone the other way and pressed record again. 

so after reading your last post i decided to plug my headphones into the iphone and
watch the video just to see ( hear ) just how strong the bass actually is. 
yeah.... that's about right, it BLASTS. 
been trying to get some decent bass out of these doors for years and never achieved it. 
far from it actually, so when i cranked these up for the first time i was amazed and
SO happy. 
checked the EQ settings today :
80hz + 4
100hz +2 
125hz -1. 

haven't done any other work in the mid range area yet but will because male
voices are a bit weak. 
the treble area has been worked on more, cuts in the 1 -4 khz regions and boosts in
the 8 - 16 khz regions ( hearing loss as a mechanic ). 

i would suspect that cabin gain has a LOT to do with the response, but cabin gain
didn't help with other drivers, maybe it's the lack of door panel resonance that is
helping the situation ? most of the door vibration is gone now. 
maybe doubling up on the speaker rings helped ? i dunno. 
" maybe " rockford just got them right for a door. 

I REALLY cranked on it today. 
" time stretch " ( dub step i think ? ) dunno who recorded it. 
they wiggle. and they took a big amount of power. and kept going. 
tried a few other songs, new orleans is sinking, party out of bounds, good drum in these,
and they just kicked it out, the volume was turned up WAY higher than i would normally
play it, they just wiggled harder. 
so they are staying put. no foreseeable ugrade in the door speaker area anticipated
in the near future. 
finally.


----------



## Grinder (Dec 18, 2016)

lurch said:


> that video was taken maybe 5 seconds after the first ?
> i just aimed the phone the other way and pressed record again.
> 
> so after reading your last post i decided to plug my headphones into the iphone and
> ...


CONGRATULATIONS!!!

BTW, just remembered there's a big mfg. sticker on the back of the magnet, and it feels as if there might be a vent hole beneath it (and if there is a vent, I wonder WTF they'd cover it with a sticker!). Have you noticed this? I considered removing that portion of the sticker, but...


----------



## Grinder (Dec 18, 2016)

lurch said:


> *time to look at dayton like others have mentioned. *
> just helped a friend of mine with a 15" dayton. we kept it sealed and he is VERY impressed.
> ( he is hard to impress ). he raves about it, loves it, wants to marry it.


Thoughts? (wondering if you saw any of my subsequent posts, when I was looking at Dayton specs and thinking out loud)


----------



## lurch (Jan 20, 2014)

Grinder said:


> CONGRATULATIONS!!!
> 
> BTW, just remembered there's a big mfg. sticker on the back of the magnet, and it feels as if there might be a vent hole beneath it (and if there is a vent, I wonder WTF they'd cover it with a sticker!). Have you noticed this? I considered removing that portion of the sticker, but...


probably just the bolt that holds the phase plug ?


----------



## lurch (Jan 20, 2014)

Grinder said:


> Thoughts? (wondering if you saw any of my subsequent posts, when I was looking at Dayton specs and thinking out loud)


ok, let's back up a minute, how is this thing going to be used ?
inside a home ?
outside for parties ?
how tough does it have to be ? ( will it be moved around alot ). 
a drawing would help too, let's see what you're really doing.


----------



## Grinder (Dec 18, 2016)

lurch said:


> probably just the bolt that holds the phase plug ?


Ah, ha! That makes sense.


----------



## Grinder (Dec 18, 2016)

lurch said:


> ok, let's back up a minute, how is this thing going to be used ?
> inside a home ?
> outside for parties ?
> how tough does it have to be ? ( will it be moved around alot ).
> a drawing would help too, let's see what you're really doing.


It's the next evolution of http://www.diymobileaudio.com/forum...sion/318938-my-car-audio-boombox-project.html or rather the ultimate, final evolution (the boombox from hell).

The "car audio test rig" was built to test my original car audio-based boombox concept. After the boombox was built, I removed the Polk coaxials and installed the RF PPS4-8s, in order to test concepts for Mom's system, and for my own computer sound system. Then, with Mom's system done (and my computer sound project on hold), I began to focus on the next evolution of my boombox project, which led to porting the test rig's IX-8.

Having given up on building (speakers, etc. for) my computer sound/mobile DJ/PA system (LOLOLOLOLOLOL!!!!!!!!!), and bearing in mind that I'd rather not continue using the test rig for my computer sound, I'm thinking that my boombox from hell will end up being used primarily for my computer sound. Apart from that, it could be used anywhere a sufficiently sized extension cord would allow, indoors and out (fair weather). It could be moved around fairly often, so it needs to be fairly rugged (though I'm quite adept at this sort of thing EDIT: moving delicate things without damaging them).

I need it to be as small as possible, and very impressive (to the average person, at least) for its size, indoors and out. I know I'm dreaming, but I fancy the idea of folks being impressed enough to want to buy one of these, or something more like my existing boombox (which is pretty impressive in its own right).

I'm not _entirely_ averse to just going with a ported IX-8, but I think that would be a much better match for my other set of Polks (I'll likely build an intermediate boombox). For the boombox from hell, I'd like some low end better suited to the capabilities of my RF mids and tweets.

Take a look at my boombox. I think you'll get the idea, but I can draw something if you'd like.

Sorry about the novel.

THANKS!!!


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## Grinder (Dec 18, 2016)

Here are a few thoughts and ideas (in lieu of drawings, and to help narrow-in on the concept):

Picture a larger version of my boombox, with a 10" Dayton, tucked up close to the HU, in place of the IX-8; with the 8" RFs in place of the coaxials, their sealed chambers immediately behind, occupying the upper L/R portions of the cabinet (with the RF tweets, more or less tacked onto the top of the cabinet, on either side); and below the RF 8s, two 10” PRs, tucked into the L/R lower corners, on either side of the sub (forming a triangle, with the sub on top and the PRs on either side)
.
Earlier I had mentioned having the passives on either side of the cabinet (90 degrees from the front baffle), but I doubt that would work very well (and there would be considerable packaging issues), and it would seem the same goes for mounting them on the rear of the cabinet.

Another idea would involve more or less the same thing, but porting (without port noise) the 10” or 12” Dayton (instead of using passives), in which case I assume the port would be so long as to require an elbow (or two?), which I guess shouldn’t be a problem.

And the only other idea I can think of, would be very much like my boombox, with a sealed 10” or 12” Dayton in place of the IX-8 (and the RFs in place of the coaxials).

I’m thinking my (500W RMS @ 2 Ohms/300W RMS @ 4 Ohms) amp(s), and my (700W @ 12.3V) power supply(s) are on the weak side for these Daytons, which would seem to be much less of an issue with PRs or ported than with sealed. Theoretically, couldn’t I pair them up on a 2 Ohm DVC sub (one amp per VC)? If so, perhaps it’s too bad they don’t make a 2 Ohm DVC 15” Dayton, LOL! 

Priorities? Small, SQ, low F3 (30s or less?), loud (if it won't be significantly louder and/or lower than a ported IX-8, then why bother…); in that order. 

I wish I knew how one of these 10" or 12" Daytons in a sealed alignment (with, say, a solid 400W RMS) would compare to a maxed out IX-8 in a ported alignment. Would I likely be right in assuming the Daytons would sound better and go lower? If so, then perhaps the only question is how much louder (if any) one or the other sealed Dayton might be than a ported IX-8. And even if it were only equal in loudness, a lower F3 and better SQ might be enough to cinch the deal. The trouble is, I don't have any idea...

Ideas?


----------



## lurch (Jan 20, 2014)

well i've spent the last two hours browsing PE's web site, looking and comparing
many 10's and 12's. 

i keep coming back to the dayton RSS315HO-44 12" Reference HO DVC Subwoofer. 

with all the requirements listed this seems to be the best choice of the bunch. 

consider that you have room for a 10" driver and two passives, wouldn't you want
a powered 12" that fits the desired impedance, can use a very small sealed volume
or can reach an f3 of 27hz in a 1.3cuft volume ?
1.3 cuft feet is not huge, quite manageable if you ask me. 
aluminum cone and rubber surround for " toughness ", and not too silly heavy. 

for the price this is almost the only woofer that fits the bill. 
i would port this and design the enclosure with the needed depth & room. 
but at the 500 watt power level this sub could be sealed and use a larger box to bring
down the f3 ( stuffing could also help ). 

seems like a winner to me. best of all worlds for the application.


----------



## Grinder (Dec 18, 2016)

lurch said:


> well i've spent the last two hours browsing PE's web site, looking and comparing
> many 10's and 12's.
> 
> i keep coming back to the dayton RSS315HO-44 12" Reference HO DVC Subwoofer.
> ...


Thanks!!!

I have no preference for the 10" (apart from its higher sensitivity spec and lighter weight) or for PRs (apart from potential port length and port noise issues). I've been just as (or more) attracted to that 12," for it's slightly smaller enclosure requirements, for both sealed and ported (and greater cone area).

I'm not even sure its 47Hz F3 is an issue. I wonder what the F3 would be (sealed) at the same 1.36 as ported (or somewhere in between the 1.36 and 0.49). *In either case, how do you think it might compare in SPL and extension to the ported IX-8 (is there any way to predict this?)?*

As for building the cabinet with the needed depth for a port, it looks like (with 1.36 cubes, 27Hz, and a 3" dia.) it would be 17" long (4" dia. would be over 31" long). Wouldn't I need at least 4" dia.? Seems like I'd need one or two elbows, and quite a bit of extra cabinet volume...

Okay... So, it seems we've narrowed down to this 12." But I'm still not sure how best to use it.


----------



## lurch (Jan 20, 2014)

ok, this is " old school " and flawed but in " the olden dayz " we used to compare 
woofer sizes as follows :
1 x 8" = 8
2 x 8" = 10
2 x 10" = 12. 

so you " almost " get the area of four 8's in a twelve inch cone. 
you would have the authority of your mom's speakers in one sealed 12" enclosure. 
add approx another 3db if ported or slotted. 
slotting this design could be the best compromise as the the port volume becomes
integral to the cabinet and can be designed take up the least depth. 
again, the only issue with that is not easy to adjust tuning if desired. 

a larger sealed box would probably be about .75cuft. ( but i will do it up on the computer
to be sure, later ) 

for a really interesting design look up 
" decware deathbox "
this is an adjustable bandpass box that may give you a few new ideas. 
take a look at all their plans on the web site. interesting stuff !


----------



## Grinder (Dec 18, 2016)

lurch said:


> ok, this is " old school " and flawed but in " the olden dayz " we used to compare
> woofer sizes as follows :
> *1 x 8" = 8
> 2 x 8" = 10
> ...


I like the sound of that!

...and that too! Thank you!!!

Hmmm... "deathbox from hell" has a nice ring to it.  I'll take a look at that. Thanks again!


----------



## Grinder (Dec 18, 2016)

lurch said:


> ok, this is " old school " and flawed but in " the olden dayz " we used to compare
> woofer sizes as follows :
> 1 x 8" = 8
> 2 x 8" = 10
> ...


8" (flat circle) = 50.27 sq. in.
2x 8" = 100.54 sq. in.

10" (flat circle) = 78.54 sq. in.
2x 10" = 157.08 sq. in.

12" (flat circle) = 113.1

4x 8" = 201.08 sq. in. (or 1.78 x 12", suggesting the cone area of four 8s would be closer to that of two 12s than one).

However, the ratio of surround area to cone area (assuming their surrounds would be approximately the same width) would seem to favor the 10" over the 8", and the 12" over the 10" (and would skew the above comparisons to that extent).


While I'd really like to know how well the 12" models sealed (and ported), I'm leaning more and more toward ported. And bearing in mind that I'd like to go with the .4 ported cubes for the RFs (assuming successful testing), such a cabinet (assuming 1.4 cubes for the ported sub) would be 2.5+ cubes (gross) in total (or a bit larger than the test rig), I'm considering the option of purchasing two of these 12s, and building a killer pair of speakers instead. Thoughts? (I wouldn't be surprised if you're questioning my sanity, because I am... LOL)


I think I see what you mean about the Deathbox (lots of great food for thought toward ported and sealed enclosure testbed ideas). However, I'm not nearly as much of an audio-experimentation enthusiast as I might otherwise be (due to limited time, money, inclination, and extremely confusing and frustrating psychoacoustics). Unfortunately, I'm much more of an "immediate gratification" kind of guy than I'd like to be. As for bandpass subs, I don't think I'll ever build (or be happy with) one of those, particularly in a time when amplification seems to be cheaper than ever.


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## lurch (Jan 20, 2014)

actually, i was going to suggest building a pair of enclosures, a pair will KILL a single
boogie box. so, YES, do that !

gonna plug in the numbers for a ported / sealed design on the daytons later tonight. 
i will pay special attention to the pipe diameter and see what's best.

" later "
well i see why people recommend this driver so often. 
I modelled a few different sizes and tunes. 
I also see why builders don't use a 4" tube, it needs to be stupid long, like in the
30" area !
so best bet at 1.4 cubes = 
BLUE LINE
tune = 33hz
tube = 3" x 10"
if we go any lower with the tuning freq the port gets noisey, but not terrible. 
you could go down to 30hz ( pipe = 12.6" ) RED line, which is just over
the port velocity limit. 

yellow line = 0.8 sealed
green line = 1.628 cuft @ 23.5 hz ( 4" tube x 34 inches long ! )


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## lurch (Jan 20, 2014)

graph pic


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## Grinder (Dec 18, 2016)

WOW! THANK YOU!!!

If I do a pair of cabs, I won't mind going a bit bigger (maybe up to 2 cubes or so?), if it would get me closer to the green line, with a manageable tube length. 

Also, are elbows a problem? Given the necessary 12"+ width, and the minimum height required for the three drivers and two ports (and incidentally, should the RF and sub ports be separated by some distance, lest they interfere with each other?), the cab(s) won't likely be very deep - even at 10" I'll likely need an elbow (would two 45s be better than one 90? Or, if I could find them - think conduit - would 90 deg. "sweeps" be that much better?). And, other than gobbling up cabinet volume, are there other reasons that give shorter ports an advantage over longer ones? I assume that I'd need some sort of bracing for a longer port, particularly one with an elbow (to keep it firmly in place).

FWIW (probably not very much, LOL), I'm worried about 3" ports... I can't seem to wrap my head around the fact that I'm getting port noise from an IX-8 with a 3" port; and yet one of those 12" beasts would be fine (i.e. no port noise) with a 3" port. Simply mindboggling!


----------



## lurch (Jan 20, 2014)

I remember reading in " the loudspeaker cook book " that ports should be as 
long as possible and as wide as possible. 
so a long 4" pipe is better than a short 3" pipe, but it is always a trade off in the design. 
i modelled a 3.5" tube that looked pretty good, can't remember the specifics now. 
if you can find a diameter that is in between 3-4 i can do up a model. 
even another quarter of an inch can make a big difference. 

elbows :
elbows are not a problem, just measure ( or calculate ) the distance through
the center and that's the length of the pipe. 

I've seen conduit used, but not personally, need to be carefull of the ribbing because
of turbulence. i may try this myself if i can find the right type in the future. 
conduit needs to be pretty stiff, else it will start to vibrate and cause odd harmonics. 

not sure about the proximity of the mid port to the bass port. dunno. 

anyways, i'll do up a 2cuft enclosure later tonight, see what winisd has to say about that.


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## Grinder (Dec 18, 2016)

lurch said:


> I remember reading in " the loudspeaker cook book " that ports should be as
> long as possible and as wide as possible.
> so a long 4" pipe is better than a short 3" pipe, but it is always a trade off in the design.
> i modelled a 3.5" tube that looked pretty good, can't remember the specifics now.
> ...


KEWL! THANKS!!!

Come to think of it... I've been focusing on tubes, partly for tuning flexibility, and partly for minimum weight (in the case of a boombox), but if I'm making a pair of speakers instead (where weight is not as much of a concern), I might as well go with a slot port instead. And here's an idea: Through the 11" sub cutout, I might be able to adjust the port length, by trimming a weather-strip-sealed removable panel that would form the first several inches of interior port length. I'd drill pilot holes (which I always do anyway), and run the screws in and out a bit first, to make life a lot easier when I'm in there later with a stubby screwdriver, pulling/replacing the panel for tuning. Sound like a plan?

And bearing in mind the "longer and wider ports are better" concept, do you think the seemingly short length of the RF port (3" dia. x 3.5" long, IIRC) would present any problems? In any case, I suppose I could do slot ports for those as well. EDIT: though tuning such short slot ports would seem to be less practical.


----------



## Grinder (Dec 18, 2016)

Also, I'm seriously considering going active with the RFs (scrapping the RF passives and getting a small, clean amp to run them by themselves - at 105dB sensitivity and 8 Ohms), which would allow all 125W RMS (at 4 Ohms) to go to the RF 8s, instead of whatever they're getting now (RF Tech has led me to believe that, with the current configuration, the amp is seeing approximately 6 Ohms nominal), and perhaps later on, getting a Crown XLS 1002 or XLS 1502 (replacing the two R500X1Ds) for the subs.


----------



## lurch (Jan 20, 2014)

Grinder said:


> KEWL! THANKS!!!
> 
> Come to think of it... I've been focusing on tubes, partly for tuning flexibility, and partly for minimum weight (in the case of a boombox), but if I'm making a pair of speakers instead (where weight is not as much of a concern), I might as well go with a slot port instead. And here's an idea: Through the 11" sub cutout, I might be able to adjust the port length, by trimming a weather-strip-sealed removable panel that would form the first several inches of interior port length. I'd drill pilot holes (which I always do anyway), and run the screws in and out a bit first, to make life a lot easier when I'm in there later with a stubby screwdriver, pulling/replacing the panel for tuning. Sound like a plan?
> 
> And bearing in mind the "longer and wider ports are better" concept, do you think the seemingly short length of the RF port (3" dia. x 3.5" long, IIRC) would present any problems? In any case, I suppose I could do slot ports for those as well. EDIT: though tuning such short slot ports would seem to be less practical.


we will need to know what the dimensions are before i can model anything,
keep in mind that if the box is shallow an " L " slot will be required and that
could be difficult to adjust. 
I'm sure you'll figure out a way though ...

start drawing. 

the RF round port will be just fine, there are many enclosures with much shorter
ports than that.


----------



## lurch (Jan 20, 2014)

Grinder said:


> Also, I'm seriously considering going active with the RFs (scrapping the RF passives and getting a small, clean amp to run them by themselves - at 105dB sensitivity and 8 Ohms), which would allow all 125W RMS (at 4 Ohms) to go to the RF 8s, instead of whatever they're getting now (RF Tech has led me to believe that, with the current configuration, the amp is seeing approximately 6 Ohms nominal), and perhaps later on, getting a Crown XLS 1002 or XLS 1502 (replacing the two R500X1Ds) for the subs.


GOOD PLAN !!


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## Grinder (Dec 18, 2016)

lurch said:


> GOOD PLAN !!


SWEET! 

Any recommendations on an amp for those 8 Ohm tweets?


----------



## Grinder (Dec 18, 2016)

lurch said:


> we will need to know what the dimensions are before i can model anything,
> keep in mind that if the box is shallow an " L " slot will be required and that
> could be difficult to adjust.
> I'm sure you'll figure out a way though ...
> ...


Thank you!

Do you mean port dimensions (and net cabinet volume)? If so, I understand. If not, could you elaborate?

Yeah, it'll definitely have to be an "L" slot, but the vertical portion of the "L" will surely be long enough to adequately trim its length before running out of vertical port (but maybe I've misunderstood you. Might I be missing something?).

Yeah, I'm rather fond of desk blotter sized 1/4" graph paper, and attaching multiple sheets to together, when necessary, for full-size drawings. I'm itching to order those subs, but I really should (and will) put pencil to paper first.

10-4 on the RF ports! 

This is very exciting!!

Thank you (once again!) for all of your help!!!


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## lurch (Jan 20, 2014)

Grinder said:


> SWEET!
> 
> Any recommendations on an amp for those 8 Ohm tweets?


i went and looked at RF's site and looked at what i think are your tweeters :
PPT-4 
right ?
4 ohm and rated 50 watt rms. ( a little surprising, i figured they'de be 
at least 100 rms )
anyways, an amp.... ****, anything between 75 - 125 watts per ch ?
find something second hand and newer for 50 bucks in your local online
buy& sell ?


----------



## lurch (Jan 20, 2014)

Grinder said:


> Thank you!
> 
> Do you mean port dimensions (and net cabinet volume)? If so, I understand. If not, could you elaborate?
> 
> ...


ok, yup, that's the right idea regarding the " adjustable " slot, just so's
we're talking about the same thing.


----------



## Grinder (Dec 18, 2016)

lurch said:


> i went and looked at RF's site and looked at what i think are your tweeters :
> PPT-4
> right ?
> 4 ohm and rated 50 watt rms. ( a little surprising, i figured they'de be
> ...


I bought the PP8-Ts instead, the 8 Ohm version (which have evidently been discontinued), to help deal with their ultra-high 105dB sensitivity (compared to the 94.5dB sensitivity of the PPS4-8s). 

And I just remembered that these things (and the PP4-T as well) have built-in crossovers: "Built-in 6dB/Octave crossover." Also, my PP4-X "crossovers" (along with the PP8-X 8 Ohm version) have evidently been discontinued as well (and it's no wonder - all they do is low-pass the midbass, and attenuate the tweeter @ a selectable -0dB/-3db/-6dB ...and -6dB is still too much. It seems that 50W @ -0dB setting might cause permanent hearing loss! LOL). 

Maybe I could bypass/remove their built-in crossovers.


As for tweeter amplification:

(according to) Peak SPL Calculator

105dB sensitivity @ 50W, 3 feet = 125.8 dB SPL!!!

105dB sensitivity @ 12W, 3 feet = 119.6 dB SPL

94.5dB sensitivity @ 125W, 3 feet = 119.3 dB SPL (PPS4-8s + P400-X2 amp)

Am I missing something?

I looked around awhile back (last year, before and after I purchased these tweets) for an affordable small clean amp for these, and soon gave up... I assume class D is out (waaaaayyyyy too noisy for 105dB sensitivity, aren't they? - think HISSSSSSSSSSSSSSSSSSSSSSSS). I'm thinking I'll need something very clean... But then there's the power rating versus gains settings - do low gains generally mean less noise (i.e. a 30W amp's gains turned halfway up should be a lot noisier than a similar 60W amp's gains turned up 1/4? 

I just don't know... 

I don't have much money to spend, but I'm not at all big on used. And I live in the boondocks (rural Northeast - so "local" isn't likely a viable option).


----------



## lurch (Jan 20, 2014)

NOW i understand, LOUD tweeterage !

i just came across an old school yamaha YPA-600 on our local internet buy & sell. 
50+50 watts, bridgable 150 , very conservative ratings. 
55 bucks. 
something like this would be perfect. 
but if you're in boony-land ( and i know where that is ...) i totally understand being
hesitant, more trouble than it's worth. 

i still say get more power, you are right about the gains, if kept low the noise won't 
creep in so easily. 
stick to class a/b and look for 100 per side, 75 would be sufficient. 

there is so much choice out there I couldn't begin to list all the amp,ifiers in that 
power class. even a large boss would probably be fine. 
i have a boss four channel in the closet as a backup in case i ever need a spare to
get me through, it's ok, really. it claims outrageous power ( 2400 watts , LOL ) but
it works just fine and I haven't experienced anything particularly bad about it. 
a two channel 400 watt boss would most likely run just fine for you and be delivered
to your door for less than 80 bucks. just sayin ....
just be sure that it has the appropriate xover settings. 
and yeah, once that is figured out you can ditch the capacitor and have a better slope
through the amp. 
maybe that's something more important than power, a decent built in xover. 
a good preamp section may be more desirable than power in this case.


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## Grinder (Dec 18, 2016)

Good stuff! Thanks, it helps a lot!

But I'm wondering about your built-in x-over recommendation. Since I'll be using my miniDSP's x-overs and PEQs for the mids and tweets (separately), I'm thinking I'll have no need for built-in x-overs (except to protect the tweets, should the miniDSP ever fail to adequately high-pass them? But barring that particular issue, wouldn't it be best to let the miniDSP do all of the processing?)


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## lurch (Jan 20, 2014)

oh ****, i thought you were going to run passive, or something, when did i lose
my way here ? 

GREAT ! mini dsp , excellent. 
personally, i would still bypass the cap on the tweeter. 
labell the rca's clearly and the amp channels, safe enough. 
you will have SO much control with the processor, the system will improve 
100% just by implementing the minidsp.


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## Grinder (Dec 18, 2016)

lurch said:


> oh ****, i thought you were going to run passive, or something, when did i lose
> my way here ?
> 
> GREAT ! mini dsp , excellent.
> ...


My thoughts, EXACTLY! 

Remember this? 
"Also, I'm seriously considering going active with the RFs (scrapping the RF passives and getting a small, clean amp to run them by themselves - at 105dB sensitivity and 8 Ohms), which would allow all 125W RMS (at 4 Ohms) to go to the RF 8s, instead of whatever they're getting now (RF Tech has led me to believe that, with the current configuration, the amp is seeing approximately 6 Ohms nominal), and perhaps later on, getting a Crown XLS 1002 or XLS 1502 (replacing the two R500X1Ds) for the subs."


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## lurch (Jan 20, 2014)

how' bout a pioneer GM a3602 ?
very good value.


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## Grinder (Dec 18, 2016)

lurch said:


> how' bout a pioneer GM a3602 ?
> very good value.


Thanks!

Not finding those in stock, but this looks like it might be a newer version of the same, for $59.99 (not sure of the price for the 3602).
https://www.crutchfield.com/S-7LKFXgOeHDP/p_130GMA3702/Pioneer-GM-A3702.html


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## lurch (Jan 20, 2014)

i figured the american version would be a bit different than the canadian model, and
yes they are, just slightly. 

i compared them to the RF prime 150x2, guess what, these little pioneers out do
the rockford, and by a good margin. 
then compare the price .....

these little guys are everywhere ( GM series ) in canada, i've installed more than a 
few myself. 
one of our largest store chains in this country sells kagillions of these for cheap, they are
always on sale...... Canadian Tire ....

i've seen them under the seats of pickups, not bolted down and full of snow, ice, gravel,
both, hay, horse ****, cow ****, chicken ****, emersed in a puddle in a trunk, bouncing
around in the box of a pickup, mounted under a dog bed in the back seat ( to keep
the dog warm ...) , rattling around in the engine compartment , etc. etc. etc. .

they ALWAYS work !
i have never found one not in working order. 

i had a few of the first line of the these " GM 120 " , when the exterior was full of
big radiating fins. these are the staple of car audio amplifiers, and they just keep
going and going and going. 
and they sound good !

for sixty bucks.


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## Grinder (Dec 18, 2016)

I happened to notice, for the same price, the Sony XM-N502 https://www.crutchfield.com/p_158XMN502/Sony-XM-N502.html?tp=35757 has a better S/N ratio (93dB, compared to 75dB for the Pioneer).

In either case, considering my tweets are 8 Ohms, I'm wondering (@ 60W or 65W) if their gains would be low enough for minimal hiss.


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## Grinder (Dec 18, 2016)

Working on a drawing. Wondering if the RFs would be fine with 2" dia. ports instead of 3"?

I hope so, because it would allow a shorter port, and thus a shallower depth for the RF portion of the cabinet (in which case the interior dims would be approximately 15" H x 12" W x 4" D).

EDIT: Turns out this isn't going to be a problem.

Of course, I still need to port the RFs in the test rig, and see how they sound, but I need to draw the whole concept first, to see how everything will go together, and to work out the slot-ported subwoofer portion of the cabinet.


----------



## lurch (Jan 20, 2014)

Grinder said:


> Working on a drawing. Wondering if the RFs would be fine with 2" dia. ports instead of 3"?
> 
> I hope so, because it would allow a shorter port, and thus a shallower depth for the RF portion of the cabinet (in which case the interior dims would be approximately 15" H x 12" W x 4" D).
> 
> ...


just brought up the RF sim,
a 2" port at that freq yields a length of .82". 
but if we go 2 x 2" ports we get 3.11". 
hhhmmmm ...


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## Grinder (Dec 18, 2016)

lurch said:


> just brought up the RF sim,
> a 2" port at that freq yields a length of .82".
> but if we go 2 x 2" ports we get 3.11".
> hhhmmmm ...


OH YEAH!!! I LIKE THAT!!!! Twin ports will look a lot better, and they'll fit a lot better on precious baffle real estate!

Been having fits over porting the subs. The main issues are that the RF compartments will be in the way of the adjustable portion of the slot port, and it seems there might be airflow issues from the sub to the port for the same reason (remember the long vertical "L" shaped port).

So, I thought about turning the port upside down, but I want the mids and tweets as high in the cabs as possible, as they're likely to be a bit short to begin with, and I'm thinking that the sub port opening should be close to the floor.

I also thought about a variation on that theme, where the horizontal portion of the "L" (instead of exiting at the top of the cab) would take a 90 degree turn downward, behind the RF compartment, and take another 90 degree turn toward the front of the cab, exiting just below the RF compartment (which would still be rather far from the floor, as it would only be about 14" - 15" from the top of the cab, which might be well over 30" tall). But this seems rather convoluted as well, and I'm worried about possible turbulence and/or flow issues of the extra turns (not to mention how all of this might affect the sound and/or tuning).


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## Grinder (Dec 18, 2016)

FINALLY, I’m gonna port the RFs in the test rig tomorrow (at least that's the plan). Played around with a calculator and scrap pieces of 2x4 today, and it seems I'll need to cram 7 feet's worth of them (and/or bits of scrap MDF, etc.) into each 0.6375 cube RF chamber, to cut their volumes to 0.4 cubes each.

I only have 1.5" and 3" PVC (no 2" stock - apart from the shop-vac tube, which is rather problematic). And since twin ports would definitely fit the baffles better, it would seem best to go ahead and test twin ports - even though a pair of single 3" ports will fit the test rig better than a pair of twins. So, unless you think twin 1.5" would be fine, I'll go get some 2" and go with those instead (it'll be no big deal at all).

I've been reading the http://www.diymobileaudio.com/forum...sion/11192-sealed-vs-ported-sq-myth-fact.html thread (I’m only about halfway through page 3 so far), and I've been thinking about some stuff I read there (about porting heavy-cone, low fs subs designed for small sealed cabs, versus lighter, efficient, higher FS subs designed for ported cabs), and about your comment in our PM regarding my need for these HO 12s to be tuned somewhat more like traditional tower woofers than full-on subs; and I’ve been thinking that, if porting the RFs doesn't work out well (and maybe even if it does work out), I might be better off (in terms of blending the RFs with the HOs) going sealed with the HOs, and sacrificing their efficiency, extension and SPL, for better SQ (or maybe I should consider using different subs - ones designed more for porting). HOWEVER…

…I'm just “thinking” out loud, and I take for granted that I'm still mostly clueless. It's just that I'm on the verge of ordering these babies (and the ports to go with them), and I just want to sort of tie up these last-minute loose ends in my head before I take that big leap forward.


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## Grinder (Dec 18, 2016)

I promised ported IX-8 impressions of my test rig, and having done further tuning and listening, I am evermore impressed! It still seems WAY more powerful than it has any right to be, and I think it sounds (or at least it is capable of sounding), SQ-wise, much better than I ever expected (and light-years better than sealed - due to the fact that it simply plays much flatter, lower, and waaaayyy punchier than when it was sealed). 

I don't yet feel qualified to say much more than that. For all I know, objectively it might sound like crap; however, for what it is, I am very happy with it's overall performance in it's present ported alignment.

And I owe it all to you, lurch! THANK YOU!!!!


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## lurch (Jan 20, 2014)

i don't think 1.5" tube will work, a 2" single port is barely longer than the thickness of
3/4" thick wood, meaning that a 1.5" tube will be even shorter, even if two 1.5" ports 
were used. 

so, stick with a single 3" or two 2" ports. 

i've read that books can be used as cabinet reducers. or bricks for experiments. 

as for sealed vs. ported ...... PORT it.. ( but that's just me, cuz i like it loud ). 
the efficiency bandwidth of this woofer is right smack in the middle of best of both
worlds, you can't lose either way. ( i still say port it ). LoL.

edit :

you are very welcome, sometimes i get it right. 
crossing fingers for this next one, looks good on the computer, although
" HAL 2000 " has been known to lie.


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## Grinder (Dec 18, 2016)

OKAY!!! I'll port them, thank you very much, LOL!

And thanks for the 2" vs 1.5" ports feedback!

edit :

  -you are too modest, my learned friend!
me too, but I'm very optimistic (and I've got a good feeling...) 
good thing we don't rely solely on HAL, LOL!


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## Grinder (Dec 18, 2016)

Well... 

I'm not sure how to go about telling you this...

So, I guess I'll just come right out and say it...


----------



## Grinder (Dec 18, 2016)

...as you can see, I managed to get the ports installed today, and...




IT"S A MIRACLE!!! epper:

ABSOLUTELY STUNNING!!! :stunned:

The difference is INCREDIBLE!!! :rockon:

YOU! ARE! THE! MAN! :bowdown:


THANK YOU!!!!!! :

(detailed impressions to follow, when I've begun to wrap my head around it all)


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## Grinder (Dec 18, 2016)

...haven't turned the sub on yet, and I'll be listening to them for a while without it. 

I was pretty sure the ports would help, but I was completely unprepared for this... 

I'm all out of superlatives (and all this raving is cutting into my further discovery and listening pleasure) so I'll shut up for now.


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## Grinder (Dec 18, 2016)

...and I just ordered the pair of 12" HOs and 3" flared ports!

SO EXCITED!!!


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## lurch (Jan 20, 2014)

Grinder said:


> ...as you can see, I managed to get the ports installed today, and...
> 
> 
> 
> ...


lmao !
YAAAAAAY !


----------



## Grinder (Dec 18, 2016)

(First of all, I should mention that I spent yesterday morning gathering wood and MDF scraps - good thing I throw nothing away, LOL - and carefully taking measurements and calculating volumes. It took some doing to get all the scraps fitted into the cabs (and it seems as if there couldn’t be 0.4 cubes open space in there, but… Anyway, I shoved some Poly quilt-filling in there, and the two pairs of 2” dia. X 3” long ports, and got down to business…)

Okay, here goes...

To begin with, I turned off the sub, set all the RF PEQ settings flat, bypassed x-over settings, and cranked (moderately cranked) some tunes.

First impressions (apart from, stuff like “WOW!!!” and "Holy ****!!!” and “It worked!!!"): 
For the first several minutes I moved quickly from song to song (listening for only 30 seconds or so before moving on to the next), with a big ol' ****-eatin' grin on my face, marveling at the newfound (and 100% natural) rich fullness of sound.

Depending on the track, there’s anywhere from about 70% to 110% of the “ideal” (according to my taste) amount of warm, effortless midbass (i.e. stuff like Rush, and Robert Plant were, as expected, on the 70% end of the spectrum and rather thin, while stuff like Medeski, Martin & wood, and Stanley Clarke were, as expected, on the 110% end of the spectrum and a bit thick), which is, I think, just about right (perhaps an 80% to 120% spread would be perfect, according to my somewhat bass-heavy taste), evidenced by the fact that the majority of what I’ve heard so far seemed to have about the right amount of midbass. And they seemed noticeably sharper/livelier/lighter/clearer than before, and (dare I say it again) effortless.

I soon moved on to the Online Tone Generator - generate pure tones of any frequency , to see what I could learn (about how much lower they were going, and how much flatter their response was than before, and to make sure my ears weren’t lying), and WOW… they were going solidly down into the 50s!!! (whereas they used to begin falling off, IIRC, in the 200 Hz neighborhood. 

And then today I played around with the tone generator again, as a means to set the PEQs (nothing over +/- 5 – 8 dB or so, mind you – and mostly dealing with room resonances, I think), but in the end, I simply liked flat better (with a bit of + 70 - 80 Hz thrown in, and the HP set to 60 Hz - with a 48 dB BW slope). And excursion is way, way, way down from what it was! And no disconcerting “PUH” sound anymore either.

I think that pretty much covers it. 
Got any questions? 
Have I left anything out?

Also, I’ve been thinking all day about how I might best port Mom’s RFs (without building new cabs), and the best I’ve come up with: Picture twin 3” dia. (not sure how long) ports elbowing out the top of the cabs (facing forward). Why twin 3”? So they’ll (hopefully) be long enough to extend below the tweeter chamber (so I may close off or fill in the area behind the tweeter chamber, to help get down to 0.4 cubes). I don’t want to build new cabs, but I will if I can’t find a predictably workable option. Ideas?

Oh yeah… and one last thing: 
Now you’ve got to figure out a way to port your doors! LOL!


----------



## lurch (Jan 20, 2014)

A W E S O M E ! !

this is great news !

have you played them with the sub yet ?

interesting that you mention dropping the HP to 60Hz, i did the same thing the other
day with a 12db slope and no ill effects whatsoever, and the PUH sound has disappeared,
making me think that this could have been a loosening up period, and the distortion that
was present under 80hz when driven hard has also vanished.
go figure ....

it seems we got your tuning pretty close to right given that the cones are not moving
much, this does show that they are happy and the cabinet is doing most of the bass
duty and not over driving the rf's. 

HAL got it right !

my eq through the same pass band is similar to yours too, basically flat except for a gain
in the 70 - 90 hz region and of course pulling down bits in the 1 - 3 Khz zone. 

right now I'm experimenting with time delays between the rf's and the sub, think i may
have almost got it right today, progress. 

hhhmmmm..... elbows through the top, hhmmmm .....
there's got to be a better way. 
i would definitely need to see a drawing to wrap that around in my head. 

i put some thought into porting my doors too , LoL. 
it " could be done " but sheeeesh, a lotta work to build a .4cuft enclosure in there. 
wish i had the time and energy though, sounds totally worth it!


----------



## lurch (Jan 20, 2014)

something like this ?


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## Grinder (Dec 18, 2016)

lurch said:


> A W E S O M E ! !
> 
> this is great news !
> 
> ...


Oh yeah... How could I have forgotten *that* (thank you. Long day I guess)? Of course, integration/blending of the RFs and sub is a million times better than before. The RFs are so much happier, now that they're not being *forced* to play midbass (but rather doing it so much more naturally); and the IX-8 sounds so much better (and all the happier), now that it's not being asked to be a ported sub *and* a midbass at the same time.

...Which has solved the only issue I had with this ported arrangement: Boominess. When the IX-8 was sealed, it almost sounded as much like a midbass (or woofer) as it did a sub. And while I really, really (really!!!) like the effortless/powerful punch and low-end from porting the IX-8, it has unfortunately (pre RF ports) or fortunately (post RF ports), lost much of its midbass potential, due to a tendency toward boominess in the lower midbass range, which made the ported IX-8s integration/blending with the non-ported RFs rather problematic. And I think this is why I was having such a hard time giving my impressions of the ported IX-8, because I knew on some level that the ported IX-8 should be judged on its own terms, for what it is meant to do (not for what my non-ported RFs happened to still need it to do); and until now, I haven't really understood all of that enough to put it into words.

And yesterday I set the sub's H/L x-overs (48 dB BW slopes) to 25 Hz and 80 Hz respectively (with a moderately steep 10 dB bump of 30 Hz PEQ), and it has never sounded better! And the blending/integration (not sure of these terms) of the RFs and IX-8 (in terms of their respective frequencies - IDK about TA and such) seems very good (and sooooooooooooo much better than ever before!).


Thanks for the interesting x-over and EQ feedback! It's really good (and rather reassuring) to hear that we've been pretty much on the same track!

And I was thinking the same thing (must be spot-on tuning), regarding the vastly decreased excursion (way to go, HAL!!!). 

I was mostly kidding about porting your doors (though I had no doubt that you would give it some thought). I can barely imagine how one might build an enclosure inside a door. Like a ship in a bottle? LOL


----------



## Grinder (Dec 18, 2016)

lurch said:


> something like this ?


Great idea, thank you!

...I'd already considered something like that, but looking at my drawing, it seems there's too little room around the RFs (less than an inch between the inside corner of the cab and the outer edge of the basket). So, even with four such triangular ports (one at each corner), I can't imagine they'd add up to much more than one 2" port's worth of area. 

In any case, it'll be worth popping one out to have a look. And if it turns out to be a definite no-go, I'll follow-up with a drawing of my uber-chic "stereoscopic-periscope port" concept (I know... it sounds ultra-kewl, doesn't it? ).


----------



## Grinder (Dec 18, 2016)

More good news (I think):

Turns out I didn't even need to pick up a screwdriver... 

Having suddenly remembered that I'd snapped a number of pictures of the raw enclosures, I was quickly reminded of the fact that, during the enclosure assembly process, I'd made a last-minute change (in order to further maximize RF enclosure volume, LOL!), placing the horizontal divider panels (immediately above and below each RF) about an inch further apart; which, as dumb luck would have it, will allow four triangular ports of at least 1.5 sq. inches each (or 6 sq. in. total), or as much as 1.8 sq. inches each (or 7.2 sq. in. total ), while a pair of 2" ports = 6.28 sq. inches total. Practically speaking, I'd prefer the 1.5 (or 1.6), for margin of error.

So, it looks quite doable (though rather messy and labor intensive) - provided these ports won't need to be any longer than about 5" or so (the depth of the tweeter compartments). However, I suppose could deal with another few inches if necessary.

And while these wouldn't be anywhere near as kewl as Stereoscopic Periscope Ports; having described them to Mom, she'd *much* rather have the four triangular ports - if I must *insist* on adding ports at all (and I must, LOL).


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## lurch (Jan 20, 2014)

LOL !

yeah, mom doesn't want her speakers looking like an old WW2 " victory ship " with
the horn shaped thingies sticking out all over the place, and I can't blame her. 

ok ! settle on what size they can be and i'll do up a quick HAL sim. 
or put a few more days thought into it, sometimes the light bulb will come on
and the problem is suddenly solved. 
cuz i know what you're thinking , those triangular slots look kinda ugly.


----------



## Grinder (Dec 18, 2016)

Grinder said:


> Oh yeah... How could I have forgotten *that* (thank you. Long day I guess)? *Of course, integration/blending of the RFs and sub is a million times better than before. The RFs are so much happier, now that they're not being forced to play midbass (but rather doing it so much more naturally); and the IX-8 sounds so much better (and all the happier), now that it's not being asked to be a ported sub and a midbass at the same time.
> 
> ...Which has solved the only issue I had with this ported arrangement: Boominess. When the IX-8 was sealed, it almost sounded as much like a midbass (or woofer) as it did a sub. And while I really, really (really!!!) like the effortless/powerful punch and low-end from porting the IX-8, it has unfortunately (pre RF ports) or fortunately (post RF ports), lost much of its midbass potential, due to a tendency toward boominess in the lower midbass range, which made the ported IX-8s integration/blending with the non-ported RFs rather problematic. And I think this is why I was having such a hard time giving my impressions of the ported IX-8, because I knew on some level that the ported IX-8 should be judged on its own terms, for what it is meant to do (not for what my non-ported RFs happened to still need it to do); and until now, I haven't really understood all of that enough to put it into words.
> 
> ...


Whaddaya think of all that?



As for the four (or eight) triangle ports: 

Generally speaking, I like things to look as good as they can - within the context of "form follows function." To me, a thing's function has a beauty all its own. 
And as small as they'd be (relative to the size of the driver), I think they might look pretty cool.

In the last couple days, I haven't been able to think of a more elegant solution.


So, for modification/fabrication, port length, and appearance reasons, I'm inclined to think the smaller (1.5 sq. inches) ones would be best - if their slightly smaller area (6.00 vs 6.28) wouldn't be a problem. 

But let's see what HAL says... 

I'm champing at the bit to do this... 

I feel like such a schmuck for making those cabs so huge - in an effort to (ironically) enhance their midbass response. 

...and I relish the opportunity to (more or less) make it right (I'll always see those massive upper cabs as a ridiculous mistake, but at least those RFs will finally be all that they can be). 

Thank you!


----------



## lurch (Jan 20, 2014)

" whaddya think of all that? "

i think it took me three tries of reading to understand it all , LoL !
and it should be VERY interesting to see how the rf's sound with your moms sealed sub
arrangement. 

ok, just did a quick sim. 
what i get for port area differs from yours :
if i calculate four triangular ports with 1.5" sides ( consider them to be TWO square 
ports that are 1.5 x 1.5 ) i get 4.5 square inches. 
maybe i've screwed up here ?
a round 2" port = 3.14 sq in. ( x 2 would be 6.28 )

anyways HAL says that the triangular ports should be 2.2" long if we are using the
same enclosure volume and tuning as your computer test rig. 

so : each rf 8" woofer needs FOUR triangular ports, short sides of the triangles
being 1.5" long and 2.2" inches in depth. 
if just two triangular ports that size are used the length becomes 1/2" which is
shorter than the thickness of the wood of the baffle. ( and probably noisey to boot )

looks like you have some intricate work ahead of you !


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## Grinder (Dec 18, 2016)

Geez... I hadn't really thought about that... However, I've got Mom's RFs PEQ'd to beat the band, and her subs operating in a small, low passband; and I'm reasonably certain that it's gonna be a HUGE improvement. Anyway, I think it can only help.

My 1.5 number was their area (approximate square inches), and their dimensions would be a 1.75" x 1.75" Right Triangle (1.53 square inches).


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## lurch (Jan 20, 2014)

OH !

ok hangon ...

edit :

3.2" deep !
( very interesting how that all worked out .... )


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## Grinder (Dec 18, 2016)

I love it!

Thank you very much, kind Sir!!!

I'm gonna try to get started on this today.


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## Grinder (Dec 18, 2016)

Grinder said:


> I love it!
> 
> Thank you very much, kind Sir!!!
> 
> I'm gonna try to get started on this today.


Still haven't started yet. Having second thoughts, mostly due to previously unforeseen problems with making decent guide lines on the speaker cabinet carpet to accurately follow with the jigsaw. 

And I'm thinking I'd mess up the carpet with a ton of MDF powder (among other things).

So, it's looking like I'm going to build Mom a new pair of cabinets (with ported IX-8s instead of sealed).


Also, those HO 12s (and ports) arrived today, and boy are they beautiful beasts! Hooked 'em up (one at a time, and one coil at a time - to make sure they're working ok) to my boombox amp (the RF R400-4D, bridged rear channels), and played around with the tone generator at low volume for a few seconds, and rattled the house! Now I REALLY see why double baffles and lots of bracing are so important!


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## Grinder (Dec 18, 2016)

Grinder said:


> Still haven't started yet. Having second thoughts, mostly due to previously unforeseen problems with making decent guide lines on the speaker cabinet carpet to accurately follow with the jigsaw.
> 
> And I'm thinking I'd mess up the carpet with a ton of MDF powder (among other things).
> 
> ...


It’s been an interesting process determining the overall shape and requisite dimensions of Mom’s new speaker cabinets, as the tweets, 8s and twin 2” ports require a LOT of baffle area, compared to the relatively small 0.4 cu. ft. volume required for the upper chamber of the cabinet (and I am loath to build-in any useless cabinet volume).

So, to address the upper chamber’s conflicting need for large baffle area versus small volume (and to reduce internal standing waves), the rear panel is angled inward toward the top. And at 41” H x 9” W x 19” D (at the bottom), and 3.5” D (at the top), they’re several inches taller than Mom’s current cabinets (for everything to actually fit on the baffle, for internal port clearances, for better alignment with listening positions, and for a reasonably nice baffle layout), which are 33.5” H x 9” W x 15” D. Net cabinet volumes will be 0.4 cubes (with twin 2” ABS x 3” ports), and 1.0 cubes (with 3” flared port x 9.6”), with plenty of extra volume for bracing, particularly within the subwoofer chamber.

Waddaya think?


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## lurch (Jan 20, 2014)

THAT WORKS. 

just doooo it.


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## Grinder (Dec 18, 2016)

Thanks!

I suppose it's going to look a bit strange, but it's the best way I could think of to meet so many more or less conflicting design goals - and if nothing else, I'm pretty excited about that. 
So, hopefully I'll start cutting MDF within the next few days. And while I'm at it, I'd like to go ahead and cut all the pieces for my new cabinets as well - for which I've just begun to put pencil to paper... 


...Which brings me to my only real (and overriding) concern with designing my new speakers - namely, port diameter (as it might relate to chuffing). 
I'll absolutely lose my mind (not _really_, but you get the idea) if I end up with port chuffing from the 3" flared ports (with the 12" HOs). 

Part of my renewed and heightened concern stems from this part of a response I got on PE Q&A: “…Id check the port velocity with the 3" port. U may hear some chuffing…” 
The other part, as I’ve said before, stems from the chuffing I’m getting from the 3” (straight) port for the test rig IX-8, and Skar’s recommended 13 sq. in. port area (which seems about right, based on the above experience).

And I still can’t begin to wrap my mind around how a 12” HO, with almost twice the excursion, more than twice the cone area, and more than three times the power handling of an IX-8, might work well with the same (or smaller) port size.

So, the other day I started a new thread here http://www.diymobileaudio.com/forum...sion/349001-3-4-flared-port-12-dayton-ho.html (and on AVS Forum), in an effort to get feedback from anyone who has first-hand experience with flared ported 12” HOs, to no avail (so far).

And I just sent an email to Dayton tech support, asking about port sizes (and port chuffing prevention) for the 12” HO.

Do you remember what HAL’s Mach numbers suggested about a 12” HO chuffing with a 3” port?


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## lurch (Jan 20, 2014)

yeah, i understand your concern here. 

a 3" tube is very close to being at the limit ( 0.16 mach or there abouts ) depending
on how low you want to tune the box. the lower we go the faster the velocity, same
goes for the volume, the larger the volume the faster the velocity. 

just opened winisd to check, turns out that I didn't save the work for the dayton. 
please remind me what the size and tuning were ?
i seem to remember 1.4 cubes @ 32-ish hz ?
if I'm right we are are right around the 0.15 mach area.


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## Grinder (Dec 18, 2016)

THANKS!

It's 1.4 cubes (or 1.36? This is what's on Dayton and PE websites), and you recommended 33 Hz.


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## lurch (Jan 20, 2014)

ok, yeah, that's probably why I recommended 33, to stay under that mach number. 
and it's a good place to be for the application, tune any lower and you will lose
the upper impact that you crave. 

looks like a 3" will work .... but with a narrow margin for error. 

wasn't a 4" tube like 32 inches long or something ? ( I can't remember )


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## Grinder (Dec 18, 2016)

...and perhaps I'd have a lot more confidence in this if I knew what HAL would say about the IX-8, with its correct 7mm one-way Xmax, as I seem to remember a 2" dia. port was supposed to be on the edge, while a 2.5" dia. was supposed to be well below the threshold - but in the end it turned out that these figures were for a 7mm full-stroke Xmax?).


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## Grinder (Dec 18, 2016)

A 4" would be (according to Precision Ports' calculator), for 1.4 cubes and 33 Hz, 20.3" long. The 3" would be 11.3". Two 3" would be 23.8". Three 2" would be 16.2". Four 2" would be 21.7".

Does HAL make any distinction (in terms of chuffing noise) between flared and straight ports?


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## Grinder (Dec 18, 2016)

The 30+ inches was, IIRC, for a 22 Hz tune or something like that, as per the PE Tech recommendation.


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## Grinder (Dec 18, 2016)

This is what I was referring to above. My question for PE Tech was: "I'm*planning to purchase a pair of these for home and (occasional) outdoor SQ use (one sub per cabinet). Assuming a 2.0 cu. ft. maximum cabinet volume, would I be better off with sealed or ported? If ported, what is the minimum recommended port area (to avoid port noise); and the recommended*port length (and tuning frequency) for my application? If sealed, what would be the recommended cabinet volume."

PE Tech: "With that woofer you would be better off vented for 2.0 cubic feet.* The port would need to be 3" wide and 22" long, and I would suggest using a flared port.* Their should not be any port noise with that setup but the flares will help to avoid it as well.* You would have an F3 of 22 Hz with the port tuned to 20 Hz. The recommended sealed volume is 0.49 cubic feet."

Translating all that to 1.4 cubes yielded that super-long port.


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## Grinder (Dec 18, 2016)

...32.8" to be exact, according to Precision Sound's port calculator.

EDIT: AND THAT'S FOR A 3" PORT!!! A 4" port would be 58.54" long!!!!!!!


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## Grinder (Dec 18, 2016)

If I went up to 2 cubes (which I'm not sure I want to even think about, but I'm not yet ruling it out), a 4" port at 33 Hz would be 13.6" long.


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## lurch (Jan 20, 2014)

Grinder said:


> ...and perhaps I'd have a lot more confidence in this if I knew what HAL would say about the IX-8, with its correct 7mm one-way Xmax, as I seem to remember a 2" dia. port was supposed to be on the edge, while a 2.5" dia. was supposed to be well below the threshold - but in the end it turned out that these figures were for a 7mm full-stroke Xmax?).


yes, i had entered the parameter as 7mm instead of 14. 

so i just fixed that and get nearly the same result, a 2" pipe is very close
to 0.15, a 3" is down at 0.06. 

my version of winisd makes no distinction regarding flared ports. 
not sure if the " pro " version does or not. 
and I don't think that this version takes into account the amount of power
being used accurately, the pro version is much better.


----------



## Grinder (Dec 18, 2016)

lurch said:


> yes, i had entered the parameter as 7mm instead of 14.
> 
> so i just fixed that and get nearly the same result, a 2" pipe is very close
> to 0.15, a 3" is down at 0.06.
> ...


Are its numbers pertaining to flared or straight?


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## lurch (Jan 20, 2014)

i remember 1.6 cuft. as being a nice size. 
maybe I'll model that again and report back.


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## lurch (Jan 20, 2014)

​


Grinder said:


> Are its numbers pertaining to flared or straight?


 straight


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## Grinder (Dec 18, 2016)

lurch said:


> i remember 1.6 cuft. as being a nice size.
> maybe I'll model that again and report back.


Sounds good. Thanks!


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## Grinder (Dec 18, 2016)

lurch said:


> ​
> straight


That's what I was afraid of... Then something - either Skar's specs, or HAL's Mach number cypherin' (or both) - is WILDLY off; because, as I've said a number of times, I'm getting pretty significant chuffing from a 3" port.


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## lurch (Jan 20, 2014)

ok, 

if we move up in volume it become IMPERATIVE that 4" ports be used. 

at a volume of 1.4 we can just squeek by with a 3" port at 33hz, 
but as soon as we increase volume the mach numbers surpass 0.15. 

if box = 1.6 cuft a 4" ( straight ) pipe will be 16" long. mach 0.08
same box using a 3" pipe would be 8.5" long with a mach of 0.15. 



looks like a 4" pipe is the best choice in either scenario, or two x 3". 

using two x 3" ports :
1.4 cuft @ 33 = 22.3" ( mach 0.04 )
1.6 cuft @ 33 = 19.24" ( mach 0.04 )


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## Grinder (Dec 18, 2016)

lurch said:


> yeah, i understand your concern here.
> 
> a 3" tube is very close to being at the limit ( 0.16 mach or there abouts ) depending
> on how low you want to tune the box. *the lower we go the faster the velocity, same
> ...


I don't doubt it. However, it seems to be in stark contrast to the PE Tech's 3" (flared) port recommendation for a 2 cube volume and 20 Hz tune. I mean, if this scenario would produce minimal chuffing, then what you're saying here would strongly suggest that 1.4 (or 1.6) cubes at 33 Hz would be miles from the chuffing threshold. And yet, somehow I don't find any of this very reassuring...


----------



## lurch (Jan 20, 2014)

maybe this will help, i think he mentions exactly what you are worried about. 
something to the effect of " as frequencey gets lower chuffing diminishes be ause
velocity drops "
which is a new concept to me ...

http://www.diymobileaudio.com/forum...ion/349265-improved-port-area-calculator.html


----------



## Grinder (Dec 18, 2016)

lurch said:


> ok,
> 
> if we move up in volume it become IMPERATIVE that 4" ports be used.
> 
> ...


THANKS!

3" is out, no matter what. I have zero faith in HAL's Mach numbers (as I said above, something is WILDLY off - either HAL or SKAR or both, because I've got chuffing from a 3" port...)

I'll just go with 4" and 1.6 cubes (if that seems to model best at 33 Hz).

Those two 3" ports are going in Mom's cabs.


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## lurch (Jan 20, 2014)

yeah, HAL isn't perfect. 

i once saw him cut an astronaut's air tube and push him into outer space !


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## Grinder (Dec 18, 2016)

lurch said:


> maybe this will help, i think he mentions exactly what you are worried about.
> something to the effect of " as frequencey gets lower chuffing diminishes be ause
> velocity drops "
> which is a new concept to me ...
> ...


WOW! THANK YOU! (and to think this was posted just 8 hours ago)

Very interesting (and depressing - though nowhere near as depressing as building a chuffing sub would be!).


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## Grinder (Dec 18, 2016)

lurch said:


> maybe this will help, i think he mentions exactly what you are worried about.
> something to the effect of " as frequencey gets lower chuffing diminishes be ause
> velocity drops "
> which is a new concept to me ...
> ...


You gotta love this:

Plug in 1 cube, 200 Watts, 42 Hz = 13 sq. in. (Skar's recommended port area)


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## lurch (Jan 20, 2014)

Grinder said:


> You gotta love this:
> 
> Plug in 1 cube, 200 Watts, 42 Hz = 13 sq. in. (Skar's recommended port area)


maybe they were designing a potato gun ?:laugh:


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## Grinder (Dec 18, 2016)

...and by the same token, plug in 1.36 cubes, 700 Watts, 33 Hz = 26 sq. in. port area.

Two 4" ports = 25.14 sq. in. (port length = 43.8")

Even at 20 Hz, I'd still need 20 sq. in. (or three 3" ports, at 103.85"!!!!!!!!!)

Back to the drawing board...


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## Grinder (Dec 18, 2016)

lurch said:


> maybe they were designing a potato gun ?:laugh:


HUH?


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## Grinder (Dec 18, 2016)

lurch said:


> maybe they were designing a potato gun ?:laugh:


It seems you missed my point (something finally adds up in all this port area nonsense. No wonder why I've got port noise...).


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## lurch (Jan 20, 2014)

i was just thinking about port velocity and that potato gun image popped into my
mind, thought it was funny ....
I'm probably just tired ....


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## Grinder (Dec 18, 2016)

lurch said:


> i was just thinking about port velocity and that potato gun image popped into my
> mind, thought it was funny ....
> I'm probably just tired ....


I see. Nice imagery (and I'm very tired too. Sun is coming up already).

However, HAL was the only one designing a potato gun, while Skar has been spot-on with their 13 sq. in. port area recommendation all along.


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## Grinder (Dec 18, 2016)

Unfortunately, I seem to have reached an impasse regarding subwoofer ports; wherein, if I want a practical subwoofer port, I've got to except port noise. However, since I find port noise to be unacceptable, and a subwoofer port that would be free of port noise is not likely to be practical, subwoofer ports don't appear to be a viable option for me.

But to the extent this is true, I'm quite fortunate to have become aware of it at this point.


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## Grinder (Dec 18, 2016)

...I'm going to replace the test rig's 3" PVC port with one of my 3" flared ports, and see if the chuffing goes away. If it does, I'll happily continue with Mom's new cabinets as planned. If chuffing persists, I'll be happy enough to build them with the twin sealed subs instead.


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## Grinder (Dec 18, 2016)

Grinder said:


> ...I'm going to replace the test rig's 3" PVC port with one of my 3" flared ports, and see if the chuffing goes away. If it does, I'll happily continue with Mom's new cabinets as planned. If chuffing persists, I'll be happy enough to build them with the twin sealed subs instead.


I swapped ports today, and the chuffing is mostly gone. See my posts in the http://www.diymobileaudio.com/forum...ion/349265-improved-port-area-calculator.html thread for details.



Next I need to try reducing length from the current 9.5" (to achieve the target 42 Hz tune). Also need to find a better way to temporarily seal the port to the cabinet, as I'm getting some leakage (and resultant noise).


----------



## Grinder (Dec 18, 2016)

lurch said:


> yes, i had entered the parameter as 7mm instead of 14.
> 
> so i just fixed that and get nearly the same result, a 2" pipe is very close
> to 0.15, a 3" is down at 0.06.
> ...


I know you said winisd assumes "straight" (non-flared) ports, but could it be that winisd assumes a flared port? If so, it would go a very long way toward explaining the chuffing of my 3" straight port (versus my 3" flared port), and the seemingly small port diameters suggested by winisd.


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## lurch (Jan 20, 2014)

that's an awesome thread, it answers many of my questions that I've had for years. 

i think i understand the frequency vs. airflow equation and will try to explain it as such :

at 20 hz a driver is moving powerfully but s l o w l y. 
at 100 hz the driver is moving faster but doesn't have the same excursion. 
this means that the pistonic movement through the tube is faster at 100 hz than it
is at 20, so turbulence is more likely at 100 than at 20. 

there is a big difference between cycles per second and air movement. 
this is why pro audio drivers can work well in ported enclosures, it's not the amount
of air they are moving it's the frequencey they are moving at, excursion hardly
matters, the sound pressure waves are what's creating the port and cabinet to resonate, not the air velocity. 

winisd beta is pretty simple and has been around for years & years, most of the modelling
done in this program would be geared toward the older style woofers that could never
achieve 25mm xmax. 
the help file says nothing about flared ports and the icons for " type " of alignment
only show ordinary pipe or an ordinary slot, no flares imaged or mentioned anywhere. 


glad to hear that your flared ends worked out !
this gets me thinking i might do the same on my truck enclosure. 

i remember you said that the minidsp had 20db gain per channel ?
if the eq sliders are boosted this high near port tuning it would contribute to noise but i would imagine you can hear that coming and adjust accordingly. 

don't overthink this when it comes to the daytons, use what has worked for others in
the reviews, i would still go with 4" pipe, they could give enough output just being sealed, 
but where's the fun in that ??


----------



## lurch (Jan 20, 2014)

also, we need to clarify what sound is. 

sound is a wave that moves through air ( or another medium ). 
sound is transfered from one molecule to another. 
the molecule moves in the diection of the wave,up or down or sideways, and transfers its
energy to the next molecule. 
the original molecule is theoretically back to its original position once the wave has passed. 
the air hasn't moved ....

the same thing is happening in a port, the air vibrates, but each molecule only needs to
complete a wave length for the creation of sound.


----------



## Grinder (Dec 18, 2016)

lurch said:


> that's an awesome thread, it answers many of my questions that I've had for years.
> 
> i think i understand the frequency vs. airflow equation and will try to explain it as such :
> 
> ...


Yes, that is an awesome thread. Thank you for the explanation of frequency vs. airflow. It makes a lot more sense to me now.

And yeah, I’m quite pleased with the flared port. It seems output is up quite a bit (?), but I plan to put that to the test tomorrow, by putting the PVC port back in for a bit, while I shorten the flared port to hone-in on the target 42 Hz tune. And it will be nice to sort out the sealing issue, so I can rule out confusing leakage noise with mild chuffing. Also, I think I’m hearing some resonance of the port tube itself, so it might need some sort of solid bracing and/or dampening.

Yes, +/- 20 dB gain (per PEQ), but the highest I’ve ever gone is 15 (and that’s only been with Mom’s subs, or maybe once with the RFs?), and I’m never intentionally raising levels near tuning (with the ported sub I’ve been boosting a steep slope of 5 – 10 dB at 30 Hz, with a 48 dB BW HP at 25 Hz (I know this is really pushing it, and risking overexcursion, but I’m very careful with the “volume knob”).

I get what you’re saying about overthinking ports for the Daytons; though, despite all my searching, I have yet to encounter a specific first-hand-experience example of port area for this driver, let alone chuff-free and/or non-automotive examples.

And I haven’t yet ruled-out sealed, partly because (*for a number of reasons) I’m reluctant to go with the recommended .049 cubes. 

*I’ve been lead to believe that it’s common practice for MFGRs to discourage folks from using larger enclosures, to prevent them tearing their subs up with the gobs of full rated power needed for such small “recommended” enclosures.

* …while I’ve been lead to believe that in reality one would simply gain efficiency (needing less power to get to the same SPL) and lower extension/F3 (among other niceties?) with a larger enclosure.

*I’d have a tough time designing anything resembling a “tower,” with only .89 cubes total net volume (.49 sub + .4 RF) and 13” width.

What say you about (*)?

And despite what I said earlier (mostly out of sheer frustration) about having “reached an impasse regarding subwoofer ports,” I haven’t ruled ports out either (and to that extent, for a number of practical reasons, I’ve been leaning toward slot ports - though I still prefer the 4" flared port for a number of other reasons).

Thank you, once again, for all of your awesome feedback!!!


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## Grinder (Dec 18, 2016)

...Also, I got word back from my email to Dayton, which they must have forwarded to PE.

My email:

"I recently purchased a pair of these subs. I plan to use them (one each)*in a pair of*3-way active home stereo towers. The subwoofer portion of*each cabinet would be 1.4 cu. ft., tuned to 33 Hz, with one 3" dia.*x 11.3" long*flared port (Precision Sound PSP3-BKHT).

My question is, am I likely to hear port noise (chuffing) from such a port? I*would like*to start drawing plans for the cabinets, but first I need to be able to account for the displacement*of the port. 

A*3" dia. flared port*would be ideal, in terms of its minimal length and displacement; as compared to a 4" dia. flared*port, which would be*more than*twice*as long, and way*more than twice the displacement. But if it*were*the only way*to prevent chuffing, I would*go ahead and install*a 4" dia. flared*port.

Also, is there a*recommended port area for this sub (again, to prevent chuffing)? This would be very good to know, particularly if I decide to build a slot port instead of installing a flared port."

PE response: 

"I ran the numbers and a 4 inch precision power that is 17 inches long gets pretty close to the same tuning and in this case will have much less chuffing."

"Pretty close" works out to 35.7 Hz, according to Precision Sound's port length calculator, whereas I was thinking 33 Hz would be as high as (or higher than) I want to go.

And I didn't get a recommended port area number. 

And it ought to have been abundantly clear I was aware that a 4" port would produce less chuffing than a 3" port... 

Not really much help at all.


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## lurch (Jan 20, 2014)

Grinder said:


> ...Also, I got word back from my email to Dayton, which they must have forwarded to PE.
> 
> My email:
> 
> ...


i would have to agree with them ...
tuning too low is almost always disappointing for music. 
i see new designers doing this all the time, thinking that the lower they can 
tune the system the better it will sound. 
this is great if you want a true subwoofer and plan to blast star wars movies
through them, but for a pair of stereo music speakers it SUCKS. 
there is absolutely nothing wrong with a mid to high 30's tuning, even into the 40's is just fine, that's where the musical excitement is. 
take a look at some good home floor standing speakers :
their frequency response will list something like
20 hz - 22 kz 
but their sweet spot for bass can be anywhere from 32 - 45 hz or even way higher. 
if you tune too low the musical impact is lost. ( darth vader may object to this statement though ). 

* personally i like larger than spec ported enclosure, for your reasons :
efficiency and the " effortless " bass they produce. 
drawback = depdnding on how much larger we build the enclosure the less
power we can push into it, although todays woofers are tanks and can most
likely handle it anyways. 

* build the dayton cabinets to 1.4 - 1.6 cuft , you're right, a little sealed unit
under a 8" wooffer and a tweeter that is also about 8" would look " odd ", if
designable at all, unless you built a seperate enclosure for the tweets and 
RF's and just treated the system as two bass bins and a pair of satellites. 
( yuch .... )


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## lurch (Jan 20, 2014)

how'bout something like these ?

by side mounting the daytons you gain the depth needed for the ports. 
cabinets would be approx 20" deep, 9" wide, and whatever it needs
tall. 
elegant .... ( ? )

probably sound very good indoors.


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## Grinder (Dec 18, 2016)

lurch said:


> i would have to agree with them ...
> tuning too low is almost always disappointing for music.
> i see new designers doing this all the time, thinking that the lower they can
> tune the system the better it will sound.
> ...


*A few thoughts on my low-bass craving:*
I’ve been thinking… It seems to me that, over the years, low bass has become a bit of a fetish for me - partly because I think I like like it, partly because I’ve so often not had it, and partly because I know that it takes some serious doing to reproduce it with any authority (a feat which has its own reward. I'm sure you know what I mean); which is why it would kinda suck to hear low-bass roll-off (and/or drop to nil), particularly with subs that might be otherwise capable of doing the trick.


Having said that, I get what you’re saying about musical impact, and that I won’t like the sound of a 20 Hz tune. 


*Hierarchy of goals:*
Above all, I want good SQ and impact; next comes low F3; then comes SPL.

However, to the extent it wouldn’t detract from impact and SQ, I’d like to hear a flat response down to the mid-20s (or barring that, as low as good SQ and impact would allow, knowing that it will likely take some PEQ to do it).


*Fundamental (or unrealistic? or stupid?) ported alignment question: *
Might there be a ported Fb that would achieve all of the above goals, without need for a high pass filter to prevent decoupling (and would this be your recommended 33 Hz Fb)? 


*One last look at sealed alignment:*
When I mentioned “larger than spec enclosures,” I was specifically referring to sealed enclosures (and the notion that one man’s reduced power handling might simply be another man’s higher efficiency and lower F3, so to speak), bearing in mind that (at present) I don’t have 700 W RMS to throw at these subs. I’ve got maybe 400 W RMS a piece, from the 12.3 V-downrated R500X1Ds, or maybe 400 W RMS/channel from Mom’s likely overrated 525 W RMS Crown XLS 1002. And while I’d prefer not to buy another amp (if more than 400 W RMS should become overkill through the use of a larger sealed enclosure that might result in a 300 W RMS reduction in power handling), I will do so if necessary (a Crown XLS 1502, for example). 

...and then there’s the question of .707 Qtc. According to the calculator at Car Audio - Sealed Subwoofer Speaker BOX DESIGN - Qtc Calculator a .8165 cube sealed enclosure for the 12” HO yields a .707 Qtc, and a 41.09 Hz F3 (whereas the PE recommended .49 sealed cubes yields a Qtc of .8613, and an F3 of 42.64 Hz). 

In that case, would .8165 cubes not be the optimum sealed volume for my application? (not at all to say that I’m leaning toward a sealed alignment) 
By way of comparison, I entered the IX-8 specs and found that it would take a whopping 2.085 cube sealed enclosure to yield a .707 Qtc (and a 51.75 Hz F3). At .5 cubes, Qtc is .8386, F3 is 53.22 Hz F3). 
It’s very interesting (though I don’t know why) that the IX-8’s Qtc dropped very slowly while adding relatively large chunks of enclosure volume - compared to the HO 12, whose Qtc dropped rather quickly, with much smaller chunks of volume added to the enclosure. 


BTW, I still haven’t had a chance to play with the test rig’s sub port (re-install the straight port for output comparison to flared port, and shorten flared port to achieve 42 Hz target Fb, and then listen again...). Tomorrow looks very promising. 


Also, I've been thinking of porting all four of Mom’s IX-8s (instead of just two), in four 1 cube chambers (two per tower), though I haven't given much thought as to how the hell I'm going to fit all of that on the baffle, LOL. 

I’m thinking “effortless” response and power (and that much less risk of decoupling). Do you see any potential downsides (other than increased cabinet size and weight)?


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## Grinder (Dec 18, 2016)

lurch said:


> how'bout something like these ?
> 
> by side mounting the daytons you gain the depth needed for the ports.
> cabinets would be approx 20" deep, 9" wide, and whatever it needs
> ...


GREAT IDEA!!!

...and only $80 at Walmart!!! (I was surprised to find they're only 26" tall though - they look HUGE in the picture!) LOL!


Seriously though, it is indeed an elegant solution to a tricky problem, and I will definitely keep it in mind. However, since these things might be used anywhere (including outdoors), I'd really like to keep everything on the baffle to maximize punch (and to help prevent odd room modes and/or boominess?).


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## lurch (Jan 20, 2014)

ok, i have read through your latest posts ( whew ! lots going on here ...), and have
this to say :

the operative words in your questions are
- punch
- impact 

this says a lot about what you want your speakers to sound like. 
so i stick to my original statements about tuning in the mid 30's. 

there are always trade offs and in the end, no guarantees. 

going with sealed cabinets is usually the safer bet, they work. 
ported enclosures can be somewhat of a gamble if not thought out
and calculated but can be very efficient and sound amazing. 

the question regarding a tuned port and not using a subsonic filter :
years ago there were no subsonic filters, we did just fine without them. 
the power you will be running may not need one if the amp is giving half
the rms rating of the woofer. 
and a subsonic filter is not a brick wall, with the minidsp you can set the
filter to roll off gradually or sharply ( mine is set to 25hz @ 6db, just to be safe,
i am also running ****loads of power where as you won't be running crazy wattage ). 
none of my home equipment ever had a high pass filter, ever, there was
never an issue. 

the rest of it :
i dunno, i am at the limits of my knowledge now, eventually instinct takes over and you 
know what works and what doesn't. 
if we we get too wrapped up in technicalities we get nowhere. 

i used to own a set of NHT towers with side firing 12" woofers, i seem to remember
that they were ported to the front. LOVED them, great imaging and very good
extension, they just weren't " loud " enough for me. they were never taken outside 
though, so I can't comment on that. 
I didn't notice that the pic i attached was a wallmart product, that's pretty funny. 

did you try out those flares today ??


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## lurch (Jan 20, 2014)

" I'm thinking " effortless "response and power (and that much less risk of decoupling). Do you see any potential downsides (other than increased cabinet size and weight)? "

yes !
personally i feel that this is the way to go. build on the larger side of what the simulation
suggests. 
this also makes achieving the target response easier because the port length is
more forgiving. 
efficiency goes up too, less power is needed. win win.


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## Grinder (Dec 18, 2016)

lurch said:


> ok, i have read through your latest posts ( whew ! lots going on here ...), and have
> this to say :
> 
> the operative words in your questions are
> ...


Thank you for your great feedback!!!


I still haven’t quite decided whether to go sealed or ported with the HOs. In this case, “perfection is the enemy of progress” (especially when there’s no deadline to force a decision). However, if the ports were only 6” long, I’d surely be listening to them by now …which points to the fundamental issue.

If I go with sealed, it will be primarily a matter of packaging practicalities (and to a far lesser extent, the slight advantage of predictable performance and overall simplicity) having won the tradeoff war - over higher output, efficiency and potentially amazing sound (I know… WTF am I thinking?!).

I’ve pretty much ruled out side-firing the HOs for a number of reasons, primarily because of problematic room-placement issues in my home environment.

At this point, it looks like my options are down to sealed versus slot port - the primary issue being that I’ve yet to come up with an elegant (or even practical) adjustable slot port.


On a brighter note, I played with the test rig’s flared IX-8 port for several hours today:

I began by comparing it to the 3” PVC port. They both seemed to be in the 39 – 37 Hz range and, apart from port noise and the incredible blasts of air from the PVC port, I couldn’t really tell them apart. The PVC port was just as loud (perhaps a little louder?) at fairly low volume (though I can’t speak for how they’d compare at higher levels). 

I repeatedly shortened and lengthened the flared port, ranging from as low as 29 - 30 Hz, to as high as 42 – 43 Hz (as judged via tone generator and minimum excursion). 

The shortest (42 – 43 Hz) length was most efficient (i.e. loudest per volume knob), but to my ear it seemed a bit peaky and boomy, and lacking oomph. 

The longest (29 – 30 Hz) length was least efficient (and it didn’t do much more than move air in that range, with little accompanying sound), with an unpleasant droning hump in the 50 – 70 Hz range (centered at about 60 Hz).

To my ear, the sweet spot was in the 34 - 35 Hz range, with an overall length of about 10.5”.

And I tried every port arrangement with (and without) a number of HPF/SSF settings (from 20 Hz to 35 Hz) and slopes (and flat EQ).

Also, for some strange reason, the port lengths were all considerably shorter than those suggested by Precision Sound’s port length calculator. Accordingly, the 34 - 35 Hz port "should be" 14.5 - 13.75 inches (instead of 10.5”). 

I suppose I might have slightly underestimated cabinet volume… but certainly not by that much. And the cabinet seems far from ideal, what with the funky cut-out section below the port, and the tight confines above the cut-out. 

FWIW, I’ve read that the internal port opening should be as far away from the rear of the sub as possible, and not aligned with the back of the sub; whereas, in this case the port’s internal opening is fairly closely centered above the sub. I’ve no idea how good or bad my arrangement might be in this regard, or if it might be contributing to the shorter-than-calculated port length… 

And I’m no longer worried about needing or using an SSF.


Anyway… with all of this in mind (along with your steadfast recommendation), I am 100% convinced that I’ll be happiest with a “mid-30s” tune (or 33 Hz). 

BTW, is there a reason you’ve seemingly increased your earlier 33 Hz recommendation to “the mid 30s?” 

And do you recall if 1.6 cubes net volume modeled better than 1.4 (at 33 Hz), or was it more a means of reducing port length?


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## Grinder (Dec 18, 2016)

lurch said:


> " I'm thinking " effortless "response and power (and that much less risk of decoupling). Do you see any potential downsides (other than increased cabinet size and weight)? "
> 
> yes !
> personally i feel that this is the way to go. *build on the larger side of what the simulation
> ...



Perhaps you misunderstood me, as I don’t understand how what you’re saying here relates to: 

_“Also, I've been thinking of porting all four of Mom’s IX-8s (instead of just two), in four 1 cube chambers (two per tower), though I haven't given much thought as to how the hell I'm going to fit all of that on the baffle, LOL. 

I’m thinking “effortless” response and power (and that much less risk of decoupling). Do you see any potential downsides (other than increased cabinet size and weight)?”_

To be clear, along with porting Mom’s RFs, awhile back I decided to port her IX-8s as well. So, I’ve been planning new cabinets that would port her RFs, while replacing both sealed IX-8s per side (presently in .5 cubes each), with just one ported IX-8 per side (in 1 cube each).

However, the only difference in this latest scheme (italicized above), is that there would be two ported IX-8s per side (instead of just one per side), each with its own 1 cube chamber.

The objective would be to make life easier for each IX-8, by using four of them instead of just two, making their sound/impact/punch that much more effortless, while retaining their present combined ability to (more or less) make full use of available power from the XLS 1002. 


And then this evening I began wondering if I might achieve the same results, with both ported IX-8s per side paired together in 2 cubes (rather than 1 cube each), as it would greatly enhance cabinet design simplicity, construction and aesthetics (i.e. no need for slanted rear panel, as open space behind RF chamber would simply help fill-out the 2 cubes total sub volume), at the risk of blowing the other sub if one or the other member of either pair were to ever stop working while at elevated volume levels (an acceptable risk, me thinks).

Of course, port area must increase accordingly, and port length (at 35 Hz Fb in this case, based on today's testing subjective testing results) would be based on the larger area, and on 2 cubes instead of 1.


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## lurch (Jan 20, 2014)

oops, yeah, I'm getting mixed up between the two projects. 

i'll do up a sim for the 8's. 
one for the drivers sharing a 2cuft enclosure and another for individual 1ft enclosures. 
pretty sure that the seperate boxes will out perform the shared box in regards
to overall output. 

may as well sim the dayton too, see which is better, 1.4 or 1.6 ( or in between ). 

so the reason i say " mid " 30's is because we can ask a computer to shoot for
a tune of 33 Hz, and it will give a port length, but there are so many variables 
the answer can be off by quite a bit. 
in the end the only way to know for sure is to measure and listen to the built 
enclosure and adjust from there. the mathematics are usually different than the
real life results. 

anyways, I'll be back with the sims later.


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## Grinder (Dec 18, 2016)

Yeah... when I read War and Peace (another very long novel, LOL) it was particularly difficult to keep track of each of the many characters' different names (i.e. diminutive, patronymic, title, rank...) depending on who is talking to whom... but I digress.

I get my projects mixed up too (and they're _my_ projects! LOL).

10-4 on "the mid-30s" (and thanks to your great advice, I've considered adjustable ports more or less essential from early on - and yesterday's port-length experimentation further emphasizes the wisdom in this).

And thank you, once again, for your kind offer to run sims for me!!!


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## lurch (Jan 20, 2014)

SIMS SAY :

skars 

1 skar in 1cuft tuned to 38 Hz =
3" tube X 10.74". 
mach 0.07

2 skars in 2cuft tuned to 38Hz =
4" tube X 8.57"
mach 0.07

comments : it's a mystery as to why your present alignment has such high
port velocities, maybe a T/S parameter is off, but i have triple checked all
the info fields. it could also be that the tuning is too low, im doubting that though. 
both the single and dual woofer alignments have the same f3 in the sims and
both sims show the same mach number. 
i did a 32Hz sim ( i think that's the one you tried that had no ummmph ? ), and
the graph clearly showed the lack of output, a big inverted dogleg that
started way up in the 120Hz area. 
38Hz is almost as low as we can go with this woofer. 

daytons

1.6 cuft tuned at 33Hz =
4" tube X 16.13"
mach 0.08. 

1.4 cuft tuned at 33Hz =
4" tube X 18.85"
mach 0.08

comments : both sims are VERY close and both give tons of leeway for tuning. 
if wanted you could start with a 20" tube for a tuning of 30Hz, and work your
way down to a 13" tube length for 38Hz, or anything in between. 
this should be easy to tune, forgiving as all get-out-a-town. 
just stay between 1.4 and 1.6, the rest will fall into place. 
both sims peak in the 40Hz area, tuning at 35Hz gives the lowest f3 of 29.5Hz. 
pretty good, should sound lively !


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## Grinder (Dec 18, 2016)

THANK YOU!!!

Skars: 

Interesting results. Looks like 2 in 2 is the way to go.

Actually, the low-oomph one (to my ear) was the 42 – 43 Hz port (it seemed a bit peaky/boomy, and lacking depth and kick drum punch). The 29 – 30 Hz port was least efficient, “with an unpleasant droning hump in the 50 – 70 Hz range (centered at about 60 Hz).” I’m sure room gain, odd listening and cabinet positions, and the test rig being 24” above the floor, are having significant effect. And I’m at a loss to explain my significantly shorter port length-per-Hz ratio.

Same goes for the low Mach numbers vs observed velocities and port noise. So, I just checked my data sheet against Skar website specs for the IX-8 D4, and unfortunately (de-ja-vu, all over again...), we’re dealing with conflicting mfgr specs ($#@%!!!!).

…and worse still, I just remembered (DOH!) we’re dealing with two different Skar IX-8s – a newer group of D4s (the one in the test rig + five more, all having been earmarked for my speakers, prior to opting for the Daytons), and an older group of D2s (the four IX-8s in Mom’s speakers). Argh!!!


(D4s) Per website “Info:” 
RMS power: 150 W, Fs: 53 Hz, Spl: 82.5, Qts: 0.85, Xmax: 7mm one-way.

(D4s) Per website “Specs:” 
Sens: 83.2 Fs: 51.1 Hz, Re: 7.1 Ohms, Qms: 4.29, Qes: 0.75, Qts: 0.64, Rms: 5.3 Kg/s, Cms: 0.14 mm/N, Bl: 13.8 n/a, Vas: 7.8 L, Xmax 7mm

(D4s) Per website “Enclosures:” 
sealed: 0.45 cu. ft., ported: 0.75 cu. ft. net., port area 13 sq. in., port length 18”, tuning frequency: 41 Hz

(D4s) per spec sheet (these specs were previously posted in # 20 of this thread): 
Re: 6.4 Ohms, Fs: 51.3 Hz, 200 W RMS, Qms: 4.29, Qes: 0.75, Qts: 0.64, Xmax: 6 mm (one way), Md: 70.4 g, Sens: 83.2 dB, Rms: 5.3 Kg/s, Cms: 0.14 mm/N, Bl: 13.8, Vas: 7.8 dm3

(D4s) "Recommended Enclosure Volume": 19L sealed (0.67 cu. ft.), 32L ported (1.13 cu. ft.)
No port area or length is listed.

(D2s) per spec sheet (also previously posted in # 20 of this thread): 
150 W RMS, Re: 2*1.8 Ohms, Vas: 9.6 L, Fs: 45 Hz, Bl: 10, Qms: 4.8, Qts: 0.64, Qes: 0.74, n: 0.12 %, Sens: 82.6 dB

I don’t know which set of specs pertain to your IX-8 sims (or how D2 and D4 sims might compare, or how my D4 port length experiments might pertain to Mom’s D2s), but I’m kind of stuck with using the D2s for Mom’s setup, for a 2 Ohm/channel load, for use with either the R500X1Ds or the Crown XLS1002 (versus the 4 Ohm/channel load of the D4s). But it wouldn’t be the end of the world if I had to use the D4s instead.

This whole D2 versus D4 (and dodgy specs) thing really sucks, and I feel very bad that I lost track of all this (and I wouldn’t blame you one bit if you said “screw it… I’m tired of this $#!%!”).


Anyway, I’m really excited about the very promising sims of the Daytons! Now I’ve got some serious sketching to do!


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## lurch (Jan 20, 2014)

wow yeah .... that's a lot to digest. my head is hurtin. 
most specs are close, others vary by a significant amount. 

i forgot to mention that the double woofer / single encloser looks EXTREMELY good
for output. ( this is a given of course, I expected to see approx 3db improvement). 
not only do we get the expected rise in output but we also get a much better low
frequencey extension. this is where the double alignment out performs the single
stacked units. 
the single stacks will be " louder " ( barely ), while the twinned alignment reaches down
with some authority. the dual drivers in a single box is easily the winner here.


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## Grinder (Dec 18, 2016)

I know... sorry about that.

HAH! I was wondering about that! For some reason I was hoping I might get lower extension too - something to do with greater cone area (and cabinet volume?)?

Anyway, combined with the easier/simpler and nicer looking design, this twinned alignment is a win/win/win/win!! YES!!!

Thank you for the great news (and much needed encouragement)!!!


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## lurch (Jan 20, 2014)

kewl news eh ?

the double woofs will just " sound " better, regardless of output. 
instead of two units that could sound " forced " the double cabs will breath along
with less effort, and this translates into going louder because distortion will be lower
and the volume can be turned up ( maybe even to " 11 " ! ).

this is getting interesting !

now I'm wondering if we should look at a larger volume, 2.5cuft - ish ?
( that port velocity thing is still bugging me ... )


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## Grinder (Dec 18, 2016)

lurch said:


> kewl news eh ?
> 
> the double woofs will just " sound " better, regardless of output.
> instead of two units that could sound " forced " the double cabs will breath along
> ...


I love it!!

And larger is no problem. There's plenty of room, they don't need to travel well, and it will only tend to make the cab design easier (and the baffle layout less crowded).

It just keeps getting better and better!


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## lurch (Jan 20, 2014)

2..5 cuft @ 38Hz 
4" X 6.27" 
f3 = 31 Hz. 

mach number doesn't change though, still 0.07. 

looks good but may not be worth the needed space.

EDIT
it gives a cushion just in case the velocities are still high. 
" wiggle room "


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## Grinder (Dec 18, 2016)

Awesome!!! That seems like a pretty flat roll-off/curve!

I think the space will be fine (and well worth that low F3).

EDIT: All the better!


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## Grinder (Dec 18, 2016)

Update: 

Took a bit of a break from thinking about speakers (to let it all sink-in for a few days), but not before having drawn-up a design for Mom's new speakers (with the twin-ported-IX-8s). 

They’re 43” H (minimum height required to fit everything on the baffle, with an IX-8 immediately above and below the 7.25" O.D. 4" flared port) x 9” W (to my eye, a narrow baffle looks best) x 20.5” D (for 3.422 gross cubes: 2.5 net cubes for twin ported IX-8s + 0.4 net cubes for ported RF PPS midbass + more than enough room for driver, port, midbass chamber divider, and bracing displacement – so, in the end, they’ll probably be slightly less deep). 

I’m not 100% settled on this design, but I think it’s by far the best one yet.


And then, yesterday, it was back to the drawing board (again) - in an effort to sort out conflicts between a 13" baffle width (for the 12” Dayton HO), a very deep cabinet depth (for the relatively long 4” flared port), a very tall cabinet height (for optimal alignment with listening position, and to fit everything on a very crowded baffle), a very tall and shallow midbass chamber (.4 cubes for the ported RF PPS), a smallish 1.4 – 1.6 cubes for the HO, minimal weight, forward-firing drivers and ports, and reasonably good looks = too many conflicting design goals (and no fun at all).


...However, all things considered, it’s perfectly fine with me, as I’ve pretty much decided to use the HOs for a pair of ported subs (to go with the horns, in place of the old muddy-boomy Paradigm PS-1200).


On an even brighter note, I decided late last night to try my hand at WinISD (WinISD 0.7.0.950) again - and ran into data-entry problems (again)… until I found http://www.diymobileaudio.com/forum/how-articles-provided-our-members/70256-guide-using-winisd.html and read just enough of it (so far) to learn that the T/S parameters must be entered in a specific order (while leaving others blank, to be computed instead) …and PRESTO! It worked! Very exciting (and I feel slightly less like an idiot)!

EDIT: Actually, it was here that I found the necessary T/S parameter entry info: How to correctly use WinISD - diyAudio 

So, I got to play around with sealed, 4th order bandpass, and (QB3?) ported alignments, for the 12” HO, into the wee hours. What fun!

I’ll obviously need to play around with it a whole lot more, to get a better feel for it all. 

Next, I’ll have a go at the IX-8 (both paired and alone), and the RF PPS as well – just for the fun of it, for the experience, and to learn whatever I can.



I’d also like to explore the (ridiculous?) concept of using ported IX-8s as midbass, to fill the gap between ported PPSs and ported HOs, as part of a theoretical modular 4-way active set-up. For example, the RF mids and tweets sharing a pair of small cabinets (for 100-150Hz and up?), and two pairs of ported IX-8s in a larger pair of cabinets (for 50-60Hz – 100-150Hz?), and the ported HOs in an even larger pair of cabinets (for 20-30Hz – 50-60Hz?). 


In any case, I’m quite attracted to the notion of having my ported RFs in their own separate cabinets, to serve (if nothing else) as satellites for computer sound, and as the “detachable” satellites of a boombox-from-hell.


And similar to my other crazy idea (okay… my “latest” crazy idea), I’d like to explore the (even more ridiculous?) concept of using two different ported alignments for Mom’s IX-8s (with a separate amp for each alignment, of course); for example, one IX-8 per channel for 60-80Hz – 120-170Hz (?), and two IX-8s per channel for 30-40Hz – 60-80Hz (?).


Now my brain hurts, LOL. 

I hope your brain doesn’t hurt now too.


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## lurch (Jan 20, 2014)

WOW, so much going on here i don't know where to start !

SO happy that you have discovered WINISD, especially the better version than
my old " beta " copy. 
I'm hoping that it explains the high port velocities that those 8's are producing, if
it has the answers please let me know. 
your version of winisd will have excursion plots and other goodies that mine
does not so it should be much more revealing. 

pairing those horn loaded speakers with dedicated dayton subs is probably
a very good idea. i like it. this would be the ultimate party system !

and using the RF's in separate enclosures ( with the tweeters ) is another
good idea. this way you can mix n match as the situation demands. 

it all adds up to more pieces to load and carry, but ends up being way more
versatile, especially if the 8's are also portable. 
bringing the RF' and the 8's in separate enclosures to a small venue party
would be easy to transport and loud. 

i'm not so sure about the IX's as mid bass drivers, but winisd could have
better answers in this regard, maybe they would be awesome MB's ? 
i dunno. 

if you do sims of all the different versions of those IX's please post the graphs,
i would like to see those. 

looks like you have some wood to buy !
yoo gonna be busy !

yes, my brain hurts .....


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## Grinder (Dec 18, 2016)

Funny thing about the WinISD versions...

I had started out with WinISD Pro ("ALPHA") aka "WinISD Pro Alpha" back in January, but didn't get very far... and then subsequently forgot which version I'd tried (and that it was actually still on my computer).

So, the other day I downloaded WinISD ("betaversion"), managed to get past the data entry hurdle, and was more or less off and running...

Then, last night, after downloading WinISD Pro (again), I realized I already had it... And when I started to use it, I thought: "this looks like lurch's screenshots," with a black field, green grid, red 0 dB and purple -3 dB lines, and individual Project windows; whereas the WinISD ("betaversion"), aka "WinISD," has a white field, gray grid, black dotted 0 dB and -3 dB lines, and window-integrated (for lack of a better term) Project fields.

Yours, if it isn't WinISD Pro Alpha (last update 11.09.2004), is different from the WinISD "betaversion" I have (last update 15.01.2002); and these are apparently the only two versions currently available on the Linear Team website.

As for "excursion plots and other goodies." I'll let you know if/when I find/stumble across them.



Indeed, "ultimate party system" is right, LOL! 

And yeah, those RFs keep calling out for their own enclosures. And modularity/mix & match is a great advantage (while more/smaller pieces is much easier on the ol' back).



Modeled IX-8 MBs don't look very promising, as smaller cabs look best, but would need rather long (and not to mention rather phaaaat) ports. 

Incidentally, I wish my six IX-8s were the same as Mom's. From what little I've modeled of each type so far, I like what I'm seeing from Mom's a lot more than from mine (I'll share graphs of each when I feel I've got more or less definitive examples).



Been sitting on two sheets of MDF for months (earmarked for my fabled speakers), and it looks like I'm gonna need to get couple more sheets. However, one excuse for my procrastination is, as nice as my magnesium worm-drive Skilsaw might be, it really sucks not having a (proper, meaning $$) table saw.

Ah, well... In the end, it’s all the more gratifying to know that I’ve done it the hard way, LOL.


Sorry about your brain (again)…


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## lurch (Jan 20, 2014)

BTW :

i changed the background in whatever version of winisd i have , ( i'll check that later ),
from black to a green, just so that the pictures would look better. 
the black background was hard for my phone to capture so i changed a few things. 
it's all change -able to however you want it to look. 
the -3db line, the 0db line, the background, graph db limits, width of the trace line, all of it. 
just go into preferences and choose your poison.


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## Grinder (Dec 18, 2016)

I wondered if that might be possible. I don't care for the white background.

Thanks for the heads-up/tip!


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## Grinder (Dec 18, 2016)

*miniDSP update:*

The day after my last post, I created new settings for my test rig’s miniDSP (two channels, full range, with fairly steep PEQ bump of +15 dB at 30 Hz, and a 20 Hz HP with a 48 dB slope), to see what that would do for my horns (with the “line-straight” setting on my big Kenwood HT receiver), as this receiver actually has 5-channel amp inputs/preamp outputs (in this case, using only the L & R main/front channels, of course).

First thing I noticed when I turned the receiver on, was an ungodly HISSSSSSSSSSSSS. That miniDSP added an enormous ****-ton of noise. I expected hiss, given my experiences with Mom’s RFs and mine (particularly those 105-dB sensitivity monster-tweeters …even with the -6 dB maximum-attenuation setting of their passives!), but I was somehow unprepared for that extreme amount of hiss …and to think that their L-Pads are only turned halfway up! On the other hand, these truly gigantic (and extremely efficient) tweeters, make those RF tweets look like Fisher Price toys.

…And I was frankly underwhelmed by the modestly improved bass response. 

Ah well, I’m not at all bothered by either result. Those horns are perfectly fine without DSP; and I’m not the least bit interested in wasting any (or all) of my receiver’s headroom on forcing 100 Hz bass horns to produce 30 Hz.

…And now, I’m readier than ever for a pair of serious subs to go with my horns. 


*IX-8s-as-midbass update:*

As indicated earlier, _“Modeled IX-8 MBs don't look very promising, as smaller cabs look best, but would need rather long (and not to mention rather phaaaat) ports.”_
However, as it seemed well worth giving *sealed* IX-8s a shot at midbass duty, I flattened Mom’s miniDSP’s IX-8 PEQ settings to zero and (ultimately) raised the resulting flat line to +13 dB (due to the Crown’s preference for a much hotter (i.e. more Pro-level) signal than it’s getting via the DAC and miniDSP), and then (ultimately) set their x-overs to 60 Hz HP, and 300 Hz LP, with 24 dB slopes. And then I simply listened for a while, now feeding her RFs a flat +0 dB PEQ, and an 80 Hz HP (instead of the big bump of midbass PEQ they’d been getting).

I was amazed at how good it all sounded. It seemed so much more powerful, punchy and effortless than ever before (and unmistakably warmer, fuller, richer, as all of the seemingly characteristic RF harshness and over-brightness was (ultimately) gone, with the possible exception of that beast of a tweeter at times) ...and I’ll bet _someone_ out there is grinning like a Cheshire Cat right now. 

Two days later, I split the DAC’s output signal, bypassing the RF channels of the miniDSP, to feed the receiver a full-range signal, in order to properly run my PS-1200 sub, to hear how well the IX-8s-as-midbass might blend with a sub (and to hear how much less hiss there would be without the miniDSP in the loop. Turns out the DAC seems to be making at least 50% of the total hiss, the miniDSP more like 40%, and the receiver maybe 10%).

I got the IX-8s pretty well dialed in this afternoon (as per the settings detailed above - with the PS-1200’s 50 Hz - 150 Hz LP knob set to 50 Hz) …and it sounds so much better than ever! And I played it so much louder than ever before, and it seemed so much more effortless! 

Sometimes, all you can say is _“****!!!”_


*Mom’s new speakers update:*

…So, it’s back to the drawing board – to figure out how I’m going to build IX-8s-midbasses into Mom’s speakers. To begin with, I need to swap a pair of Mom’s D2s for a pair of my D4s, to see how just one IX-8 (D4) per channel might work, and so I can find out how one of those D2s likes being ported in my test rig.

I’m hoping one D2 (or maybe two) per channel can be tuned low enough to blend nicely with one D4 (or maybe two) per channel, in small sealed (say, .2 or .25 cubes ea.). 


*WinISD update:*

Been playing with WinISD here and there (after an hour or two of this, my brain shuts down), and I’ll soon post results of several alignments of the D2 and D4 IX-8s and the HO.


----------



## Grinder (Dec 18, 2016)

*WinISD update*

*IX-8 D2 (older version) vs D4 (newer version) WinISD modeling comparison*


Transfer function magnitude (From top to bottom, along the 30 Hz line):


Aquamarine/Blue – D2 vented/twin vented - 1.5/3.0 cubes - 33 Hz

Gray/Yellow – D4 vented/twin vented - 1.5/3.0 cubes - 33 Hz

Orange/Hot Pink – D2 sealed/twin sealed – 0.5/1.0 cubes

Light Green/Dark Green – D4 sealed/twin sealed – 0.5/1.0 cubes

Red/Pink – D2 sealed midbass/twin sealed midbass – 0.2/0.4 cubes

Dark Green/Light Green – D4 sealed midbass/twin sealed midbass – 0.2/0.4 cubes

Blue/Dark Blue – D2 vented midbass/twin vented midbass 0.5/1.0 cubes 70 Hz

Army Green/Brown – D4 vented midbass/twin vented midbass 0.5/1.0 cubes 70 Hz


SPL (D2 vented midbass is highest curve, just touching the 96 dB line. Lower lines are 94, 92, 90, etc.):



I'm thinking the ported midbasses would be way too peaky, especially considering Mom’s sealed IX-8 midbass tune sounds pretty good to me.

Overall, the D2s and D4s look very similar, with the D2s seemingly better subs than midbasses (as compared to the D4s).

Still need to do the D2/D4 swap on Mom’s speakers and the test rig, to see how well their modelling aligns with reality.


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## lurch (Jan 20, 2014)

so what is this " transfer function magnitude " graph ?
does it relate to room size ?

i would agree that a good sealed enclosure is the way to go for mid bass, but just
for kicks why not try a bandpass alignment ? say from 50hz to 2 or 3 hundred hz. 
( could be a waste of time but it would be interesting to see the predicted output ). 
I'm thinking a BP setup " could " be a good compromise to fill the gap between
the 8" RF's and the dayton subs with very high output capabilties. 

i never did find a ported alignment with the xl8's that wasn't peaky, they are definitely 
designed for car audio, not a flat home response sub. 
so yeah, keep them sealed up if mid bass is what you need out of them. 
the good news here is that they can play higher up. male singers and snare drum etc. 
could sound very good !
i would still be interested to see what a band pass configuration could do here. 

so what does your version of winisd say about the port velocities ?


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## Grinder (Dec 18, 2016)

lurch said:


> *so what is this " transfer function magnitude " graph ?
> does it relate to room size ?*
> 
> i would agree that a good sealed enclosure is the way to go for mid bass, but just
> ...


I guess I assumed it was techno jargon for the anechoic response curve (or whatever it's called). Which one should I be using (and/or which one were you using for your graphs?)?


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## lurch (Jan 20, 2014)

there should be a help file in the program, that will explain it. 

i was using the " gain " and " spl " windows for our discussion. 
i would also look at the " group delay " for the ported alignments, some of
those traces can be wild.


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## Grinder (Dec 18, 2016)

As for port velocities, I hadn't looked 'til now. "Rear port - Air velocity" looks like 1.8 - 3.3 (D2 twin midbass - single D4) m/s - though I'm not sure what to make of it.


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## Grinder (Dec 18, 2016)

Group delay ranges from 14 (midbasses) to 45 (D4).


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## Grinder (Dec 18, 2016)

I don't have a "gain" graph - only "port gain," and I never saw a graph looking anything like that.


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## lurch (Jan 20, 2014)

Grinder said:


> As for port velocities, I hadn't looked 'til now. "Rear port - Air velocity" looks like 1.8 - 3.3 (D2 twin midbass - single D4) m/s - though I'm not sure what to make of it.


those numbers " should " turn red if they are too high. 

seems your version uses meter per second whereas mine uses mach percentages.


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## Grinder (Dec 18, 2016)

lurch said:


> those numbers " should " turn red if they are too high.
> 
> seems your version uses meter per second whereas mine uses mach percentages.


They don't turn red, even with 1" dia. ports...

m/s, cm/s, ft/s, km/l (or km/t? I can't tell), or mph.


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## lurch (Jan 20, 2014)

Grinder said:


> They don't turn red, even with 1" dia. ports...
> 
> m/s, cm/s, ft/s, km/l (or km/t? I can't tell), or mph.


hhhmmmm... no idea of what km/l or km/t means. 

the help file should say what the limits are.

i have seen some threads here that discuss port speeds in both
mach and m/s but can't remember what a high m/s would be. 
weird that a red flag wouldn't come up somewhere in the program 
to warn of impending doom. 

BTW
I've noticed that my RF's just keep getting better. 
turned the input gain up a little on them the other day and no sweat at all. 
system is starting to sound nice & balanced now, I'm still very pleased
with them, no buyers remorse at all.


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## Grinder (Dec 18, 2016)

Not liking the look of bandpass midbass, as I can't get wide enough range (even with ridiculously small cabinet volumes of less than 0.1 cubes), and there's too steep curves, particularly on the high side, where I seem to need a gradual rise in SPL from as high as the 300s, to as low as 60 or so.


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## lurch (Jan 20, 2014)

are you seeing peaks at the upper and lower port tuning frequencies ?
this is normal for a BP alignment, if i understand you correctly ?


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## Grinder (Dec 18, 2016)

lurch said:


> hhhmmmm... no idea of what km/l or km/t means.
> 
> the help file should say what the limits are.
> 
> ...


I've pretty much given up on trying to predict port noise. I Just know that I need 3" for the IX-8s tuned in the 30s and 40s (and I'll go with 4" for pairs), and I'll go with 4" for the HOs (and 2" pairs for the RFs).


Nice! Maybe that's part of why I was able to crank Mom's speakers to _"****"_ levels the other day. I'm happy with them too. But I do wish they had a flatter (much less bright, and punchier) response (though, to a lesser extent when vented).


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## Grinder (Dec 18, 2016)

lurch said:


> are you seeing peaks at the upper and lower port tuning frequencies ?
> this is normal for a BP alignment, if i understand you correctly ?


I see just one "tuning frequency" (and 95 - 100 Hz seems to work best). 

There does tend to be a bit of a dip in the middle, the wider the range. But in any case, the range simply isn't wide enough (70 - 150 Hz at best, with a 1 dB dip, and no SPL gain over sealed, or 80 - 130 Hz, with no dip, and a 3+ dB gain over sealed), and I'm happy with the overall performance of sealed.


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## lurch (Jan 20, 2014)

gotcha. 

good, sealed it is !


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## Grinder (Dec 18, 2016)

Found the help files. I'll have to study up on those before I do any more modeling (or to even begin to fully understand what I've done so far). 

In any case, I'll be drawing Mom's speakers again as soon as tomorrow...


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## Grinder (Dec 18, 2016)

On the speaker-build front, I'm still weighing my options, but I think I’ve narrowed it down: 

(bear in mind that all of the following observations resulted from a flat signal)

1)	While venting had greatly improved the RFs’ midbass response, they still lack depth and punch; and there is a hollow-sounding, high-boominess that I can’t seem to shake, which only gets worse when I set the vented IX’s LP high enough to make up for the vented RFs’ midbass shortcomings, as the vented IX tends toward a slight hollow-sounding boominess, the higher the LP setting. I think I’d settle for the vented RF’s slight “hollow-sounding, high-boominess,” if only they’d provide enough depth and punch on their own.

2)	With a very high HP setting (rendering the ports utterly pointless), the vented RF’s “hollow-sounding, high-boominess” is gone; and commensurately raising the vented IX’s LP improves the overall sound, fully compensating for the RF’s very high HP response, and it’s significantly less hollow/boomy/muddy than the more normal HP/LP RF + IX combination (given enough HP/LP overlap to make up for the vented RF’s midbass shortcomings).

3)	Also, I’ve noticed with Mom’s speakers, that the sealed RF’s roll-off seems to blend nicely with the sealed IX’s natural response curve, nicely compensating for the RFs’ lack of depth and punch, with none of the hollow boominess of either ported alignment (or combination thereof).

4)	And lastly, given their necessarily high F3, vented IX-8s seem more or less out of place, and with relatively little to do (within only the 35 Hz – 60 Hz range) within the above context (i.e. sealed RFs with ~150 Hz HP + sealed IXs with ~150 Hz LP and ~60 Hz HP), particularly with respect to Mom’s system, whose primary function is HT.


Bearing all of this in mind, it seems like my two best options are as follows: 

A)	Sealed RF + twin sealed IXs + vented HO (pair of towers or modular) for me. 

B)	Sealed RF + twin vented IXs (pair of towers or modular) for Mom.

(or, eventually build two pairs of option A – the first pair for Mom, the second pair for me)


However: 

1)	I really need new speakers like a hole in the head (EDIT: not that I don't _want_ new speakers).

2)	Mom’s speakers don’t need to be nearly as loud as option A (and her receiver is a bit weak for the RFs anyway).

3)	Option A would be rather large (and look a bit ridiculous) for Mom’s system and living room (though they would physically fit), and there’s still the issue of very long ports, and resultant serious cabinet-dimension/port placement challenges, for a mid-20s to low-30s tune.

4)	Option B is a bit too much of a compromise in terms of SQ (boomier midbass, possibly overtaxed subs, and mediocre low-extension), for me to be all that enthusiastic about it.

5)	Mom’s Crown would seem to have plenty of power to push sealed HOs loud enough for her system (with her miniDSP to easily PEQ them into the low 20s).


And bearing all of this in mind as well, it seems like my best option would be:

C)	Sealed RF + sealed IX + sealed HO (pair of towers) for Mom. 

(Of course, I’d need to come up with an amp for the IXs, but maybe I’d go ahead and splurge on a Crown XLS 1502, to power the HOs instead of the 1002, and use the 1002 for the IXs)


Also, I seem to have learned something about WinISD air velocity graph (“rear port – air velocity”):

As per “WinISD Pro Help”: 
“In order to keep chuffing noise low, you should limit the peak velocity at 5% of velocity of sound, or about 17 m/s.”

The IX-8 D4 is at 41.5 m/s (1 cube, 200 watts, 37 Hz, 3” vent dia.). With a non-flared port, I was getting fairly severe chuffing (at way less than full volume, BTW). However, with a flared port, I’m getting virtually no chuffing at all (at whatever volume I’ve dared to try).

This leads me to conclude that the < 17 m/s recommendation pertains to non-flared ports.

By way of comparison, the HO is at 49 m/s (3 cubes, 500 watts, 25 Hz, 4” vent dia.).


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## Grinder (Dec 18, 2016)

...On the other hand, given all of the very helpful porting discussion in this thread, I feel sort of obligated to port the HOs.

My only consolation is that I plan to build a new boombox, based around a ported IX. And I would like to build a pair of ported HOs to go with my horns (which could also be used with a pair of RF + IX midbass towers).

It's just that Mom's replacement speakers are the priority right now; and all things considered, sealed HOs seem to be the best option (even though I'd really like to keep the HOs for myself, and even though I'd really like to make maximum use of the IXs).


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## Grinder (Dec 18, 2016)

Grinder said:


> As for port velocities, I hadn't looked 'til now. "Rear port - Air velocity" looks like 1.8 - 3.3 (D2 twin midbass - single D4) m/s - though I'm not sure what to make of it.


UPDATE:

These figures are flawed. At that time I somehow hadn't yet realized that I'd need to enter "Signal/system input power" (DUH!). Default is 1 watt, which is why those velocities are so inconceivably low.

The correct figures are:

At 150 watts, 1 cube, 70 Hz, two 3" dia ports, D2 twin midbass is 22 m/s.
At 200 watts, 1 cube, 70 Hz, one 3" dia. port, D4 single midbass is 36 m/s.
At 200 watts, 1 cube, 37 Hz, one 3" dia. port, D4 single sub is 41.5 m/s.


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## Grinder (Dec 18, 2016)

Grinder said:


> *I've pretty much given up on trying to predict port noise*. I Just know that I need 3" for the IX-8s tuned in the 30s and 40s (and I'll go with 4" for pairs), and I'll go with 4" for the HOs (and 2" pairs for the RFs).
> 
> 
> Nice! Maybe that's part of why I was able to crank Mom's speakers to _"****"_ levels the other day. I'm happy with them too. But I do wish they had a flatter (much less bright, and punchier) response (though, to a lesser extent when vented).


In light of recent developments, I'm feeling a lot more optimistic about port noise prediction; and for the time being, I'll assume that anything under 40 m/s in a flared port should be okay.


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## Grinder (Dec 18, 2016)

More on port velocity noise (actual) versus WinISD (predictions):

As per post # 243, in WinISD the IX-8 (D4?) in 1 cube, 42 Hz, 3" dia port, 200 watts = 0.06 Mach port velocity (?).

I come up with 41.5 m/s (at 37 Hz). 

...or 43.0 m/s at 42 Hz x 2.23694 = 96.18842 mph x 0.00130332 = 0.12536429 Mach

m/s to mph = 2.23694
mph to Mach = 0.00130332
17 m/s = 38.02798 mph 
38.02798 mph = 0.0495626 Mach

Either way (Mach or m/s), the result is more than 2.5 times the WinISD-recommended 17 m/s chuffing threshold.

?????


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## lurch (Jan 20, 2014)

so after reading through all your latest posts i decided to go back to skar's site and
take another look at the parameters and box recommendations. 

in the box / tuning section they recommend huge port areas for this xl8, actually larger than
most of the 10's and some of the 12's !

so what gives with this little 8" beast ?
maybe it has something to do with motor strength VS cone area. ( ? )

double checked my inputs to winisd, one thing i notice is no matter what size
the enclosure is or how long the tube is ( three inch dia. ) the mach number stays relatively 
the same .... 0.06. 
that doesn't make sense. 

i asked my friend to look at his QTS number for the sealed alignment that we made
for him regarding that 15" dayton that he adhores. 
turns out that his is the HF version not the HO. 
i was hoping you could shoot for the same qts with your 12's but they are two different
drivers by design, the number would be moot. ( sorry ).


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## Grinder (Dec 18, 2016)

Thank you! 

I'll try to double-check everything on my end tomorrow.

I wasn't sure if you were using the Skar website specs, or those of my D4 spec sheet (which I posted somewhere in here fairly recently), including the 150 W RMS website spec (same as Mom's older D2 spec sheet) versus the 200 W RMS per my D4 spec sheet. Incidentally, while I can't be sure, it seems to me that my D4s do handle more power than Mom's D2s.

Yeah! So glad you mentioned it; I too poked around a bit on Skar's website awhile back, and scratched my head at the same (or similar) 13 sq. in. port area spec for a few larger subs. I need to go back and look at that again as well.


And having listened to Mom's D2s (and a pair of my D4s) on midbass duty in her speakers, followed by re-tuning her D2s for sub duty once again, I've learned a whole lot more about what I like and how to achieve it, and it turns out that it seems best to just let the RFs and IXs (Mom's D2s in this case) be what they want to be (more or less). All I'm adding is a fairly sharp spike of about 5 dB at 30 Hz, with 24 dB slope HP/LP of 25/250 Hz, and a _very wide_ -10-ish dB curve, centered around 6K Hz; with a 24 dB slope HP of 100 Hz for the RFs -and everything's sounding a lot better than ever (I know... I sound like a broken record, LOL). 

...so much so, that I'm very seriously considering not replacing them. And consistent with that notion, I'm nearly finished with the process of moving all of the enclosure-volume-reducing wood pieces from my test rig and boombox, to Mom's RF chambers (which will maximally reduce their volume - not yet sure what their reduced volume will be, but I can easily remove wood to increase it if necessary). 

If all goes reasonably well (and if I don't change my mind once again, LOL), I'll very likely return to the modular speakers concept, with ported HOs, multi-IX-8 midbasses (and the RFs, of course). 

And while I'm at it, this will give me a chance to play around with the test rig's ported RF cabinets; namely - add bracing, to hopefully address their hollow (or resonant?) sound, and play around with enclosure volumes and port lengths.


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## lurch (Jan 20, 2014)

well you are obviously right about the high port velocities. 
for an 8" 200 watt woofer to need more than the area of a 4" pipe is kind of
mind blowing. skar seems to know what they are talking about. 
M/S in the mid 40's ...... no wonder you can feel the ports blasting from a distance. 

i would like to know what's going on too, maybe the xmax numbers are way under
what the xMECH numbers are. perhaps this little woofer easily overshoots the xmax
and still sounds composed doing it ?

interested to see what you come up with regarding the RFs. 

with the HO : you will have a very broad range of what will sound good regarding
box design, sealed/ported, it will forgive you for wide varients..
the big concession for a ported design will be size, could be worth it for the efficiency 
though. weight will be the factor. 
my friends HF series 15 was going to end up LARGE and weigh in at 175lbs by the time
the design was agreed upon. 
in the end he decided to try a sealed unit at less than half the weight, he wouldn't trade
it for the world. 
my point is that the HO should be pretty damned loud, even if you need to compromise
with a sealed design. 
also, there are ****loads of good designs on the net already for the HO series, i would follow
the designs by dayton and just build the one they recommend for the sound you want.

edit

forgot to mention that for every lx8 i modeled the input wattage was set at
200.


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## Grinder (Dec 18, 2016)

All great stuff! Thank you!!!

Finished stuffing Mom's RF compartments with wood (and lots of cabinet 
carpet scraps, tightly crammed in every gap to prevent vibration) this 
morning, and there seems to be a noticeable improvement in midbass 
(though I'll need a lot more listening time; and there's no back-to-back 
reality check).


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## Grinder (Dec 18, 2016)

lurch said:


> ...double checked my inputs to winisd, one thing i notice is no matter what size the enclosure is or how long the tube is ( three inch dia. ) the mach number stays relatively
> the same .... 0.06.
> that doesn't make sense...


In an effort to affect WinISD port velocity, I first tried changing xmax; and then Vas; and then Qes, by reentering and then saving one parameter at a time, and then close and reopen a project ...to no avail (m/s remains unchanged).

I'm very confused... I mean, shouldn't there be one or more T/S parameters that effect port velocity?


And then get this: As I gradually reduce box size from 1.0 to 0.1, port velocity gradually drops to 16 m/s for 0.1 cubes - incidentally, at about 19 Hz; and 41.5 m/s peak velocity for 1.0 cubes is at about 33.5 Hz)!

And, while I can only indirectly change port length via tuning frequency, I found that a 11.5 Hz tune produces just over 24 m/s (at just over 10 Hz), and a ~97 Hz tune produces just under 58 m/s. From there, at about 60.0 (yes, sixty) cubes, a peak of 85 m/s is reached. And then from there, a peak of 112 m/s can be reached with a 52 Hz tune!

It seems HAL and Deep Thought need to have a serious CPU-to-CPU, LOL.


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## Grinder (Dec 18, 2016)

Great news!

Having removed all of the cabinet volume-reducing wood pieces, I simply filled the below-ports portion of the test rig RF chambers with poly fill, and then covered all remaining surfaces with ~1-inch-thick poly batting (with no added bracing) - and voila! They sound so much fuller, richer, and way punchier than ever before! And their slight (but annoying) peaky hollow/high-boominess seems to be gone.

At about .64 cubes, with two 2" dia. x 3" ports (same ports as before), technically it's tuned to 77 Hz, but it seems closer to 70 Hz. With no PEQ or HP, they start falling off at around 90 Hz, play fairly strongly through the 50s, and can be heard well into the 40s! 

It's almost as if these things were made for largish ported cabinets... 


On another note, Mom's RFs don't seem to like _very small_ sealed cabinets all that much either (not sure exactly what volume remains in Mom's RF chambers, but they must be on the smaller end of the 0.1 - 0.2 cubes range). Whatever gain there might be in midbass, it is negligible; and it seems to have come at the cost of a harsh peakiness in the upper-mid speaking-vocal range (first noticed this evening, while watching movies). 

So, for better or worse, I'll be installing twin 2" dia. x 3" ports (as a starting point) in Mom's RF-chamber rear panels, as soon as tomorrow (I tried to talk Mom into a pair of très chic periscope ports ...mais hélas, Mère est si démodée). While I have no idea how good/bad rear ports might sound (compared to front ports), I think it's certainly well worth a try.


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## lurch (Jan 20, 2014)

KEWL !

how are they in the male vocal area now ?
I'm thinking of reinstalling the old daytons in the doors and making a set of boxes
for the the RFs to throw in the back of the suburban, i want to increase the
lower vocal range and can't seem to attain that through EQ. 
either that or close up my sub enclosure and reduce the cuft volume to see if i can
get the results that way. 

interesting results with winisd, I'm glad you investigated that. 
i wonder if the 2016 version of winisd would give the same results ?

" deep thought "
heee heee heeee, awesome.


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## Grinder (Dec 18, 2016)

lurch said:


> KEWL !
> 
> how are they in the male vocal area now ?
> I'm thinking of reinstalling the old daytons in the doors and making a set of boxes
> ...


Not sure about male vocal strength/weakness. I'll try to look into that - any artists and/or tracks you'd recommend? 

It's intriguing, as I can't say I would ever have noticed that anyone's vocals weren't strong enough. Perhaps it's because I tend to favor instrumentals, and because I tend to pay a lot more attention to lyrical content than the voices singing them (though there are a number of female vocalists who really do it for me; and I suppose these ladies could sing about anything, and I'd still be "grinnin' like a mule eat'n garlic," LOL).


Hmmmm... kinda surprised you'd go back to the Daytons; or is the RF honeymoon more or less over (as you seemed to be very happy with them early on; but perhaps enough of your early adoration has worn thin - partly due to the male-vocal weakness - enough to make you want to try the Daytons again)?

Deep Thought...  (I really crack myself up sometimes ).


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## Grinder (Dec 18, 2016)

Oh, and about WinISD... I surely must be missing something, because I'll be damned if I have any idea how it arrives at whatever port velocity, or which T/S parameter is most important to the result.

I'll have to try it again, as I must be re-entering the parameters in the wrong order or something... My results don't make any sense at all, so they must be wrong.


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## Grinder (Dec 18, 2016)

Grinder said:


> Oh, and about WinISD... I surely must be missing something, because I'll be damned if I have any idea how it arrives at whatever port velocity, or which T/S parameter is most important to the result.
> 
> *I'll have to try it again, as I must be re-entering the parameters in the wrong order or something... My results don't make any sense at all, so they must be wrong.*


Well, so much for that... I just created eight new drivers - seven versions of the IX-8, each with just one of the T/S parameters significantly raised: Qes, Qms, Fs, Re, Vas, (no Pe), Xmax, BL - with no change in port velocity. Only the eighth version, in which I raised the value of all T/S parameters at once - and to the same degree - did the port velocity change (to just over 44 m/s, with 1 Qes, 7 Qms, 60 Fs, 9 Re, 10 liters Vas, (no Pe), 28 Xmax, 20 BL).

I give up (for the time being, anyway)...


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## lurch (Jan 20, 2014)

oh i havent given up on the RFs at all. 
i still remember how happy i was when they first fired up. 
my system has lacked the lower vocal range ever since my 10" fosgate sub was
blown up and tossed. that thing was magic for some reason and I can't replicate
the upper resonse it had. been chasing that " sound " ever since and RF doesn't 
make that particular driver any more. 
pretty sure this is a subwoofer tuning issue, not a midrange driver issue. 

instead of swapping out the RFs with the daytons i will more likely build a set of 
enclosures for the daytons. 

for male vocal try these
" hello city " / bare naked ladies , album = gordon (this entire album is very well recorded ) 
" too sexy " / he said fred
roy orbison tracks
i'll think of more later.


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## Grinder (Dec 18, 2016)

I wasn't going to say it, but it sounds like what you need are some IX-8 midbasses back there, LOL!

(Right) Said Fred... as soon as I read that, I think I got the picture. I'm thinking "Put Your Lights On," from Santana's "Supernatural" album might be another prime example.

Not sure I'll ever be able to say much more than, porting the RFs (particularly with the larger enclosure volume) _must_ have improved male vocals immensely (along with the whole midbass range), but I really can't say for sure.


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## Grinder (Dec 18, 2016)

...anyway, to give you an idea how much difference the larger RF cabinets have made, I've currently got their HP way down at 60 Hz (I know! But it sounds great, and there seemed to be the least hollowness with this setting - yeah, there does still seem to be some hollowness, but lower in tone, and less noticeable than before), with a 24 dB BW slope, and no PEQ (just the -12 db wide-curve in the 5K - 7K range); and the IX-8's HP at 25 Hz, with a 48 dB BW slope; and its LP at 60 Hz, with a 24 dB BW slope, and a ~7 dB bump of 35 Hz, curving increasingly upward from 80 Hz.

And bear in mind that the test rig is in an extremely poor location for critical listening and tuning, with a wall just 8 inches to its left (90 deg. from baffle), extending to a corner and wall just 7 feet in front, with the rear wall about 5 feet to the rear of the baffle. Its midbass/bass sound changes dramatically as I move around within the very small area in front of the test rig.


Also bear in mind that Mom's speakers are often used to listen to the radio, in which case there is no DSP, and no IX-8s, which makes them sound ridiculously thin (whether their sealed RF enclosure is large or small). So, in this case, any added midbass/bass will be very welcome, even though it may not be of the highest quality (which could be addressed with a high HP setting and/or PEQ adjustments, for 2.2 stereo and HT duty).

It's still way too early to tell if I'll port my RFs, when/if I ever get around to building those modular speakers. If I do, it'll likely be because it would be nice to have some very loud, efficient and reasonably compact satellites/bookshelf speakers (and maybe they'll even match well with ported or sealed HOs). If I don't, it'll likely be because I've traded that option for optimal SQ and maximum impact/punch, with the addition of IX-8s on midbass duty (or the like).


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## Grinder (Dec 18, 2016)

Finally got Mom's RF rear ports done today, and they're a great success! I obviously haven't had much time to listen to and tune them; but I’m very pleased with their baseline performance. Actually, they sound waaaaaay better than I’d have any right to expect (and I’m very grateful for that!) ?

I ended up going with single 3" dia. ports instead of twin 2", though I'm not sure of their exact length (read on).

To prevent back wave midrange escaping through the ports, they're located 3" from the top panel, in the form of a 45 (a 90 elbow sawed-in-two, + a 2" pipe section - just long enough to mount the 45 through the rear panel - to keep overall port length short as possible - 3" - 4", for a tune in the 70 Hz range) aimed upward; and added an MDF panel, extending 3.5" downward at a ~45 from the lower-rear edge of the tweeter chamber, as a line-of-sight shield between the rear of the cone and the port opening. And it all seems to have worked like a charm!


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## lurch (Jan 20, 2014)

YAAAAAAAAAY !

take any pics ??
( trying to envision the description)

glad this is working out.


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## Grinder (Dec 18, 2016)

Thanks!

Thought of taking pics, but when I finally get busy on a project, it's full steam ahead...

But since I'm so happy with the results (even watched a couple movies tonight, without the subs, and it really is amazing how well these things do without them) I'll take a few pics tomorrow.

Definitely going to build some satellites with my RFs, and play around with port lengths. Not sure what size to make the cabs, though... I'd like to try even bigger (than .63 and .71, IIRC), like 1 cube , but I'm not sure how much lower I can go without creating a big dip or something.


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## Grinder (Dec 18, 2016)

It might not look like it, but there's plenty of space for airflow between the angled back wave shield (for lack of a better term) and the rear panel (and port opening).

And I suppose I might have gone a bit overboard on the polyfill, but there's none at all in the entire area above and behind the back wave shield.


BTW, while it's not nearly as astounding as that of my IX-8 D4, the air movement from the RF, through the same 3" diameter, is pretty impressive!

Also, I've been mostly running them without HP, PEQ (just a very wide -5 dB curve in the 5 kHz range) and subs, to get a feel for their natural strengths and weaknesses.


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## lurch (Jan 20, 2014)

Grinder said:


> Thanks!
> 
> Thought of taking pics, but when I finally get busy on a project, it's full steam ahead...
> 
> ...


im not sure they will like much over .5 cuft. 
i seem to remember that the freq response started to suffer after that. 

good pics, thanks for takin ng the time !


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## Grinder (Dec 18, 2016)

lurch said:


> im not sure they will like much over .5 cuft.
> i seem to remember that the freq response started to suffer after that.
> 
> good pics, thanks for takin ng the time !


Oh, I definitely hear ya! I haven't forgotten that (and I've modeled them myself), but it seems the larger I go, the better they sound (not that I assume this trend would continue). 

I really didn't like the sound when I went from .6-something to .2; and Mom's .7-something sounds best yet. It would be nice if WinISD could predict boominess or hollowness, since those issues (unlike dips and spikes) can't be fixed with x-over or PEQ. 

Granted, the test rig is in a crappy location, has twin 2" ports (instead of a single 3"), a significantly higher tune, much shallower cabs (particularly in the .2 config), and I didn't try many port lengths - but in the end, none of that matters very much, as I can't ignore what I'm hearing from Mom's RFs. 

Interestingly, while they seem to be tuned ~ 65 - 70 Hz (and they sound pretty nice, and have _amazing_ depth, without an HP), they do seem a bit boomy - which goes away with an 80 Hz HP (24 dB BW).


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## lurch (Jan 20, 2014)

ok, how'bout we both do a few sims with the RFs at 1 cuft and compare the
two different winisd versions ?

I'm going to try three different dia. ports: 2" ( X2 ), 3" , and 4". 

could be interesting …


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## Grinder (Dec 18, 2016)

All three 1-cube alignments, given the same tuning frequency, modeled exactly the same (SPL).

All used “BB4/SBB4 (Super-)boom-box” default alignment (BTW, I’ve no idea if this or other alignment might be best for this driver - or which alignment might be best for the IXs and HO).

(All @ 125 watts)
(EDIT: In descending order of SPL peak):
Brown: .4 cube, twin 2” x 3.21”, 95 Hz, 24 m/s (reduced volume test rig).
Blue: 1-cube, 4” x 3.95” port, 70 Hz, 17.5 m/s.
Light green: .64 cube, twin 2” x 3.22” ports, 75 Hz, 29 m/s (test rig).
Black: 1-cube, 3” x 3.07” port, 60 Hz, 30.5 m/s.
Red: .71 cube, 3” x 4.13” port, 65 Hz, 25.75 m/s (Mom’s RFs).
Dark green: 1-cube, twin 2” x 5.28” ports, 50 Hz, 31.5 m/s. 

EDIT: These larger-cabinet/lower-tune WinISD graph results seem misleading in terms of their bass/midbass dips (or lack thereof), particularly in the case of the red line which, among the three versions I've actually heard, sounds the best in terms of bass/midbass response.

NOTE: I’ve been using the “latest” version of WinISD - “WinISD 0.7.0.950” (BETA).
WinISD Pro is “WinISD 0.50a7” (ALPHA) I’ve hardly used this version, because I’d already had a number of projects (and their drivers) in the other version, and I didn’t want to start over – beside the fact that I have no idea which version is best.
Which version are you using? (on both of mine, their version code is shown in the upper-left corner of the window)


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## Grinder (Dec 18, 2016)

$#!+ Useless minuscule thumbnails...


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## Grinder (Dec 18, 2016)

Here's an actual camera "screen shot":

...which is sadly not much better.


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## lurch (Jan 20, 2014)

here are HAL's winisd results :

basically identical to Deep Thought's. 
i kept everything around the 70hz range, just separated by a few hertz
to keep the traces apart and readable. 

the orange line is the " control " at 0.4cuft and ~95hz. 

notice that the lines take a dip across most of the bass range until tuning
frequencey is reached, then we get the hump, just as Deep Thought predicted. 
no surprises here. 
but take a look at the group delay graph, this is what could be important, as the
enclosure gets larger the group delay also becomes more pronounced. 
in other words, the bass response at tuning lags behind. ( all ported enclosures
exhibit this behaviour, the amount of M/S determines the severity ). 
this may or may not be too important, depending on how critical the listener is,
how the other speakers in the system behave, and the room the speakers are in. 

HAL's winisd version = 0.44

let's see if i can attach the pics ...


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## lurch (Jan 20, 2014)

PICS

GAIN


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## lurch (Jan 20, 2014)

pic 2

GROUP DELAY

one day i'll manage to get attachments right side up


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## Grinder (Dec 18, 2016)

I'm not exactly sure what to make of the group delay. In any case, I think I've reached a decent compromise with Mom's RFs.


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## lurch (Jan 20, 2014)

Grinder said:


> I'm not exactly sure what to make of the group delay. In any case, I think I've reached a decent compromise with Mom's RFs.


yeah, and with the lack of T/S specs who's to say what will work without
experimentation. 
a computer can only tell us so much, especially if the input data is this
limited.


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## Grinder (Dec 18, 2016)

lurch said:


> yeah, and with the lack of T/S specs who's to say what will work without
> experimentation.
> a computer can only tell us so much, especially if the input data is this
> limited.


...I was wondering what might be going on here - how much of this results from T/S specs, and how much from enclosure volume (and port volume?) and tuning frequency. 

BTW, under "Choose Alignment," which do you use (and why)? (though I seem to answer these questions below, it seems well worth mentioning these "alignments") 


QB3
BB4/SBB4
C4/SC4
EBS3
EBS6

Any idea why WinISD seems to favor one "alignment" (over the others), for any particular driver?

For example, it suggests/automatically pre-selects: 

QB3 for the Dayton HO
C4/SC4 for the Skar IX-8
BB4/SBB4 for the RF PPS4

I wonder what drives this preference, whether WinISD is making the right choice, and how this (or another "alignment") might effect the modeling results.

WinISD help was no help at all (in terms of this "alignment" quandary), as it refers to a different version than mine (one very much like, or identical to, yours and/or the Pro version, even though I'm accessing WinISD help via the help function within my version of WinISD (BETA)), and makes no mention of those "alignments" whatsoever.

Googling the interwebz netted _some_ info on those alignments, but I couldn't really make heads or tails of it; and I still have no idea what effect they might have on WinISD results (and real-world SQ).

I suppose I wish I'd started with the Pro version instead (in my case, version 0.50a7) - if for no other reason than the aforementioned Pro-oriented help files. I've continued using the BETA version (0.7.0.950) rather than scrap all of my WinISD projects and start from scratch in Pro (ALPHA)... But maybe my beta version is somehow better? (and so I should stick with it? Any thoughts on this?)


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## lurch (Jan 20, 2014)

finally took a look at my version , ( 0.44 ) to see what alignments were
available in this particular program. 
only three !

sealed
ported
4th order band pass

6th order band pass is also listed but when i open a new project and
select it a message comes up saying that this version is not capable
of calculating a 6th order BP. 
I actually laughed !

there are drawings of the boxes in each different alignment which makes
the selection self explanatory. 
does your version show a drawing of the suggested enclosure ?

when i get a chance i'll download your version onto the business laptop
and take a look. 
0.44 must be a VERY early version. i think it's time to try a new program
anyways, i do miss the pro version. while I'm at it I'll download a few others, other than winisd. 

the alignment that winisd recommends is based on the " efficiency bandwidth "
of the driver. this is a calculation between the Qms, Qts and a few others of the
T/S parameters ( I don't remember the formula ).


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## Grinder (Dec 18, 2016)

Thanks.

The "alignment" I'm referring to, comes right after having selected "type of design" (i.e. enclosure type - vented, 4th order, 6th order, passive radiator, and ABC, whatever that is - the "alignment you're referring to EDIT: yes, there is a drawing - and now I see what ABC is ), when it says "choose alignment," and gives a drop-down menu for: 

QB3 Quas1-butterworth
BB4/SBB4 Super Boombox
C4/SC4 (Sub-)chebyshev
EBS3 extended bass shelf -3 dB
ESB6 extended bass shelf -6 dB

...followed by "project information" (project name and description)


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## Grinder (Dec 18, 2016)

...Those five "alignments" are different versions of the ordinary "vented" "type of design" (enclosure type). Under 4th order bandpass enclosure type, there's another "choose alignment" drop-down menu, for selecting one of five different values of: "x.xx dB passband ripple, x dB passband gain." 

And like your version, I get the "current version of WinISD can't calculate alignments for chosen box type" message when selecting 6th order (and ABC). For PR (enclosure type), I'm then prompted to enter "passive radiator parameters": Vas, Fs, Xmax, Qms, and Sd - and then I once again get the "current version of WinISD can't calculate alignments for chosen box type" message.


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## lurch (Jan 20, 2014)

OOOOOHHHH K

that all makes perfect sense now. 
each major design has another menu/ choice for variants of that design, and once
you pointed that out the acronyms became clear. 

I can't remember if winisd pro does this or not. 
it probably does but i didn't delve into them. 

i wish this ipad could run the software, having a desktop computer that is not
hooked up to the net really sucks sometimes ...


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## Grinder (Dec 18, 2016)

...And BTW, in my version of WinISD (Pro "ALPHA") 0.50a7, for 6th order I get: 
_"WARNING! Current version of WinISD can't calculate 
optimum box parameters for this box type. 
You need to adjust the parameters by hand." _

...And it _appears_ that, if I were to enter the PR parameters, it would go ahead and model a PR enclosure.

...And there is no "ABC" box type.


...And this version of WinISD has the "Choose Alignment" part (QB3, BB4/SBB4, etc), where it says: 
_"Here you must select an alignment for your box. 
If you don't know what an alignment is, then just click on "finish.""_ 
(slightly cheeky wording, eh?)


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## Grinder (Dec 18, 2016)

Finally, back to the drawing board...

I've been down the Group Delay rabbit hole for a while: 

* Partly out of curiosity, as GD would relate to Mom's large-cabinet vented RFs; where it is an acceptable compromise in full-range duty (receiver's radio/USB source), and entirely irrelevant in miniDSP duty (computer media source), due to low Fs and high HP setting; whereas my RFs will be in small sealed (with my IX-8s on bass-midbass duty). 

* But mostly out of necessity, as GD would relate to venting my HOs. And in this regard, it seems that I've learned a few things:

I read here: subs and group delay - AVS Forum | Home Theater Discussions And Reviews :

_" Years and years ago, I was given a rule of thumb by an experienced and well-respected speaker designer. Multiply the group delay by the frequency at which the delay is reproduced. As long as the result stays below around 400, you needn't worry.

I have built several vented systems since then, following that guideline. They all sound remarkably similar to the sealed box version of the exact same system (which as you probably know, tend to have significantly lower group delay in the bottom two octaves). In fact, if you didn't know they were vented, I'd go so far as to say that the only thing giving away that fact is the low frequency extension - exactly what I wanted.

Also based on the rule of thumb, you can clearly see that as your frequency drops, the amount of group delay which can be considered acceptable and possibly even inaudible, increases. Whereas 20 ms group delay at 50Hz would be much too high, 20 ms at 20 Hz is probably ok."_

And I've read, over and over again, that GD is inaudible at 30 Hz or less.

So, in light of all this (and the HO's high GD at >30 Hz), I'm pretty much settled on either 707 Qtc sealed, or 3.7 - 4 cubes volume (for a 4" dia. flared port length of 17" or less), and a 22 Hz tune.

The best one-piece vented design I've come up with is absolutely MASSIVE - something like 18" W x 20" D x 42" H - waaaaaaaay too big and heavy. So, it would definitely have to be modular. 

If I go sealed, they'd be one-piece replacements for Mom's speakers (which she's more than happy with as they are, and I suppose I am too... but still...); but for my purposes (to go with my RFs and IXs), they're going to have to be vented.

What say you?


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## lurch (Jan 20, 2014)

i say THANKYOU for diving into that rabbit hole !
you may have just explained to me as to why my car sub sounded so boomy until i
moved the SSF up from 20hz to 28hz. 
i did the " rule of thumb " calculation as soon as i read your post and discovered
that group delay could very well have been the issue. 
the calculation yielded a 575 and the frequency directly relates to harmonics that were
very loud in my vehicle. 

in your case i would build the 707 sealed unit first. try it out, see what you think of it. 
ask yourself : 
will this be enough for what i need as a portable unit ?
if yes, build two of them and enjoy. 
if no, move on to the vented designs. 

i would personally be tuning the party enclosures higher. 
most of the excitement for dancing etc. is not down low, it's in that kick drum.


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## lurch (Jan 20, 2014)

i mean, 
bang up a sealed enclosure out of plywood, not pretty, just quick. 
try it out with mom's system, the output may surprise you in a living room, maybe two
of them built in to the main enclosures will be too much, or maybe your mom won't
like the result. 
at least it gives you a starting point. 
and it's portable, so you can try it out in different situations then make a better
decision as to what direction to take.


----------



## Grinder (Dec 18, 2016)

lurch said:


> i say THANKYOU for diving into that rabbit hole !
> you may have just explained to me as to why my car sub sounded so boomy until i
> moved the SSF up from 20hz to 28hz.
> i did the " rule of thumb " calculation as soon as i read your post and discovered
> ...


KEWL! I intend to keep learning what I can about GD, etc.

Great advise, thank you!



lurch said:


> i would personally be tuning the party enclosures higher.
> most of the excitement for dancing etc. is not down low, it's in that kick drum.


I definitely get that ...but then I'd be back to BIG GD (in the heart of that higher Fb - incidentally, I recently wrote "Fs" when I meant "Fb"), which I fear will destroy SQ, and the punchy tightness that I seek, at least partly by virtue of the HO's seamless integration with the IXs.


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## Grinder (Dec 18, 2016)

lurch said:


> i mean,
> bang up a sealed enclosure out of plywood, not pretty, just quick.
> try it out with mom's system, the output may surprise you in a living room, maybe two
> of them built in to the main enclosures will be too much, or maybe your mom won't
> ...


Better still! 

I don't have any suitable plywood, just two full-sheets of MDF...

And I've been wondering how much in-room response might improve LF extension - but if Mom's IX's are any guide, it seems very promising.

I wonder how one (or two) of these would compare with my (4th order bandpass) PS-1200. That thing is pretty damn potent (and I've barely got it turned up halfway). I've been testing it with Mom's system again, with all four of her IXs on bass-midbass duty - and talk about "effortless" power and impact...!!! Pretty impressive, and it does seem to sound pretty nice, but then it wasn't exactly "critical listening" - and I wonder what sort of GD the Paradigm might be adding to the mix.

Of course, I really don't know, but I seriously doubt that one sealed HO (given maybe 400 watts from a 12.2-volt power-supplied R500X1D) would match my Paradigm in terms of SPL (though I'd certainly be overjoyed if it would!). I'd even be a bit surprised if two sealed HOs (given ~ 400 watts each - or perhaps much more (?), from a Crown XPS 1502) would match my Paradigm in SPL (though I certainly hope that they would).

If there were (or seemed to be) a good/ideal place for one sub in Mom's living room, I might give it a try. But it seems that my best option is to build a pair of them, and place them beneath her towers, which would raise those towers to a height of almost 47" (talk about "towers!"). By necessity, their cabs would be 13.5" x 13.5" (to nicely fit the driver) x 15" (to match the depth of her towers), which comes to 1.125 gross cubes (or ~ 1.0 net cube, with a Qtc of .672). And when I showed Mom how this would look, she said, "What's wrong with that? That sounds like a great idea," God bless her.

Anyway, it sounds like a plan (finally!!!). Thanks once again for your great feedback!

Will they be "too much?" I sure as hell hope so! LOL


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## Grinder (Dec 18, 2016)

Damned psychoacoustics… and flawed judgement, hasty assumptions, erroneous conclusions, and general confusion... led me to mistakenly think that IX-8s are suitable for midbass duty. :blush:

Although Mom’s IX-8s seemed to add some midbass punch while they were accompanied by the PS-1200, it turned out to be mostly my imagination, as I noticed very little difference when I repeatedly turned the IX-8s’ amp off - apart from improved clarity (presumably due to reduced distortion).

So, Mom's IX-8s are back to "subwoofer" duty (and the PS-1200 is collecting dust again), operating in the 30Hz to 100Hz range - with a wide -4dB dip at 50Hz, a +7dB 30Hz spike, and a 48dB BW 25Hz HP - and they’re sounding better than ever!  …or maybe it’s just that I’m appreciating them more than ever. 


…all of which has led me to suspect that my RFs might blend just fine with the HOs (ahem… with no need for IX-8s on midbass duty - even IF they happened to be remotely suitable for midbass duty).

...which is why, among several other reasons (*), I'm once again leaning toward building a pair of three-way towers (RFs + HOs), LOL. 


*I favor indoor SQ over outdoor SPL. So, I’m reluctant to trade <30Hz F3, flatter response, and low GD (<400 ms x Hz at >30Hz) for enhanced 40Hz excitement (and peaky response, >30Hz F3, high GD at 50Hz). 

*I’d like the center-point between the RFs to be almost 40” high; and the RFs require such a small cabinet volume; and I don’t want to go much deeper than 17” - with a straight (no elbow) 4” dia., forward-facing port (necessitating a nearly 4-cubes sub cab volume) and driver; and it doesn’t make any sense to build an overly wide and tall stand-alone sub cabinet.

So, I’m thinking of a pair of cabs at 44” H x 13.5” W x 16” or 17” D (depending on how much bracing I’ll need; whether I decide to port the RFs or not; and how many cubes I’ll give the RFs), for ~3.7 cubes, a ~27Hz Fb, and a ~10.6” flared 4” port.

And with that low Fb, I could simply swap the longer port tube (the section of tubing between the inner and outer flares) with a shorter one, as needed, for a higher Fb (and higher SPL and ~40Hz excitement) by using packing tape to hold those pieces together (as I’ve done all along with the test rig’s 3” Precision Port). Sure, there’d be higher GD than I’d have with a smaller cabinet, but it would be louder (than a smaller cabinet, which couldn't be so easily converted to a lower Fb); and it wouldn't wouldn’t exactly be a in critical listening environment; and if I was bothered by the high GD, I could always build a second pair of (smaller) cabs, and swap drivers to the appropriate cabinet, as needed. 

...or maybe buy a second pair of HOs and RFs. Hmmmm… or maybe HO 15s instead… or better yet, pro 15s... 


And for the record, while doing some last-minute WinISD modeling of the HO and IX-8 D4 last week (LOL), I noticed that there are no excursion results for the IX-8 D2/D4 and PPS4-8, just flat lines at zero-point (sealed/vented/bandpass notwithstanding; and at 150 watts, 200 watts, and 125 watts respectively).

Anyway, while it would be nice to see IX-8 excursion in WinISD, given my real-world experience with IX-8s, I guess it just sort of is what it is.


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## lurch (Jan 20, 2014)

awesome !
i knew that the cabinets would end up being deep, this is the most asthetically pleasing. 

i havent read through everything in detail yet, but heres an idea for joining pipe
quickly and easily ( works for me very well ...). 

Fernco 4 in. x 4 in. PVC Clay to Clay Flexible Coupling-1001-44 - The Home Depot


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## Grinder (Dec 18, 2016)

Thanks, but the Precision Ports come with two thin sleeves for joining the inner and outer flares to the included 12" section of tubing (and I simply apply tape over the joint on both sides of each sleeve), or for simply joining (with just one sleeve) the inner and outer flares together, for the shortest possible port length - which, come to think of it, would be 5"; and given 3.7 cubes, would (only?) get the Fb up to 34Hz - and 120dB at 36Hz (+8dB!!!), and an F3 of ~27.5Hz. GD x Hz would be 250 at 50Hz, but up to 680 (280 over 400) at 40Hz, and 1,400 (1,000 over 400) at 35Hz (peak GD).


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## lurch (Jan 20, 2014)

Grinder said:


> Thanks, but the Precision Ports come with two thin sleeves for joining the inner and outer flares to the included 12" section of tubing (and I simply apply tape over the joint on both sides of each sleeve), or for simply joining (with just one sleeve) the inner and outer flares together, for the shortest possible port length - which, come to think of it, would be 5"; and given 3.7 cubes, would (only?) get the Fb up to 34Hz - and 120dB at 36Hz (+8dB!!!), and an F3 of ~27.5Hz. GD x Hz would be 250 at 50Hz, but up to 680 (280 over 400) at 40Hz, and 1,400 (1,000 over 400) at 35Hz (peak GD).


oh right, i was thinking of the black pvc pipe. 

so i wonder how much group delay actually matters in a party environment,
or especially outside, it may not be an issue ?
if it is a problem just set the appropriate high pass with a steep slope, probably
18db as a minimum. 

on another note,
i believe that just one of the daytons at 500 watts will blow that paradigm
off the map. 
you gonna love 'em !


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## Grinder (Dec 18, 2016)

lurch said:


> so i wonder how much group delay actually matters in a party environment,
> or especially outside, it may not be an issue ?
> if it is a problem just set the appropriate high pass with a steep slope, probably 18db as a minimum.


Me too. As I said, _"...it wouldn’t exactly be (a) critical listening environment..."_

However, if GD did prove to be a problem: To the extent I might use the HP to cut those frequencies, it would sort of defeat the purpose of shortening the port for a higher Fb - because Fb, GD and SPL seem to go hand-in-hand (from what I've learned while modeling the RF, IX-8, and HO), and both GD and SPL are highest at Fb.



lurch said:


> on another note,
> i believe that just one of the daytons at 500 watts will blow that paradigm
> off the map.



In terms of SPL? 

Given such a large cabinet, and a 34Hz (or higher?) Fb, I wouldn’t be at all surprised if it were a lot louder. But would it sound any better than the PS-1200 in-room, where all that outdoor excitement and high GD would seem to be highly undesirable? I’d be surprised if it did.

Even with the 27Hz Fb, which would be down 3dB from the 34Hz Fb, I wouldn’t be surprised if it were a lot louder. But would it sound better than the PS-1200 in-room? I’d be surprised (and sorely disappointed) if it didn’t. Though, _in this case_ it would seem to be a matter of simply adjusting the HP and slope - if its response were too peaky (in the 30Hz range) for the room.

However, I’d be surprised if it would be appreciably louder, given a smaller cabinet and lower Fb, for a smooth/flat response, and (only?) 110.5dB (at 500 watts). And TBO, if it were possible to achieve a mid-20s Fb and smooth response, with a ~2-cube cabinet and a <12” x 4" flared port, I would have done it by now (particularly if one of these would be louder than a PS-1200).

Of course, I really have no idea, but I suspect that the paradigm might be a lot louder than you think (might you have forgotten that it’s a 4th order bandpass?), bearing in mind that it never failed to keep up with my horns (at intolerable levels - in a 240-sq. ft. room, mind you), pretty much maxing-out my big ol' Kenwood KR-X1000 (at _“125 watts minimum RMS per channel into 6 ohms”_) into 8 ohms nominal horns (measured at 6.2 ohms), with the PS-1200's green "on" LED dimming to the beat. 


BTW, the Crown XLS 1502 (which arrived yesterday) is rated at 775 watts RMS per channel (at 2 ohms); and ever since Sept. 6th (when I ordered the new amp), I’ve been modeling the HO at its rated 700 watts (no longer modeling at 400 watts - which was my best-guess as to what I’d get from a R500X1D at 12.1 volts, via a 700 watt PC power supply).



lurch said:


> you gonna love 'em !


I'm glad to hear it!

I'm 100% convinced that they're great drivers, and I'm confident that I'll get there in the end. It's just that I'm trying to do everything I can to get these things right the first time.


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## Grinder (Dec 18, 2016)

:stunned:

epper:

:happy:


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## Grinder (Dec 18, 2016)

FINALLY! The toilet paper rolls are gone (replaced by Crown amps)! 

...And with the addition of the Crown XLS 1002 and XLS 1502, my test rig/computer sound is now three-way active; with (one channel of) the 1502 driving the 12" Dayton HO, the 1002 (via miniDSP) driving the RF PPS4-8s, and the RF P400X2 (via miniDSP) driving the PP8Ts - instead of the P400X2 (via miniDSP) driving the PPS4-8s and PP8-Ts via PP4-X passives.

Obviously, I’ve got hours and hours of fine-tuning to do; but the improved SQ is already quite amazing! Unfortunately though, as I’m not well versed in audiophile terminology (and rather wary of psychoacoustics), I’m reluctant to describe what (I think) I’m hearing. Having said that, overall clarity (particularly cymbals and sibilance and such, which had been rather harsh and amorphous by comparison) seems greatly improved. And everything is simply more pleasant and less fatiguing than before.


And, as for the HO… well… there’s simply no comparison between it and the IX-8…

It performs sooooooooooooooo much better in every way; and it's every bit as good as I hoped it would be. Still, the biggest surprise is its “musicality” (a mysterious quality that I had only heard of - and can now clearly hear for myself!!! It is truly a wonderful thing!!!). I’m also rather pleasantly surprised that it seems to be a good deal more efficient than WinISD modeling results seem to suggest (compared to those of the IX-8, at the same input power).

VERY HAPPY!!!


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## nutt7 (Nov 15, 2015)

Grinder said:


> This thing started out with a pair of Polk Audio DB651s (and the Skar Audio IX-8). I originally built it to test some of my ideas for a car audio boombox. (See my boombox project at)
> 
> My car audio boombox project
> 
> ...


I remember coming across your build when I was designing mine! I like it. The Polk component is basically the exact same thing as what you have but separate tweeters and xovers. I would have mounted them like yours but the tweets were kinda hacked to fit whatever the previous installer did. All my speakers are low-mid entry level so they play well together.


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