# Fi IB3 15s - just had to post



## oca123 (Aug 16, 2010)

Hi all,

*Background*

I was going to make an install log, and post everything all at once, but I had to post about this right away, as it might save someone some time.

I've gone through a lot of speakers, processors, amps, etc. in my car. Like a lot of you guys, I just like going through gear.
One thing that I never changed in my system is the subbass... not for lack of trying.
I had a single SPG555 in a sealed box which I built larger than recommended (on purpose) and it sounded fine.... but I wanted more, and I wanted less demands on my electrical system.
Don't get me wrong, the box was LOUD.... bolted to the backseat, it fired right through the ski hole, and due to its size it had a fairly flat response (for a sealed box that is)

For months, I've been thinking about trying IB. I figured, I was the perfect candidate for IB... I don't mind drilling holes in my car, I can hear all the way down to 20Hz, am a bass head, my car audio hobby vehicle is sturdy, it has a ski hole, and the trunk is fairly well sealed from the cabin.

There are tons of subs that will end themselves to IB, but I had decided on dual 15s, which is the biggest I can fit in my trunk without having to angle them. Dual 15s would fit perfectly, at the same angle as the backseat.

*Ordering process*

I narrowed down the choice to the JBLs, AEs, and Fi. Always curious about Fi, I ordered a pair of IB3 15s. Their website (which has been revamped since) offers two versions, single 2 Ohms and single 4 Ohms. Accidentally, I ordered the 2 Ohms. 

After about a week of waiting (they quote lead time as 10-15 days, as they only build subs when you place an order) I emailed to ask for status. I got a reply that my subs where shipping on Thursday, by UPS Ground. I replied that I would love to upgrade shipping speed if possible, but I did not get a reply.

On Thursday morning, my doorbell rings. When I get to the door, I am surprised two big boxes. A larger sticker on the boxes says "Fedex." Weird, I wasn't supposed to get them so early???

My phone beeps at that point, signaling an email. Sure enough, it's from Fi, saying " I took care of the shipping upgrade for you. Your subs will be there today, they are out for delivery right now."

If thats not great customer service, I don't know what is.
*First impressions*

The baskets are black, the cones are black. There are no markings. The basket has room for two pairs of terminals for dual voice coils, an indication that it is not exclusively made for the IB3 series. The suspension is very stiff, a sign that it is made for IB. There are no screws, no manual, nothing. Just a pair of subwoofers.

I forgot how big a 15'' is. Here are some bad pictures. Let me know and I can post more detailed pictures.



















*Install*

I am very impatient at this point, so I dive right into it. In fact, I was so focused, I forgot to take pictures. Basically, what I've got is a board that screws into the backseat, with some foam and ensolite. I then have a 2nd layer which is a "riser" and provides the clearance needed for the subs, as well as allows the baffle to follow the shape of the backseat better. Finally, I have a board with holes for the subs.
Remember, this is temporary, I just want to know what IB sounds like. Temporary still means applying some vinyl and carpet though 

After about a day of cutting, talking on the phone, smoking cigarettes, scratching my head thinking about how to make it work all by myself, I've got my baffle board screwed into the backseat. It could use some bracing, I guess, maybe a 2nd layer... but I really want to see what it sounds like, and it seems stiff enough. You can probably pick up the car by the baffle board at this point.

I had the presence of mind to predrill the board, so that the terminals would be lined up. What I didn't think about is how to lift up the subs to line the holes up while they are in the trunk.
Getting the first sub screwed into the board took an entire hour, as I struggled to lift it up, hold the screwdriver, line up the screws, etc.

I decided I would finish the next day.


































This morning, I woke up with a great idea. I found an old inflatable ball (the swimming pool kind) and a pump. I crawled into the trunk, and used the ball/pump to slowly lift up the subwoofer until the holes lined up, and I attached the f.cker to the baffle board.

I'was boiling with excitment at that point, so I decide to take a break, eat something, answer some emails... I wanted to be calm...

*Note: pics are at the end. remember this is a temporary setup to decide if I like infinite baffle or not*


*Testing the subs*

I hooked up my amplifier, set the gains all the way down. Since the subs are in parallel, they are presenting a 1 Ohm load to my amp, which is less than adequate, since my amp can probably weld these voice coils into place (amp is rated at 3500W+ @ 1Ohm)
I don't know how I ended up ordering the 2 Ohm version of this sub. I must have accidentally clicked the wrong button.

I then connected my tablet to the amp directly. Low pass is set to 300Hz at 12db/oct, subsonic is set to 20Hz for now.

My car doors are shut, windows are rolled up. I pick a southern rap song whose bassline I am very familiar with, and I slowly turn the volume up until I can hear muffled voices. I have no other speakers running the car.

I can already tell the setup is flat, and it hits all the way down to 20Hz without breaking a sweat. It's CLEAN. It's efficient. It's what I've been looking for. **** in my garage is rattling everywhere. My custom heavy double wide, teak garage doors are rattling. The bolts that hold them together are shaking.

This is all the testing I was able to do. I have rattles coming from EVERYWHERE. I can't tell what is coming from the car, and what is caused by things in my garage rattling. I can tell you that I'm going to be spending A LOT of time finding every rattle and fixing it.

In comparison, my sealed box was very loud, and I had no rattles that I could hear.

It's impressive the amount of bass that these two 15s can put out, barely moving. I can't wait to crank them up. I just don't know if it is safe to do so in my garage. I know my wife will probably panic and think there is an earthquake.


*What's next*

I really wanted to post an install log, as I am currently rebuilding my system for the 3rd time in this car. I will probably be doing it in the next weeks. I just really had to post about IB, because I realize now that I have been a fool for years, going with amplifiers putting out tons of watts, and subwoofers that are able to convert these watts into tons of heat without burning up.
IB gives a flatter, better sounding response. It is louder off of much less power. And it takes a lot less room, so now I have more room to lay out my amplifiers on the trunk floor. It looks cool. (you should see the size of the box PKW Designs designed for me... I never built it because it didn't leave enough room to fit my amps in my trunk)

My only gripe? I really hope I can deal with all of the rattles.

*Questions for those reading*
Most cars have rubber "flaps" that act as a way to equalize pressure in the cabin/trunk. These tend to flap out of control and make a lot of noise, especially in IB. I am considering either:
1) removing them altogether
2) sealing them up
3) using something like Gore-Tex instead of sealing them completely?
Obviously 1) and 2) each have drawbacks.

Thats it for now... Thanks for reading.
If you want more pictures, please ask. I can take better pics.

PS I did not proof-read this, so I apologize if it makes very little sense.


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## benny (Apr 7, 2008)

Dude...is that a Bentley?! And yes, 15s IB rock. Sounds like we got another convert


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## beef316 (Dec 12, 2006)

Thats a bentley. Nice.

Tapatalk owns my productivity.


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## oca123 (Aug 16, 2010)

benny said:


> Dude...is that a Bentley?! And yes, 15s IB rock. Sounds like we got another convert


It is :embarassed: I actually got it as a car audio hobby car. I thought it was perfect... the ski hole, the large, deep trunk, the fact that its heavy (less damping needed) and the stock alternator puts out 190A, two batteries stock in the trunk... heavy wiring everywhere....

There was very little documentation on how to integrate with the OEM system. Sonic even had the wrong speaker sizes listed on their site.
Nothing that can't easily be figured out though. I got some docs from a forum member, also.

Within a few days of buying it, I had the door panels out, borrowed a compressor and airsaw, and I cut up the metal in the doors to fit the Focal KRX3 midbass drivers.

I've learned a lot since then, not just about car audio, but also about what I like in a system. That's why the next step is to cram 8'' midbass in these doors.

I hope someone who has not switched to IB reads this and decides to make the switch.


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## BuickGN (May 29, 2009)

oca123 said:


> It is :embarassed: I actually got it as a car audio hobby car. I thought it was perfect... the ski hole, the large, deep trunk, the fact that its heavy (less damping needed) and the stock alternator puts out 190A, two batteries stock in the trunk... heavy wiring everywhere....
> 
> There was very little documentation on how to integrate with the OEM system. Sonic even had the wrong speaker sizes listed on their site.
> Nothing that can't easily be figured out though. I got some docs from a forum member, also.
> ...


I like the way you think. I've been saying for a while that as long as the car is IB friendly I will never run a box again.


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## bassfromspace (Jun 28, 2016)

Bentley, huh?


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## IBcivic (Jan 6, 2009)

3.5kw ....headroom, much?


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## IBcivic (Jan 6, 2009)

I have heard rumors that the up & coming front stage will be as equally impressive.


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## beef316 (Dec 12, 2006)

oca123 said:


> It is :embarassed: I actually got it as a car audio hobby car...


I was thinking of getting a rolls for my hobby car.

Tapatalk owns my productivity.


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## IBcivic (Jan 6, 2009)

I would try removing the trunk vents, altogether, as long as it does not let water and/or exhaust fumes in.

The gore-tex idea, sounds like something that should be explored.


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## danno14 (Sep 1, 2009)

When you said teak garage doors I thought "um-hmm".... then when I saw what the car was I though "yes sir!"

Nicely done.


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## oca123 (Aug 16, 2010)

LMAO at the 2 thumbs up pic. It let me to RapGenius. I'd heard of it, but never been there before.... and it looks like where I'm going to be spending the rest of the afternoon.



IBcivic said:


> I would try removing the trunk vents, altogether, as long as it does not let water and/or exhaust fumes in.


It doesn't rain in SoCal 
Actually the reason I am redoing my system is water got in there.... I hadn't driven the car in a few days, and forgot that the rubber seal was NOT in place... then I took the car to the car wash.
On the electronics side, one of my amps lost 2 channels, everything else was fine, but the amp rack got wet, and because it was made out of MDF and I hadn't sealed it or anything, I decided to start over.



> The gore-tex idea, sounds like something that should be explored.


Yeah, I'm going to try that and compare it with just open. I don't think I'll be able to hear the difference, but it might help with moisture and closing the trunk/doors easily.

Now to clarify... I mostly work from home, and I really wanted to dive more into car audio, so I knew that I would spend a significant amount of time screwing around with speakers and amps in that car... and I was right... I have spent more time experimenting with audio than I have spent driving the thing... which qualifies it as a car audio hobby car 

I have another car, but I don't even wanna toy with the idea of doing anything to it.



> I was thinking of getting a rolls for my hobby car.


 I actually know a guy who got one. I can't share much, but I will tell you that he has done some straight up GHETTO **** to that car. I have a similar sense of humor. Wait till I wrap this thing in black carbon fiber 3M 1080.... j/k



> I have heard rumors that the up & coming front stage will be as equally impressive.


I have XS69s as midbass, they're OK. I mainly wanted the peerless as a challenge to see if I can even fit 8'' midbass in there. I have a feeling they will sound better, if I can fit them. As to the mids/highs.... I'll be posting here as soon as they're in ;-)

These are my current pillars. I am very proud of how they came out cosmetically, but they sound like a$$. The KRX3 are great speakers mind you, but I didn't know how to aim them, and I thought I'd just glass them in to see if I even like speakers in the pillars. Turns out I do, and turns out they don't play as low as I want them to, but it's all good, because at the end of this week, they should be gone 











I know I'm talking a lot... it's because I have not shown my system to anyone, so I'm excited  I should probably hit up some local events, but I was too shy to go to the last one, and I thought everyone would automatically assume i'm a douche because of the car...which is nonsense... I'm going next time for sure though.


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## req (Aug 4, 2007)

ib is awesome. been doing it for nearly 10 years now.

i will not go back


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## oca123 (Aug 16, 2010)

IBcivic said:


> 3.5kw ....headroom, much?


Well, I accidentally ordered the drivers with 2 Ohm coils.
I read somewhere that wiring speakers in series has negative side-effects, but I don't recall what they were.
Initially I wanted to get the 4 Ohms so I could run both speakers at 2 Ohms with still a lot of headroom, but my goal was really to try 8 Ohms in series where the amps and speakers would be a better match.

I guess I'll just try hooking these up in series for a 4 Ohm load and see how it sounds.

As to the teak garage doors... some guy gamed the system and built this house, taking out loan after loan, using each one to pay off the previous one. He was very picky and built an amazing property, with attention to detail that is indicative of someone that has OCD. Then the banks foreclosed, it went to auction, and long story short, it was perfect, big garage, great location, etc. and at a great price....
I would never choose to put teak garage doors. They are a major PITA due to their weight.

OK I'm rambling on, i better go


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## oca123 (Aug 16, 2010)

req said:


> ib is awesome. been doing it for nearly 10 years now.
> i will not go back


Yea, it took a few months of consideration, then 8 hours of fabrication... i turned the music on, and gave it 3 minutes of paying attention....

If there's a church of IB, I'm joining.

Is there an easy way to mount the speakers to the baffle board? My rear seat doesnt fold down, I literally had to crawl in the trunk and it was really hard, there has got to be a way....


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## oca123 (Aug 16, 2010)

req said:


>


Wow, nice job with the techflex! I just got some last week for the first time, it actually makes working with wires a pleasure, whereas before it was all messy and tangled up.

Now, what are these mounting clips around your woofers? I think I need something similar, because the surround on the IB3 15s is thick, and I routed the opening with a cove bit, which caused one of the screws to end up screwing into nothing, and some of them not having as much wood around them as I would like them to.

EDIT: nevermind, I t hink they're just wire tie-downs... damnit, I thought I'd just learned about a revolutionary way of mounting speakers....


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## benny (Apr 7, 2008)

conduit clamps. and "Cult of the Infinitely Baffled"Hear The Bass, Not The Box The definitive online resource for Infinite Baffle subwoofer designEstablished 1999 - Home


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## oca123 (Aug 16, 2010)

benny said:


> conduit clamps. and "Cult of the Infinitely Baffled"Hear The Bass, Not The Box The definitive online resource for Infinite Baffle subwoofer designEstablished 1999 - Home


I thought they prohibited threads about car stuff


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## benny (Apr 7, 2008)

Yeah, but they still have some interesting stuff there...and it's where I first saw the conduit clamps used to hold woofers in!


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## miniSQ (Aug 4, 2009)

oca123 said:


> Yea, it took a few months of consideration, then 8 hours of fabrication... i turned the music on, and gave it 3 minutes of paying attention....
> 
> If there's a church of IB, I'm joining.
> 
> Is there an easy way to mount the speakers to the baffle board? My rear seat doesnt fold down, I literally had to crawl in the trunk and it was really hard, there has got to be a way....


I'm starting my first ever IB this week, but i've only been messing with car audio for about 30 years

For mounting i am doign a 3/4" front baffle with 4 holes cut out a little larger than each driver...then a 1/2" baffle cut board which i will mount the speakers to that and then mate the 1/2" with speakers up from behind the 3/4" board. Glueing and screwing the two boards together to make a single 1.25" baffle.


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## slpery (Jan 14, 2011)

I too am new to the church of IB. I think its more like a secret cult, and we all have special handshakes.

Im running 2x15 JBL's in my Camry. 
I sealed my trunk air vent completly. I got a bit of flack from a few people on here, but the only issue that came from it was the A/C fan. On recirc, it works fine, but when you have the air coming from the outside, it cant get out and you can feel the pressure slightly. If you crack the window, a slight whistle will appear as the air gets pushed out. Not really a concern for me as i only run it with recirc anyway.

Other comments from people who hadnt actually done it where...its harder to shut the doors.(not true). The airbags will blow the windows out (i couldnt stop laughing at that one), and if you fart, theres no escape for the poo particles.

Also last weekend we hooked up the termlab just for fun. I wasnt expecting much at all. 
Well, how about 139.1 db at 24Hz!!!!
Im going to add some volume to the trunk via a suitcase of books and clothes to try and raise the frequency a bit and try for 140.
Apparently the car was flexing, a lot!!!


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## quality_sound (Dec 25, 2005)

oca123 said:


> Well, I accidentally ordered the drivers with 2 Ohm coils.
> *I read somewhere that wiring speakers in series has negative side-effects, but I don't recall what they were.*
> Initially I wanted to get the 4 Ohms so I could run both speakers at 2 Ohms with still a lot of headroom, but my goal was really to try 8 Ohms in series where the amps and speakers would be a better match.
> 
> ...


I thought it was better in series. Something about one of the parameters getting noticeably better. Dammit, now I have to find the article.


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## BuickGN (May 29, 2009)

slpery said:


> I too am new to the church of IB. I think its more like a secret cult, and we all have special handshakes.
> 
> Im running 2x15 JBL's in my Camry.
> I sealed my trunk air vent completly. I got a bit of flack from a few people on here, but the only issue that came from it was the A/C fan. On recirc, it works fine, but when you have the air coming from the outside, it cant get out and you can feel the pressure slightly. If you crack the window, a slight whistle will appear as the air gets pushed out. Not really a concern for me as i only run it with recirc anyway.
> ...


Why would you want to seal the trunk off from the outside world? I purposely increased vent size to the outside. Adding objects reduces volume. Reducing volume does not add SPL in the higher frequencies, it reduces output in the lower frequencies.


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## fish (Jun 30, 2007)

quality_sound said:


> I thought it was better in series. Something about one of the parameters getting noticeably better. Dammit, now I have to find the article.


I believe wiring in series raises the inductance... but please find that article so we'll know what all goes on.


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## oca123 (Aug 16, 2010)

quality_sound said:


> I thought it was better in series. Something about one of the parameters getting noticeably better. Dammit, now I have to find the article.


no need. i must have been mistaken. i just tried series and it sounds better. though its hard to tell cause so much rattling.
the subs make a weird noise also. sounds like whipping air. still better than any box i ever had...


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## RattyMcClelland (Nov 28, 2008)

I run the IB3 12". One single 12" sub IB with 280w. Its sounds absolutely jizztastic. Plenty of headroom and loud bottomless bass at volume.
Very dry and transparent.


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## oca123 (Aug 16, 2010)

OK, I take it back, I believe it sounds better in parallel. It's not easy to tell, due to the volume difference, and the rattles. Once I fix the rattles I will have to make a way to switch from series to parallel with a button so I can A/B test it.


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## spl152db (Dec 20, 2007)

Without gain adjustments you're going to like parallel better if you're wanting more bass. Running in series drops the power significantly. To about 1/4. Usually. That equates to 6db. Quite significant. 

Sent from my DROID RAZR using Tapatalk 2


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## oca123 (Aug 16, 2010)

spl152db said:


> Without gain adjustments you're going to like parallel better if you're wanting more bass. Running in series drops the power significantly. To about 1/4. Usually. That equates to 6db. Quite significant.
> 
> Sent from my DROID RAZR using Tapatalk 2


I understand that. First power varies with resistance, and resistance varies depending on what frequency is playing. That said, if we simplify things and go by ratings:
The IB3 15 is rated at 550W RMS (@ 20Hz - that is, playing a 20Hz note non-stop)
Two of them can take 1100W RMS (I feel a little nauseous every time I write this, since the term is incorrect, but let's roll with it)

Now at 1Ohm, my amp is supposed to be able to provide 4103W (I have an osci, I will test with a 20hz sine wave if I can find a 1ohm resistor,) which is ~4x what the subs are rated for.

Now I believe that whether I send these 1100W or 4103W, at 20Hz, they will max out, and mechanical limits will dictate the kind of sound (or smoke) that the woofers produce.

So in my case, it could be viable to run them in series instead, because a 4 Ohm load would be better "matched" for the amplifier.

This is where it gets confusing. Wiring woofers in series raises inductance, but it also raises resistance. I quote werewolf:


> nope ... subs in series will cause no more phase shift than subs in parallel. It's true that the voicecoil is an inductor, but the corner frequency of the resulting filter ... which determines phase shift at any frequency ... is determined by inductance and resistance. For subs in series, inductance increases but so does resistance, keeping the R/L ratio the same. For subs in parallel, inductance decreases but so does resistance, keeping the R/L ratio the same.


So I guess, it would sound the same, which answered my question to begin with.

But!! I also read somewhere else that class D amps actually LIKE smaller loads and perform best when presented with a smaller resistance.

Really, to be honest, the difference is probably inaudible, but I'm curious to see what an actual EE would have to say.


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## req (Aug 4, 2007)

Your shouldn't be able to hear the difference, only thing that you should hear is that with a lower resistance the amp should produce more power. With out changing anything in the system other than the vc configuration, the power produced by the amp will increase and there should be a higher amplitude of low frequency information produced, again, all other things equal without changing any settings, up until the speaker reaches power compression and it's mechanical limits. With the volume at a normal listening level, it should be obvious.


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## BuickGN (May 29, 2009)

oca123 said:


> I understand that. First power varies with resistance, and resistance varies depending on what frequency is playing. That said, if we simplify things and go by ratings:
> The IB3 15 is rated at 550W RMS (@ 20Hz - that is, playing a 20Hz note non-stop)
> Two of them can take 1100W RMS (I feel a little nauseous every time I write this, since the term is incorrect, but let's roll with it)
> 
> ...


I believe the 500w/20hz rating is more of a mechanical rating than a thermal rating which is probably a good thing for that sub's intended use. 

I got slammed for mentioning this a while back but when I had a pair of 12W6s and dropped the resistance from 8ohms to 2 ohms they seemed to reach up a little higher and the bass felt a little "tighter". I was told it's just my imagination but it was a pretty large change to be my imagination, especially when I wasn't expecting a change in sound, only output.


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## oca123 (Aug 16, 2010)

What if you change voice coils? Wouldn't having a heavier voice coil, with more copper, be technically better for SQ? I see a lot of home audio speakers are 8 Ohms.
The reason I am wondering is that I used to have a Boston SPG555 with interchangeable voice coils. I used a few different class D amps on it. This happened with every one of them, but where it gets interesting is with the Alpine PDX-M12, which Alpine claims does 1200W whether given 2 or 4 ohms.

SPG555 with 2Ohm voice coil => reaches lower and with more authority, almost "sloppier"-sounding bass (always low passed 80Hz/12db)

SPG555 with 4Ohm voice coil => "tighter" sounding, less authority down low, but probably more accurate sounding. Same exact settings. 

This was a long time ago, but I remember checking SPL @ 60Hz with both coils. Without changing gain settings or anything, SPL was within 1db using Radioshack meter ziptied to headrest so it did not move during measurements.


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## oca123 (Aug 16, 2010)

BuickGN said:


> I believe the 500w/20hz rating is more of a mechanical rating than a thermal rating which is probably a good thing for that sub's intended use.
> 
> I got slammed for mentioning this a while back but when I had a pair of 12W6s and dropped the resistance from 8ohms to 2 ohms they seemed to reach up a little higher and the bass felt a little "tighter". I was told it's just my imagination but it was a pretty large change to be my imagination, especially when I wasn't expecting a change in sound, only output.


LOL, I just posted the opposite experience. Mine was with switching actual voice coils though. I forgot to mention that I decided to measure in the first place because the difference was VERY obvious, sounded like a different sub. Sealed box, btw.

You're probably right on the mechanical rating.

What kind of subsonic filter should I run with these? Is it going to be obvious if I'm over-driving them, or are they going to burn silently like a bandpass box would do?

I have some time this morning so I'm going to hook up my processor and current front stage, until I receive the new front stage later this week.

I stuffed polyfill and foam in various places inside, took care of a lot of rattles, but I think I'm going to have to find a mechanic to help me figure out where and how to fix the rattling coming from under the car. I think I located it, but I need to jack the car up to get to it, and I hear you need some kind of device to turn off the air suspension.


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## oca123 (Aug 16, 2010)

OK, I answered my own question again. I just read this document: *Zed Manual 2012*, and learned more in 30 minutes about car audio than I have in the last 6 months.

One of the things that I got out of it is that as a general rule, higher impedance speakers are supposed to sound better, and they are more efficient, which compensates for the lower power the amplifier will produce at this higher load.

I also found out why Alpine's PDX amps are rated the same at 2 Ohms and 4 Ohms, and that's because they're ****ty amps with cheap unregulated power supplies. What they do is increase the rail voltage when driving lower impedance loads, but do not deliver higher currents, and current is what drives speakers.

I was always told that "all amps sound the same, a watt is a watt" but I always thought that the PDX sounded awkward, especially with mids/highs, and it wasn't until I bought myself a proper amplifier and built a ghetto A/B testing rig with a remote switch that I was able to notice that the PDX sounds like someone is holding a trashcan lid over your speakers.

Anyway. Read the Zed manual. It's good reading.


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## quality_sound (Dec 25, 2005)

oca123 said:


> OK, I answered my own question again. I just read this document: *Zed Manual 2012*, and learned more in 30 minutes about car audio than I have in the last 6 months.
> 
> One of the things that I got out of it is that as a general rule, higher impedance speakers are supposed to sound better, and they are more efficient, which compensates for the lower power the amplifier will produce at this higher load.
> 
> ...


I'm pretty sure that's wrong. ALpine and JL both use very, VERY tightly regulated power supplies. They just add a step upon startup where the amp reads the impedance and adjusts the rail voltages. Once the rail voltage is set it doesn't change. Well, that's not entirely true but it's outside the scode of the discussion.


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## oca123 (Aug 16, 2010)

quality_sound said:


> I'm pretty sure that's wrong. ALpine and JL both use very, VERY tightly regulated power supplies. They just add a step upon startup where the amp reads the impedance and adjusts the rail voltages. Once the rail voltage is set it doesn't change. Well, that's not entirely true but it's outside the scode of the discussion.


JL HDs do, that I know, but I can't find a mention of the PDX using a regulated power supply anywhere. Knowing alpine, they'd be advertising it if it was the case, no?
What I did find (mind you i searched for 5 minutes) is mentions of a regulated output stage, but unregulated (also saw "semi-regulated") power supply.

Here is what I can say. My 3 PDX-F6s all sound terrible. It could be that they are damaged, but there is something very different, and not very pleasant, about the way they sound with mids+highs. I have been told the JLs are much better.

I have a Zed Audio Leviathan III, which I received this morning, but I have to go and I'm late to a meeting


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## miniSQ (Aug 4, 2009)

the alpine PDX's i believe are class D amps....in general, and without opening another 3 pages of discusion, Class D amps afre not your best choice for mids and highs. Primarily they are a VERY efficient means of producing power for subwoofers.


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## fish (Jun 30, 2007)

The older PDX amps had a known history of having a high noise floor. As far as the PDX1.1000, it performed MUCH better at 4 ohms than at 2. It never even got warm. 

Class D (JL HD) work just fine on mids/highs.


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## BuickGN (May 29, 2009)

miniSQ said:


> the alpine PDX's i believe are class D amps....in general, and without opening another 3 pages of discusion, Class D amps afre not your best choice for mids and highs. Primarily they are a VERY efficient means of producing power for subwoofers.


That's another one of those myths. I've got a JL HD setup on Dyns that says othewise. This might have been true 10 years ago but I own a McIntosh and the JL HDs, both have been in and out of the same car on the same speakers and the Mac is sitting under my mattress while the HDs are in the car.


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## BrianAbington (Jul 27, 2012)

The cult of IB site has some great material to learn about the science of it. 

There are also some pretty boss home theater installs on that forum.

I plan to go IB in my bonneville. It's something I've always wanted to try but just never did it. I figure it would be a great way to welcome my self back to the hobby.


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## miniSQ (Aug 4, 2009)

BuickGN said:


> That's another one of those myths. I've got a JL HD setup on Dyns that says othewise. This might have been true 10 years ago but I own a McIntosh and the JL HDs, both have been in and out of the same car on the same speakers and the Mac is sitting under my mattress while the HDs are in the car.


i said " in general"...and yes i know some D amps sound great.


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## oca123 (Aug 16, 2010)

This might be over-simplifying things, but if you've ever made music and used a vocoder, the way a class D amp is similar, where the power supply is used as a carrier signal, and then it is modulated using your input signal, so I guess you could say that your signal is not exactly "amplified" per se, at a lower level.
That is the way I simplify it in my head anyway.

What that means is that the switching frequency needs to be high enough that you will never hear it. I guess the problem with that is that a lot of cheap class D amps are switching at frequencies not high enough, and the filters added to remove the switching noise, etc. cause their own problems.

Again it's over-simplified, but that's the way I take that thought and box it up in my head so I can go on with my day.

I would have to take sides with BuickGN on this one. I have heard very good class D amps (well, I guess you could say a perfect amp doesn't sound like anything, so technically, I *didnt* hear very good class D amps) so I dont discount the topology.

I haven't fired up the Leviathan III yet. I am itching to do so, but I'm going to wait until I get the front stage. I am excited because I will be reviewing it mostly ahead of everyone else, and I am certain you will all enjoy the pictures.

That said, I got back from my meeting and fired up my current front stage along with the IB. This time, I left the garage door open ;-)

I dont know how many times I am going to be saying this in the next few days, weeks, months, years...
OH MY GOD IT SOUNDS GOOD.

I have said many times before "This is all the bass I need" and I was fooling myself, so this time. I do regret not doing this sooner, especially because I had been putting it off for almost a year.

I think I might even consider building an IB sub for my house. That cult of IB has some pretty cool photos, and the room I'm thinking about is perfect for this... It's on the 2nd story, and the entire room is sitting on a hollow platform. I'm thinking, an array of 3 18'' AE subwoofers... UNDER THE COUCH 

That way, I might become the first person to actually listen to sine waves... for the purpose of getting a good back rub!


By the way, I tried the conduit method. It works, but I'm slightly uncomfortable with it. I have instead added another 3/4 MDF layer to the baffle board, but I carefully routed a groove to countersink the woofer. it helps with centering it. I used t nuts this time.

I think I am very close to the setup I've been wanting for a year. IB turned out great, I have 8'' peerless XLS on the way, great amplifiers, and what looks like is going to be a killer mids/high setup. I even have an Arc Audio PS8 reserved, and it should be here right around my birthday!


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## oca123 (Aug 16, 2010)

Worked on a proper baffle board for the subwoofers today. The T-Nuts gave me some problems, so I ended up epoxying them in place, which took me entirely too much time. Here are some pics.

I wish I could just edit the first post to add these pictures, but I guess I can only edit the last message I posted to this thread???


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## IBcivic (Jan 6, 2009)

Beau travail!

Forget t-nuts...


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## oca123 (Aug 16, 2010)

what do you call these, and where do I find them. Now I'm going to have to unmount the subs, unmount the baffle board, re-cut 2/3rd of the baffle board. i will not sleep well until then.

i think i saw a pic of one of Bing's installs where he didnt use a single wood screw, and used nothing but used those... maybe i can look for it on here



IBcivic said:


> Beau travail!
> 
> Forget t-nuts...


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## benny (Apr 7, 2008)

Threaded inserts


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## oca123 (Aug 16, 2010)

thanks... guess i'll hit up a couple hardware stores today


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## miniSQ (Aug 4, 2009)

oca123 said:


> what do you call these, and where do I find them. Now I'm going to have to unmount the subs, unmount the baffle board, re-cut 2/3rd of the baffle board. i will not sleep well until then.
> 
> i think i saw a pic of one of Bing's installs where he didnt use a single wood screw, and used nothing but used those... maybe i can look for it on here



OCD is a *****


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## IBcivic (Jan 6, 2009)

Canadian H-depot has em.

IIRC ACE hardware in Cali has an extensive hard to find fasteners, dept.

Btw...I just got back from the Champlain P-office.


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## BrianAbington (Jul 27, 2012)

How far do these protrude into the trunk?


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## oca123 (Aug 16, 2010)

Can you specify?


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## req (Aug 4, 2007)

get yourself some CA glue dude. any glue that contains cyanoacrylate, i ususlly get stuff from bob smith industries... local hobby shops should have it - the places that sell model rockets and rc cars and train sets and ****.

here is a bottle for $30 that has 10oz - it should last a while.
FastCap 2P-10 Medium Adhesive 10 oz - Amazon.com

here is some CA glue aerosol activator
Aerosol Activator,7 oz. - Amazon.com

i recommend the aerosol stuff because its easier to spray. the reason im suggesting getting some of this stuff is because you said you epoxied the T-nuts in place. dont waste your time waiting for expoxy to dry, use something like this. put the T nut in, squirt some glue under the T nut, bolt the speaker in place, and then squirt some of the glue on top of the T nut, and spray the activator. the T nut wont come out again.

you could also use baltic birch plywood and then the T nut will just bite into the wood like its supposed to instead of MDF too... i like plywood over MDF. it lasts longer, its lighter weight, and its stronger.

those other threadded insert nuts are sometimes called hurricane nuts. drill the hole, insert them in from the BACK side like a T nut, and then bolt in your speaker.


when i installed the aruasound NS15's in the honda civic (black subwoofers in my first post) i was laying in the trunk with the speaker on my chest trying to line up the bolts... it was not easy... but IB setups are worth it.


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