# 40 hz Low Pass Midbass



## DanMan (Jul 18, 2008)

Can anybody name any midbass drivers, up to 10'', that are actually designed and recommended to be played around 40 hz?

I realize that it is a bone of contention around here whether or not certain drivers, in certain installs, should actually be played that low.

The L8 comes to mind, but was hoping to get other recommendations.


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## UCF52 (Nov 20, 2007)

I think you meant high-pass (just being corrective) 

Maybe the Peerless SLS 8"


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## UCF52 (Nov 20, 2007)

I have to question that crossover point (as I'm sure you expected).. 

Why drop all kinds of coin on a sub woofer and have it play next to nothing on the frequency spectrum...? As someone else said in another post, let the sub woofer do it's thing, then accommodate your mid woofer at a more reasonable crossover point. 

I will say, I like to see people challenge the norms, so by all means, give it shot and give us your thoughts.


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## keep_hope_alive (Jan 4, 2009)

i think any decent 10" or 8" should be capable of 40Hz playback (except maybe pro-audio drivers). course, it really depends on how much output you expect at 40Hz. and the real question is which ones can do it in the airspace you have available.


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## gymrat2005 (Oct 4, 2009)

I have 2 pair of Dynaudio MW170's in each door and they give me all the midbass/bass I need. The older 170's have an fs of around 41hz, while the newer MW172's are around 45hz. In the right application, they pound it out pretty good. The L8's are like 2mm deeper in depth than my MW170's, but also share the same low resonant frequency.


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## gymrat2005 (Oct 4, 2009)

UCF52 said:


> I have to question that crossover point (as I'm sure you expected)..
> 
> Why drop all kinds of coin on a sub woofer and have it play next to nothing on the frequency spectrum...? As someone else said in another post, let the sub woofer do it's thing, then accommodate your mid woofer at a more reasonable crossover point.
> 
> I will say, I like to see people challenge the norms, so by all means, give it shot and give us your thoughts.


I don't get that he is saying anything with regards to a crossover point, but rather if some drivers are capable of playing well at that frequency. Nothing wrong with a running an 8" driver low pass from say 200Hz and down (provided you have a dedicated midrange)...especially if like me, you have no sub (yet)

_I stand corrected UFC52..I tend to just click on the thread instead of looking at the title of it. I now see the name of the thread being "low pass Midbass"_...yes why on earth would you only want the 8" or 10" to play *ONLY* 40 Hz and down, unless it was acting as a sub in a proper enclosure, and again providing you had adequate midbass/midrange for a front stage.


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## DanMan (Jul 18, 2008)

UCF52 said:


> I think you meant high-pass (just being corrective)
> 
> Maybe the Peerless SLS 8"


:blush:


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## DanMan (Jul 18, 2008)

UCF52 said:


> I have to question that crossover point (as I'm sure you expected)..
> 
> Why drop all kinds of coin on a sub woofer and have it play next to nothing on the frequency spectrum...? As someone else said in another post, let the sub woofer do it's thing, then accommodate yo:ur mid woofer at a more reasonable crossover point.
> 
> ...


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## kyheng (Jan 31, 2007)

Well, depending on brands, as long as its FS value is low enough, say 30Hz, you won't have much problem with it.


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## UCF52 (Nov 20, 2007)

DanMan said:


> :blush:


It happens 



DanMan said:


> UCF52 said:
> 
> 
> > I have to question that crossover point (as I'm sure you expected)..
> ...


It seems logical, having as much of the frequency spectrum being reproduced up front... but if you are trying to reach that low, why not try and fit a 10" in each door (or door pod) and just use those as dedicated woofers and integrate it with the rest of the front stage. The more you extend the pass band on your mid woofer (or any driver) the lower their power handling becomes. 

If I had room, I'd love to do a pair of 10" drivers up front (in the doors) and eliminate a rear mounted enclosure altogether.


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## BigRed (Aug 12, 2007)

I think its important that we at least consider two important things when considering crossover point:

1. driver
2. installation

if you put the wrong driver in the wrong enclosure......well you get the point


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## pirate (Mar 17, 2009)

Provided that the doors, if u plan on placing them there, are properly dampened, you can try the Morel ELATE SW 9" WOOFER. It goes down to 20Hz.
The 10" is quoted as 15Hz - 3K capable.
With both of these I wouldn't run them that low about 40-50Hz is fine and let the Sub handle the rest. With a proper design, at those low frequencies, the sub should disappear.


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## WLDock (Sep 27, 2005)

Your install is going to pretty much determine how low you can go...even with a capable 8". How much roll off you get will depend on many factors. However, in reality....I don't know why a 40Hz number is thrown out there for midbass? What is wrong with striving for a 60Hz crossover between the midbass and the sub? That seems more realistic for more installs.

The SQ cars that I know about that had 8" midbasses upfront pretty much used some type of vents. The drivers were allowed to play down to their natural roll off. The subs were crossed at very low points like 40Hz etc. Morel and Seas Excel, and Nextel drivers were used. OTOH, the enclosures were super solid and TONS of deadning was used and these systems were setup to play at normal listening levels.....not flat out balls to the wall. The problem I think that many have is that many like too high a sub level to get a good "Bass Up Front" effect.

So, there are a TON of variables to consider before just thinking it is just a special driver that can get down low.


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## iarechaga (Oct 27, 2009)

I had a pair of Scan Speak Revelator 18W/4531G00 in my doors, fully loaded with Dynamat and me and another guys founded that the best HPF was 40Hz in my ex- Genesis Four Channel, ever better than cutting from my ex - Pioneer P88RS (in Europe, in USA is the P800RS)

Now I'm gathering again all my drivers and the Scan Speak will be mine again... I love them!

Note that i'm speaking in Hi-Fi terms, i had no subwoofer and it was great, really clear bass and sub-bass, they can move your back giving you a really nice sensation...


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## DanMan (Jul 18, 2008)

Maybe desired volume level is a limiting factor with these sq set-ups that I believe I want to try to emulate, even though I have never heard any.

Is 85 db really what these cars shine at?

I am not a bass head but I do want a dynamic, accurate system more along the lines of 105-110 db+.

Is it a simple fact that higher mid and sub crossover points are necessary for higher outpu tsystems?


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## gijoe (Mar 25, 2008)

DanMan said:


> Maybe desired volume level is a limiting factor with these sq set-ups that I believe I want to try to emulate, even though I have never heard any.
> 
> Is 85 db really what these cars shine at?
> 
> ...


I'm kinda with you on this one. No 85db's is not all a typical SQ system should be able to do. I wouldn't run anything smaller than an 8" down that low regardless of how well they perform in the midbass region. It's just too much work for too small of a driver.


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## rockinridgeline (Feb 2, 2009)

I run Dynaudio MW182 crossed at 50 Hz and they work very well. Note that I spent some time and money to get the doors done right. I ran them for a while with about 250 watts on each and most people that listened to my system thought that I had a subwoofer, which I did not at the time. I like having the sub to be able to dial in the bass output that I want for the song that I am listening to, for my taste. If not for that I probably wouldn't run one.


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## Mic10is (Aug 20, 2007)

DanMan said:


> Maybe desired volume level is a limiting factor with these sq set-ups that I believe I want to try to emulate, even though I have never heard any.
> 
> Is 85 db really what these cars shine at?
> 
> ...


I dont even tune at 85db....ID XS65 Xo'd at 56hz @24db/octave


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## DanMan (Jul 18, 2008)

Mic10is said:


> I dont even tune at 85db....ID XS65 Xo'd at 56hz @24db/octave


Thanks all for the replies.

Mic10is- Always appreciate your input, especially. What volume would you say you tune at?

I see that Eric Stevens is a proponent of higher crossover points. He typically recommends 80hz. I am experimenting with these higher points, but see myself slowly getting lower and lower. 

Mic10is- Another thing I would like to get a better grasp on is matching frequency response of left and right. Can you give me some advice, maybe a brief outline of how to best do this? Are tones effective or is pink noise best?


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## WLDock (Sep 27, 2005)

Mic10is said:


> I dont even tune at 85db....ID XS65 Xo'd at 56hz @24db/octave


WOW, you got them robust Pro Sound ears obviously. I always had pretty sensitive ears...even being a drummer for years I always had to use ear protection when I could. My ears fatigue fast during tunning. When I go to some arena concerts or clubs and the sound is not balanced and loud I feel the urgency to put ear plugs in because it hurts. I think my high freq hearing was pretty good in my young adult life but I think I am starting to notice a difference....getting older... ...Years of practicing in a small room, playing in a 300 member marching band, and high powered audio will catch up with you at some point...

And XS65 at 56Hz @24dB ....With one driver I would think getting past 85dB in the lower range playing Black Eye Peas _BoOM BoOM PoW_, Mary Mary _God In Me_, or even the Planet Krypton Track would start to get nasty given the specs of those drivers:

No 92 dB 1w/1m
SPL 95dB 2.83 volts
*Fs ~80Hz*
Qts .26
Re 3.4 ohms
Imp 4 ohms
Xmax 4mm 1 way 8mm p-p
Xsus 10mm 1 way 20 mm p-p

But they obviously have a nice motor and we all know that you are running two drivers per side to increase output....and spend some time and money on the doors for the said drivers....combined with cabin gain...etc....an amazing feat non the less and your drivers are pretty much rolling off naturally with low end protection. Would love to hear it.

However, I don't think all would be able to pull it off with a single set in every install.


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## Oliver (Jun 25, 2007)

DanMan said:


> Can anybody name any midbass drivers, up to 10'', that are actually designed and recommended to be played around 40 hz?
> 
> I realize that it is a bone of contention around here whether or not certain drivers, in certain installs, should actually be played that low.
> 
> The L8 comes to mind, but was hoping to get other recommendations.


The IB series by JL will do what you want 



> Mic10is- Another thing I would like to get a better grasp on is matching frequency response of left and right. Can you give me some advice, maybe a brief outline of how to best do this? Are tones effective or is pink noise best?


http://www.diymobileaudio.com/forum...888-help-my-soundstage-ate-my-windshield.html


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## 2500hd (Aug 22, 2009)

I'm trying to get a bass up front system going on too. This what I'm looking at: Tang Band WT-1427G. 3-1/4 inches deep

Here's how it models @ 200watts
















With cabin gain it should sound decent with some eq


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## Mic10is (Aug 20, 2007)

DanMan said:


> Thanks all for the replies.
> 
> Mic10is- Always appreciate your input, especially. What volume would you say you tune at?
> 
> ...


I usually tune around 90-100db, so do most other competitors I know
Eric recommends 80hz as a starting point. Every time he has tuned my car the midbass was run as low as possible ,usually into the 50hz range to keep the bass up front as much as possible and its always w/ a very steep slope to prevent bleed through.

Due to irregularities from side to side, steering wheel, center console etc...very few cars will have a really similar response side to side. Which it is why Its usually best to tune each side independently. 

Matt Roberts and Randy Edy (Audiguy) are 2 great guys to ask about tuning as well. I know these both use a combination of pink noise and tones when tuning and then a very eclectic variety of music.


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## SoundChaser (Apr 3, 2009)

6spdcoupe has a set of Dynaudio either 8” or 10” (I forget) for midbass duty in his front doors. I’m sure he’ll let you give them a listen. They sound awesome... :rockon:


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## gymrat2005 (Oct 4, 2009)

I run two Dyn 8's in each door, playing as low as they'll go. Bass is solid, and deep. Many have asked...where's the sub?.

Here's a test fit of the speakers on the bench









panels in the car (sorry crappy cell phone camera  ) 



















Waiting on my HAT L 4's as we speak so I can replace my Dyn domes in the kicks, but the midbass/bass is staying put for now.


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## 6spdcoupe (Jan 12, 2006)

If your willing to come down to Edison, I would be more than happy to give you a listen. Drivers are Dyn MW182. Crossover point, sub (if any), how they are installed, power, etc is all irrelevant until After you listen.


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## thehatedguy (May 4, 2007)

When did 40 hertz become midbass? You don't need a midbass...you need a straight up woofer b/c that is bass.


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## gymrat2005 (Oct 4, 2009)

Don, I don't think it's irrelevent. I'd really like to know because I've thought about going to those speakers, and I can't get to Jersey to listen...lol. Are the 182's in an enclosure, or just IB in the doors? How much power are they getting? Are they playing all out, or where do you have them crossed over at?


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## m3gunner (Aug 6, 2008)

6spdcoupe said:


> If your willing to come down to Edison, I would be more than happy to give you a listen. Drivers are Dyn MW182. Crossover point, sub (if any), how they are installed, power, etc is all irrelevant until After you listen.


You gave up the sub and power in your sig... now we need to find out what car you drive that can use 10" drivers up front...


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## rockinridgeline (Feb 2, 2009)

Don has his in a SS SUV. Mine are in a Honda Ridgeline. I have run about 300 watts each to mine, IB in the doors. I have ran every kind of music you can imagine. I have never heard them bottom our or sound compressed or at their limits, mechanically or electrically. I have done so both at 40 Hz and 50 Hz 18db crossovers. 

Why run a crossover point that low? Simple: up front bass. ....and also because you can


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## thehatedguy (May 4, 2007)

Because you can doesn't always you because you should.


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## 6spdcoupe (Jan 12, 2006)

gymrat2005 said:


> Don, I don't think it's irrelevent. I'd really like to know because I've thought about going to those speakers, and I can't get to Jersey to listen...lol. Are the 182's in an enclosure, or just IB in the doors? How much power are they getting? Are they playing all out, or where do you have them crossed over at?


I meant it was irrelevant until he listened, no reason to 'taint' his mind into thinking anything until after the fact.

I have zero problem sharing the info, but he may set expectations based on the information.


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## miniSQ (Aug 4, 2009)

thehatedguy said:


> When did 40 hertz become midbass? You don't need a midbass...you need a straight up woofer b/c that is bass.


correction...40hz is *SUB* bass.......


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## 6spdcoupe (Jan 12, 2006)

m3gunner said:


> You gave up the sub and power in your sig... now we need to find out what car you drive that can use 10" drivers up front...


It is an old sig.


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## rockinridgeline (Feb 2, 2009)

thehatedguy said:


> Because you can doesn't always you because you should.


I disagree. The reason why people say that you shouldn't is that most midbass drivers can 't handle the job, not because there is some proof that says it isn't a good idea. It is dependent on a combination of the driver being used and the installation.

If you have a driver that is capable of going that low, then it gives you more options to tune the sound to the the best it can be in the installation.

If the driver is not capable, then you simply don't have the option. 

If you have not heard the driver correctly installed, then you are not qualified to make generalizations on whether it is a good idea to cross it at a given point.


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## RyanM923 (May 12, 2007)

I just grabbed a pair of Morl MW-267's from PE. Haven't tested them out, but with a fs of 31hz I can imagine they'd work well in the range you're wanting(not to mention I know a couple of guys running them down to 45-50hz and love them)...<3" mounting depth is a plus, also.


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## DanMan (Jul 18, 2008)

thehatedguy said:


> When did 40 hertz become midbass? You don't need a midbass...you need a straight up woofer b/c that is bass.


The reason I am asking for help in the <80hz range is because I feel my system is lacking in lower end ''OOMPH''. 

I know you used to run x69's. Maybe you could give me some advice. The x69s are dynamite drivers but seem to do best crossed 70-80hz. It seems to me that many sq competitors cross their mids and subs real low. Hence my op.

Actually, Eric mentioned in a post a while back that differences in driver design between my AE IB15's and the x69s may be giving me difficulty getting the response I want. I am hoping to treat myself to some new subs, most likely ID. I had also considered adding a dedicated mid, but that idea does not seem to be a well received option.


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## gijoe (Mar 25, 2008)

thehatedguy said:


> Because you can doesn't always you because you should.


I'm with you on this. I understand that there are sub drivers out there capable of going that low, but with the added excursion distortion rises. Since a LP up to and even above 100hz on a sub still doesn't create localization, why force your mids to work that hard? I'm running the ID oem mids, the midbass is great for a 6.5 but I still HP them at 100hz or above. Sure they'll play lower, they also get a workout doing it. I'll keep 40hz on my subs where I think 40hz belongs. 

I think this is very similar to running an amp at 1ohm. Sure the amp is stable there, but it wasn't necessary designed to be pushed to those limits. Things fail when pushed hard. For the sake of my equipment my subs stay wired at 4ohms, my subs play sub-bass, my mids play mid-bass/range, and my tweeters cover the rest. I've read opinions that if you can see the cone moving you're pushing the driver too hard, now I don't hold this as gospel, but any mid playing 40hz at any decent volume will be working hard.


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## rockinridgeline (Feb 2, 2009)

I have to restate what I already said. If you have not experienced the driver running at that crossover point, then you are just applying your knowledge of OTHER drivers to the problem and drawing a conclusion.

If it only made sense to cross over at 100 Hz, then why do companies like Theil, Dynaudio, BW, etc make full range speakers with 8 " or 10" midbass drivers that easily play down to 40 Hz or so? Granted, those companies use enclosure design to help, but speakers can and are designed to run IB and do very well.

I have personally NEVER heard a system with the midbass drivers crossed over at 100 Hz that had the perception of the bass line always being part of the front stage. That must be why many competitors cross lower, plain and simple.


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## Fast1one (Apr 6, 2007)

Personally if you are running a dedicated midbass than by all means use it to its full potential at a lower crossover point. This is assuming it has good distortion performance at high excursion levels.

However, those that are running a two way front stage should be conscious of *doppler* distortion that arises from high excursion levels. This adds a very noticeable coloration to the midrange, which worsens with a higher crossover point to the tweeter; smaller wavelengths and higher excursion increase this effect. 

Just a thought


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## thehatedguy (May 4, 2007)

I have heard it.

But a midbass is different than a woofer. Two different applications. Something needing to play to 40 hertz with gusto is a woofer.

When did Dyn and BW get into the fullrange driver market? You forget most home speakers are ported to help out that bottom end...they aren't IB in the house, not from those companies. And most home setups running IB are using rather large drivers to get that low- I'm talking pairs of 12s or 15s...not an 8 or a 10 because that isn't going to happen.

You want the short and sweet answer as to why most people cross their fronts so low to get the bass in front? It's easy to do. But you kill any dynamic output. Most cars with midbasses running that low have no balls to them whatsoever. There was a time when SQ cars ran high XO points on the midbasses and it sounded awesome. But people today have gotten really lazy and don't know how to install, so they take the easy short cut way out.



rockinridgeline said:


> I have to restate what I already said. If you have not experienced the driver running at that crossover point, then you are just applying your knowledge of OTHER drivers to the problem and drawing a conclusion.
> 
> If it only made sense to cross over at 100 Hz, then why do companies like Theil, Dynaudio, BW, etc make full range speakers with 8 " or 10" midbass drivers that easily play down to 40 Hz or so? Granted, those companies use enclosure design to help, but speakers can and are designed to run IB and do very well.
> 
> I have personally NEVER heard a system with the midbass drivers crossed over at 100 Hz that had the perception of the bass line always being part of the front stage. That must be why many competitors cross lower, plain and simple.


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## SSSnake (Mar 8, 2007)

> Eric mentioned in a post a while back that differences in driver design between my AE IB15's and the x69s may be giving me difficulty getting the response I want


Can you elaborate? I have ythe AE IB 15s as well...


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## rockinridgeline (Feb 2, 2009)

thehatedguy said:


> I have heard it.
> 
> But a midbass is different than a woofer. Two different applications. Something needing to play to 40 hertz with gusto is a woofer.
> 
> ...


I agree with what you are saying to the degree that crossing the midbasses low makes them work a lot harder and they do suffer from compression that isn't the case when they are crossed higher. That is a physical reality with small IB drivers. I already stated that home audio drivers are helped out by the enclosures. But it is worth noting that the car audio specific drivers have different design parameters to make them work IB in doors.

For the sake of the OP I would concede that if you are after very high volume clean sound, a higher crossover point is going to make that easier to achieve. If you insist on a low crossover point, the Dyns and a few other drivers will help you get there, better than most. But you do give away some dynamic capability in doing so.

If you choose a higher crossover point, then the quality of the sub and integration is going to be more important.


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## DanMan (Jul 18, 2008)

SSSnake said:


> Can you elaborate? I have ythe AE IB 15s as well...


Well, here is what Eric replied:

"Most likely the AE15 and the X69 dont want to play nice with each other. X69 is a low Q motor high efficiency driver he AE15 is a high Q low motor design."

My problem is that my system seems to lack some low end "oomph". I feel it is sub/mid integration, and I have tried and tried to get things to sound the way I want.

I don't know what Eric's response means as far as the technical aspect, but the bottom line makes sense to me. I love the x69's and I think the AE's do exactly what they should. But something needs to be changed to get the type of response I am looking for.


Any input is appreciated.


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## MarkZ (Dec 5, 2005)

x2 thehatedguy... I think we just need to kill the word "midbass" altogether, because nobody seems to know what it means. That's kind of understandable though, because the definition is ambiguous to begin with.

So what plays good down to 40Hz? Subwoofers do a great job.  

Your selection should depend on (1) usable bandwidth; (2) output capabilities; (3) duzitfit? Hell, a tweeter will play down to 40Hz. Just not very loud. All three of those factors are inter-related. It's not clear to me in this thread that you've told us what the required lowpass point will be, what kind of output levels we're talking about, and what your size constraints are.


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## MarkZ (Dec 5, 2005)

DanMan said:


> Well, here is what Eric replied:
> 
> "Most likely the AE15 and the X69 dont want to play nice with each other. X69 is a low Q motor high efficiency driver he AE15 is a high Q low motor design."
> 
> ...


This post screams tuning issues.

Describe your install. What do your xover points look like between midbass and sub? Time alignment and phase adjustments at your disposal?


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## SSSnake (Mar 8, 2007)

Well the AE is definitely a high q design as it is intended for IB apps. Without a box you get the target .7 q response. 

Not familiar with the x69s but I would not be surprised if they are low q design. However, I'm not sure why this would make integration particularly hard.


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## DanMan (Jul 18, 2008)

MarkZ said:


> This post screams tuning issues.
> 
> Describe your install. What do your xover points look like between midbass and sub? Time alignment and phase adjustments at your disposal?


Yes-obvious tuning issues!

I have tried everything. I am happy with my system-well as happy as the average "tweaker". Maybe I am just looking for an excuse to try something different.

The x69's are in fiberglass kicks, well damped and packed with 2 1/2 lbs. clay each, vented into the frame rails. Doors are well damped and sealed. The subs are mounted to a baffle of 3 layers of 3/4 mdf well seperated with foam, clay and deadening to a trunk damped with ample Raamat/Ensolite.

Lately I have been experimenting with higher crossover points, 60-80 hz. Also with "cascading" slopes using the hu and Zapco dpn.

I really need to get out there and hear other cars to get better reference to what is possible and what I want from a system.

Thanks for the input!


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## mosconiac (Nov 12, 2009)

Is the motivation of digging down to 40Hz with the front stage to decrease/eliminate localization of the sub? Before you attack the idea, I am referencing the fact that a sub has definite distortion characteristic. These distortion contributions would be multiples of the signal (frequency) presented to it.

For example, let's say we are playing a trunk-mounted sub which is crossed over at 40Hz with a 18dB slope. Let's say we are playing a 50Hz signal. Even though the signal is above our crossover frequency, the sub is playing a portion of that signal & the front stage is playing a portion of that signal. The sub is also contributing some amount of 2nd order distortion at 100Hz, 3rd order at 150Hz, 4th order at 200Hz, & so on. These higher-order distortion components (around 200Hz & above) would become localizable as the distortion level (SPL level) increases.

By comparison, if we change the crossover point to 80 Hz, the sub will contribute more of that 50Hz signal than the front stage will & it's distortion components would be that much more audible...hence localizable. Hell, it's contributing fundamentals at 200Hz too for that matter, just much lower than the front stage.

Am I thinking straight? Is this the motivation for ultra-low crossover points?


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## thehatedguy (May 4, 2007)

Well the real motivation is two fold- laziness and a lack of understanding how to build and tune a car.

Which will have more distortion- a sub that has a lot of surface area and displacement reproducing 40 hertz or a pair of 8s? I would put my money on the sub winning that contest. And given how insensitive our ears are to distortion and low frequencies, the cards get stack more towards in favor of the sub winning out.


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## SSSnake (Mar 8, 2007)

IMO-Distortion has a LOT to do with localization... WHile LF distortion products are not that noticable as part of full range music they do contribute considerably to localization of a sub to the rear. Reducing the xover freq however is just a band aid. Get a better sub or use an acoustic filter or both.


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## WLDock (Sep 27, 2005)

SSSnake said:


> Well the AE is definitely a high q design as it is intended for IB apps. Without a box you get the target .7 q response.
> 
> Not familiar with the x69s but I would not be surprised if they are low q design. However, I'm not sure why this would make integration particularly hard.


I am not certain myself exactly what is going on. I would point the finger at the car first before the drivers....even without knowing anything about it or hearing it. I am sure many here have taken a sub from one car to another and had totally different results. Some cars blend bass very well and other are a pain in the ass to get seamless sound.

Anyway, I was comparing the specs of the IB15 to the old IDQ15 that many used to use IB found it interesting. 

AE SPEAKERS IB15A-4 :
Fs: 20.4Hz
Qms: 4.5
Vas: 387L
Xmax: 18.5mm
Sd: 825sqcm
Qes: .45
Re: 2.7ohm
Z: 4ohm
Pe: 300W
Qts: .41
1W SPL: 90.6dB


IMAGE DYNAMICS IDQ15 D2 V.2
Fs: 20.5Hz
Qms: 4.96
Vas: 265L
Xmax: 13.5mm
Sd: 840 sqcm
Qes: .265
Re: 4.1 ohm
Z: 4 ohm
Pe: 400W
Qts: .251
1W SPL: 94.2dB

? I know some drivers don't play nice together but never really had a theory on it in terms of the subbass to midbass transition.


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## SSSnake (Mar 8, 2007)

I didn't catch the change in q between the home and auto version of the AE IB (.7 to .41 respectively). Given that I haven't put them in yet, I'm liking the looks of the AEs more and more. 

FWIW - My preference is to get the sub to play as high as possible wo localization...


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## mosconiac (Nov 12, 2009)

I think a lot of people that would be shocked by the amount of distortion their subs are producing. We scour over amplifier specs and rank one against another on fractions of a single % distortion, but totally ignore the same statistic in our speakers.

When have you ever seen a distortion statistic for a loudspeaker system?

To my point, would you be shocked to hear that your sub is producing 10% distortion on a regular basis?

What about 20%...no way, right?!?!

Depending on the alignment of you enclosure & the type of sub you are running & the frequency of the signal being reproduced...you could be seeing WAY more.

For example, here's a typical (once a very popluar) sub used in the Home Theater DIY environment. The 15" TC Sounds TC-2000.

Test#1 is that sub in a 270L ported enclosure measured in free-space.

Test#2 is the same sub in a 90L sealed enclosure measured in free-space.

*Could the results be more shocking? You'll have to trust me that these are typical results for subs. Surely, this is the motivation for ultra low crossover points.*


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## WLDock (Sep 27, 2005)

SSSnake said:


> IMO-Distortion has a LOT to do with localization... WHile LF distortion products are not that noticable as part of full range music they do contribute considerably to localization of a sub to the rear. Reducing the xover freq however is just a band aid. Get a better sub or use an acoustic filter or both.


What makes this interesting is the op DanMan's AE 15IB is a low distortion sub and several others who have used it talk of the clean output, seamless blending with the midbass and so forth. So, in theory he has a "clean" sub and very capable "clean" midbass drivers...Sounds like a great combo and bass to midbass should be awesome.
I think what he is experiencing is "real world" car audio related issues. Something is messing up the transition....the drivers or the space....maybe both? I think measurements are the only way to really see what is going on....??? How well do these drivers play together in a different space....like a large open room? What is the freq resp on just the midbasses? Just the sub? Combined? Would be interesting to she how much of an effect his car has on the response. What does the res look like in the kicks? What about the sub? Bass boost? Bass dropout?


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## mosconiac (Nov 12, 2009)

Just so someone doesn't think I cherry-picked a bad driver to make a point, here's a few more very popular DIY subs to ponder.


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## mosconiac (Nov 12, 2009)

How's the RTA on the ID/IB15? Phasing an issue? A dip in the range of 50-80 Hz would really kill the perceived impact of the sub...when the sub itself (and the the midbass too) is just fine.


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## WLDock (Sep 27, 2005)

mosconiac said:


> I think a lot of people that would be shocked by the amount of distortion their subs are producing...*Could the results be more shocking? You'll have to trust me that these are typical results for subs. Surely, this is the motivation for ultra low crossover points.*[/IMG]


Damn! This is my thinking on why I don't see crossing midbass down to 40Hz unless we are talking low volume listening. Also, I think it is a wise choice to go for low distortion drivers like the AE subs with the Lambda motors...I think anything one can do to help the cause in keeping distortion down the better off the system will be.

Again, I still think many like bass slam and have sub levels up too high to get a good bass upfront effect. I have listen to waay too many cars where the bass levels were too high. Don't get me wrong....I love slamming drums and slappin' bass but.....this is just one man's opinion....Turn your sub levels down!


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## SSSnake (Mar 8, 2007)

Mosconiac's graphs bolster my argument. Even with a low distortion sub there is a lot of distortion and it will be higher in freq than the fundamental. This makes it MUCH easier to hear.


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## jonnyanalog (Nov 14, 2007)

My question would this: 2 way or 3 way front stage? If you go 2 way and cross that low, say 40hz, wouldn't you be setting yourself up for beaming issues playing that wide of the spectrum from one driver esp. if you are door mounted or way off axis?


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## T3mpest (Dec 25, 2005)

SSSnake said:


> Mosconiac's graphs bolster my argument. Even with a low distortion sub there is a lot of distortion and it will be higher in freq than the fundamental. This makes it MUCH easier to hear.


Yeah but how much distortion is a midbass running into it's xmax trying to play a 40hz tone going to produce? Let's not forget the coils are super hot at this point too since most of these mids can't take more than 150 watts without smoking. The AE subs he's using have a a very low inductance, more powerhandling and alot more xmax than his midbass drivers. I'd be greatly suprised if his mids were producing less distortion trying to reproduce a 40hz tone, even a 80hz tone for that matter. If he's lacking oompf he's probably getting cancellation somewhere which is a phasing issue. Trying to run the mids into the ground isn't the answer especially not if dan likes his music at 110 to 115db's. 40hz at 110db's isn't going to reproduced by anything but a subwoofer cleanly. To get that kind of output at higher midbass frequencies your going to need effeciency, which usually means less xmax in most cases. I also run the xs69 mids. I've ran them as low as 53hz IIRC, but with the power levels and listening levels I was using I felt that was a bit abusive. I usually stick to the 60's or 70's at 24db/octave. Less punch, but a bit cleaner in the midrange at higher volumes.

Even with an a pair of 8inchs mid you going to need 15mm of xmax give or take a bit to get 110db's at 40hz, it's actually like 20mm, but cabin gain helps quite a bit.


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## DanMan (Jul 18, 2008)

Man, you guys are good. I need to start learning something about t/s parameters.

The AE is a great sub. Accurate and musical. The x69's are dynamite. My whole issue with thinking I wanted a mid that can get down to 40 hz or so is because it seems to me that many sq competitors speak of doing so. Mind you I have never even heard these cars.

On the other hand, several guys around here who I have the utmost respect for talk of using higher crossover points mid/sub.

I realize now that I just want something in a sub with the ability to get a bit more output for the needs of a daily driven system. Overcoming road drone and the like.

I am thinking of trying the IDQ or ID 15's. I would like to learn more about interpreting a subs specs. As I get more experience with this car audio thing, I am seeing what a profound effect sub performance has on overall system response.


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## SSSnake (Mar 8, 2007)

> Quote:
> Originally Posted by SSSnake
> Mosconiac's graphs bolster my argument. Even with a low distortion sub there is a lot of distortion and it will be higher in freq than the fundamental. This makes it MUCH easier to hear.
> 
> ...


This is why:



> FWIW - My preference is to get the sub to play as high as possible wo localization...


One thing that no one seems to have picked up on is the use of an acoustic filter...



> Get a better sub or use an acoustic filter or both.


The AE is an excellent sub (the quote wasn't directed at the OP). However, my point is that harmonic distortion is higher freq than the fundamental. If this distortion is coming from the rear it will pull the image to the rear. If it is coming from the kicks it pulls the image to the kicks (which is up front where you want it). However, this usually limits your dyanmics significantly. That's why I suggest using an acoustic filter to attenuate the distortion products.

DanMan, 

You've got a PM to discuss further...


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## WLDock (Sep 27, 2005)

DanMan said:


> I am thinking of trying the IDQ or ID 15's.


Why? The AE has a better motor IMO?


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## mosconiac (Nov 12, 2009)

SSSnake said:


> One thing that no one seems to have picked up on is the use of an acoustic filter...


So you would attempt to "trap" the higher order distortion? How would you go about that? I imagine firing the sub thru the rear seat acts as an impromptu low pass filter. A layer of rigid fiberglass will start absorbing sound at a little over 100Hz. Below that, the soundwaves would pass right on thru with no discrenable absorption.

For example, a 2" layer or Owens Corning 703 (plain, 3.0 pcf) fiberglass would provide the following attenuation by frequency:

125Hz: 0.17
250Hz: 0.86
500Hz: 1.14

Another 1" of 703 (3" total) would triple the absorption at 125Hz. BTW, don't make the mistake of saying it attenuates 17% of the sound at 125Hz. That's not how it works. These numbers are relative to one another...otherwise, how could the material above absorb 114% of the sound???

Also, if you think about it...this is how an aperiodic membrane is made (a pre-determined layer of fiberglass).

If you would like to explore this further, check out this website for absorption characteristics of a wide variety of materials. This is a very commonly used website for the Home Theater freaks (myself included).

http://www.bobgolds.com/AbsorptionCoefficients.htm


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## SSSnake (Mar 8, 2007)

Yes, I would recommend using open cell foam or fiberglass for just the reason you mentioned...

Let's take a 60 hz tone. The harmonic distortion products appear at 120, 240, 360, 480hz ....
The attenuation to the priniciple tone is minute compared to the harmonics. This makes open cell foam and/or fiberglass effective in reducing the distortion products.

I would also recommend using some type of bandpass arrangement (properly tuned of course). With an IB setup it is difficult but not impossible (the trunk acts as a LARGE sealed volume and the front chamber acts as a low pass filter) and the results are worth the effort (again IMO). 

These results can't be duplicated with any electronic processing because the noise/distortion is induced in the speaker system well beyond the electronics.

Just think about this for a minute... In your experience, do sedans typically have more of the bass up front than SUVs? IME, this is pretty true (there are exceptions). Most of those sedans had the subs firing through the back seat (with leather seats this is NOT typically true - the leather tends to cause noises that cause localization to the rear).

BTW - IME the difference between the aperiodic use of fiberglass is that the fiberglass is tightly compressed. This WILL change the absorption characteristics substantially,


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## thehatedguy (May 4, 2007)

How big are the natural instruments that make 40 hz tones? You are fooling yourself if you think small speakers playing that low will recreate them properly.

Actually an SUV or a hatch back would have better UFB than a typical sedan. Why? They don't have a back seat to act as a passive radiator and a large radiating surface with it's own acoustical problems.


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## SSSnake (Mar 8, 2007)

> How big are the natural instruments that make 40 hz tones? You are fooling yourself if you think small speakers playing that low will recreate them properly.


Again 




> FWIW - My preference is to get the sub to play as high as possible wo localization...







> Actually an SUV or a hatch back would have better UFB than a typical sedan. Why? They don't have a back seat to act as a passive radiator and a large radiating surface with it's own acoustical problems.


The only issue I have seen w sedans were w leather seats (as noted). With cloth this was typically not true. Besides as long as the freqs radiated (by the "passive radiator") are low, you should not be able to locate them. The only other issue I have seen is the need to put something between the top seat hook pieces and or the top of the seat and rear deck (to prevent rattles).


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## mosconiac (Nov 12, 2009)

Aww crap, my DD (that I'm planning a system for) has leather seats...which suck for another reason now! I hate how cold they are in the winter & now this?!?

I can work around firing the sub thru the leather rear seat though, the Mercury Milan has a vertical panel right below the rear edge of the glass (center of which is open obviously) that I can seal & mount the IB sub to. I can then seal off the rear of the fold-down seats to create a make-shift box with an open top (facing the rear shelf). I can then line the underside of the rear shelf with fiberglass & vent the sub thru that. Also, maybe I can mount the amps inside that make-shift box to reduce trunk usage. Hhhmmmm.


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## thehatedguy (May 4, 2007)

Why do you keep going back to that? You can play your sub high and get no localization...and have better midbass punch and better musical realism.



SSSnake said:


> Again
> 
> 
> 
> ...


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## SSSnake (Mar 8, 2007)

> Why do you keep going back to that? You can play your sub high and get no localization...and have better midbass punch and better musical realism.


I keep going back to that because I think that we are in agreement. 

I mentioned earlier that:



> Reducing the xover freq however is just a band aid


Rather than crossing your sub over low, use other means to keep it from being localized (acoustic filters/subs that don't create as much distortion). Just to be clear, I like to try to run the subs crossed over around 80hz (and I would love to push this number higher). IME this is tough to do without the sub giving away its location. Certainly "proper installation and tuning" is required but even then localization can become a problem if distortion products are ignored.


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## thehatedguy (May 4, 2007)

Word. Must have been reading it wrong...lot going on at the house today.


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## T3mpest (Dec 25, 2005)

DanMan said:


> Man, you guys are good. I need to start learning something about t/s parameters.
> 
> The AE is a great sub. Accurate and musical. The x69's are dynamite. My whole issue with thinking I wanted a mid that can get down to 40 hz or so is because it seems to me that many sq competitors speak of doing so. Mind you I have never even heard these cars.
> 
> ...



For IB neither sub will give you anything more than your already getting from your IB15 and you'll end up paying more money. The only sub in the ID line that would be an upgrade in output from what you have would be the IDMAX if we are talking IB. If you like your subs, but want more output I'd try AV15, unless the building wait time scares you off and use an enclosure. Other than that if you want to stick with IB you can try an Fi IB3 as they have 32mm of xmax and will displace quite a bit more air than your current sub. Incriminator Audio flatlynes are said to be nice as well, but those I've never heard in person, just the DP's, which was NOT SQ oriented (6 18's in a wall lol). If you want to stick with ID then the IDMAX would be the only real option for an upgrade. The Fi's are a good deal and both IA and ID have good customer service, can't go wrong either way just depends what you want.

Personally my setup is a set of cd-2 neos mated to xs69's in the kick with 2 AV15h's in 5.25 at 28hz. I think we have similar goals, just food for thought. I can't tell you how my subs sound because they aren't built yet lol. Still waiting on my order to come in.


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## DanMan (Jul 18, 2008)

T3mpest said:


> For IB neither sub will give you anything more than your already getting from your IB15 and you'll end up paying more money. The only sub in the ID line that would be an upgrade in output from what you have would be the IDMAX if we are talking IB. If you like your subs, but want more output I'd try AV15, unless the building wait time scares you off and use an enclosure. Other than that if you want to stick with IB you can try an Fi IB3 as they have 32mm of xmax and will displace quite a bit more air than your current sub. Incriminator Audio flatlynes are said to be nice as well, but those I've never heard in person, just the DP's, which was NOT SQ oriented (6 18's in a wall lol). If you want to stick with ID then the IDMAX would be the only real option for an upgrade. The Fi's are a good deal and both IA and ID have good customer service, can't go wrong either way just depends what you want.
> 
> Personally my setup is a set of cd-2 neos mated to xs69's in the kick with 2 AV15h's in 5.25 at 28hz. I think we have similar goals, just food for thought. I can't tell you how my subs sound because they aren't built yet lol. Still waiting on my order to come in.


If the ID Max 15 becomes a reality, I'd love to check it out.

I'll look into the AV-thanks for the suggestion.

Definitely curious how you will make out with your subs. Sounds like an interesting set-up. Good luck and keep us posted.


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