# Infinite Baffle Subs ... Pros and Cons ...



## JAG

I have a customer asking me about something I don't have a lot of experience with , so I thought I would seek your advice .... Npdang  Just joking , anyone can answer ....
If the front wave is completely sealed off from the backwave , and the mounting baffle is thick and well mounted, and you have a VERY high Qts sub and VERY high damping factor with your amp , *are there ANY drawbacks to going with IB , or is there anything that could be said about IB not sounding as good as a properly sealed enclosure *? Thanks


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## ludlamtheory

the main drawback in my opinion is the loss of output.


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## DS-21

The only drawback to IB is that your drivers will be easier to bottom (and thus, possibly damaged) than a woofer in a small sealed box.


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## JAG

ludlamtheory said:


> the main drawback in my opinion is the loss of output.


If you use a VERY powerful amplifier , this should be a non-issue though , right ?


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## JAG

Bottoming out should be a non-issue though. I'm using an amp with a 2000 damping factor ( Arc SE ) , and also a sub with a VERY high Qts , so the suspension is very stiff ....


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## npdang

No drawbacks, all things being equal. You can use any sub you'd like, it doesn't necessarily have to have a stiff suspension or high qts. Dampening factor has little to do with anything. 

You don't lose any output necessarily; it's still the same sub. You do gain some sensitivity in the lower frequencies, but lose some above that.

Your biggest problem will be mounting and install is more difficult than with a sealed box, for what would be IMHO very little to no gain (unless trunk space, cooling, or getting bass into the cabin is an issue).


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## chuyler1

Usually you don't need nearly as much power for an IB setup as you would for a sealed. It is possible to bottom out subs with 2/3 or sometimes 1/2 their RMS rated power.

The reason it is not popular is because it is never a plug-and-play install. It takes time and effort to properly install and dampen a rear deck baffle. You often need to relocate electronics, trunk tension bars, and other things to make room. On top of that, you usually have to dampen the entire trunk also to prevent things from rattling and flexing.

But if you have a customer willing to pay for the install time and dampening materials then there are some major SQ benefits. Some of the top competition installs use IB to get a flat response down to 20Hz. Just make sure the customer knows this is not the cheap or easy way out.


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## JAG

npdang said:


> No drawbacks, all things being equal. You can use any sub you'd like, it doesn't necessarily have to have a stiff suspension or high qts. Dampening factor has little to do with anything.
> 
> You don't lose any output necessarily; it's still the same sub. You do gain some sensitivity in the lower frequencies, but lose some above that.
> 
> Your biggest problem will be mounting and install is more difficult than with a sealed box, for what would be IMHO very little to no gain (unless trunk space, cooling, or getting bass into the cabin is an issue).


The customer has two concerns actually that are steering him towards an IB set-up .... One is the weight he would save as compared to using a 1" thick sealed box , and the other is trunk space. he doesn't have a very large trunk, and doesn't want to take up a lot of room in there. 
What frequencies are you speaking of that would be down in db ? I assume you mean 40 to 80 hz ? There is no reason this couldn't be adjusted out with an EQ is there ? 
My main concern would be aiming the subs towards the rear windshield. I've read what I can understand of Werewolf's technical thread about this , and it seems it can be a real ***** to tune around the subs aimed this way ... 
Any thougts on this ?
Thank you for your help ....


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## JAG

Hmmm ... The subs he's using have nearly 4" of excursion, so while bottoming out is possible , it is less likely. I don't understand the dampening factor not being an issue comment. An amp with super high dampening factor should control the sub's changes of direction better than one without as much control , shouldn't it ?


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## chuyler1

I think an EQ is a must if you want it to sound good in that configuration. If you have a 30-band or something equivalent it should be fine to bring down any peaks the window-loading may create.


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## JAG

Ok ... I apreciate the advice so far. If you can answer this , it will pretty well tell me if my customer should be happy ..... He comes from the world of snappy and robust SQ subs played LOUD on mostly rock music. In his installs , these are always in sealed enclosures. If I do my part right , should this IB set up be able to compete with a GREAT sealed SQL sub ?
Thanks again ...


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## JAG

Ok ... So You're going to try IB .... ( I guess I am  ) Would you skip the rear deck due to the possible tuning/reflection issues, and just fire them into the back seat since there will be a 3/4" MDF board mounted there to seal off the cabin from the trunk anyway ?


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## npdang

You can equalize almost any response you'd like... even approximating a sealed box.


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## DS-21

AVI said:


> Bottoming out should be a non-issue though. I'm using an amp with a 2000 damping factor ( Arc SE ) , and also a sub with a VERY high Qts , so the suspension is very stiff ....


No it won't. The damping factor has naught to do with it. The operative factor is the lack of a restorative mechanical airspring to keep the cone in line. Well, not entirely; depending on the parameters of the suspension a 5-15 cubic foot box (the trunk) may actually be smaller than true I-B...

But sonically I think a well-executed IB is superior to a typical car-fi box, which is far too high in Q.


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## chuyler1

Sealing off the back of the seats isn't as important as you would think...However, you do have to make sure that the subwoofer fires into the cabin. Here's some IB inspiration for you...
http://www.roadgearmag.com/article.asp?section_id=11&article_id=485&page_number=1&print_page=y


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## JAG

Thanks to everyone who has helped .... I'm going to go ahead and give it a try ... The only decision left to make , is do I fire them up through th erear deck and into the rear glass , or through the fold down rear seat openings .... Once again , thanks.


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## strong*I*bumpin

Of course mine is not finished yet(the amp is under the reardeck now),but just to give u an idea what I went thru here are some pix .BTW I'm loving IB so far...


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## strong*I*bumpin

Another site with alot IB setups....http://www.sounds-good-stereo.com/apmm/album.asp?categoryid=13


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## chuyler1

The IDv3s are a great looking sub, front and back! Perfect for IB!


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## Oliver

Was this site here in . . . 06-01-2006 11:21 AM ?


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## buddhaV6

hey guys, i read in another thread here that Cerwin Vega HED's might do well in an IB set up. these are looking attractive to me since where i live, the HED's are the closest to an IB sub that i can get. any thoughts?


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## Aaron'z 2.5RS/WRX

If you have a sub-sonic filter, use it, if you don't get one... 

This way you can limit excursion at the low end... It will help prevent bottoming.. EVEN with 4" of excursion, you could easily push the sub into bottoming... remember the control of a sealed box isn't there... this is also why power handling is lower... it's easier to reach mechanical limits..


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## Chaos

a$$hole said:


> Was this site here in . . . 06-01-2006 11:21 AM ?


Longer than that, even 

<<<<<


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## drocpsu

a$$hole said:


> Was this site here in . . . 06-01-2006 11:21 AM ?


way to bring it back from the dead. I'm assuming so. Chuyler registered in April 2006, so it was obviously around at that point. Npdang's registration date was June 2005...so it probably started sometime around then.


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## Aaron'z 2.5RS/WRX

It's gotta be a glitch or something, unless a$$ bumped the old thread..


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## chuyler1

This is just an old thread.


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## meelo

well i'm glad this is brought back from the dead I was curious and was gonna start a thread about the same thing....

...about using an IDQ10" in the space where you put it chuyler for your car...do you guys think an IDQ10 v2 is good for that in that spot?


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## gijoe

meelo said:


> well i'm glad this is brought back from the dead I was curious and was gonna start a thread about the same thing....
> 
> ...about using an IDQ10" in the space where you put it chuyler for your car...do you guys think an IDQ10 v2 is good for that in that spot?


The IDQ 10vs works great IB, but it won't take a lot of power, so I doubt you'll find the output adequate. I've got 2 of those subs IB and it sounds great, but there are times where I think I need a 3rd sub.


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## meelo

gijoe said:


> The IDQ 10vs works great IB, but it won't take a lot of power, so I doubt you'll find the output adequate. I've got 2 of those subs IB and it sounds great, but there are times where I think I need a 3rd sub.


well i also have an IDMAX 10" as IB too..it's gonna be longer but i'm wondering if that will help with handling more power?

the only problem with that is it's over 2 inches longer and weighs a heck of a lot more.... i'm fearing bending on my rear deck possibly? I'd like to keep it firing up towards my rear deck but i suppose that's not 100% required..


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## gijoe

I'm guessing an ID max will handle a bit more power IB, but I've never used one. The problem is, without an enclosure there is no natural spring keeping things from getting crazy. It doesn't take a lot of power to bottom out an IB setup. Personally I don't think 1 10 IB is going to be enough for most people, I think you'll try to get too much out of it and damage it, the same way people damage gear by cranking the gains on a low powered amp.


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## reker13

Is your customer going to have some hearty mid bass speakers up front? Most IB setups run out of gas above 60hz or so....


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## Ttowncls

Even in such an old topic, the same misconceptions are alive and well. I have plenty of output in an IB system. The trick is using the right sub with the right amp and sealing the trunk from the cabin completely. IB can easily hit mid 130's to low 140's in a SQ system with the right equipment and install. The IDQ's are one of the best in IB, but there are others that have better accuracy, output, and detail.


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## sqshoestring

I would never run less than a pair of 10s for adequate and not really that loud listening. You could get more if you HP them I suppose. I've had plenty of IB setups that would play over 100Hz no problem, it depends on what type of sub you use. My current quad 12s have lots of output though I have no idea in db, and they are tuned to run down to 20Hz. They would have a lot more output at 50-80Hz otherwise. And I only have 100w per sub on them.


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## chuyler1

I would sooner use the ID10 instead of the IDQ10. It has a lower Fs and higher Qts. The IDQ10 has always been designed for small sealed enclosures so using it IB is just wrong.

IB systems don't necessarily run out of gas above 60Hz. From my experience they are highly efficient from 60-100Hz but unless you detune that range you'll never hear anything below 50Hz. So basically IB is good if you only are interested in using your sub for 60Hz and below with a steep 18-24db slope.


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## kevinski118

Anyone ever used a 15" sub in an ib setup? I have an Adire Tumult and not much trunk space. qts is .36 and fs is 19hz. Are those ideal specs?


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## Oliver

drocpsu said:


> way to bring it back from the dead. I'm assuming so. Chuyler registered in April 2006, so it was obviously around at that point. Npdang's registration date was June 2005...so it probably started sometime around then.





Aaron'z 2.5RS/WRX said:


> It's gotta be a glitch or something, unless a$$ bumped the old thread..





chuyler1 said:


> This is just an old thread.


The info seemed worth mentioning, again  ^^^^^


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## meelo

I'll take everything into consideration and see what is the best thing for me. I guess i'll do some more hw, but i would like to use IB just for space saving for my car.


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## sqshoestring

kevinski118 said:


> Anyone ever used a 15" sub in an ib setup? I have an Adire Tumult and not much trunk space. qts is .36 and fs is 19hz. Are those ideal specs?


Seems like it would work. Many newer subs are lower qts, but they work because they can take a fair amount of power compared to more efficient subs we used to use for IB long ago. Most subs roll off the bottom when IB, that is why low fs and higher qts will get you closer to the right response....but everyone has an EQ now as well. Just remember you can only use around half the RMS on a sub when it is IB vs. in a box, and the limit is xmax you need to visually verify that. The lower you make it play the faster you hit xmax, another reason to run more cone area.

You can model them, just make a sealed larger than vas, or large as your trunk.


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## 14642

For what it's worth, unless the enclosure contains some kind of acoustic filtering (bandpass box), the enclosure has NOTHING to do with the woofer's response at higher frequencies. The box is an acoustic aid to the suspension and modifies the LOW FREQUENCY roll off by adjusting the -3dB point and the Q of the roll off (sealed boxes). Vented boxes do something similar, but it's more complicated. 

Mounting a woofer in Infinite Baffle simply doesn't provide this modification to the low frequency roll off, so Qts=Qtc and the suspension of the woofer has to do all the work in preventing overexcursion. You don't lose output compared to a sealed box with a similar Q. The difference between any woofer in a high-Q sealed box and in IB will be a reduction in midbass, an increase in sub bass and better transient behavior (competely described by the system Q). 

Firing the subs through the back seat IS an acoustic low pass filter, so doing that will affect the midbass you hear and will also affect the system Q, if the wofere are very close to the seat. If you fire them into the seat, put some big midbass drivers somewhere. 

Damping factor is meaningless for this discussion and shouldn't be considered. As I wrote, the transient behavior is completely described by system Q.


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## azngotskills

Andy Wehmeyer said:


> Firing the subs through the back seat IS an acoustic low pass filter, so doing that will affect the midbass you hear and will also affect the system Q, if the wofere are very close to the seat. If you fire them into the seat, put some big midbass drivers somewhere.


Would this be the case for most subwoofers used in your typical sedan install because the subwoofer is placed in the trunk, therefore forced to play through the seat? Or are you only referring to when the drivers are right up against the seat? At what distances would this apply if that was the case?


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## chuyler1

azngotskills said:


> Would this be the case for most subwoofers used in your typical sedan install because the subwoofer is placed in the trunk, therefore forced to play through the seat? Or are you only referring to when the drivers are right up against the seat? At what distances would this apply if that was the case?


I'm interested in hearing Andy's response to this as well but I think the difference is that with an IB setup, you need to seal off any other openings...rear deck, sides of the trunk, etc. So the only way for sound to make it into the cabin (if done right) is through the seats.


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## 14642

I've had the most success in building IB systems by firing the woofers though the package tray (rear deck). It's important to eliminate rattles and to seal the openings in the package tray, but I find that sealing the back of the seat is only necessary in entry-level cars where the seat is thin or doesn't include any backing of its own. If you drive a European car with fold-down seats, sealing that part isn't worth the loss of utility.

If you place a box in the trunk and don't do any sealing of the trunk, the midbass isn't such an issue and you can be reasonably sure you'll get most everything below about 100Hz. It's still helpful to eliminate rattles.

Mounting IB subs against the back seat within a few inches of the back of the seat and pushing the box as far against the forward-facing trunk opening as possible ensures that the sound of the bass has to pass mostly through the seat. If you seal the package tray, then the space between the seat and the woofers becomes part of a lossy and poorly-sealed bandpass box and the trunk is the other part. The seat acts as the port (acoustic low pass) in the vented side and the trunk is a large lossy sealed box. Can it work? Sure. Do I recommend it? No. Will someone come on here and write a diatribe about how it works perfectly and successfully divert would-be believers with some supposed evidence that's rooted in conjecture without proof? Probably.


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## The Drake

I have always wanted to do a IB install with the sub firing through the rear deck but with my car, it would literally protrude right in the middle of my trunk and would be next to impossible to hide, on top of the fact that I would rather NOT cut the rear deck, lol. But I can certainly see what Andy is saying.


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## azngotskills

Thanks for your response Andy, what you were saying is more clear now


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## meelo

Thanks for the response Andy. Helps me understand what I can do to utilize my rear deck. Man this just gets deeper and deeper *sigh*


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## charcoal grey

I am also looking to build an IB setup. I can't fire thru the back seats because my old car does not have fold down seats, and that portion of the seat is all metal. So I am looking to go thru the rear deck. I would like to build a baffle as shown below. It would take up less room in my trunk and be easier to make a grill and hide vs. putting directly into the rear deck. Does anyone see an issue with this setup?


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## 14642

The bottom setup looks better than the top, but I suggest just mounting the woofers to the board that will attach to the rear deck. You can sometimes save some room by mounting the woofers upside down and placing the magnets near the factory grilles.


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## sqshoestring

You can manifold the subs into the deck, but I'd not do it if there was another way. I've had better luck with a large spacer under the deck and firing through a partial or odd sized hole when the sub did not fit into the deck. The manifold will work and must be used in some installs.

I run my IB 12s into the seat, but the seats don't fold. I took them apart so just the frame and foam is left. Figured they would low pass/attenuate but after trying the subs with seat in/out the seat does not seem to affect the sound at all. However I have never LP them over 50Hz so the foam might do that at a higher frequency.

I think the rear deck works best in general, into the seat works ok and near as well if you xover low. I've had subs in the deck and the seat at same time and it worked nice too. With this setup I do get more noise from the trunk, mostly road noise. I think with a deck mount the noise has to go around corners through the sub so you get less, or maybe this seat is just that transparent. I did deaden around the baffle and a little in the trunk but obviously the trunk needs more with this setup. But, I'll be changing it soon as I can for other reasons and I'll deaden the new setup.


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## trunks9_us

Some good things to know in my future setup thx for the words of input. I am still going to be firing them thru the seats how ever I am going to just fold the seats down when I am driving since no one is really ever in the back seat any how


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## Izay123

Because Qts=Qtc for IB, wouldn't a sub with a Qts of .6 to .8 work the best for optimum damping? 

What impact would an Fs around 30hz have on the FR? I have a graph of my cabin gain and am designing the sub system to just barely over-emphasize the lowest lows so I can lightly EQ the hump in response out.

I am looking at running 4 Boston SPG555's in either 1.5 cu. ft. each or IB. My goal is to keep all drivers within their xmax even during the the most dynamic transients to keep distortion to a minimum.

I am hesitant to run them IB because Npdang's Klippel test results indicate that the SPG555's Bl curve and suspension are noticeably offset in the forward direction. The Boston engineers could have done that specifically to cause the SPG555 to behave better in the ultra-small sealed boxes they recommend. Perhaps the offset curves and compliance work better with a stiff air-spring than other manufacturer's subs.

What do you think?

Andy, what's your opinion???


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## 14642

I honestly can't imagine putting those woofers in a box. They look just right for IB to me, especially if that Xmax spec of 22mm is one-way linear. Who knows, though. As far as the suspension offset goes, unless you talk to the engineer who designed them, you'll never know whether that offset was intentional. Usually, those kinds of offsets are "corrected" by moving the coil forward or rearward on the former or changing the suspension. If you already own the woofers, don't worry so much--just mount them and have a good time. Bass is the simplest part of the system.


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## Izay123

Andy Wehmeyer said:


> I honestly can't imagine putting those woofers in a box. They look just right for IB to me, especially if that Xmax spec of 22mm is one-way linear. Who knows, though. As far as the suspension offset goes, unless you talk to the engineer who designed them, you'll never know whether that offset was intentional. Usually, those kinds of offsets are "corrected" by moving the coil forward or rearward on the former or changing the suspension. If you already own the woofers, don't worry so much--just mount them and have a good time. Bass is the simplest part of the system.


Thanks for your reply, Andy. 

I don't have the subs yet. I am still in the design phase (and probably will be for several more months) and am trying to come up with a comprehensive plan before I purchase the equipment and begin the lengthy install process. I am attemting to design a system that would be very competition-worthy, but also with the capability of producing very high undistorted output levels (not just from the subs but full range). I am planning to install a pair of high end components for each side in front, and for the center (that's 3 pairs). I am also planning to split a pair for the rear surrounds (that's 4 pairs total in the car).

With that in mind, would you still recommend the four SPG555's in IB?


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## 14642

I'd recommend a pair of W12GTi in IB.


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## Oliver

http://manuals.harman.com/JBL/CAR/Boxes and Parameters/W12spl_f.pdf

YouTube - JBL GTI 15's


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## chuyler1

Regarding not wanting to "cut holes in the rear deck"...

Many cars have 6x9" speakers on the rear deck stock. The opening for this size speaker may not be large enough to mount a 10" or 12" sub but the amount of air you can pass through that hole would certainly be more free flowing than trying to force the air through the rear seats. In fact, if you've ever seen Scott Buwalda's award winning Nissan Altima he ran 3 12" subs IB without cutting any holes (he did add massive amounts of deadening and reinforcement though).

My point being, don't assume you have to cut holes to run IB through your rear deck instead of the seat.


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## sqshoestring

chuyler1 said:


> Regarding not wanting to "cut holes in the rear deck"...
> 
> Many cars have 6x9" speakers on the rear deck stock. The opening for this size speaker may not be large enough to mount a 10" or 12" sub but the amount of air you can pass through that hole would certainly be more free flowing than trying to force the air through the rear seats. In fact, if you've ever seen Scott Buwalda's award winning Nissan Altima he ran 3 12" subs IB without cutting any holes (he did add massive amounts of deadening and reinforcement though).
> 
> My point being, don't assume you have to cut holes to run IB through your rear deck instead of the seat.


That is what I mean by using a spacer. Remember the old cutlass and monte RWD with that tiny rear deck about 4" deep? I used to run a pair of 10s in those with a slot in the deck over them, they worked great. The 10s just missed the trunk opening.

I've used quad 10s and 12s with $15 subs and had it work great, because they don't need the xmax with that amount of cone area. For SQ use I would figure loud enough to overcome road noise at 80mph with all the windows down, I can do that to 20Hz with my 12s on far less than 400rms. They hardly move. I clip the sub amp and the rear of the car shakes and can't hear the 4x70 highs. Cool for showing off but overkill for SQ.

Anyway, I don't have to deal with any xmax issues at all if I can fit enough cone area.

http://manuals.harman.com/JBL/CAR/Boxes and Parameters/W12GTi_rev_f.pdf

That is a lot of sub for IB, I've never used one like that IB.

I just model them to see what I have, just use a huge sealed.


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## 14642

It's pretty simple with that GTi driver. It can't bottom out--physically impossible, as there's no backplate. The Qts of the driver is .51, and that's critically damped and will be transient accurate in IB. The in-car response will rise gradually from 100Hz or so down to below 20Hz and can be flattened with an EQ if necessary. 

It'll work great and you can apply almost as much power as you want.


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## Aaron'z 2.5RS/WRX

I've herd the 15GTi in IB and to be quite frank, they sucked... 

Now, it was likely due to the SQ tuning that the car had (competing member here from Mi, installed in a Ford Contour, Anthony was his name)

I just didn't/don't understand the sound in the car, it was like the subs where shut off.. 

I was rather disappointed really, I thought I would get to hear "Whale speak" and I didn't and still don't get, why they weren't doing more...

But you say the GTi has no back plate? can't bottom.... I didn't know this...


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## 14642

Anthony's car is often tuned for IASCA or some competition format.


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## Aaron'z 2.5RS/WRX

Andy Wehmeyer said:


> Anthony's car is often tuned for IASCA or some competition format.


That's what I thought, so does the SQ competition format completely remove the low end? 

I mean the car sounded great, as i'm sure you likely know, but for a pair of 15's I was expecting more...


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## 14642

Too much bass in an SW competition kills the score. It's not a head-banging contest, which is why so few consumers are interested anymore. Who the F wants to subject their car to a couple of judges who will listen to Rebecca Pidgeon mewling about a picnic gone bad? I almost can't stand it.


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## BigRed

lol....I love Andy's response


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## Oliver

Andy Wehmeyer said:


> Too much bass in an SW competition kills the score. It's not a head-banging contest, which is why so few consumers are interested anymore. Who the F wants to subject their car to a couple of judges who will listen to *Rebecca Pidgeon mewling about a picnic gone bad*? I almost can't stand it.


.....


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## RMF419

How do you think these will perform setup as infinite baffle, firing thru the 6x9 holes. Parts-Express.com:Tang Band W6-1139SI 6-1/2" Subwoofer | subwoofer 6" subwoofer neodynium subwoofer tangband tb speakers tangband-22008


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## gijoe

RMF419 said:


> How do you think these will perform setup as infinite baffle, firing thru the 6x9 holes. Parts-Express.com:Tang Band W6-1139SI 6-1/2" Subwoofer | subwoofer 6" subwoofer neodynium subwoofer tangband tb speakers tangband-22008


You'll need a lot of them. I don't think you'll get the output you want with any less than 4 of those.

That's just an opinion based on the output of my 1 10's IB.


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## sqshoestring

Andy Wehmeyer said:


> It's pretty simple with that GTi driver. It can't bottom out--physically impossible, as there's no backplate. The Qts of the driver is .51, and that's critically damped and will be transient accurate in IB. The in-car response will rise gradually from 100Hz or so down to below 20Hz and can be flattened with an EQ if necessary.
> 
> It'll work great and you can apply almost as much power as you want.


Hmmm, so you think a pair of the 12s would work well and get to 20Hz...

What about a single W*15*GTi, how much power could one abuse it with IB and what kind of db would it manage running to 20Hz....for music in a daily driver. I have four w1252 infinity IB now and actually they have more output than I need on 400rms, but I would not want to step down to much less and risk not getting that low. I see 46lb shipping weight on it, what a machine. I'll have to dig out winISD...

----

RMF419--I've run 10s through 6x9 holes. You can run 8s but don't expect much output. I never run less than 10s IB, on the other hand I expect to get low with them at least 30Hz with 10s and more with larger.


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## chad

Andy Wehmeyer said:


> Who the F wants to subject their car to a couple of judges who will listen to Rebecca Pidgeon mewling about a picnic gone bad? I almost can't stand it.


Ha! You suckers missed me that time!!! 

I had time to swallow the beer *before* I blew it thru my nose


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## RMF419

Thanks GI and Shoes, I was just wondering. Maybe I will try the 6x9 Tang Band , since I alread have them. I just did not want mess up my rear package.


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## gijoe

RMF419 said:


> Thanks GI and Shoes, I was just wondering. Maybe I will try the 6x9 Tang Band , since I alread have them. I just did not want mess up my rear package.


Just read up a bit on IB to see why. In IB the power handling drops (although, apparently not with a WGTI) because there is no resistance to keep the cone under control. You need more surface area to provide you with good volume. My 2 10's IB are approximately as loud as 1 12 that I had in a sealed box a few years back.

If you want the lows to play loud in an IB configuration, you'll probably want at least 2 10's. The surface area of 2 10" circles is 157.08 (it'll be slightly more since a woofer is a cone, not a flat circle), figure out how many 6.5's or 6x9's it'll take to get you in that ballpark for surface area.


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## trunks9_us

so much love for the wgti's its a good thing I have 3 of them going into a Ib config


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## Oliver

Andy Wehmeyer said:


> It's pretty simple with that GTi driver. It can't bottom out--physically impossible, as there's no backplate. *The Qts of the driver is .51, and that's critically damped and will be transient accurate in IB.* The in-car response will rise gradually from 100Hz or so down to below 20Hz and can be flattened with an EQ if necessary.
> 
> It'll work great and you can apply almost as much power as you want.


U just can't beat this with an ordinary sub


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## jimmyjames16

I got my OA8's in my rear deck and I like them. They don't hit massively hard but they do blend in well with my front stage.


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## Aaron'z 2.5RS/WRX

Andy Wehmeyer said:


> Too much bass in an SW competition kills the score. It's not a head-banging contest, which is why so few consumers are interested anymore. Who the F wants to subject their car to a couple of judges who will listen to Rebecca Pidgeon mewling about a picnic gone bad? I almost can't stand it.



LoL.... well, don't tell Anthony that...


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## Aaron'z 2.5RS/WRX

Andy Wehmeyer said:


> It's pretty simple with that GTi driver. It can't bottom out--physically impossible, as there's no backplate. The Qts of the driver is .51, and that's critically damped and will be transient accurate in IB. The in-car response will rise gradually from 100Hz or so down to below 20Hz and can be flattened with an EQ if necessary.
> 
> It'll work great and you can apply almost as much power as you want.


You might not bottom it, but at what point do you run out of surround/spider? or jump the coil out of the gap?


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## meelo

Andy Wehmeyer said:


> It's pretty simple with that GTi driver. It can't bottom out--physically impossible, as there's no backplate. The Qts of the driver is .51, and that's critically damped and will be transient accurate in IB. The in-car response will rise gradually from 100Hz or so down to below 20Hz and can be flattened with an EQ if necessary.
> 
> It'll work great and you can apply almost as much power as you want.


interesting but geez it's a long sub! I will have to factor this into my next build


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## chuyler1

Andy Wehmeyer said:


> Too much bass in an SW competition kills the score. It's not a head-banging contest, which is why so few consumers are interested anymore. Who the F wants to subject their car to a couple of judges who will listen to Rebecca Pidgeon mewling about a picnic gone bad? I almost can't stand it.


:laugh: LOL!

Yeah, if they changed the demo CD for competitions to something you'd actually listen to at 70mph on the highway it would make things more interesting...

Track 1) Edgar Winter -- Free Ride or Frankenstein
Track 2) Tom Cochrane -- Life is a Highway
Track 3) Metallica -- Seek and Destroy
Track 4) Disturbed -- Down with the Sickness
...

because when your system is finished, that's the stuff you listen to at full volume on the highway. If you want to hear Nora Jones, go home and listen to it on your headphones.


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## RMF419

That looks good Autio.


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## gijoe

I'd love to try a W15GTI in my car, but I can't afford to buy one outright, and I am kinda partial to my IDQ's I'm not sure I want to get rid of them just to experiment. I am really interested in seeing how the design works IB, I'll bet it's a fun sub to play with.


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## wild_eye

Are there any shallow mount subs good for IB?


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## wild_eye

Who here has or has tried 2 8's in a IB setup?


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## jimmyjames16

I have 2 DLS OA8's in my rear deck and they sound awesome..


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## jawn swagg3r

Everyone tells me that IB setups sound nicer, but they can't bump nearly as hard as an enclosure. is this true at all? what varies this?


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## sqshoestring

jawn swagg3r said:


> Everyone tells me that IB setups sound nicer, but they can't bump nearly as hard as an enclosure. is this true at all? what varies this?


If you tune an enclosure to hit at say 50Hz, it will get loud there like SPL, but it will have no <40Hz (for example). IB will have a flatter response, depending on the subs used, so it will not hit as hard in the higher bass because you can't push the Q up like a box. You can get close my 12s were like that, you still might not get quite as much output IB. But if you tune IB lower for SQ, then you lose a lot of output at 50 compared to an SPL setup (or your typical small box bumping sub you find out there). But my 15s will dole out the 30hz no problem, and about the same up to around 100 but I'd never run subs that high personally.

My 12s were Infinity 1252w and iirc 1262 are the same, the ones with the magnet inside the basket. Should be able to find them used cheap, if anyone is interested grab a couple (or four like I did) and mount them IB. Run a SS filter at 30 or so and I'd say they will go quite loud at 50hz. I had to EQ them a lot and run 2 LP at 50Hz to calm them down.

I put a pile of 8s in IB many years ago. They can sound really nice and four can be ok. But pair or 8s didn't have enough output for most people 10s were much nicer quite a difference. Since you can blow a 10 through a 6x9 hole why use 8s, as most cars had 6x9 in the back deck then. Today there are 8s with more xmax likely they are better to a point, still you go larger in general you get a lower Fs and more output for 'free' when it comes to IB and you also get less distortion with less xmax with larger cones. So it really depends on your needs. You can run a subsonic and get more output, long as you are not after the low bass you are cutting with the SS.

So in short all things equal to get low and loud you need larger subs with IB. With small subs you get one or the other not both.


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## Thrill_House

I cant wait to get my 2 IDMAX 12's going in an infinite baffle setup, these subs could not be more perfect for such an application.


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## BuickGN

jawn swagg3r said:


> Everyone tells me that IB setups sound nicer, but they can't bump nearly as hard as an enclosure. is this true at all? what varies this?


Since this was brought back up, might as well reply.

IB will be as loud as sealed. To get the most output in the upper bass you might have to play with the SS filter. Sealed and IB are both about displacement. If you use the same subs running the same excursion they will be just as loud in IB as sealed but it will require far less power in IB.


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## carfreak1024

BuickGN said:


> Since this was brought back up, might as well reply.
> 
> IB will be as loud as sealed. To get the most output in the upper bass you might have to play with the SS filter. Sealed and IB are both about displacement. If you use the same subs running the same excursion they will be just as loud in IB as sealed but it will require far less power in IB.



So let's say you were doing an IB setup. Your choices in Drivers would be a pair of AE IB15, a pair of Image Dynamics ID15s, a pair of JBL W10GTis or anything from RE Audio, Image Dynamics, and Sundown Audio what would you choose. Car is a 2005 Honda Accord Sedan.

I work at the local authorized dealers for RE, Image, and Sundown Audio so getting product is no issue, nor is the build, just wanna know what drivers would sound the best. From what i have been reading people say the Image 15s are great for IB, but they are a really low Q driver as opposed to the IB15s which are really high Q. I have a pair of w10gtis from a past build, but am wondering if a pair of 10s IB is gonna do anything for me, i will be honest i do appreciate a NICE LOW END, and if using that pair of 10s is not gonna give me the output i desire i do not mind shelling out the extra cash for a pair of 15s or a combination of other drivers.

Thanks alot guys for all the input in this thread, it really made the decision to go IB an easy one!


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## BuickGN

carfreak1024 said:


> So let's say you were doing an IB setup. Your choices in Drivers would be a pair of AE IB15, a pair of Image Dynamics ID15s, a pair of JBL W10GTis or anything from RE Audio, Image Dynamics, and Sundown Audio what would you choose. Car is a 2005 Honda Accord Sedan.
> 
> I work at the local authorized dealers for RE, Image, and Sundown Audio so getting product is no issue, nor is the build, just wanna know what drivers would sound the best. From what i have been reading people say the Image 15s are great for IB, but they are a really low Q driver as opposed to the IB15s which are really high Q. I have a pair of w10gtis from a past build, but am wondering if a pair of 10s IB is gonna do anything for me, i will be honest i do appreciate a NICE LOW END, and if using that pair of 10s is not gonna give me the output i desire i do not mind shelling out the extra cash for a pair of 15s or a combination of other drivers.
> 
> Thanks alot guys for all the input in this thread, it really made the decision to go IB an easy one!


Out of the 3 you can get a discount on I would say ID because they're the only ones I've actually heard lol. They were the IDQ15v2. I prefer the low Q drivers. I've recently vented my trunk to atmosphere to lower the Q a bit. With a pair of 15s I would not worry about the low Qts, the trunk will raise the Q. 

The AEs are wonderful in every way but you would have to be patient because it could take anywhere from 6 weeks to 6 months to get them. Everyone seems to love the JBL in every possible configuration. 

There's just no reason not to do a pair of 15s other than fitting them and I know they fit since we basically have the same car. All else being equal 15s will be better in every category whether it's frequency response, efficiency, or distortion.

Your pair of 10s should have just as much low end IB as they do in a sealed box assuming the install is done correctly. I ran my 12W6s in every possible configuration and the low end was just as good and even better in IB than any other setup and the best thing about it was 100W would put it close to xmax. 

Sorry for just posting random thoughts, I've gotten a total of 9 hours of sleep for the entire week, this is worse than trying to post drunk lol.


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## carfreak1024

BuickGN said:


> Out of the 3 you can get a discount on I would say ID because they're the only ones I've actually heard lol. They were the IDQ15v2. I prefer the low Q drivers. I've recently vented my trunk to atmosphere to lower the Q a bit. With a pair of 15s I would not worry about the low Qts, the trunk will raise the Q.
> 
> The AEs are wonderful in every way but you would have to be patient because it could take anywhere from 6 weeks to 6 months to get them. Everyone seems to love the JBL in every possible configuration.
> 
> There's just no reason not to do a pair of 15s other than fitting them and I know they fit since we basically have the same car. All else being equal 15s will be better in every category whether it's frequency response, efficiency, or distortion.
> 
> Your pair of 10s should have just as much low end IB as they do in a sealed box assuming the install is done correctly. I ran my 12W6s in every possible configuration and the low end was just as good and even better in IB than any other setup and the best thing about it was 100W would put it close to xmax.
> 
> Sorry for just posting random thoughts, I've gotten a total of 9 hours of sleep for the entire week, this is worse than trying to post drunk lol.



thanks for the advice and being so cool about it too dude. I really like the Image Dynamics drivers and have had experience with the ID15s, however there is no longer an IDQ 15" driver. I think based on your advice that i might go with the ID15s over the IB15s due to the simple fact that i can get it way faster and at a pretty good price as well. Its hard to get good drivers in my country so i got to know the guy that had the Image Dynamics stuff. As mentioned before i used to run the JBL W10GTi subs ported with massive output ~140db @ like 37hz, but it took a JBL BPX2200.1 to get it that loud. I do not hope to get that loud with the new IB setup but i do not expect it to be a slouch either. I like it loud and LLLLLLLOOOOWWWW for when the occasion arises, but able to be toned down and blend with the front stage when ready, from what i am reading IB is the way to go to get those qualities!

You ever SPLed your TL to know what number it does?

Forget to mention that running the bassline would be one of 2 amps! Either a JBL PX300.4, or a US Amps USA-1000X. Running the front stage actively is the US Amps AX-600TU and an AX-4360TU. Processing is via a DEH-P800PRS.


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## BuickGN

carfreak1024 said:


> thanks for the advice and being so cool about it too dude. I really like the Image Dynamics drivers and have had experience with the ID15s, however there is no longer an IDQ 15" driver. I think based on your advice that i might go with the ID15s over the IB15s due to the simple fact that i can get it way faster and at a pretty good price as well. Its hard to get good drivers in my country so i got to know the guy that had the Image Dynamics stuff. As mentioned before i used to run the JBL W10GTi subs ported with massive output ~140db @ like 37hz, but it took a JBL BPX2200.1 to get it that loud. I do not hope to get that loud with the new IB setup but i do not expect it to be a slouch either. I like it loud and LLLLLLLOOOOWWWW for when the occasion arises, but able to be toned down and blend with the front stage when ready, from what i am reading IB is the way to go to get those qualities!
> 
> You ever SPLed your TL to know what number it does?
> 
> Forget to mention that running the bassline would be one of 2 amps! Either a JBL PX300.4, or a US Amps USA-1000X. Running the front stage actively is the US Amps AX-600TU and an AX-4360TU. Processing is via a DEH-P800PRS.


I've never put it on a meter but I might this weekend at our meet. 

I assumed you had your JBLs in a sealed box. You're going to lose output for sure over ported. Watt for watt they will probably be close but in the end you're going to end up with the same output as the same subs in a sealed box. When I was researching IB I remember one guy hitting 140db at something like 25hz with the pair of IB15s but that's going off of memory. I'm going to search for it because I may be wrong.

You're right in that IB will go low. That's what I love about this system, it will blend so well that sometimes I'll turn the subs off to make sure they're playing and other times I'll crank the gains and drown out the front stage.


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## sqshoestring

BuickGN is right on.

I like 15s for the following: less xmax (for X output) means less distortions, typical they have a lower Fs and can dig deeper, getting low requires moving a lot of air. So larger is often win/win if you are looking to get significant low end extension and low distortions.

Another factor is what bass do you like, if you are not looking to go real low you don't need to go as large....don't need to move as much air but can still get loud.

Another factor is output, it is roughly cone area and xmax and also the ability of the sub to handle using all of it. So if you really want to beat them this is when a real HD sub like the GTi can shine with braking coils and all that. I'd pick AEs for quality and a pair of them would give me more output than I need, but for a meter I'll guess something like the GTi or similar that is made to take a full xmax beating....might do better to hammer you. Sure it will tune differently, will need more EQ, but will have the raw output if that is what you need. Low and loud is all about displacement of air, even my cheap pyle 15s have significant output imo for what they are.

I'd also model them of course, IB is no different than any other sub setup in that way its just a large sealed.


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## carfreak1024

BuickGN said:


> I've never put it on a meter but I might this weekend at our meet.
> 
> I assumed you had your JBLs in a sealed box. You're going to lose output for sure over ported. Watt for watt they will probably be close but in the end you're going to end up with the same output as the same subs in a sealed box. When I was researching IB I remember one guy hitting 140db at something like 25hz with the pair of IB15s but that's going off of memory. I'm going to search for it because I may be wrong.
> 
> You're right in that IB will go low. That's what I love about this system, it will blend so well that sometimes I'll turn the subs off to make sure they're playing and other times I'll crank the gains and drown out the front stage.


I had the 10s in a ported box, for some reason they were tuned to 35hz and would drop stupid low. I remember demoing the car for a local pro sq competitor and he commented that the sub bass was the best aspect of my system. He was astonished at how low it would drop with the ported box tuned that high! And at that point it was way underpowered with 2 Sony 2 channels playing at 3 ohms bridged each giving it just about 1000RMS. He helped with the redesign of the enclosure and it was way louder than before, but lost some of the stupid lowness. Looking to get some of that back with the IB setup. 

The most impressive sub setup i have ever built was in my friends car when we built a pair of image dynamics id8 v3s for a demo for his store and tuned low to 33hz the subs hit a 139.1 sealed up on the dash. Powered off ~500RMS. We beat a pair of RE Audio SX10s on 2500RMS, and at the end came out to be the second loudest at the small TL meet. 

I have to admit i have ultra respect for Image Dynamics Subs. They have the ability to play STUPID loud for SPL purposes, they can hammer the subsonics, or they can blend with a front stage perfect. Its all in the box design and tuning that you choose. It is by far the easiest sub i have ever used to get the results that i am looking for whether it be a loud or accurate setup. 

And after talking to you guys here on DIYMA i am sure that i am gonna get what i am looking for!


*But a quick question pertaining to IB!!!!

How are the transients going to be using low Q drivers like this infinite baffle with no aid of the air cushion a box provides? I have RE Audio XXX midbasses upfront so i think my midbass would be fine, but what about the transients of the subass if that makes any sense?
*


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## Bluenote

Andy Wehmeyer said:


> Too much bass in an SW competition kills the score. It's not a head-banging contest, which is why so few consumers are interested anymore. Who the F wants to subject their car to a couple of judges who will listen to Rebecca Pidgeon mewling about a picnic gone bad? I almost can't stand it.


Andy is hilarious!!! Old post but funny as hell... Carry On!


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## hurrication




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## JoshHefnerX

This thing is a zombie a couple of times over


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## AtlasMick

Would it be alright to use 15" subs with a low QTS then if you are going infinite baffle? 

Also, I found it strange that a company claims they have very stiff suspension but then a QTS of around 0.5, how is that possible?


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## BuickGN

Qtc is what matters and even then Ive had great luck with low-ish Qtc setups. 

With "car ib", Qts rarely equals Qtc as it does in real home IB. Usually Qtc will be higher than Qts, at least by a little. The are plenty of exceptions though. With a high vas (combined with multiple subs) and a small trunk it's more likely to raise Qtc. 

The way I look at it and I could be wrong is even if you have to eq a lower Q setup a little to get the desired response, you still have the superior damping and "tighter" sound. An under damped high Q system is pretty much stuck being under damped. Personally I would rather have to eq the system a little. With that said every IB setup I've used has never needed 1/10th as much eq as any sealed setup and every IB setup has sounded Better right out of the gate and I've been lucky enough to use the same subs both IB and sealed and some bandpass and ported as well. With my mid Q IB systems (.4-.6) I've needed very little boost on the low end as some say you will. There are other factors such as the Fs and the car itself too. My lower Qts IB15s needed no boost while my smightky higher Qts Max15s need 3db at 20-25hz. They still dig down to the 20-30hz range better than any sealed setup I've had. 

I would not worry about Q too much to be honest. As long as it's not too high you should be fine. I say this after hearing and really liking some old IDQ15s that had a Qts in the .2 range in a fairly large trunk. 

About the suspension, the stiffness doesn't affect Q much ultimately. The motor is responsible for the vast majority of the cone control. My IB15s had a very soft suspension and my IDMax15s have a pretty stiff suspension and Qts is similar. The Max 15s have a stronger motor. 

I'm sure many will disagree with me saying not to worry about Qts when going IB but few stress over it when going sealed and I believe it's more important sealed than IB since so many tend to put a sub in as small of a box as possible and push Qtc way up from Qts and many times too high. I guess the real question is what is low or high Qts. My personal preference is <.6 when possible but that's not a hard rule by any means. It's just what I've preferred from the beginning. I've only had one IB setup that modeled around .8 Qtc and I hated it compared to every other IB setup I've had. Maybe it was just a crappy sub but it sounded slow and boomy and I hate to say it, like a sealed sub setup, not the smooth effortless sound that I'm used to in an IB setup. To be fair, inductsnce was the highest of any of my setups by a mile (Tempest X 15)


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