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post #1 of 38 Old 03-09-2013, 08:40 AM - Thread Starter
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I'm about to do a infinite baffle setup. I was thinking of doing 2 18" fi ib3 subs powered by a crown xls1500 amp. Are these the best bang for my buck?
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post #2 of 38 Old 03-09-2013, 09:07 AM
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Fi IB3 18s all the way IMO

"I should really see what dB levels I'm pushing. Long as it can't foam my beer during a movie we are ok "
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post #3 of 38 Old 03-09-2013, 09:43 AM
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Two IB3-18's may not be enough. How big is your room?

I'd recommend a quad set of them minimum, and an EP4000 amplification. The Behringer's -3dB point is verified, whereas the Crown's is suspect.

A (4)x IB3-18, EP4000 is quite the bang for the buck approach, when properly executed.

I'd suggest checking out these FAQ here.
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post #4 of 38 Old 03-09-2013, 06:07 PM
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+1, I had 2 in an outie manifold in approx. 3k cu ft room. It wasn't enough.
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post #5 of 38 Old 03-10-2013, 08:38 AM
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Even a quad set in a 2600cube room isn't quite enough IMO. If I high pass, yes, it's ample. But wide open with powering scheme for max power at 10hz, yet not allowing any bottoming, it's mucho, mucho fun and high quality, but a bit more is needed.


So I got more smile.gif

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post #6 of 38 Old 03-10-2013, 09:26 AM - Thread Starter
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Right now that's about all the budget I have. I'll go with 4 ohm so I can upgrade in the future then.
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post #7 of 38 Old 03-10-2013, 10:20 AM
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I understand entierly.

If you start with two, a simple high-pass implemented would allow you to get incredible output by eliminating the concerns for the big big effects down in the ULF range.

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post #8 of 38 Old 03-10-2013, 01:11 PM - Thread Starter
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What frequency would you suggest I hp them? The crown only goes down to 50hz so I'll have to get an external crossover. What's a cheap, effective solution for this?
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post #9 of 38 Old 03-10-2013, 01:16 PM
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Behringer's MIC2200 is a two channel, parametric EQ, with high pass filtering, polarity, etc, and it's under $100. I've got one.

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post #10 of 38 Old 03-10-2013, 01:21 PM
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Quote:
Originally Posted by rr14 View Post

What frequency would you suggest I hp them?

This all depends on what impedance the drivers are, and how they're connected ... and what amp, in what load config (ohms).

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post #11 of 38 Old 03-11-2013, 10:42 AM
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I respectfuly disagree with my fellow IB user. I have 4 ib3s in a 1800 cf room. They are not even close to bottoming. Also i use a crown xls 5000 for 500 watts per driver. No problems. Plenty of 5 hz sound.
Get what you can and leave room for expansion.
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post #12 of 38 Old 03-12-2013, 09:35 AM
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My 4 x 15" line array filles my 2,347 cu ft room powered by my EP4000 and the gain knob is "only" at 10 oclock - plenty of leftover headroom for running "hot" to show off above 115db ref.

Mine NEVER bottom out unless I crank up the gain almost all the way, and only then when ULF is there very low and I'm running the main volume at 0db full Ref, which is quite loud..
I don't run a hi pass...have thought about adding it to my set-up....but 4+ years this way and still good to go.

However due to single sub location I've embarked on multi-sub strategy to help flatten the response at all my seats.
(all my bass traps help flatten the peaks and lower overall modal decay time, but they don't fill the nulls)

IMO, plan on (at least) 2 IB manifolds, each with 2 x 18" driver.
If you can only afford 1 now, so be it, then add then 2nd one later to help flatten your seat-seat variation.
(determine those locations in advance by measurements, FAQ that FOH pointed you to can help)

I'd add a 2nd IB to my set-up if I could, but due to my usage of utility room as a backchamber I can only have 1 IB, so going with multiple sealed subs as "helper" subs
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post #13 of 38 Old 03-12-2013, 10:29 AM
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Quote:
Originally Posted by S_rangeBrew View Post

I respectfuly disagree with my fellow IB user. I have 4 ib3s in a 1800 cf room. They are not even close to bottoming. Also i use a crown xls 5000 for 500 watts per driver. No problems. Plenty of 5 hz sound.
Get what you can and leave room for expansion.

No problem.

When I bought mine, I free air tested them, individually, in pairs, and in a group of four. With a Behringer EP4000, as I raised the drive level, I could ease them into bottoming prior to full power in both the 4ohm config (one amp channel per 4ohm driver), and the bridged 4ohm config (two sets of series connected drivers, paralelled across the amp. In both scenarios, I could tap the VCs on the back plate.

The EP4K puts out 650w per channel into 4ohms, and ~1600w-2000w into 4ohms bridged.

I tested them once fully installed too, in various configs, even with a second EP4K,..to allow one driver per channel operation. The only config I can operate in without worrying about bottoming, is series connected 8ohm loads,...which is 450watts per channel, 225watts per driver.

I can't explain the differences, however I believe you. Something is influencing the difference. Maybe the signal chain possesses some roll-off, or the drivers are different. A year or two ago, I inquired specifically with the designer/builder at Fi (Nick I believe), he stated there's no differences in either of the two versions of IB3-18s with regard to the excursion capability, Xmech, Xmax, clearances, etc. They re-tooled and thus, I was interested in what was going on wrt the driver.

No biggie, as it's still plenty strong cool.gif

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post #14 of 38 Old 03-12-2013, 01:35 PM
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Quote:
Originally Posted by FOH View Post

No problem.

When I bought mine, I free air tested them, individually, in pairs, and in a group of four. With a Behringer EP4000, as I raised the drive level, I could ease them into bottoming prior to full power in both the 4ohm config (one amp channel per 4ohm driver), and the bridged 4ohm config (two sets of series connected drivers, paralelled across the amp. In both scenarios, I could tap the VCs on the back plate.

The EP4K puts out 650w per channel into 4ohms, and ~1600w-2000w into 4ohms bridged.

I tested them once fully installed too, in various configs, even with a second EP4K,..to allow one driver per channel operation. The only config I can operate in without worrying about bottoming, is series connected 8ohm loads,...which is 450watts per channel, 225watts per driver.

I can't explain the differences, however I believe you. Something is influencing the difference. Maybe the signal chain possesses some roll-off, or the drivers are different. A year or two ago, I inquired specifically with the designer/builder at Fi (Nick I believe), he stated there's no differences in either of the two versions of IB3-18s with regard to the excursion capability, Xmech, Xmax, clearances, etc. They re-tooled and thus, I was interested in what was going on wrt the driver.

No biggie, as it's still plenty strong cool.gif

How big is your room? Mine is on the small side, less than 1800 cubic feet and sealed. I suspect my room gain is quite large.

BTW, I finally figured out how to reproduce the missing "punch" that box subwoofers have and IB subs lack. Simply playback a quality recording of a box woofer playing a song, and the IB will reproduce the "punch" (ie, distortion) of the box subwoofer perfectly. It's kind of irrefutable evidence of the superiority of IB. BTW, I disagree vehemently with Mark Seaton and others who posit the clarity of IB can be reproduced with box subs of equal displacement.

Which is why I feel mtbdudex shouldn't sully his awesome room and it's fantastic IB with lowly box subs. biggrin.gif
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post #15 of 38 Old 03-12-2013, 03:40 PM
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Quote:
Originally Posted by S_rangeBrew View Post


BTW, I finally figured out how to reproduce the missing "punch" that box subwoofers have and IB subs lack. Simply playback a quality recording of a box woofer playing a song, and the IB will reproduce the "punch" (ie, distortion) of the box subwoofer perfectly. It's kind of irrefutable evidence of the superiority of IB. BTW, I disagree vehemently with Mark Seaton and others who posit the clarity of IB can be reproduced with box subs of equal displacement.

Which is why I feel mtbdudex shouldn't sully his awesome room and it's fantastic IB with lowly box subs. biggrin.gif

Huh?
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post #16 of 38 Old 03-12-2013, 04:01 PM
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IB's are great but they have to be planned out. I've seen to many guys just have to put one "where it fits" and not be too happy with it. I was one of those guys as well, once I moved it to a better location, It was great but being a basshead and all, 4 IXL's were nowhere close to enough and the builds began piling up hahaha

Blasting brown notes for 10 years and counting!

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post #17 of 38 Old 03-12-2013, 06:11 PM
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Quote:
Originally Posted by S_rangeBrew View Post


BTW, I finally figured out how to reproduce the missing "punch" that box subwoofers have and IB subs lack. Simply playback a quality recording of a box woofer playing a song, and the IB will reproduce the "punch" (ie, distortion) of the box subwoofer perfectly. It's kind of irrefutable evidence of the superiority of IB. BTW, I disagree vehemently with Mark Seaton and others who posit the clarity of IB can be reproduced with box subs of equal displacement.

Which is why I feel mtbdudex shouldn't sully his awesome room and it's fantastic IB with lowly box subs. biggrin.gif

Hi S_rangeBrew, I'm following the strategy laid out here, http://mehlau.net/audio/multisub_geddes/, where definitely the IB sub is the "king", low distortion and all, and each sub is "filler" of the nulls and exciting them via different placement in the room, as such each sealed sub will be definitely operating below its distortion point, since not carrying the load but helping.
At least that is the theory, and for now I'm betting on it as being real world.

I'll be trying out 40hz and 60hz xover on the mains also, vs the traditional 80hz xover.
Quote:
Make sure that the main loudspeakers are not high pass filtered as they act as additional low frequency sources, which is desirable.

"First setup the mains and the nearest sub [(the sub nearest to the mains)]. Set your spectrum analyzer to a very low bandwidth but not less than 200 Hz and fairly long averaging time. This will yield a very long average of the sound signal. Take your mic and move it through large spatial positions near but arround the prefered listening position. Be carefull as small bumps of the cable can generate large erroneous signals into the mic. The sweeping has to be smooth. When the analyzer has completed its run you will have a plot of the frequency and spatial averaged low frequency sound field. Try adjusting the sub - never adjust the mains - to see if you can get a better response by changing the gain, the low pass point, the phase and or delay if you have it. The bass should be sagging slightly at this point since you will be adding in two more subs.

Now add in the next closest sub and repeat the entire procedure again. You should be able to improve upon what you had before. If not try turning off the first sub and setting the second one optimal and then add in the first sub. If you still can't get a better response with two subs than with one then you will need to move one of them. You need to get an improvement from the second sub or something is wrong.

Now repeat this process with the third sub. The third sub, when you are close to it should barely be audible. If it is loud, then once again, something is wrong. It should only be filling in holes at this point and not adding any actual level. The level after two subs should be about flat or possibly a slight rise - based on preference. I find a few dB rise at the low end is desirable for best effect.

With the three subs things should be quite smooth when spatially averaged. You can now use any EQ that you have to make a final flattening of the response, but these bands should never be more than a few dB. When you are done, if things go as they usually do for me, your should have a spatial average of about ± 2-3 dB. This can take several hours so don't be impatient. [...] Make sure and write down all the settings!!

Back to the OP.....congrats on joining the IB side, once you decide to go IB join the cult forum and make a thread there....activity seems to be slowly picking up.....i wish this recession-recovery would pick up faster...
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post #18 of 38 Old 03-13-2013, 01:58 AM
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Don't need to look far to see what drivers I think are best for IB's, but @ $1,400 a driver shipped to Japan and $1,000 a driver in the US I guess they are not the best value. But, if you want virtually unlimited bass that you don't ever have to worry about busting drivers the RE Audio XXX's 18" are my choice.

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post #19 of 38 Old 03-13-2013, 07:39 AM
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I did a small workup of all the high excursion large diameter drivers I could find information about and the Fi IB318 ended up at the top of the list for displacement per $, followed very closely by the Stereo Integrity 18". The SI18 is not due in until June and the per driver displacement is about 70% of the Fi, but has a high bang for buck factor.
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post #20 of 38 Old 03-13-2013, 08:56 AM
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Quote:
Originally Posted by audiovideoholic View Post

Quote:
Originally Posted by S_rangeBrew View Post


BTW, I finally figured out how to reproduce the missing "punch" that box subwoofers have and IB subs lack. Simply playback a quality recording of a box woofer playing a song, and the IB will reproduce the "punch" (ie, distortion) of the box subwoofer perfectly. It's kind of irrefutable evidence of the superiority of IB. BTW, I disagree vehemently with Mark Seaton and others who posit the clarity of IB can be reproduced with box subs of equal displacement.

Which is why I feel mtbdudex shouldn't sully his awesome room and it's fantastic IB with lowly box subs. biggrin.gif

Huh?

+1... Huh?

I don't believe I said any box sub will equal the sound of an IB with just having equal displacement. In fact I often point out that subs of different sizes Fb and raw responses will have slightly different character, even after EQ. I have at a few points mentioned that it would be possible to mimic the sound of an IB with the properly scaled sealed box, as a prototype we had at ServoDrive was pretty close to. That sub also had an Fb in the low 20s or teens. I do disagree that the "infinite" part of the design is a dominant part of the sound, but rather the efficiencies afforded by a very large box and the resulting Fb and related occurrences create the sound often observed. Of course any sub is only as useful as the location it gets placed in. The more testing you can do before building, the better.

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post #21 of 38 Old 03-13-2013, 09:10 AM
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Quote:
Originally Posted by S_rangeBrew View Post

How big is your room? Mine is on the small side, less than 1800 cubic feet and sealed. I suspect my room gain is quite large.

BTW, I finally figured out how to reproduce the missing "punch" that box subwoofers have and IB subs lack. Simply playback a quality recording of a box woofer playing a song, and the IB will reproduce the "punch" (ie, distortion) of the box subwoofer perfectly. It's kind of irrefutable evidence of the superiority of IB. BTW, I disagree vehemently with Mark Seaton and others who posit the clarity of IB can be reproduced with box subs of equal displacement.

Which is why I feel mtbdudex shouldn't sully his awesome room and it's fantastic IB with lowly box subs. biggrin.gif
I have two IB manifolds with four Acoustic Elegance IB15 drivers in each manifold. Last year I heard 2 quad subwoofer systems, 12 dual subwoofer systems, and 7 single subwoofer systems in addition to my infinite baffle. One of the quad systems and at least two of the dual systems had more displacement than my IB. I would take my IB system over any of them. The bass is just so delicious and nuanced.
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post #22 of 38 Old 03-15-2013, 04:27 AM
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Quote:
Originally Posted by S_rangeBrew View Post

How big is your room? Mine is on the small side, less than 1800 cubic feet and sealed. I suspect my room gain is quite large.

BTW, I finally figured out how to reproduce the missing "punch" that box subwoofers have and IB subs lack. Simply playback a quality recording of a box woofer playing a song, and the IB will reproduce the "punch" (ie, distortion) of the box subwoofer perfectly. It's kind of irrefutable evidence of the superiority of IB. BTW, I disagree vehemently with Mark Seaton and others who posit the clarity of IB can be reproduced with box subs of equal displacement.

Which is why I feel mtbdudex shouldn't sully his awesome room and it's fantastic IB with lowly box subs. biggrin.gif
If your IB sub is lacking that 'Punch' then your IB sub is not doing what it is supposed to do. Sorry.

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post #23 of 38 Old 03-15-2013, 07:12 AM
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"BTW, I disagree vehemently with Mark Seaton and others who posit the clarity of IB can be reproduced with box subs of equal displacement."

something probably got lost in the translation.

mark is right.

if you start with an infinite baffle subwoofer and work your way down to sealed subs with equal displacement, there are a large number of parameters that you have to consider in order to not muck up the sound. just because it is frequently done incorrectly does not mean that it cannot be done properly.

Listen. It's All Good.
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post #24 of 38 Old 03-15-2013, 03:32 PM
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Mark kind of said it above... but in short a huge downside of IB is that you can't move it. It better be in the right or good location.

Unfortunately, unless testing is done prior.. in most cases the optimum location for the sub isn't your first place to put it. Nothing worse than having a bass solution (of any kind, capability, or size) that can't deliver the energy to the listening position. Take if from a guy who had a theater room with seating in a huge null area. That said a well executed sealed design can be compact in relation to other designs which makes it easier to stuff it somewhere where it will do the most good.

If you've got a great place to put an IB that will light the listening position up properly then go for it.. That said don't forget that backwave has to go somewhere so keep that in mind when planning the layout.
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post #25 of 38 Old 03-29-2013, 12:08 PM
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Quote:
Originally Posted by JapanDave View Post

If your IB sub is lacking that 'Punch' then your IB sub is not doing what it is supposed to do. Sorry.

Let me explain a bit more. My IB only lacks "punch" on some music/soundtracks that have been mixed with box subs.

The "punch" is just fine on music/sounds recorded live and unedited... every time.

An IB subwoofer reproducing sounds made by a box sub is like using a CD to reproduce MP3 music. Not a problem.
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post #26 of 38 Old 08-31-2013, 10:11 PM
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I am going to try the IB route myself. I am building a new home, and am positioning one or possibly two manifolds above the screen in front of my HT between the mains. I love extreme bass, so which subs do you guys say work best? I am hearing everyone loves the FI IB318's, but how do they compare to the Stereo Integrity HT18 subs? the HT18 seem to have a low QTS, but I've heard good things about them from forum posts. Any input would be great.

Thanks
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post #27 of 38 Old 09-01-2013, 06:20 AM
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I am also not interested in the XXX subs. If I were driver limited (ie car audio) due to space, then these would be a good choice. I know they will perform well, but they are a terrible value since you can get four of the other subs for the price of one XXX.
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post #28 of 38 Old 09-01-2013, 03:13 PM
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When it comes to infinite baffles, there are a few things to consider. Of course you will need displacement to create output. You can easily determine how many drivers you need based on how loud you want to play. Displacement directly relates to SPL. There is much more to a good infinite baffle subwoofer than that though. Many people think they can simply put any high excursion driver in a baffle, throw some power at it, and have good results. Unfortunately many drivers miss out on a lot of the real benefits for infinite baffles.

An infinite baffle means you are not really limited by Hoffman's Iron Law which states that the size of the enclosure determines the low end rolloff. In a sealed box, the compliance of the driver has little to do with the overall low end response because the enclosure dominates the compliance of the system. The requirement is to use EQ and put a large amount of power back in to compensate for this enclosure rolloff. In an infinite baffle though that isn't the case. The low end rolloff is determined only by the compliance of the driver. Without the enclosure rolloff, there is an ability to be very "bass efficient" as Mark Seaton once called it, but many drivers fail to do this. Often you will see an IB woofer with a stiff suspension and a large, heavy coil is needed to get the FS low enough. Even though Qts may look good for the application, this stiff suspension still makes the driver roll off very quickly, and it is not efficient. A large amount of power still needs to be applied to the driver to compensate for this rolloff and lack of efficiency. This means the infinite baffle then loses its most important benefit over a sealed box.

When done right, the woofer should be able to be pushed to high excursions with minimal power. This requires a soft suspension. At the same time, a smaller voice coil can be used to get the same resultant driver Q and Fs. Less power needs to be applied to a smaller coil, to get the same driver Qts but with more efficiency. This lowers thermal issues as less power is needed. More importantly distortion related to flux modulation is also lowered. When the coil is larger with more power applied it becomes a stronger electromagnet and distortion is increased from several aspects. The larger the coil and more power applied, the more it will modulate the permanent magnetic field causing distortion. The smaller coil with less power drastically lowers this effect. Not only that, but the smaller coil will have significantly lower inductance to begin with. This also lowers issues with Le(x) distortion which greatly affects the midbass range.

Many IB woofers are designed for car applications. In an automotive environment you have massive cabin gain. You actually want to decrease the low end output to keep it from being too overpowering. In addition, the Vas needs to be much smaller as the "infinite" space in the trunk is actually limited to between 10-20cubic foot in most vehicles. The automotive IB environment and home theater IB environment are drastically different. While the same woofer could be used for either, optimizing a unique woofer for both uses is much more ideal.

Here you can see the curve of the IB15HT-4 in green. The blue curve is the IB15AU-4 which is intended to roll off more quickly to work better in an automotive environment. The Red curve is the IB3-4ohm. You can see the difference in efficiency and also in the upper end response. The IB15HT has the most low end efficiency by far. The result is no need for EQ to boost the low end and also significantly lowered distortion.

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John E. Janowitz
Acoustic Elegance, LLC
"Learn from the mistakes of others... you can't possibly live long enough to make them all yourself"
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post #29 of 38 Old 09-03-2013, 07:13 PM
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Thanks John for your information. Do you still have a special on four 18" IB subs?
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post #30 of 38 Old 11-04-2013, 08:12 PM
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Quote:
Originally Posted by staffcurtis View Post

I am also not interested in the XXX subs. If I were driver limited (ie car audio) due to space, then these would be a good choice. I know they will perform well, but they are a terrible value since you can get four of the other subs for the price of one XXX.


You know,  a scan of that might encourage one to hope that some inexpensive 15 inch driver,  car or home audio, stands a good chance of serendipitously landing within a very close proximity of near ideal OB parameters. 

 

How far have members here searched these out?

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