# Acoustic Elegance SBP15-4 review



## decibelle (Feb 17, 2011)

*Acoustic Elegance SBP15-4
*


















Fs............21.30hz
Qts..........0.41
Qms........5.35
Qes.........0.45
Vas.........338 L
Xmax.......18 mm
Re............2.7 Ohm
Pe............500 (continuous) (thermal)
Sd.............825 sqcm
Le.............0.3 mH
Bl..............11.1 Tm
SPL...........90.65 dB

The Acoustic Elegance SBP15-4 is the successor to the presently retired IB15 series of infinite baffle subwoofers. Each sub is hand-built by John Janowitz as it is ordered – for those of you who are frustrated from having not received your sub(s) yet, keep this in mind. 

I ordered the sub last July from John and was fortunate enough to receive one of the first SBPs that were made. Unfortunately I had the sub sitting in its box since September of last year, but it has since been installed in my car in January 2012. After nearly four months of playing time, I’d be lying if I said I had any complaints thus far.

I know many of you are waiting eagerly on your own pair of these subs, and since it appears to be taking some time, I hope to be able to give you more insight into what exactly you are about to receive. I will say this, it is worth the wait.

It's a bit of a read, but there is much to praise.

*Transient response. *Despite pushing the sub to its limit, the SBP-15 has never shown signs of lethargy. A good example of this is Brombo, by Brian Brombers and Akira Jimbo. The song consists of a drum set and bass, but I only listened to the first 1.5 minutes in which there is a solo drum set. The pace is quick and the drummer is really slamming on the drums which make for a strong, hard-hitting bass impact from the kick drum. The AE handles this with great ease, never missing a beat. You can clearly hear and feel each separate impact’s attack and decay from one beat to the next. The sub does an outstanding job of playing only what it is told to play and nothing more – there is no overhang or muddiness. Due to its lightweight paper cone and stronger motor (over the IB15), I have yet to hear a song where sub bass accuracy hasn’t lived up to expectation. 

*Efficiency. *Simply because the sub is infinite baffle doesn’t mean it can’t get loud. I am giving my SBP15 the rated 500w. With the right EQ, I have found the sub is very capable of being almost overwhelming – if you so wish to make it. I am no super-heavy basshead, but I have found it surprisingly easy to get a single infinite-baffle 15” to go from a normal listening level to holy-****-turn-it-down loud with very little adjustments.

That said, I’m now going to compare the SBP15-4 to the McLaren MP4-12C. And here’s why: the McLaren is an incredibly well-built sports car that performs outstandingly on the open track, and it is also a VERY forgiving machine. There are so many electronic safety controls you have to purposely turn off to really endanger yourself or the car. Otherwise, if you make a mistake, the technology is there to save your butt. The SBP15 is similarly a VERY forgiving subwoofer. You can, of course, make it sound bad, but that has got to be your ultimate goal. Barring that, it’s hard to make the sub sound bad even with EQ flops. For example, boost it too much and it will still sound clean and composed. It seems counterintuitive, but that has been my experience.
*
Low frequency extension. *The sub plays cleanly well into the low sub bass frequencies without distortion. A fine example of this is Bass I Love You – the song dips down below 10hz. While watching and listening to the single SBP15 at high volume, there was NO distortion, each cycle is still felt independently and the driver showed no signs of struggle or strain – it was happy doing its thing. 
*
Sub-to-midbass transition.* Since demoing the sub’s abilities, I’ve had numerous listeners give their compliments to the sub-to-midbass transition. As I mentioned above, the SBP15 has no trouble blending seamlessly into your midbass range. Even crossed at 120hz I was surprised at how well the transition blended together.

*Summary:
*
The sub can handle anything you throw at it, from Brad Paisley’s I Wish You’d Stay, to the extreme lows of an organ, to fast-paced, hard-hitting dubstep and everything in between. The kick drum in Alice in Chains’ No Excuses will hit you so hard it is painful. The sub always moves with authority. In Metallica’s One, the double-bass towards the final half of the song are clear and extremely distinguishable – you can hear and feel each full, individual strike of the drum in perfect time. Limit to Your Love by James Blake begins abruptly with absurdly quick pulsating bass, which the SBP keeps up with perfectly. When the pulsating stops on a dime, so does the sub. This song is a magnificent test for any subwoofer, and the sub passes it with flying colors.

As is with any rear subwoofer, without time alignment, lower notes will of course reveal the location. With proper time alignment, this only occurs with drawn-out low frequencies and the great majority of the time you will forget the sub is even back there.



I will summarize this long post to say this: although the SBP15-4 was only my second subwoofer, it will without a doubt be my last.


Here's the sub installed in my trunk:


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## strakele (Mar 2, 2009)

Lies. All lies.




















But seriously, it is a great sounding sub. We tested it in 2 different cars with 4 different processors, and it never sounded bad. Convinced me to go IB as well. Good stuff.


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## WLDock (Sep 27, 2005)

Nice review, thanks for taking the time.


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## Sulley (Dec 8, 2008)

Excellent review, Are these priced similar to the IB15? I was going to wait for the Sundown IB woofer but I may have to look in to these now.



Edit: Found pricing on AEspeakers.com



> The SBP15 will be available to order immediately at $289 individually. Current lead time as of 3/7/11 is about 4 weeks. SBP12's will be $249 each and have the same lead time. I expect to have these stocked for immediate shipment in small quantity once I am caught up on other orders here.


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## IBcivic (Jan 6, 2009)

Holy price hikes, Batman!!!....all the better reason to never sell my "ol school" IB12-8a


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## bertholomey (Dec 27, 2007)

Great review Ally. I loved the sound of this sub in your car, and I concur with your praise of this great driver. It is also cool that I know most of the tracks you mentioned in this thread


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

IBcivic said:


> Holy price hikes, Batman!!!....all the better reason to never sell my "ol school" IB12-8a


Without the price hike, Jon wouldnt be able to stay in business. Material costs have skyrocketed, but he never upped the price on the IB15's. He was pretty close to losing money on each one he sold.


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## fish (Jun 30, 2007)

Great in-depth review. I'm with ya on your description of AIC & "One". What low-pass point did you settle on.


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## bassfromspace (Jun 28, 2016)

Great review!

This is off topic, but how do you like the Quart amps?


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## IBcivic (Jan 6, 2009)

TOOSTUBBORN2FAIL said:


> Without the price hike, Jon wouldnt be able to stay in business. Material costs have skyrocketed, but he never upped the price on the IB15's. He was pretty close to losing money on each one he sold.


No doubt. 
Like everything else in this "great" economy, you have to adjust or die.


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## decibelle (Feb 17, 2011)

bertholomey said:


> Great review Ally. I loved the sound of this sub in your car, and I concur with your praise of this great driver. It is also cool that I know most of the tracks you mentioned in this thread


Thanks! I used your whole meet disc from last year to test it actually. 



fish said:


> Great in-depth review. I'm with ya on your description of AIC & "One". What low-pass point did you settle on.


Honestly, it has always varied. I've had it down to 50, 70, 80, 100 and 120 and they all sounded good. The one I used specifically for this test was 80hz. Don't know if that's the crossover I will keep it at in the future though. I'm thinking I need more time at each crossover point to see which it likes the best.



bassfromspace said:


> Great review!
> 
> This is off topic, but how do you like the Quart amps?



The Q series are perfect for what I want/need. Only issue is occasional overheating, but I'm thinking of installing fans to combat that. I doubt I will change them in the distant future.


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## kaigoss69 (Apr 2, 2008)

Bringing this back from the dead. Miller, what crossover point did you settle on and what slope(s) did you use for the best sub to midbass transition? - Thanks, I'm still breaking this baby in but so far I really like it!


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## decibelle (Feb 17, 2011)

The xover I use for competition is 45 @ 24db for the sub and highpassed the midbass at 63 @ 24.


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## stryke23x (Jun 22, 2007)

millerlyte said:


> *A
> Summary:
> 
> The sub can handle anything you throw at it, from Brad Paisley’s I Wish You’d Stay, to the extreme lows of an organ, to fast-paced, hard-hitting dubstep and everything in between. The kick drum in Alice in Chains’ No Excuses will hit you so hard it is painful. The sub always moves with authority. In Metallica’s One, the double-bass towards the final half of the song are clear and extremely distinguishable – you can hear and feel each full, individual strike of the drum in perfect time. Limit to Your Love by James Blake begins abruptly with absurdly quick pulsating bass, which the SBP keeps up with perfectly. When the pulsating stops on a dime, so does the sub. This song is a magnificent test for any subwoofer, and the sub passes it with flying colors.
> ...


*


Thanks for the great review Ally. I did want to note that IB woofers are back in production now. The IB(xx)AU series will be up on the online store soon. Otherwise people can always email about them. I currently have about 20 motors built and ready to go as orders come in. 

One of the biggest things I hear all the time is how quickly transients can be played with the woofers. Most any woofer can loudly play a long drawn out tone at high levels. It is when a woofer is asked to stop and start quickly that most have trouble. This is a function of the motor and the control that it has over the VC. 

The main issue is flux modulation. As the VC is energized it becomes and electromagnet. As this electromagnet moves through the permanent magnetic field, it pushes it around, or "modulates" it. A good way to envision the effects is with a magnet near an old tv or computer monitor. As you move the magnet you can see the images move, change colors, etc. The VC has similar effect on the magnetic field in the motor of the woofer every time it moves back and forth. The more power input, the more significant effect which is why efficiency is important. 

The VC is trying to push against the permanent magnetic field, but that field is moving. Imagine trying to push off of a solid wall vs pushing off of a wall with a sponge on it. The solid wall lets you push with full force instantly. The sponge first has to compress until you reach the solid wall, then when you push off the sponge will expand and change the rate at which you push off. The modulated flux field is very similar. It is very apparent when the flux field first has to settle before the VC itself completely stops moving. There is just no real control over the VC by the motor.

Klippel has a chart stating the various types of distortions and their causes. You can see that flux modulation has effects in both the sound pressure and current. It creates harmonic distortion not only in the audible sound, but even distorts the impedance curve and amount of current being applied to the woofer. What you end up with is a VC that isn't getting the right amount of current in a magnetic field that is unable to push the VC properly. The flux modulation is the most significant factor in distortion and "provides unique symptoms which are sufficient for the identification of the nonlinearity" meaning they are measurable and audible results. This is the primary factor in odd order harmonic distortions. The odd order are much more audible than even order.










To get rid of this issue we need to short all the eddy currents coming from the VC that move the magnetic field around. This will keep the flux field from moving and as a result get rid of the distortions. We do the same thing that is done in transformers to lower inductance. The full copper sleeve on the pole shorts any currents before they are able to move the flux field around. It results in a huge difference in harmonic distortion across the board. It also is very significant in how quickly transients can be handled. Listening to bass guitar solos where notes are quickly plucked and start/stop very fast is very telling. There is a short passage at the beginning of Duende by Black Light Syndrome I use to show this often. As the notes are played quickly with most woofers you will only hear a change of tone. With woofers with proper shorting rings, you can clearly hear each note start and stop. If you want to read a little more on what is done in the Lambda motors you can see the following page:

AE Speakers --- Superb Quality, Unforgettable Performance, Definitely.

John*


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## kaigoss69 (Apr 2, 2008)

millerlyte said:


> The xover I use for competition is 45 @ 24db for the sub and highpassed the midbass at 63 @ 24.


Thank you, that seems to work well for me. How do you justify the gap, does it reduce interference?


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## robert_wrath (Apr 24, 2011)

stryke23x said:


> Thanks for the great review Ally. *I did want to note that IB woofers are back in production now. The IB(xx)AU series will be up on the online store soon.  Otherwise people can always email about them. I currently have about 20 motors built and ready to go as orders come in. *
> John


Ah, Finally. This is Excellent News John!


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## subwoofery (Nov 9, 2008)

** John ** 
Thanks for the explanation about Flux modulation and all - kinda knew that looking at all the Klippel tests done on this forum... 

Would like to know what can you tell us about MMS. A strong cone with low MMS VS a strong cone with high MMS - big difference in testing and sound? 

Thank you, 
Kelvin


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## stryke23x (Jun 22, 2007)

subwoofery said:


> Would like to know what can you tell us about MMS. A strong cone with low MMS VS a strong cone with high MMS - big difference in testing and sound?


For all practical purposes, MMS is only a tool to get a given set of parameters that best fit the design. There is always talk about how MMS has a factor in how fast or slow the driver is. There is really no validity to that statement. I can take an IB15AU and measure the impulse response which shows how fast it starts and stops. I can then go and add mass to it, even a substantial amount and it will not affect the position of the impulse, only the magnitude of the pulse. Putting more power back in to get the pulse level equal to the original makes them essentially the same. It is really only an issue of level and not time delay starting or stopping. 

There are several papers out there that verify it. This one is the original from Lambda Acoustics talking about how it is inductance, not mass that affects the "speed" of a woofer.

Bl/Mms = Nonsense

The paper Adire wrote that is hosted on Stereo Integrity's site now also explains the same.

http://stereointegrity.com/docs/WooferSpeed.pdf

Often people don't really realize the amount of force the magnet can put on the coil. The magnet in a woofer has so much strength that any amount of moving mass that can never realistically be put in a woofer will have little affect on the amount of control the magnet exerts over it. You can get a small magnetic door lock that has enough strength to keep a 200lb man from even being able to even budge the door no matter how hard it is pushed or run into. Consider now the difference between 100-200grams on a woofer being controlled by the magnet vs the force that is controlled by the door magnet. 

The one thing that is a factor though in MMS is where it comes from. Adding physical mass has no effect. Adding windings to the VC to create more mass will. It is not the mass that is creating the effects though. It is because the more windings in the VC, the stronger the electromagnet becomes, and the more it can move the permanent magnetic field. This gets back to the distortion issues of inductance again. This factor is the reason why people often think that high mass woofers sound "slower" or less controlled. It isn't because they are heavier, it is because they have more inductance.


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## thehatedguy (May 4, 2007)

But werewolf on here showed the math on why mms does matter with transients. Dan was not using a standard definition of transient.


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## subwoofery (Nov 9, 2008)

thehatedguy said:


> But werewolf on here showed the math on why mms does matter with transients. Dan was not using a standard definition of transient.


Precisely the reason I asked about the main difference between low and high MMS. I've read Dan's theory about "woofer speed" and understand most of it. Just wanted to know if there was more to it... 
I guess this part is the most important: "_*The one thing that is a factor though in MMS is where it comes from. Adding physical mass has no effect. Adding windings to the VC to create more mass will. It is not the mass that is creating the effects though. *_" 

Kelvin


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## squeak9798 (Apr 20, 2005)

thehatedguy said:


> But werewolf on here showed the math on why mms does matter with transients. Dan was not using a standard definition of transient.


Dan's definition was incomplete, looking at impulse only. 

When most people ask about the effect of Mms on transient response they are usually asking if or implying that it makes the driver "slower" or "faster", which is (IMO) why John (Dan, et al) pointed that the impulse response isn't affect by mass. 

What werewolf was saying is that Mms affects Q, Fs, etc which affects the damping of the system and transient response in that regard (overshoot, ringing, etc), but not the impulse. Which is what John touched on with the very first sentence of his post.....Mms affects the parameters of the driver (and by extension transient response), but not impulse response.


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## thehatedguy (May 4, 2007)

That's more like it...and I can't/or haven't found the thread/post in which Jeff showed the math.


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## captainobvious (Mar 11, 2006)

IBcivic said:


> No doubt.
> Like everything else in this "great" economy, you have to adjust or die.


Agreed. John offers a great, very well made (in the US) product at a very competitive (and reasonable) price. You can't ask for much more than that.
If these were made by a "big" name like a JL Audio, they'd be double the price. And that's not saying that JL would be making double on the same product...they just have much more overhead and cost. By keeping a smaller, stream-lined operation, it appears John is able to offer a superior product at a lower pricepoint to us. The only downside to this model (for us)is low supply since it's a small shop and (for John) likely higher material costs to due less economy of scale benefit. Personally, I like the lower output and attention to detail. That's worth a 4-6 week waiting period in my book.

Thanks Ally for the great review. I'd like to try one of these in my install.


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## CDT FAN (Jul 25, 2012)

I have yet to install mine, so I can't make a comment of how it sounds. I do like the fact that it has a label on it with my name. It was lovingly made, just for me. You can't say that very often.  Thanks John


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## BuickGN (May 29, 2009)

One thing I would do differently (maybe) is use only one instead of two. The trunk of my Acura TL (12.5 cubes) is seemingly not large enough for the pair, causing me to have to cut 50hz quite a bit and boost the low end. Removing all carpet (adding trunk volume) has made them quick, tight, all of the above again and I'm currently using no EQ on them. Obviously I can't go without trunk carpet forever.

They do so well in the upper frequencies that even with 9" midbasses I always want to let the 15s play up higher than normal.


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## strakele (Mar 2, 2009)

Interesting. I run a pair of IB15's in my Lancer's trunk (smaller than the TL's) and there's little to no difference with the trunk open vs closed. Their response is quite different from the single SBP15 in Ally's car though. The SBP15 sounded similar to how it does in her car when we tested it in my car. It's hard to say if the difference between the single SBP15 and the dual IB15s in my car is a difference between the IB and SBP woofers or a difference in there being 1 vs 2 speakers. I'd really like to know the answer to this question.


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## captainobvious (Mar 11, 2006)

Grayson- Are yours the original IB15's? The newer IB15AE's have a lower qts (and I believe a slightly lower FS?)so if you have the older model, I could see that making a little difference.

the newer specs: 
*IB15AU-4 :*
Fs: 20.4Hz
Qms: 4.5
Vas: 387L
Cms: .4mm/N
Mms: 152g
Rms: 4.35
Xmax: 18.5mm
Sd: 825sqcm
Vd: 3.05L
Qes: .45
Re: 2.7ohm
Z: 4ohm
BL: 10.8Tm
Le: .163mH
Pe: 300W
Qts: .41
1W SPL: 90.6dB

*SBP15-4*
Fs: 21.3Hz
Qms: 5.35
Vas: 338L
Cms: .35mm/N
Mms: 152g
Xmax: 18mm
Sd: 825sqcm
Qes: .45
Re: 2.7ohm
Le: .3mH
Z: 4ohm
Bl: 11.1Tm
Qts: .41
1W SPL: 90.65dB

Here's what John had to say about them:

_The woofers have very different parameters as the applications are far different. The IB15-HT is used in a very large infinite baffle. It is designed to have an F3 point around 16Hz in this application where there is no cabin gain factored in. They have a higher Q and require a very large area for the infinite baffle chamber. They make very efficient use of Xmax in an application with adequate room in that rear chamber. 

The IB15-AU are designed to go in a vehicle and work with cabin gain. They are lower Q, have lower mass, are much more efficient, and as a result require much smaller volumes. 

The SBP15 is the upgrade to the IB15-AU. It has a larger motor and thicker top plate. This thicker top plate gives a more broad BL curve for more force and much lower distortion._


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## strakele (Mar 2, 2009)

I have the automotive version.


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## kaigoss69 (Apr 2, 2008)

My single SBP-15 seems perfectly matched for my trunk (BMW 3-series). I believe the SBP has a lower QTc than the IB, so it may make more sense to use two SBP's rather than two IB's in a small trunk.


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## t3sn4f2 (Jan 3, 2007)

http://www.diymobileaudio.com/forum/member-reviews-product-comparisons/52079-acoustic-elegance-ib15-4ohm-car-version-idmax-comparison.html

"Here is my previous setup with 3 IdMax 12s in the same IB configuration, 100hz LP so judge from there down, no EQ. A total of 3 identical 500w amps were used. The only noteworthy aplication difference is driver orientation, IDmax dirvers were facing the cabin while the AE IB15s are facing the trunk. Polarity was reversed in the IB15 case. To keep variables fixed observe the green test where seats where up and trunk was closed for fair comparison.

(AEs are the green and red, trunk open versus closed) 











*The scale MLS used here was in 5 db steps so it may look a bit mysleading. The output is identical,* governed mainly by cabin gain! Both drivers are + - 5db over the range 20hz-100hz. With EQ work I generally obtain + - 3 db which is very acceptable."


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## S.A.-K.I.D. (May 27, 2013)

Does anyone have the specs for the SBP12-8ohms or 4ohms? Emailed AE a couple times to no avail. Trying to make a comparison w/the IB12AU in regards to: Vas, Qts, mounting depth, & lbs(which may be 25lbs for sbp). Would like to stay w/one 12" sub for height & weight limit & shooting for at least twice my former linear displacement install.

I have a 12w6v2 that I plan to IB install thru ski pass w/mag facing cabin in a 15+ cu ft' trunk & have been debating other choices. Knowing if I go AE it may be some time before I receive them. 

Also, could someone please model the first gen 10w6 for me? It was in a 19 to 21 liter sealed fiberglass enclosure, parallel for 3ohms wired to a A300.2 . Figured the Qtc was around .8 or higher in the back corner of a 4dr s10 blazer. Since I truly enjoyed that sound, I may need to use a slightly higher Q or higher Vas in my IB install to capture a similar sound as the old w6(1st gen). 

Thanks for any info.


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## robert_wrath (Apr 24, 2011)

AE Speakers --- Superb Quality, Unforgettable Performance, Definitely.

Automotive IB IB12AU
The IB12AU was designed as the ultimate infinite baffle driver for automotive use. It was designed to be the most accurate, lowest distortion driver ever to go in a vehicle. The high Xmax allows the IB12AU to move large amounts of air very cleanly. Due to the high efficiency, very little power is needed for these woofers to get loud. The optimal Fs and Qts are designed to work with the cabin gain in an automotive environment. The extended bandwidth assures optimal upper/midbass output that is lacking in most other woofers. 

The full copper shorting ring on the pole addresses two of the greatest causes for distortion in loudspeakers that are neglected in most other drivers. This copper sleeve provides extremely low and linear inductance while aiding in heat dissipation from the voice coil. The IB12AU's extremely low inductance allows it to play flat to over 500hz assuring no driver rolloff at the top end and crossover more easily to the mid drivers. 

Quite simply, no other automotive infinite baffle driver can match the high levels of clean,low distortion output of the IB12AU.

Explore the Lambda 001 Motor design



*IB12AU 8ohm*
Fs: 24Hz
Qms: 3.8
Vas: 160L
Cms: .4mm/N
Mms: 110g
Rms: 4.35kg/s
Xmax: 18mm
Xmech: 22mm
Sd: 530sqcm
Vd: 1.9L (p-p)
Qes: .59
Re: 5.5ohm
Le: .33mH
Z: 8ohm
Bl: 12.5Tm
Pe: 500W
Qts: .51
1WSPL: 88dB
2.83V: 89.3dB



*IB12AU 4ohm*
Fs: 24Hz
Qms: 3.8
Vas: 160L
Cms: .4mm/N
Mms: 110g
Rms: 4.35kg/s
Xmax: 18mm
Xmech: 22mm
Sd: 530sqcm
Vd: 1.9L (p-p)
Qes: .59
Re: 2.7ohm
Le: .16mH
Z: 4ohm
Bl: 8.75Tm
Pe: 500W
Qts: .51
1WSPL: 88dB
2.83V: 92.5dB


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## BuickGN (May 29, 2009)

S.A.-K.I.D. said:


> Does anyone have the specs for the SBP12-8ohms or 4ohms? Emailed AE a couple times to no avail. Trying to make a comparison w/the IB12AU in regards to: Vas, Qts, mounting depth, & lbs(which may be 25lbs for sbp). Would like to stay w/one 12" sub for height & weight limit & shooting for at least twice my former linear displacement install.
> 
> I have a 12w6v2 that I plan to IB install thru ski pass w/mag facing cabin in a 15+ cu ft' trunk & have been debating other choices. Knowing if I go AE it may be some time before I receive them.
> 
> ...


If you already have the 12W6 I would go with that. They sound very, very good IB. While I really like the IB and SBP subs I can't say there's anything to be gained in sound quality over the 12W6, at least in my opinion.


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## S.A.-K.I.D. (May 27, 2013)

BuickGN said:


> If you already have the 12W6 I would go with that. They sound very, very good IB. While I really like the IB and SBP subs I can't say there's anything to be gained in sound quality over the 12W6, at least in my opinion.


Thanks for info in more ways then you know, your mad info inspired me to use the w6v2 in IB anyways.You also must have a radar for when a w6v2 is posted, your on it w/a reply most of the times I've seen. I've read damn near all your post here & under your IHC sig, always enjoyed Acura(Honda). First legend I had was a 2dr '88, then a '03 cl type s(Damn good fun. Had a 8w7 for that one, IB might have went well for that.) Now I have an 2dr legend '90 collecting mad dust in the garage. Plan on single 12" IB for that one in a 11.5+ cu ft' trunk.

I plan to use this current w6v2 in a '99 4dr grand prix first anyways, sometimes I have a habit of upgrading unused equipment. Have my eye on those w6v3, mainly because of the rubber surround finally being used, lower Vas(makes it ideal using two in IB), decent Qts, but price, weight, & depth may keep me to use only one. My old 1st gen w6 foam desingrated trying to pull it from the enclosure within a short period of ownership. Could of been excellerated from fiberglass fumes, cascade fumes, or silcone fumes from 1st enclosure. I know it was a common problem & I'm aware of your many years of use(& slight abuse when enclosure wasn't bolted down w/w6v2s). Replaced w6 w/1st gen w3(same locale, same amp, same vehicle, & fiberglass enclosure not as thick but still reused the deflex pad) & it worked but couldn't put my finger on what was missing other then: impact for upper end punch. My install of sub/s is to add depth not entertain/annoy others outside of my vehicle.

I have planned to use boston 5.5lf for midwoofers for a smaller profile kick panel enclosure, & I have some exodus anarchys for standby install. Audio Physics Nz3 A/At for midrange to highs. You stated your w6v2 IB install didn't extend to high, 75hz or so there abouts I recall was the sweet spot. I'm sure if its wired to 8ohms compared to 2ohms, inductance rises slightly, that's one reason I've considered others. Even the 15w0v2/v3 looks quite appealing from weight, depth, db/spl, vas, qts,...just height I'm not digging for my choice of install to handle 15". Other wise, It's a no brainer for me to use one 15" from ae, jl, kicker, or even the 13w3v3.


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## S.A.-K.I.D. (May 27, 2013)

robert_wrath said:


> AE Speakers --- Superb Quality, Unforgettable Performance, Definitely.
> 
> Automotive IB IB12AU
> The IB12AU was designed as the ultimate infinite baffle driver for automotive use. It was designed to be the most accurate, lowest distortion driver ever to go in a vehicle. The high Xmax allows the IB12AU to move large amounts of air very cleanly. Due to the high efficiency, very little power is needed for these woofers to get loud. The optimal Fs and Qts are designed to work with the cabin gain in an automotive environment. The extended bandwidth assures optimal upper/midbass output that is lacking in most other..
> ...


Thanks but I have those from AEs site. I'm not sure if you noticed, the SBP15 has slightly different specs then IB15AU: Vas, Qts, mounting depth, & lbs was my main interest and no specs are given for the 12 or 10 SBP thru my research, only SBP15 can dug up. Very limited pdf files given like they only want to push 15's & have you constantly email to get anywhere near purchaseing or getting any info, their site is slow to update products for order.


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## S.A.-K.I.D. (May 27, 2013)

Just to pass info on, DIYCable is going out of business & some products are discounted until every thing is gone. I order a second pair of Exodus Anarchy for $49.75 per driver but it was only on the weekends for that price.:surprised:


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## S.A.-K.I.D. (May 27, 2013)

A general observation of thoughts: It appears when dealing w/infinite baffle installs, looking at Vas, desired Qtc, & Le, play an interesting mix for desired outcome. Let alone other parameters must play into it also. If one consider an install that could be at or near Vas x4 w/reasonable Qts(.5 to.6), a fair transient response could be reached w/an average designed subwoffer. AE's IB subs appears to improve transient response thru a copper sleeve & other parameters to achieve desired outcome, so x4 Vas become less of a concern.That's how I'm understanding IB installs for auto vs home, thru my limited research.


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## Schizm (Jun 12, 2011)

A tad off topic but I had a thought about strakele's and cajunner's observations that 2 of the 15s sound different than one or seem like they want more volume. 


Any way to use the box stuffing to see if it cleans up the small things you don't like it to do? Maybe stuff a laundry bag or some other breathable sack full so it doesn't just make a huge mess?


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## captainobvious (Mar 11, 2006)

S.A.-K.I.D. said:


> A general observation of thoughts: It appears when dealing w/infinite baffle installs, looking at Vas, desired Qtc, & Le, play an interesting mix for desired outcome. Let alone other parameters must play into it also. If one consider an install that could be at or near Vas x4 w/reasonable Qts(.5 to.6), a fair transient response could be reached w/an average designed subwoffer. AE's IB subs appears to improve transient response thru a copper sleeve & other parameters to achieve desired outcome, so x4 Vas become less of a concern.That's how I'm understanding IB installs for auto vs home, thru my limited research.


I was under the impression that the copper in the motor lowers distortion, and reduces power compression. The QTS determines the shape of the rolloff and the FS shows a rolloff point. The airspace the driver "sees" will also affect response with 10X VAS meaning the driver is basically not influenced by the airspace/enclosure, and as the airspace gets smaller and smaller the low end frequency response slowly decreases and the response gets more peaky with a quicker rolloff.


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## BuickGN (May 29, 2009)

Schizm said:


> A tad off topic but I had a thought about strakele's and cajunner's observations that 2 of the 15s sound different than one or seem like they want more volume.
> 
> 
> Any way to use the box stuffing to see if it cleans up the small things you don't like it to do? Maybe stuff a laundry bag or some other breathable sack full so it doesn't just make a huge mess?


My pair of IB15s acted like they needed more airspace but adding a pair of extra large pillows behind the subs had a HUGE impact on sound quality. It doesn't seem to matter were the pillows are, if they're directly behind the subs or near the rear of the trunk, the result is about the same. The upper end detail is so much better. Instead of going boom, you hear actual instruments in the sub bass. There's plenty separation between notes. It sounds like they start and stop quicker. I think we need to look into acoustic treatments when going IB. I think my problem was the rear wave making it's way back through the cone.


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## Schizm (Jun 12, 2011)

Nice. And maybe the pillow filling is doing the 'make the volume seem bigger'? Either way its a simple solution


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## BuickGN (May 29, 2009)

I thought I would add, these are cheap pillows, probably polyfill type material inside. I've bought a lot of pillows, it's nice to have an assortment for the times my back acts up at night. I took these because they were the cheapest and biggest and the only ones I could get away with sticking in the car without getting too much grief. 

It's significantly reduced the need to adjust sub level and EQ for different songs and different generes. What sounds good on rap also sounds good on classical or rock or country. I guess it makes sense. People worry about the backwave in a sealed box, why not in IB. One thing it did was make these IB15s sound a lot more like the W6s IB. I'm only guessing but maybe a reflected backwave is more likely to get through a thin light paper cone rather than the W poly cone. With the W6 it has to get through the poly and two layers of it with an air gap in the center.


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## S.A.-K.I.D. (May 27, 2013)

captainobvious said:


> I was under the impression that the copper in the motor lowers distortion, and reduces power compression. The QTS determines the shape of the rolloff and the FS shows a rolloff point. The airspace the driver "sees" will also affect response with 10X VAS meaning the driver is basically not influenced by the airspace/enclosure, and as the airspace gets smaller and smaller the low end frequency response slowly decreases and the response gets more peaky with a quicker rolloff.


Very well written & that's how I truly overstand(meaning beyond understanding to me) it.I guess we're just splitting hairs & missing the point, enjoying the music, that's why I keep studying & building.

Experiment to find what gives one audio pleasure in a truly difficult, damn near worst environment, the automobile. I will remain enjoying the passion: building, fabrication, woodworking, upholstery, electrical, elelectronics, etc...enjoy the music.


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## S.A.-K.I.D. (May 27, 2013)

Maybe one day I will get a straight forward & accurate answer to this imposing question: AE's IB12Au specs claim 18mm xmax, while I'm given 14mm (even research 10mm) for SBP12 specs. Which is true so I can get a more meaningful linear displacement comparison? Does a person have to buy said products to do their own measurements? And I've email this question before to the appropriate company before someone suggest such.


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## IBcivic (Jan 6, 2009)

The AE's IB12Au has 18mm of excursion.


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## S.A.-K.I.D. (May 27, 2013)

IBcivic said:


> The AE's IB12Au has 18mm of excursion.


Thanks but I overstand that claim. Now the SBP has conflicting info, 10mm but stated as 14mm actual. I overstand thicker top/frnt plate w/bigger magnet. They share most of the same parts but you telling me the xmax changed as such. Ok, then surface area should be different on one. 

I am damn near done researching such simple info thats not given thru said company's site, pdf files, email contact, etc.......

Thanks for trying, IBcivic, appreciate the effort.


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## captainobvious (Mar 11, 2006)

S.A.-K.I.D. said:


> Thanks but I overstand that claim. Now the SBP has conflicting info, 10mm but stated as 14mm actual. I overstand thicker top/frnt plate w/bigger magnet. They share most of the same parts but you telling me the xmax changed as such. Ok, then surface area should be different on one.
> 
> I am damn near done researching such simple info thats not given thru said company's site, pdf files, email contact, etc.......
> 
> Thanks for trying, IBcivic, appreciate the effort.


Conflicting info from where?

The AE IB12Au is a different driver than the SBP-12. I'm not sure what you're question is or what you're really looking for. Are you trying to decide between the SBP12 and IB12AU?

The latest about the specs on the SBP12 (granted it was in 2011) is that it has 14mm of xmax. That's measured using BL and not overhang. Assume 14mm of xmax with the SBP12. Which one to use would depend on your installation.


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## S.A.-K.I.D. (May 27, 2013)

captainobvious said:


> Conflicting info from where?
> 
> The AE IB12Au is a different driver than the SBP-12. I'm not sure what you're question is or what you're really looking for. Are you trying to decide between the SBP12 and IB12AU?
> 
> The latest about the specs on the SBP12 (granted it was in 2011) is that it has 14mm of xmax. That's measured using BL and not overhang. Assume 14mm of xmax with the SBP12. Which one to use would depend on your installation.


Ok, Cap, let me clarify. Yes, I'm comparing SBP12 vs IB12AU. Figured since I started my posting on a SBP15 review, I may gather needed info.

If one looks at TD15 pdf files, its mounting depth is considered the same for the SBP15. So if the IB15AU has a different mounting depth then SBP15, then one may assume a difference between IB12AU vs SBP12(in which the TD12 has it at 6.55").

That's one minor concern of mine. Next is xmax, which you already stated and was aware. So according to what was stated, SBP12 is 14mm at bl & IB12AU is 18mm. So do both share the same mounting depth as the TD subs?

Qts & Vas is slightly different between SBP15 vs IB15AU, so can we assume again there is or maybe a difference between SBP12 vs IB12AU?

I would like to at least double the surface area & linear displacement of a former install of a single 10w6(gen 1) sealed enclosure w/one 12" in IB install in a car. A single 15 would solve both but height can't be acheived w/the desired mount locale within reason. Two 12" could work decently but I want to keep weight down more then output for now.

Its been stated that the SBP15 comes in at 25lbs & IB15Au comes in about 20lbs. Do those weight differences apply for the SBP12 & IB12AU as well? I'm aware the IB15HT were about 17/18lbs, which is cool in my opinion. Hope that is clear then before Cap, I'm aware I'm splitting hairs but what else is a barber to do. Thanks for the feedback.


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## strakele (Mar 2, 2009)

Schizm said:


> A tad off topic but I had a thought about strakele's and cajunner's observations that 2 of the 15s sound different than one or seem like they want more volume.
> 
> 
> Any way to use the box stuffing to see if it cleans up the small things you don't like it to do? Maybe stuff a laundry bag or some other breathable sack full so it doesn't just make a huge mess?


The thing is, leaving the trunk wide open doesn't make a difference in my car at all.


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## Schizm (Jun 12, 2011)

Still a cheap thing to try pillows that might break up any backwave off the bottom trunk wall when its open. Though if this was the case I'm guessing there would be SOME change with the trunk open vs closed too. 

Grab a couple pillows and toss em in. Can't hurt to try! Much! Lol


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## BuickGN (May 29, 2009)

strakele said:


> The thing is, leaving the trunk wide open doesn't make a difference in my car at all.


How many subs are you runnning?


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## thehatedguy (May 4, 2007)

No where near enough suspension to support 18mm one way.




IBcivic said:


> The AE's IB12Au has 18mm of excursion.


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## thehatedguy (May 4, 2007)

http://www.diymobileaudio.com/forum...r-specs/91158-acoustic-elegance-ib12-8-a.html

Klippel verified to not be near 18mm one way excursion.


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## BuickGN (May 29, 2009)

I think the IB12 (AU12) klippeled around 10mm one way travel suspension limited. I believe it was said this type of distortion is less offensive than BL or inductance. 

As far as suspension, it is the limiting factor, these are IB subs afterall. I don't know about the IB12 but the IB15 which I believe shares the motor and spider with the 12 will most definitely do 18mm one way and more. I don't know if it's linear but it will mechanically exceed 18mm. Unless the surround is what limits the 12, I don't see why it shouldn't have the same travel as the 15. I've hit them with 18hz test tones when I first installed them while watching them to get an idea of where to limit volume. I pushed them farther than I was comfortable and they had some serious excurion. The thing about these subs is the sound doesn't seem to change as you turn the volume up. They sound exactly the same at high output as low output. Maybe it's the inductance treatment. 

I believe going by BL, xmax was 18.5mm. 

I was never aware the SBP subs had less travel. They have more motor strength, slightly lower distortion, same cone and spider and surround as far as I know, only the motor is different. I thought xmax and xmech were the same. Maybe it's time to get John in here to clarify.


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## decibelle (Feb 17, 2011)

strakele said:


> The thing is, leaving the trunk wide open doesn't make a difference in my car at all.


And it does in mine...


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## BuickGN (May 29, 2009)

millerlyte said:


> And it does in mine...


What's the chance of you two or even just one of you throwing some pillows in there like I did? I just want to see if anyone else notices the same change. I believe one person experienced the same thing but I know you guys have everything already tuned very well.


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## decibelle (Feb 17, 2011)

I did just for funsies. Minor difference in closed trunk with no pillows and closed trunk with pillows. Not as drastic as open trunk though.


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## Schizm (Jun 12, 2011)

Pillow fight strakele when he gets home!


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## strakele (Mar 2, 2009)

BuickGN said:


> How many subs are you runnning?


2. Will try some pillows and other stuff when I go out to do some experimenting later.


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## addmd (Aug 21, 2009)

Those aren't pillows! ........... How about them bears?!?:laugh:


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## IBcivic (Jan 6, 2009)

thehatedguy said:


> No where near enough suspension to support 18mm one way.


Silly me for believing AE's advertised claims. :blush:


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## S.A.-K.I.D. (May 27, 2013)

thehatedguy said:


> http://www.diymobileaudio.com/forum...r-specs/91158-acoustic-elegance-ib12-8-a.html
> 
> Klippel verified to not be near 18mm one way excursion.


Thanks for sharing this thread, it was very enlightening & cleared most of my trivial concerns. For me, it's all for enjoying the journey to enjoying the music. Be well, be safe, & take care of ones ears.


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## BuickGN (May 29, 2009)

addmd said:


> Those aren't pillows! ........... How about them bears?!?:laugh:


I haven't seen that movie in 10 years. Now I want to see it again.


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## addmd (Aug 21, 2009)

That hotel scene was filmed near my childhood home. Big news for a small town. Steve Martin and John Candy......classic!


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## thehatedguy (May 4, 2007)

I had a 12 and 15...and even at first glance I had really serious doubts about the small spider and surround being able to support the advertised claims about excursion. And then I started thinking about the suspension on the ID Maxes I had and Audiomobile Mass 2012 I had back in the day...both of which had roughly the same throw these are claimed to have, and both had much more robust suspensions. The suspension on the 15 was smaller than the IDQ-15 I had setting next to it, and the IDQ was advertised with much less throw.

I am not saying they aren't great speakers...just the excursion claims are a bit off. Which, you will see time to time like I saw in the SDX-7s I used to have 



IBcivic said:


> Silly me for believing AE's advertised claims. :blush:


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## strakele (Mar 2, 2009)

Seems like xmax is generally rated by a mechanical property like voice coil overhang, rather than how long it is truly linear.

Not a single speaker Erin has tested on the Klippel has met the claimed xmax, that I've seen anyway.


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## BuickGN (May 29, 2009)

thehatedguy said:


> I had a 12 and 15...and even at first glance I had really serious doubts about the small spider and surround being able to support the advertised claims about excursion. And then I started thinking about the suspension on the ID Maxes I had and Audiomobile Mass 2012 I had back in the day...both of which had roughly the same throw these are claimed to have, and both had much more robust suspensions. The suspension on the 15 was smaller than the IDQ-15 I had setting next to it, and the IDQ was advertised with much less throw.
> 
> I am not saying they aren't great speakers...just the excursion claims are a bit off. Which, you will see time to time like I saw in the SDX-7s I used to have


What I get out of it is if xmax were based off of BL the claimed xmax would be spot on. The suspension limits it no doubt but it kind of has to in an IB specific sub unless it uses technology like JBL uses. 

What I want to clarify is even if it isn't linear, these subs will most definitely travel more than 18mm. I've had them to roughly 2" peak to peak travel back when I had them on 1,000w and they sounded fine. Don't most people think that distortion from suspension compliance is the least offensive? Meaning that BL and LE distortion are still very, very low still when it hits the 10.8mm xmax based on suspension? Or said another way, the sub is not going to just give up after 10mm of throw, it's still going to sound very nice way past that excursion level.

Not totally irrelevant is the higher than average cone area for a 15" sub so it does not have to move as far for the same SPL. Even when I'm not caring that much for SQ and I just want the subs to drown everything out, excursion is always surprisingly low when I take a peek at the subs. That's the nice thing about a pair of 15s with lots of cone area, they don't _have_ to move much to generate decent output. Even at 10mm they're seriously loud. Usually with mild to moderate listening volumes these subs rarely move more than a couple mm. Most of the time I can't see them move.

I agree that the spider is probably holding it back. I would guess it's the spider and not the surround anyway in which case it might possibly change xmax between the 12 and 15. Looking at my 12W6 it has a spider that's at least as large as the cone. Same with the 13W7. I wish there was a way to use a really great suspension on these subs. I'll still probably end up with a pair of 13W7s eventually. The have almost as much cone area as a low cone area 15 and with over 4" of peak to peak mechanical throw they will have more output.


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## subwoofery (Nov 9, 2008)

strakele said:


> Seems like xmax is generally rated by a mechanical property like voice coil overhang, rather than how long it is truly linear.
> 
> Not a single speaker Erin has tested on the Klippel has met the claimed xmax, that I've seen anyway.


Other than PA drivers, I've only seen 3 drivers meet or exceed their rated Xmax: 
JBL Gti660 mid (Erin) - rated as 5.36mm and tested to have 7.4mm 
Scan 18WU mid (Erin) - rated as 9.00mm and tested to have 9.1mm 
Dayton Ultimax (VC Mag) - rated as 19.00mm and tested to have 21.9mm 

Kelvin


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## BuickGN (May 29, 2009)

Add the Dynaudio 430 to that list. 3.5mm klippel verified. 2.45mm manufacturers claim.


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## subwoofery (Nov 9, 2008)

BuickGN said:


> Add the Dynaudio 430 to that list. 3.5mm klippel verified. 2.45mm manufacturers claim.


More like 2.6mm (BL limited) Klippel tested but yeah, it's now on the list  

Kelvin


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## BuickGN (May 29, 2009)

subwoofery said:


> More like 2.6mm (BL limited) Klippel tested but yeah, it's now on the list
> 
> Kelvin


Two different 430s were tested at separate times. The first one was mine shipped brand new from Dyn to Erin. He saw my speakers before I did. They had zero play time and that was the one with 2.6mm xmax. 

Later Erin used one of Jerry's well broken in 430s and that is the one with 3.5mm xmax. Some people debate the importance of break-in but I put more weight on the broken in one especially knowing how consistent Dyn is in their specs and build.


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## subwoofery (Nov 9, 2008)

BuickGN said:


> Two different 430s were tested at separate times. The first one was mine shipped brand new from Dyn to Erin. He saw my speakers before I did. They had zero play time and that was the one with 2.6mm xmax.
> 
> Later Erin used one of Jerry's well broken in 430s and that is the one with 3.5mm xmax. Some people debate the importance of break-in but I put more weight on the broken in one especially knowing how consistent Dyn is in their specs and build.


Totally correct. 

Kelvin


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## thehatedguy (May 4, 2007)

I thought the v3 IDQ-10 met it's advertised claims...and it has a suspension much larger and roubst than the AE for the same amount of throw.

The Dayton Reference 12 tested here met it's claims of 14mm. I have the 15, and it too has a much larger suspension than the AE 15 I used to have had.


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## strakele (Mar 2, 2009)

To bring this slightly more back on topic.. ignore what I said about the pair of IB15s sounding totally different in my car than the single SBP15 in Ally's. I had the freaking subsonic filter on the amp up which is why I thought mine were lacking in the low lows. It's all good now.

SBP15 is an outstanding sounding sub regardless.


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## thehatedguy (May 4, 2007)

I bet it is...was my first choice, just didn't have the funds for it.


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## captainobvious (Mar 11, 2006)

One may be making its way into my hatch too (sitting in its box still in the closet)...That is, if I dont drop an 18 in there instead


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## BuickGN (May 29, 2009)

I guess this kind of belongs here since we talked about the pillows and other potential acoustic treatments in the trunk.

I just finished redoing my amp setup. I had an HD600/4 and a 900/5 under the driver and passenger seats. I replaced the 900/5 with another 600/4 and installed my oooooold Infinity Digital 300 in the trunk for sub duty. Essentially doubling power on my midbass and subs and more headroom for the tweeters and mids. This old amp seems to have a non defeatable subsonic filter but that's not important now.

With these changes I expected to have to level match a bit, obviously. Once I got it up and running the subs sounded terrible. I checked the lowpass because it sounded like there was a lot of 60-100+hz material getting through. It sounded awful. The highpass was still 50hz/12db just like before. To get it to sound halfway decent I had to bump up the slope and even then it didn't have the same quickness and tightness it had before, it sounded sloppy.

I was about to start playing with EQ thinking the amp had some sort of internal EQ making it sound like this until I saw the pillows sitting on the garage floor. I had forgotten to put them back in. So I put them back in thinking there's no way they're going to make the kind of difference I need to sound decent again. But to my surprise it was a night and day difference, back to how it was before the amp swap and before the pillows were removed. 

I don't remember it making this much of a difference the first time when I added the pillows but I noticed a large difference when the pillows were forgotten. 

I know this isn't scientific but I'm still surprised how much of a difference pillows can make and I'm guessing it's the backwave reflection making it's way back through the cone.


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## subwoofery (Nov 9, 2008)

Standing waves... 

Kelvin


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## thehatedguy (May 4, 2007)

I don't think pillows would do much for standing waves in the subbass.


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## subwoofery (Nov 9, 2008)

thehatedguy said:


> I don't think pillows would do much for standing waves in the subbass.


:shrugs: 

Kelvin


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## thehatedguy (May 4, 2007)

I'm not saying it wouldn't...or would.


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## BuickGN (May 29, 2009)

The most noticeable improvement is in the upper sub frequencies. The lower bass does sound richer and possibly louder but that could be from the upper bass sounding better and a lot of "noise" eliminated. It's a huuuuge difference.


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## fish (Jun 30, 2007)

BuickGN said:


> The most noticeable improvement is in the upper sub frequencies. The lower bass does sound richer and possibly louder but that could be from the upper bass sounding better and a lot of "noise" eliminated. It's a huuuuge difference.


You have me curious enough to go to Walmart & buy a couple pillows to check this out.  Hope I have as good as results as you've had. I will report back.

Actually, I think I'll put a couple towards the rear like you mentioned, & stuff a few smaller ones into the void areas above the rear tire wells.


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## BuickGN (May 29, 2009)

fish said:


> You have me curious enough to go to Walmart & buy a couple pillows to check this out.  Hope I have as good as results as you've had. I will report back.
> 
> Actually, I think I'll put a couple towards the rear like you mentioned, & stuff a few smaller ones into the void areas above the rear tire wells.


Looking forward to your results. For what its worth I have the pillows right behind the subs.


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## fish (Jun 30, 2007)

fish said:


> You have me curious enough to go to Walmart & buy a couple pillows to check this out.  Hope I have as good as results as you've had. I will report back.
> 
> Actually, I think I'll put a couple towards the rear like you mentioned, & stuff a few smaller ones into the void areas above the rear tire wells.


I just happened to have to buy a couple Queen sized pillows while on vacation a few weeks ago, & left them in my trunk after I got back. I did notice (no measurements taken) a very slight boost in the very low end (liked), but they also sounded too punchy in the upper bass frequencies (didn't like) with a 50hz 24db/octave low-pass. These don't need any help playing up above there, so I took them out for now.

I also tried them directly in front of the cones & back by the taillights... preferred further away by the taillights.


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## Schizm (Jun 12, 2011)

Thought about changing the xover point a tad or giving it a steeper slope to see if it smoothes out the upper freqs of your sub at all? Just to test that is lol


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## fish (Jun 30, 2007)

Schizm said:


> Thought about changing the xover point a tad or giving it a steeper slope to see if it smoothes out the upper freqs of your sub at all? Just to test that is lol


Oh yeah, I've tried just about everything imaginable with the crossover on those subs prior to tossing in a couple pillows.


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## Schizm (Jun 12, 2011)

Let us know if you like it with changes or if its too much at the higher end still


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## bradsworth (Jul 3, 2013)

Its strange (to me) that pillows would have such a profound effect considering the wavelengths of the frequencies involved. I'm truly curious about the physics involved here...


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## Schizm (Jun 12, 2011)

bradsworth said:


> Its strange (to me) that pillows would have such a profound effect considering the wavelengths of the frequencies involved. I'm truly curious about the physics involved here...


I forget what the physics involved is called, but the principle is that as the air in the box compressed, it is heated and becomes 'sticky' and doesn't have the same flow. 

This may not be the exact process so if I'm off hopefully someone can succinctly explain it better. (there is one big thread at least on this and polyfill). 

Anyhow it has been found that polyfill stuffing in a volume of air acts to reduce this effect Anson effect makes the box seem like it has a bigger volume than it really does. So in IB configuration the attempt is to have infinite volume on one side (or both?). Trunks however have defined volume (unless its cut to vent bnear the sub) thus adding pillows with polyfill make the subs 'think' the trunk has more volume


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## rockin (Sep 13, 2012)

addmd said:


> Those aren't pillows! ........... How about them bears?!?:laugh:


OMG dude. You just made me spit tea all over my laptop - years after writing that.


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