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Discussion Starter #1 (Edited)
Over the long weekend, strakele and I fabricated our own IB wall to compare a couple of big subwoofers we had:



The first was my old subwoofer, a DB Drive K3 15D4:



It sat in a manufacturer-recommended enclosure of 1.75 cu ft. It was loud, but take a look at this graph and you can see that it actually sounded like ass.



When strakele started toying with WinISD models, he noticed the sub wanted a much larger enclosure: 32 cu ft for a qtc of .7. Then he suggested we craft our own IB wall to see if it would perform better IB, as the specs suggest.

The project became really intriguing when we modeled the K3 against his current pair of Dayton HO10s (sub setup we know to sound great already) and my soon-to-be-installed AE SBP-15 (the successor to the highly regarded AE IB15).



We modeled the sub for strakele's ~10 cu ft trunk, since there's no room in mine yet (~13 cu ft).

As modeled, the DB Drive (yellow) has a surprisingly low F3 of 25Hz compared to the F3 of 37Hz for the AE (blue). The steep roll-off (24dB/oct) of the ported Daytons (white) is evident when contrasted with the shallow roll-off (6dB/oct) of the IB models.



By the way, 15s are massive.


So, the graph clearly shows a flatter frequency response for the DB Drive. However, the AE has a much higher efficiency (+5dB) and lower inductance than the K3. Moreover, John (Acoustic Elegance) states that the SBP-15 was essentially crafted for infinite baffle - in vehicles, anyway. So this should be an interesting test.

Now for the fun stuff! We took advantage of Black Friday at Home Depot and returned to the house with our loot:



:D


Basically, these are the two contenders:



A ~15lb K3 15D4 vs. a ~25lb SBP-15. As you can plainly see, this should be quite an interesting test.
 

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So now the fun began. We picked up a 2'x4' sheet of 3/4 MDF and went to work.

First, I had to remove the enclosure for the Daytons in my trunk to see exactly what we were working with:



Using cardboard to get a template:





Then cut the face of the baffle using our new power tools:





Test fit:




Now, this project was intended to be an experiment, so I didn't want to do anything relatively permanent like using expanding foam or stuff like that to seal the baffle. Everything had to be removable. My rear deck is already completely sealed, so all that was necessary to seal was the baffle against the opening between the trunk and cabin. To do this, we picked up some 2.25" thick closed cell foam weather stripping. I cut a channel in it to seal all around the sides of the baffle:



3/4" MDF is pretty sturdy, and the K3 sub is light, but to do this right, I decided to use the remaining wood to reinforce around the mounting hole, making it 1.5" thick. This had to be done in 2 pieces:





(The small arcs on the bottom are to allow wires to pass underneath)
 

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The foam was then attached to all edges of the baffle. To secure it to the car, we used 4 (for now) metal brackets, 2 on bottom and 2 on top to hold the baffle securely and compress the foam to make a good seal. I used existing holes from securing a previous enclosure:





With the thick foam on every edge, it took both of us using all our weight to compress it and screw the baffle down.

IB experts... is this enough?
I know most people usually have a massively thick baffle and expanding foam and all kinds of stuff to really seal it. As stated, I don't want this to be permanent, so this seemed like a good way to do things. There aren't really any air leaks we can find, so this should be good to get an idea of how these subs perform, right?

Anyway, here it is mounted up:



Foam gasket on the front:



And finally, after many many hours (mostly waiting for batteries to charge) the sub mounted:







Certainly not pretty, but not what we were going for. Should be able to get a good idea of how the 2 subs perform.
 

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Discussion Starter #5
This project ended up taking us about 18 hours when it should have taken half that, simply because we had a crap battery charger.

Once everything was in, we both had a listen to the K3 from driver and passenger seat with a quick tune from the MS-8, barring the front sub at first.


I was a bit surprised to find that the cheap, $60 sub that sounded really quite awful in its old home actually sounded extremely clean (low pass @ 80 without the front sub). Cleaner than strakele's pair of Daytons, actually. No, it wasn't quite as loud, but I found that to be a good thing. Too much bass isn't my cup of tea. It was at its happiest playing real low, from 25-50hz. In SQ, it sounded good and clean.

Basically, my initial impression of the first tune was precise and clean, but on the quieter side, which was pretty much what I expected.

We haven't given it a real, full-fledged custom tune yet, nor installed my AE SBP-15 to compare it to, so reviews now are just tentative and probably not doing it nearly enough justice yet. We'll have to give it a few more test runs over the course of the next few days and see how it sounds then.
 

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This project ended up taking us about 18 hours when it should have taken half that, simply because we had a crap battery charger.
She'll attest to how much I raged about this.. but seriously. It took FOREVER. But I guess I shouldn't have expected much more from basically a freebie charger. I couldn't take it anymore and went back and got a Lithium battery and charger. The new one fully charged both batteries in like 90 minutes, whereas the smaller one couldn't charge one in 10 hours. A closer look at the specs revealed why... the small charger put out .2A, and the big new one put out 3A.. a full 15 times stronger. Completely unrelated, but... whatever.



Anyway, initial impressions of the K3 in IB... pretty much the same as millerlyte. We didn't give it a whole lot of time by itself before retuning with my front sub as well, but it did sound much cleaner than in its old box, and played very low, (single sub IB on 500W), lower than my Daytons (2 ported 10's on 1500W) . I'd like to give it more time by itself, but I think I can also safely say that I will always try to have a front sub in any future car/install that I do.

More detailed thoughts will be posted as we get more time listening, and in comparison to the Acoustic Elegance sub as well.
 

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I'm really glad you guys were able to take advantage of the deals on Friday. This is extremely interesting to me. I think you are just fine with your baffle. Very cool to hear the difference in that db sub IB vs. In a box. I'm also really looking forward to hear the review of the AE sub. Good job guys.... sounded like a great time.
 

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which version of winisd is that? mine doesn't look like that
 

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Fun project.... And my experience with car audio is to always double the time estimate ;)

Way to go- DIYMA's official "power couple".... You watch- that'll catch on :p
 

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You're going to love the AE. I guarantee you will be getting rid of your secondary sub once you hear it.
 

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Fun project.... And my experience with car audio is to always double the time estimate ;)

Way to go- DIYMA's official "power couple".... You watch- that'll catch on :p
Haha thanks Ryan!

You're going to love the AE. I guarantee you will be getting rid of your secondary sub once you hear it.
Unfortunately for me, regardless of how much I like the AE, its permanent home will be in millerlyte's car, not mine. Mine is just the test bed for now..
 

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Discussion Starter #13
You're going to love the AE. I guarantee you will be getting rid of your secondary sub once you hear it.
If you read the thread carefully, you would notice that both subs are mine, but being tested in strakele's car. I haven't got a front sub. Yet, at least. I'll probably be adding a front to my car as well, after hearing both IB and footwell.

I don't honestly know what cars you've heard with such a setup that you found so repulsive, but in strakele's car, which I hear nearly every day, the combination has really grown on me. As far as SQ and competitions, I think only a front sub would suffice. As far as staging goes, with both subs on it doesn't really take much away from everything up front. However, when you're really rockin' out on your own and there's some low low bass (sub 50Hz), the IB sub REALLY adds that extra rumble. You wouldn't know what you're missing until you hear it, but when you do, it can really make a song.

Good to hear some reassurance on the AE, though, I'm really looking forward to that.


Also, we didn't get to testing the AE sub today, but I think we'll be able to do so tomorrow or Wednesday and throw up another review of that.
 

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If you read the thread carefully, you would notice that both subs are mine, but being tested in strakele's car. I haven't got a front sub. Yet, at least. I'll probably be adding a front to my car as well, after hearing both IB and footwell.

I don't honestly know what cars you've heard with such a setup that you found so repulsive, but in strakele's car, which I hear nearly every day, the combination has really grown on me. As far as SQ and competitions, I think only a front sub would suffice. As far as staging goes, with both subs on it doesn't really take much away from everything up front. However, when you're really rockin' out on your own and there's some low low bass (sub 50Hz), the IB sub REALLY adds that extra rumble. You wouldn't know what you're missing until you hear it, but when you do, it can really make a song.

Good to hear some reassurance on the AE, though, I'm really looking forward to that.


Also, we didn't get to testing the AE sub today, but I think we'll be able to do so tomorrow or Wednesday and throw up another review of that.
The point of my last post was to point out that the AE sub will play from below 20hz to above 250hz flat making the additional/front/future sub useless from a FR point of view. For having bass up front, I don't know how much more up front it can be with the MS8. It sounds like the sub is mounted in the dash.

The SQ comp cars I've seen either have the subs in the rear or they run large drivers in the doors and no subs. I'm sure there are some out there with the subs up front but is it really worth the trouble? I'm trying to save you some work. Maybe you need better midbass drivers. Try the AE sub, let it go up to 80 or 100hz, however high you would run your future secondary sub and I doubt you will feel the need for an up front sub.

When I was getting into this stuff I tried all sorts of stuff to add to that upper sub/lower midbass range but when all was said and done, it was my midbass drivers in the doors not being able to keep up that caused my bass to sound like it's coming from the rear and without that snap and impact.

I agree with you that IB adds low end, low end that you don't know you're missing until you have it..... But with the right sub (the AE) it will play the upper frequencies just as well.
 

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Discussion Starter #15
Well, I sure am really looking forward to getting the sub in my car, especially after hearing so many raves about it. I don't have an MS-8 though, and I don't think I'll be getting that processor, so I'll have to find an alternate processor that will come close to getting it to sound like it's mounted in the dash. If I can make that happen with just a simple tune, then I suppose there isn't any need for a front sub and more money spent. But we'll see I guess.
 

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I agree with you... from a purely FR standpoint, the front sub doesn't add anything. Any decent sub setup should be able to play up to 80Hz pretty well, and anything past that is a bonus.

We played with the K3 a lot more tonight, trying lots of different things. Without front sub, low passed at 50, 63, 70, 80, and 100Hz. It sounded clean with all of these... I was surprised how good it sounded all the way up at 100. The MS-8 does do a good job of this. It sounds like most everything is up front. Seems like it works best for short notes like drums, but for sustained notes like a bass guitar, you can start to tell it's coming from the back.

The other part is tactile. Even if it SOUNDS like it's coming from up front, it FEELS like it's coming from behind. I don't really know what you can do to fix that, short of modifying the seats to be decoupled from the frame or something.

Not many SQ comp cars have subs up front because it instantly puts you in a much more advanced class, which is something most people don't want to do. But the guys who really go all out with rebuilt dashes and everything usually do subs up front, or as you said, huge drivers in the doors.

And as far as extra work, it took almost as long just to make this baffle for testing as it did to make the enclosure for my front sub. I have very capable midbass drivers (H-Audio Ebony) and miller is running Usher 8945As. I have used Boston SPZ60's, the Ushers, AR6K's, Peerless SLS6's, and now the Ebony. All are very good 6-7" midbasses, but none could come close to matching the impact from a 10" in a solid enclosure.

Regardless, she'll give the AE sub plenty of time in her own car to judge whether or not there's a need for a front sub.

I have no doubt that the AE will play clean higher than we'd ever run it, and I'm excited to give it a shot after all the great stuff I've read about it.

I do believe it will sound great. Heck, the cheap K3 sounds great. It's just when you get happy with the volume knob... you can't help but feel that the bass (that still SOUNDS like it' coming from up front) FEELS like it's coming from the back.



Anyway, as stated above, we listened to the K3 more tonight at a bunch of different crossover points, with and without (mostly without) my front sub. Clean, accurate, and low. Most of the material was our normal listening music, including tracks from AC/DC, Airbourne, Alice in Chains, Disturbed, Dream Theater, The Eagles, Evanescence, Megadeth, Metallica, and others, but also SQ demo discs from some forum members. After hearing the "slow, inaccurate" bass from the K3 in its original small sealed box, I was impressed with the accuracy on fast double bass lines.

And it really can hit the lows. My current ported enclosure is tuned pretty low to 29Hz, but the 15 definitely goes lower with more authority. It's pretty impressive.

Anyway, enough of my blabbering for now.
 

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Wow, you got one of those bad boys from John at AE! When did you order/receive it?
 

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Discussion Starter #19
I ordered it in mid July, I think, and it arrived in early September. Sounds like (no pun intended) it's gonna be worth the wait though. Considering how good and clean the cheap K3 sounds, I can't even imagine what the AE's got. Should find out soon enough :)
 

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Soon would be great, since we're coming up on 4 months. Guess I shoulda ordered them 2 weeks earlier! Knowing John builds the best speakers in the world is what keeps me and probably most of the other very patient customers going.....:worried: Can't wait to see the results!
 
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