Here is the TEMPORARY setup:

04 Audi S4

Deck: stock, low signal outputs converted to RCA with Soundgate LOC.22

Highs: stock components, 2ohm each

Subs: (2) Crystal CPE 8" in rear deck, infinite baffle, 8 ohm woofers

Amps: (2) Sony XM2252HX. One is on the highs, high current mode @ 1ohm/channel. One is on the subs, high current mode @ 4ohm bridged

My question is, the subs bottom out real bad...worse than my stock 8 and at less amount of volume. I still need to seal up a major leak from the trunk to the cabin, which I will be taking care of tomorrow but that should only fix the volume portion. Considering they are just 8's, should I just run the built in amplifier high pass filter on them at 50hz since I don't have a subsonic filter? I would think that with my particular setup that a subsonic filter would be too low anyways. I am also tapping in a JBL GTE422 22 band eq, so I'm thinking that with such a high pass filter on the subs that I might be able to compensate by tuning in a little more bass around the 40hz region and overcome the crossover a bit. Could the bottoming be from not having a bumped back magnet? I fully understand that I'm overpowering a woofer, along with using a woofer that is out of it's context...I just want to get a good idea of what I have to work with before I start dropping money on a sub. Hell, I might even end up happy with what I have if I can get it setup right...or I might just be at all losses. Does anybody know if Fi is going to make an IB3 in 10"? I cant stuff the 12" in the rear deck, and a good infinite baffle woofer that can take some power is hard as hell to find!

Anybody know where I can get a Crystal CMPx2 voicecoil repaired as well?

Edited October 10, 201014 yr by S4 Matt

When you run IB you lose a great amount of mechanical power handling, you have the SSF at 50? What slope is that at? What frequencies do they bottom out at?

It shouldn't take a ton of power in most IB alignments to get full excursion out of the drivers, especially down low.

Could you post the T/S parameters of those drivers? I wonder if they are truly intended for IB. Sometimes a manufacturer will say a driver is IB capable when it is not truly optimized for this (sometimes the suspention is just way to compliant, even though the Q is right to give decent response without a box)....

Is the volume output adequate, or is it lacking in your opinion?

Edited October 10, 201014 yr by 95Honda

Expecting output and running 8's IB won't really jive either. Cone area is your friend in that alignment.

Sure you can stuff a 12 in the rear deck..you just make a manifold to hang one in there and 'port' it via a hole into the cabin.

We're not going to make IB10's, as the parameters for them are waaaaaaaaaaaaaay off.

12's is as small as they'll go.

Sure you can stuff a 12 in the rear deck..you just make a manifold to hang one in there and 'port' it via a hole into the cabin.

IIRC from his other thread, he was not wanting to obstruct the path at the front of the trunk due to his fold down seats.

That said, he could probably use the same idea and build a manifold to hold a pair of 8's or 10's on each side, not obstruct the fold down seats, and double to quadruple his displacement at the same time.

Wow, a lot to reply to lol

Duran:

No sub sonic filter right now, nor does any of my equipment have a subsonic filter. Currently I'm just using the low pass crossover on the amp, but I'm thinking I can switch it over to high pass and set it at the lowest high pass setting (50hz) and then eq in more 30 and 40hz. Slope specs are not posted for the amp, although I would have to venture to say that it is probably a 12db slope at the most. I don't have a meter or spectrum analyzer to figure out what frequencies they are smacking at, but to an educated ear I would have to say in the 30-40hz region, I will break out the old bass mechaniq cd and figure it out later after I fix some leaks.

95Honda:

T/S parameters are almost non existent to find now since Crystal died all I can find are parameters for the last year they made woofers...so I'm S.O.L. on that one. I should have printed them out about 10 years :/

It is certainly lacking, if the stock BOSE IB 8"sub with stock 25(?)watt amp was louder than the two 8's, then there is undoubtedly an issue. A lot of the output issue right now is a fat leak into the cabin. Funny thing is, my g/f said she heard me all the way down the street coming home the other day. I thought she meant my exhaust, but she said it was the stereo. I stepped out of the car, and BAM, I have bass...more bass than what I have inside of the car. Clearly my back wave is canceling the front wave inside of the car. On the bright side, that could be a two-fold situation. If I seal it up better, I may at that point need to lower my amp gain...thus reducing the power to the subs...thus reducing my voice coil from bottoming so much.

///M5:

Fully understandable, I just want to get a good handle on an IB setup before I drop the coin on buying some IB subs. If in the end I'm not so confident about it, then I'm stuck building a box. I would rather be stuck building a box than stuck w/ some subs I'm not going to use. It's better to move forward instead of backwards

NDMstng65:

Well that's a shame, and if you don't mind me asking but what made them so far off? Granted I'm no woofer engineer, but curiosity does have me wondering...especially since there isn't a huge difference between 10's and 12's in MOST applications. I understand the whole manifold thing, but the goal here is to not have the added weight of a box, as well as still be able to drop down my rear seats. I never know when I'm going to need to pick up some lumber lol. Although, if the IB setup is a complete fail then I'm saying fuqit and building a fatass box that will probably never come out of that trunk lol. I figured I have about 8 cubic feet to work with in the end if I need to...as well as some 8" opening in my deck lid to direct port with hahahaha. Any suggestions on which sub works good in a 4th order bandpass?

Gotcha..

You could easily make a 12 bolt on and hang down into the trunk area without obstructing the ski hole much at all..

Gotcha..

You could easily make a 12 bolt on and hang down into the trunk area without obstructing the ski hole much at all..

Agreed, I will take a pic in a few minutes and upload it to show what I have going so far. The magnet hangs down a bit, and it is fully acceptable as of this moment. One sub hangs lower than the other, and you will see why when I put the pics up...my rear deck had some odd discrepancies to work with. Keep in mind, it is completely temporary, so don't laugh TOO hard at how ghetto it looks lol

Edited October 10, 201014 yr by S4 Matt

Top View

Bottom View

Magnet Hang, 2 3/4". 3/4" plywood means 3 1/2" mounting depth. Fi 12's are 6 1/2" inches, so they would hang another 3 inches lower. I should make a 3" piece of wood and tape it to the back of the magnet to see how I like it

Gap between rear seat and rear deck lid, approximately 1/2". Once the rear deck lid is reinstalled, it will only take up about 1/4", so I need to make a ghost panel to seal it up. This is where I'm losing all of my output volume.

Edited October 10, 201014 yr by S4 Matt

Can't tell, are those completely sealed off from the cabin? (back side from front)

Also, was the stock 8" in IB?

Can't tell, are those completely sealed off from the cabin? (back side from front)

They are on their way to be. The last picture shows the 1/2" x 40" gap between the rear seat and the rear deck lid. I just finished reinstalling the rear deck panel, so now it is down to about 1/4". It made a significant difference, and later on I'm going to home depot to pick up a piece of 1/4" hardboard. With carpet, that should make up the rest of the gap. Whatever gap is left over I can just get some 1/4" tall foam strip, the type with the adhesive on the back and that should polish it off if needed. I also turned the high pass crossover on (50hz), turned up the bass eq on the amp (40hz center), and it sounded ten times better...minus the fact that I'm getting vocals through the subs, which might be leading me to my NEW issue. Ever since I turned the high pass crossover on, my amp goes into overcurrent mode at loud volumes. Doesn't make sense considering the amp is 2 ohm mono stable. I found out that my subs were in fact 4 ohms, and I had them parallel which would be fine for that amp. I then wired them series so that the amp saw 8 ohms, which is beyond safe, and the amp is still going into overcurrent at high volumes. Checked both subs, and they are both sitting at 3.9 ohms, and the final load was 7.8 ohms that the amp saw. Shouldn't be an issue. The only thing I can think of here is that the impedance is dropping too low when the sub is playing vocals, so I'm in the process of tapping in a PAC inline low pass crossover. Once again, everything is temporary...just getting my feet wet with this car so that I can get everything setup correctly the second time around

Also, was the stock 8" in IB?

Absolutely, and I would be embarrassed to even use it as a paper weight

Also, was the stock 8" in IB?

Btw, I want to make babies with your avatar...sweet jesus she is a 10

Also, was the stock 8" in IB?

Absolutely, and I would be embarrassed to even use it as a paper weight

Well, that leads me to believe that the Crystal 8's aren't made for IB.

Also, was the stock 8" in IB?

Btw, I want to make babies with your avatar...sweet jesus she is a 10

Thank you, I wish I knew her name!

Also, was the stock 8" in IB?

Absolutely, and I would be embarrassed to even use it as a paper weight

Well, that leads me to believe that the Crystal 8's aren't made for IB.

Also, was the stock 8" in IB?

Btw, I want to make babies with your avatar...sweet jesus she is a 10

Thank you, I wish I knew her name!

Correct, but technically you can use any sub within certain parameters, the main one of concern from what I understand is the vas...and I highly doubt that both of my 8's have too high of a vas to use my trunk. I understand certain subs are more suited for IB to begin with. Technically I have a huge leaky sealed box and not a true infinite baffle setup. I'm gonna make this SOB work!!

Looks like my low level signal might be a little too hot, and now that I think about it...I had to increase the sensitivity on one of my channels off of the LOC.22, time for more troubleshooting

Edited October 10, 201014 yr by S4 Matt

Exactly.

OK, just finished up for today....

Good: Bass output isn't half bad, but it barely keeps up with the highs...certainly to be expected. The eq really helped. Turns out my eq had a subsonic filter

Bad: Subs are undoubtedly at their mechanical limit, and my amp is smacking the crap out of them. One of the 8's sounds like it just might be on it's way out now too. Highs still sound cheap, but to be expected as well.

Uglyyyy: Something happened to my eq within the last few years...it picks up an ungodly amount of engine noise. Everything from the engine, to the brake lights. Hoping a power filter will kill it, but I'm guessing that something crapped out internally.

Consensus?

Robot Underground Gonzo highs are needed

Two Fi IB3 12's are gonna get stuffed in, whether my car likes it or not!

Find a new eq, and I'm still tossing up the idea of a headunit...I just dont know how happy I will be with losing some of the features.

Get another Sony XM-2252HX amp. Onebadmonte has one, but hopefully it's not gone by the time I can scrounge some money up.

Fried the 8's on my way to work yesterday hahahahahaha. dropped in a dual 10 box with some orion xtr pro's.

Find a new eq,.... ...I just dont know how happy I will be with losing some of the features.

What features do you need in an eq?

OK, just finished up for today....

Good: Bass output isn't half bad, but it barely keeps up with the highs...certainly to be expected. The eq really helped. Turns out my eq had a subsonic filter

Bad: Subs are undoubtedly at their mechanical limit, and my amp is smacking the crap out of them. One of the 8's sounds like it just might be on it's way out now too. Highs still sound cheap, but to be expected as well.

Uglyyyy: Something happened to my eq within the last few years...it picks up an ungodly amount of engine noise. Everything from the engine, to the brake lights. Hoping a power filter will kill it, but I'm guessing that something crapped out internally.

Consensus?

Robot Underground Gonzo highs are needed

Two Fi IB3 12's are gonna get stuffed in, whether my car likes it or not!

Find a new eq, and I'm still tossing up the idea of a headunit...I just dont know how happy I will be with losing some of the features.

Get another Sony XM-2252HX amp. Onebadmonte has one, but hopefully it's not gone by the time I can scrounge some money up.

Fixed for your good will.

Damn, Aaron beat me to it.

Damn, Aaron beat me to it.