I'm posting, to learn more about, or figure out what I've got going on. First, this is a '92 Dodge Stealth R/T-TT...BUT, I'm trying to apply what worked for me in my previous F-bodies, to this car. So far, it's not working...

I made a 1" thick, plywood baffle board, to replace the spare tire/tool cover fiber board. I used two 12" JL audio "Free air" or infinite baffle subs (IB4's).

The baffle board has a a "lip" in the front that is also 1" wood to sort of close off that "space" that would other wise exist if I didn't put the lip there acting like a non engineered port. Then I bought some dense foam gasket material and sealed up the entire perimeter of the baffle board to reduce "leakage" of sound pressure. Lastly, the subs are powered by a Soundstream Reference 500 amp, bridged and wired to the subs in parallel.

The upshot? Eh. There is certainly no shortage of power, and noise...but the bass isn't DEEP or PUNCHY. There is too much "upper/mid" bass -too "hummmy/boomy", and not enough of the good stuff. In an effort to improve the performance, I tried stuffing the air space w/stuffing. That made no audible improvement. It's almost just like, as if I had one of the subs hooked up backward, so it's fighting the other...but I don't.

I had a similar set up (1" board, carpeted, 2-12" JL IB subs, Soundstream 300 SX amp) in my 3rd gen Trans Am, and it POUNDED. What is missing in the equation here, compared to what I had going on in the TA? I also I had an '86 Camaro that had pretty much the same set up (different brands of parts) but the P.O. had installed two shitty woofers. I replaced them w/some off-the-shelf, MTX 12" subs....and THAT thing rocked too. Hard.

This thing is NOTHING like that. I feel pretty strongly that I have a basic or fundamental problem, here. I'm thinking that my "enclosure" is too tight for the IB subs....or something. I even wonder if the amp isn't performing correctly.

FYI, I'm pulling my signal from the stock head, front speaker wires, using one of those cheesy adapter/reducers. I don't think that is "the" problem either, but I also know that it's not "ideal".

 

That's a sign of an enclosure that is too small for the woofer, free air subs are designed to be loaded in enclosures that are very large.....like the trunk of a sedan.

The way your set-up is done, you would be better off getting some small box (or even regular) woofers. Especially if it's sealed pretty good. Can you calculate your airspace and see what you have?

 

I wondered about that for sure. Thanks for reading and replying. I calculated the space roughly, (as it's a rough, odd shape to try to measure) at about 2.5 cu ft. I knew that was probably "too small" for free air woofers, but wasn't sure what the effect would be. Seems like maybe the effect is major, and not good.

If my volume calcs are accurate, then would I need woofers that are meant for 1.25 cu ft enclosures, since I have two? And does the interior surface of the enclosure matter much? Right now, as you can see from the pics, it's mostly the steel floor pan.

I REALLY want to make this work (decently) as opposed to having a box floating around in there. This car is a DD and the space in back is important.

 

It doesn't matter what the surface is as long as you can seal it as much as possible.

On something like that I would at least put some sound deadening on that metal.

if it were my set-up, I would do a fibberglass tub in the spare tire well and use the baffle as the top of the enclosure.

 

Copy. It's sealed pretty well as I went to some lenght to prevent any "leakage" as I was building it.

I think that making a fiberglass tub is a great idea....but way more work than I'm willing to do on the GF's DD. It seems like maybe I should try subs that are designed for the smaller space that I'm dealing with?

Thanks again for taking time to read post. I do appreciate that.

 

Well, I did a little "testing" last night, and found that I definitely have TWO major problems;
1. The Amp is not working correctly
2. The enclosure volume I think is the other problem.

The Amp I have, the Soundstream Reference 500 is (under)rated at 500 watts RMS, bridged, into a 2 ohm load, which is how it's set up. The "test amp" that I used last night is an Alpine 3547. It's rated at 90 watts RMS, bridged into a 2 ohm load. The "little" Apline produced subjectively 3 times more bass and volume than the Soundstream will do. That's not right. So soemthing is definitely wrong w/my amp.

BUT the sound quality was still tough to take; too much upper mid bass. I guess that I'm going to try to find some woofers that will work in a 1.5 cu ft space and see what happens.

 

too bad you don't have access to another set of speakers (not free air). This would be a good way to test your current enclosure.

Maybe a buddy or someone could loan you something to test with.

 

I know it. Here in UT, none of my friends have subs to loan....or even subs. All my friend have choochie stock Bimmers and Audis.

I'm going to see if I can get a store to let me slap some 12's in, if they sound terrible "return" them or something. Repeatedly buying the wrong parts will make this little project too expensive really quickly.