Stereo installation issues...argh!

[rx7tt95]

Made another post and for some reason the title came out slightly different than I'd typed in. Very strange...anyway....

So I'm daily driving the VX again. My wife has been driving it for several years and I've been driving a Mitsubishi Evolution which has a very good Infiniti sound system with a built-in sub.

I did a bit of work on my RX7 and made it a bit closer to a full-on race car (that's street legal) and I pulled all the stereo equipment out. I had four MB Quarts, I think 6.5", two ways with built-in tweeters and an 8" Diamond Audio sub. I had been using an older Rockford 5-way amp to power everything but switched to a 4-way JL as the Rockford would overheat in the 7's rear hatch during the summer months.

I spent umpteen hours this week putting the head unit in (Eclipse w/8v preout +self amped internally) and running all the wires. Got everything hooked up last night and it sounded like absolute crap. Now I had put stock-sized JL components all around and they were just tinny sounding using the stereo's amplifier and no sub. Sounded REALLY bad to me. I thought "maybe" they were just underpowered but after hooking up the amp (probably incorrectly) it didn't sound much better.

Now the VX's interior is quite a bit larger than the 7's and maybe that's part of the problem but the difference in sound is quite dramatic. I had the stereo shop hook up the new amp and I can't remember how they integrated the sub into the system with a 4-way amp. I remember they said I wouldn't have f/r fade so maybe they just ran all four component speakers off the front speaker amp outputs and the sub off the rear (amp is bridgable on rear to 2-way). That's the way I have it hooked up now and it's ok at best but you really have to crank it to have any decent output. The stock tweeters in the a-pillar are still functional (is that an issue?) and all the JL's have built-in tweeters. Would a weak ground cause power issues and bad performance?

When they hooked up the sub, they used two single wires coming from the sub box and used a butt connector to pigtail two additional wires off of each single wire. I tried multiple configurations last night but just couldn't get it to work correctly. I figured in non-bridged mode, that each pigtail would go to two of the + sides and the other pig tail to both of the - outputs.

Also, neither amp will fit under the seat. Not even close. I'd really like to be able to slide an amp under there. Is there a decent 4-way that'll work under the seat?

My goal was to just reuse what I had and not purchase anything but I'm already purchasing a custom sub box from a list member for the rear hatch. He's offered a box with two 8" holes for subs. Would I be better off with that as opposed to say a single 12" sub? I'm not into the boomy rap thing. I have a pretty eclectic ear for music however and I'm looking for good solid, full sound.

I'll try to take pics of the amp's controls and post them later today. Might help someone trouble shoot anything I'm doing wrong...

Any help REALLY appreciated. MODS, feel free to delete the other thread. Thanks!
Michel

[etlsport]

i have 2 8's in a very well built box + a lot of dynamat in the rear of my vx and the bass sounds phenomenal

what do you mean by they sound like crap? more elaboration on that would probably help, if you are getting popping and cracking.. probably bad head unit ground, as far as i know, the VX head units dont have a true ground, they ground out through the frame of the unit, so that could be an issue

other than that.. the speaker placement isnt the best in the vx.. did you re-use the stock locations? re-using the stock tweeers along with 2 ways might give you a bit more tinny sound, but i ran mine like that for awhile with no real problems

[rx7tt95]

Yep, very tinny. And I thought about removing the stock tweeters but I wasn't sure how much it was affecting things. I managed to pull out the JL's and put the larger MB's in the driver's door. I had one bad connection coming from the head unit and fixed that. I haven't put the second pair of MB's into the rears yet, too much of a PITA to do it after work on a Friday

Once I did that, I rewired everything into the amp as a normal 4-way setup without the sub. Big improvement. Still a bit too much upper midrange but an improvement none the less. I just wired the sub inline with the fronts and didn't use a filter since the fronts can produce a wider range of sound than the smaller JL's in the rear. Using a high pass filter on those. The 8" is putting out decent bass now but doesn't rock my world.

What do you guys think? Two 8"? I was actually thinking one 12" and psycho was thinking a 10", possibly two. I feel like the one 12" will be a bit less expensive and I can get a dedicated bass amp that way too. I also think I'm just going to remove the rear seats as I carry lots of equipment back there anyway and the area behind the seats barely cuts it.

I did a bit of searching and I didn't find too many 4 channel amps that put out decent power and looked like they'd fit under the seat. The mono amps in the 400W range don't seem all that large however.

[etlsport]

i had a boss audio camp (CH-450 i think) amp under my drivers seat for awhile.. that put out 50x4.. it wasnt the best amp in the world but it did the job and sounded pretty good.. plus it fit under the seat.. ive since upgraded to a larger amp that just sits behind the drivers seat for now

like i said.. i've got 2 rockford fosgate 8's run parallel off a 300x1 @ 2ohms sub channel on my amp and they hit hard

did you try upgrading all the wiring? the stock wiring isnt going to carry a very good signal.. i ran 12ga to all my speakers when installing the new amp

[Triathlete]

If you do a search you will find a couple threads from when Biju threw a couple of "modest little" systems in his Dragon and Proton!:bwgr::bgwp:

[rx7tt95]

Ok, I've done a bit of research. Hell, I can tear down a car and put it back together, design turbocharging systems, tune just about any vehicle but I'm a novice at audio. So I found this site which is great for beginners:
http://www.bcae1.com/

I've relied on a local shop in the past but I moved about 35 miles north and haven't had time to get down there.

I found an incredible deal on an Alpine PDX-5 amp which is small enough to fit under the driver's seat and Psychos2 is building a sub box for one 12" sub.

I definitely need to do it right and upgrade the wires running to the four speakers. But I managed to get her sounding pretty decent as is after messing around with the amp's filters/crossovers and the head unit's multitude of features and adjustments. I think I could easily spend five hours tweaking it. I really need to get the sub in there before making final adjustments. Right now I just have it running parallel to the front speakers and it's probably not pushing enough wattage.

How difficult is it to get wiring through the doors? It doesn't look like I have easy access underneath the dash. As a matter of fact, I think the VX has the most tightly-packed under dash I've ever come across. There's very little room anywhere under there!

At one point I just decided to remove the rear seat and put a sub rack/amp/subs back behind the driver's seat similar to etlsport's pic above. Probably would have been the best solution. I may still remove the rear seats anyway just for space. I think I had someone sit in the back of my Evo twice in over two years of ownership.

I'm using the JL Audio 300/4v2 "Slash" amp now http://mobile.jlaudio.com/products_amps.php?amp_id=437 which unfortunately is a really nice unit. I think I paid about $500 for it and used it maybe three months total. So if anyone is interested in it...shoot me a PM. I still have the original box too. I'll also have four lightly used but mint JL Audio speakers, TR525-CXi's http://mobile.jlaudio.com/products_c...php?comp_id=60 although I may try to hook those up again with the Alpine amp and new wiring first before selling. Fit in the factory locations without modification. Also one Diamond Audio 8" sub, D3. http://www.diamondaudio.com/content/view/132/146/