added 2nd sub , it sounds horrible?

Okay well, my system previously consisted of a single 12" L7(2006)in a 2.3 cu/ft sealed box running off a clean,high quality 800W/RMS. I ran this system for over a year & it sounded acceptable even though the enclosure wasn't to spec(too big). So this weekend I decided to reorganize/rebuild my sub system. I added a 2nd identical Kicker L7(2006 dual 4ohm)& decided to build a sealed enclosure to Kickers specs....I built the box to around .92cu/ft internal volume for each sub(after driver displacement), well within Kickers specs. So now I have a box that houses TWO 12" L7 drivers, each with their own .92cu/ft sealed chamber within. Each sub has dual 4ohm coils presently wired to a 2ohm load(parallel), each one running off their own 800RMS amp. The 1st amp gets its signal directly from the head units' RCA "Sub channel" and the 2nd amp(same RMS rating but NOT identical amp) gets its signal from the pass-through on the 1st amp. So now comes the bulls#*t, I added twice the cone area, twice the amplifier and the systems output is HORRIBLE....WAY LESS than if I would have just let the single sub in there...I have been trying to mess with the phasing, EQ's and just can not get this to sound right. Now the really crazy part is that if I just simply unhook either one of the subs & run only one it then sounds pretty good, doesn't go as low as before when I had the over-sized sealed box, but defiantly WAY better that if both drivers are running. wth!!! I have tried: Taking them down to 1ohm and running them off a single 1 ohm stable amp that I have(sounds horrible still)... Reversed the phase on either one of the subs(no difference). Changed which amp I used the "pass-through RCA's on(no difference). So needless to say I'm running out of ideas, as of now I just have one driver hooked up and the 2nd sub is just back there doing nothing. Not sure where to go from here, should I just say screw it & build a whole new box, maybe a vented one without a divider and get a 2nd IDENTICAL amp and run then in a Master/Slave configuration? I tried holding off posting this as long as I could. I like to extensively test, figure & generally just know what I'm working with before posting a bunch of dumb-ass, uneducated questions. I have scoured the internet & the posts on this forum with no success to my issues so now I come to you guys (by far the most knowledgeable on the net) for some assistance...I am open to all & any ideas. Thank you

Typically if the output increases when disabling one speaker it is a phasing issue. I would check the wiring on both subs to be make sure you don't have any coils wired backward. I would also double and then triple check that the wiring between each box and the sub amps are wired correctly.Kevin Pierson

Definitely a phasing problem. At one amp or at the terminal cup of one speaker, reverse the + and - Speaker wires. Do only one of the speakers.

What is happening to your voltage with both amps running?  Did you run another battery wire for the second amp?  Allthough I agree with the others, it sounds like a phase problem. 

Thanks ac0j (and everyone)..I figured it out, I'm having major voltage drop with the 2nd amp hooked up(actually 3rd amp including my mids/highs amp)...& being that I was trying to tune this thing with it only idling I was going the whole way down to 9.8 volts every time it tried to hit any sort of low note. In addition the fact that it was always light outside while tuning, I couldn't see my lights going almost completly dim with every bass drop!!!! hahaha, damn I gotta start paying more attention!!! Lucky my car still runs!!!hahahahahaha I'm not worried about my cables cause I have huge welding cable runs going straight from the alternator and battery posts straight to each amp, so I guess its time for a second battery &/or alternator, cause I defiantly have serious overkill as far as power cable goes. So the question is: How much more 12 volt power do I need to run this setup safely? Is there some sort of a calculator or equation I could use to figure this out? I presently have three amps that will need powered; one is 600rms 4channel used for my mids/highs...two are 800rms each powering a single 12" L7...so that's presently three amps with a total of about 2200rms watts. I would also like to "future proof" this system so in a few years when I start to get tired of it(as I always do)I can add another amp or two. So what kind of 12 volt generation setup would I need for all of this? Would a second battery & alternator be fine? Maybe just upgrade the alternator to a single high-output & add a battery or two? Maybe a combination of an alternator, battery & a cap? Not sure? Although I've been installing 12 volt audio for many years this is actually the first time I had a system that pulled volts like this, I usually just added a cap or two and called it a day for my previous builds, guess its time to step up my game a little. Thanks again to you all for bearing with me on this.

2200 watts divided by 13 volts = about 170 amps, some use different formulas, but this is what I use.

SO you need to be able to deliver about 170 amps to consistantly run your system at max volume.  PLUS you need enough additional amps to run the rest of the cars electrical system.  Adding a battery alone will not solve anything, if your altenator cant keep up with one battery, it certainly wont keep up with two batteries.  Upgrade the altenator FIRST then add a battery if you need to.  I DONT like caps, unless you use an AGM battery, then MAYBE a cap.

Perfect, Thanks for answering a question for me that has probably been answered and/or covered thousands of times...very cool of you. So there is a starter/alt rebuild shop here locally(Pittsburgh) that rebuilds and modifies alternators, I called them and they said they could "rewind" the stock alternator on my car(1996 Oldsmobile Aurora) to put out around 220 amps(almost 100amps more than stock)....I'm not sure if this would be a good choice, or if I should just go all out and build my self a dual charging system. I'm thinking about fabricating a bracket to add a second "stock" alternator to run only my amps and completely disconnect them from the cars 12 volt....then if I need more power in the future I can have either one of them rebuilt by the shop? Does this sound like a good plan?

It doesnt really matter if you use one or two altenators, what really matters is that you supply enough current to meet your demands!