Car Stereos: Volume dimms, rca cable, heavy gauge

Question
Hi, I have so far installed 3 amps into my truck, one for the door speakers and two monoblocks, one for each sub. Heres the problem. I connect the RCA cable to the one monoblock , the Bass is incredible, it tries to tear the vehicle apart, i do the same to the second amp, same result. However when I connect both together the bass is reduced to nearly nothing and the subs sound a bit like "mids" (I can hear nearly no bass). When i unplug either amp, the bass returns. I really want both to work if only just because "i can". Hope I am being clear enough? any ideas? thanks. Sargon.

Answer
Sargon,
Depending on how many watts you are pushing, there may be a couple of problems.  First, There may be one sub wired opposite the other.  If the wires ares turned around on one sub, they will both sound great independently, but when hooked up at the same time, they cancel each other out.  Try reversing the wires on one of your subs.  Second, if the subs are in the same box, they can cancel out each other's power.  Be sure each has it's own box.  If you are pushing a lot of power, you may be not getting enough juice to the sub amps.  Be sure they each have their own heavy gauge power wire directly to a power manifold that is less than a foot from the battery.  If the lights are dimming with both amps going, then you may need to upgrade the charging system and battery.  Usually, the power issue is only if you are using a ton of power, and usually, it is not as dramatic a drop as you are explaining.  I think the polarity should fix your problem.  Hope this helps, Scott