specs:
ppi pcx2200 (200x2 watts to the fronts)
ppi pcx280 (80x2 watts to the rear)
ppi pcx2125 (125x2 bridged to 500 watts to the sub)
infinity perfect 12.1 sub
alpine cda7977

im having issues getting the sub loud enough. i read everything there is on gains and pretty much understand the concept completely..but im in a strange problem..seems like the amps for my fronts and rears are too strong?

heres the situation:
i have the gains for the fronts and the rears all the down to min. i have the gains for the sub at around 80-85%. i turned the subwoofer control on the head unit on max (15). the sub barely thumps. when i take the volume to between 19-23 thats when it begins to start thumping. 23 is about the highest the volume will go b4 the fronts distort..i mean it seems like i need the volume on the head unit to go up higher, but i cant do that without the fronts distorting and the gains on the fronts are already all the way down.

im sure all the wiring is correct
im sure the sub is in perfect working condition
the enclosure is perfect size
i know for sure the sub and amp are not doing full potential
my head unit has 4volt preouts
the input range on the amps is .2volt - 12 volt

i ran some tests...seems like the gains are on some kind of logrithmic scale? i put the volume to normal listening loudness, and as i took up the gains for the rears (had easiest access to theose controls) i barely noticed a difference until i reached the 70% mark.
so if its on a scale like that it seems like if i take the subs gains from around 85% to 90% it should make a huge difference? i just dont want to take it up that high..unless thats what u guys think i should do?

thanks

 

i played around with it and took the gains to about 95%. big difference in output. it now sounds as loud as its supposed to be. i dont hear any distortion so i guess i should be fine.

 

Fierce - I'm sure Master P ( Percy ) can shed some light on this topic from a technical standpoint but I need to keep it simple ( senior moments, U understand! ) Just think of the gains as "volume" controls. I know that most audiophiles don't like this comparison BUT it seems to be one most folks can understand. The gains are designed to allow U to balance the signal between different amp/speaker combos. The gain DOES NOT allow the amp to make more power as most of the bassheads around my hometown seem to think!! Just because it gets louder doesn't indicate more power being produced. I've had the differences between some of my gains be as great as 40% but as long as my ears ( & the RTA ) were pleased, who cares?

 

All other possibilities aside, you may be getting some phase cancellation of the two bass channels when you are summing them at the bridged sub amp. If the relative bass between the two channels has been shifted for some reason, it will partially cancel and reduce your overall output level. You might want to have a qualified shop look at the signals with a scope. (Same kinda thing when you have a dual-voice coil sub and you mistakenly hook up one of the channels backwards...no bass). Also check your polarities for all channels from the head unit all the way to the sub amp to make sure nothing is reversed +/-.