I have a couple 12's in Q-Logic boxes.
They sound great, but the speakers aren't getting the air space they require.
The boxes are big which requires the seat to be pushed forward 2-3 notches
from all the way back. This moves you closer to the steering wheel. Too uncomfortable for most. When I get around to redoing the door speakers and maybe getting kick panels I am probably going to sell these boxes and get something smaller (10's) so I can get the seat pushed back more. I used to 10's behind the seat and the bass wasn't enough. I went to the 12's and I was happy. Now I want the space back and will settle for some 10's.
The amp pictures show how you can mount smaller amps under the seats.
There are dips under the seat that allow you to mount the amps there so
they are not touching the bottom of the seat. Before I had an amp about
twices as long as the Sony, without any problems.
Whether you buy or build your own box I suggest you put the seat where you
want it then take the measurements to determine the largest box/speaker
setup you can fit in your space. Then go shopping. If you spend the money
and get a really nice amp and subs you can get incredible sound from a small
setup. You just have to pay more for quality.
BTW I got that Sony Amp at Circuit City on close out.
It was $199.99, but on close out I got it for $70.00.
It was NIB, never opened. They had (4) of them.
Its been a great amp, very dependable and decent power.
