[MOSFET]

However, the hard bass is not there. It is a stereo sub
hook up. My new head unit did not specify a right or left channel of the
RCA jacks. This part of the system is very annoying. Everything else is
right.

OK, first of all, I am NOT a big fan of running your subwoofer in stereo.
IMHO, it is best to combine the left and right channels (so mono) before
running that into your sub-amp. Again, this may be part of your problem.

Although there has been some debate about this on this newsgroup, it is
possible that the left channel's bass may be cancelling out the right
channel's bass (and vice-versa). Now this is generally not noticable on
your typical stock stereo system (especially because you get VERY little
output below about 70 Hz on your typical stock system). But with a amp and
subwoofer system, this DOES come into play. You see, the bass recorded on
the left channel may be SLIGHTLY different than the bass recorded on the
right channel. Again, because bass is omnidirectional you open the door to
cancellation effects that MAY be reducing your bass output. My advice would
be to sum the left/right channels BEFORE they go into the sub-amp. Also
(this may have already been said), if you are running multiple subwoofers
MAKE SURE they are both wired the same way (in phase). THIS WOULD SURELY
cause a dramatic decrease in bass output (in fact, you would get little bass
out of your subwoofer at all).

You mentioned a low-pass X-over point for your subwoofer of around 320 Hz I
believe? Buddy, that is WAY too high. You want a low-pass between 50-100
Hz (depending on the rest of your system). The reason is that, ideally, you
want to be aware of the low bass, but you want to make it SEEM like it is
coming from the front. This can be done if your low-pass X-over for your
sub is set below about 80Hz because, as I've mentioned before, bass is
omnidirectional and it is difficult for your ears to identify where sounds
are coming from below that frequency. At 320 Hz, I'm sure it's VERY obvious
that sound is coming from your subwoofer.

I'm concerned that your X-over point is so high because you are trying to
compensate for problems that are occuring at lower frequencies such as the
problems I mentioned above. A phasing issue would explain all the symptoms
you have mentioned in previous posts so I would first focus on that.

Good luck,

MOSFET









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