I finally got my whole system complete. I still need to do some asthetic clean up and tune the balance.

Here's my question:
How do you properly tune the crossovers threshold for subs and mains?
As I turn the sub low pass frequency higher, I begin to hear music, very quietly, coming from my sub. I had set that level just low enough where no vocals and such came through. However, I also here some bass notes that I'd like to be a little more present... They are usually the melodic bass tones from a bass guitar or a string bass. Should I be hearing any vocals in the sub?

 

it depends on what subs and speakers you are using, but here is a good rule of thumb i use when setting speakers xover points.

Subs: 80-100hz and down (usually i keep it right at 80)
Mids: 80-100hz up 5000-7500hz (the low end is to match the sub's xover point while high end just depends on the type of speaker it is)
Highs: 5000-7500hz and up

now i am assuming you just need to sett the high pass and low pass on your amps, so just do it like this: set you sub amp's Low Pass Filter (LPF) at or as close as you can tell to 80hz. Then on your other amp set the High Pass Filter (HPF) to as close to 80hz as you can. That ought to have you all set and ready to jam.

 

Yep, 80-100 sounds right. Sometimes people'll go a little higher to allow the mids to play louder, but to me 85/90hz is where I try to be.