#1
So first of all, I hope this is an okay place to post this, I couldn't find anything similar or a better place to put it. Anyways, I've been in various bands over the past few years and I've played many amps and played with many guitarists and bassists with their amps, and I've never been able to find a satisfying sound mix. Right now, I'm the only guitarist in the band, with a bassist, a drummer, and a singer. My amp is a Peavey 6505+ and the bassists amp is an Acoustic B600h.

Problems I've been noticing is that our tones don't seems to nest together very well at times. Mine might be a little too harsh and his might be a little too dull sounding. We always mess with our knobs trying to find something that works well. I'm hoping that some of you might have some starting points for where to find a good mix, what frequencies should be raised/cut on each instrument, what things to avoid, etc.

We also have problems with vocals. I leave the PA EQ with all the knobs at noon and it seems kind of muffled and distant, any ideas on how to make the vocals sit on top of the mix rather than get buried in it? Every time I touch a knob, it starts to feedback because we practice in a small garage with concrete and bare walls. That's another thing, any ideas on how to reduce microphone feedback, its killing me! I know nothing about PA systems.
Gear:
-Mesa Dual Rectifier (3 Channel) with KT88 and KT66 Tubes
-Peavey 6505+
-Roland JC120
-Ibanez Tone Blaster TBX150H
-Mesa 4x12 Straight Cab
-Marshall 1960BV
-Gibson Les Paul Custom
-Gibson Flying V
-Line 6 M13
#2
You guys should look into getting a couple eq pedals for the instruments.

As far as vocals, turn down the bass and boost the mids, and depending on the vocalist turn the highs up a bit or down a bit from 12 o'clock. And turn down the gain a bit, no need to make ears bleed during practice, that should help reduce feedback some.
#3
What guitar and bass are you running, and what effects are typically used? What type of music are you playing?

What are your amp settings? With one guitarist, your bassist might want to up his high mids to help fill that space a bit. Playing with a pick helps the mix "cut" as well. You'll want the gain to be as low as you can get it with it still having some balls while keeping the mids fairly high without it being "honky". The treble should be only as high as you can get it without it sounding like an icepick going through your ear. Again, though, these are general rules and I don't know your full rundown.

As for mic feedback: put your speakers/monitors in front of the mics (or facing away from them). Feedback is typically from the sound of the mic getting pushed through the speakers back into the mic. If it's not this, I don't know what it could be without knowing more info.
modes are a social construct
#4
I have tons of EQ pedals and racks. The problem is that I don't know what frequencies to adjust. I currently just use the amp EQ, and my 6505 has the gain at 6, the bass at 8, the mid's at 5, the treble at 7, the resonance at 7 and the presence at 9. That's as good as I can seem to get it for now. We play metal, all passive pickups, bass is a Schecter stilletto with EMG HZ's and my guitars are all custom built, but generally follow strat specs with high output passive pickups.

I think the least of the problems is my tone, it seems to be the bass isn't filling the bottom end very smoothly, and the vocals don't cut through at all. And of course my drummers cymbals destroy all of what little mix we have.
Gear:
-Mesa Dual Rectifier (3 Channel) with KT88 and KT66 Tubes
-Peavey 6505+
-Roland JC120
-Ibanez Tone Blaster TBX150H
-Mesa 4x12 Straight Cab
-Marshall 1960BV
-Gibson Les Paul Custom
-Gibson Flying V
-Line 6 M13