LET THE PA SYSTEM DO THE WORK IT WAS DESIGNED FOR - GET SOME MICS BUT BE CAREFUL
The idea here is to lower your stage volume for a few reasons:
A) In a smaller rehearsal venue, getting too loud smears out the sound and after a few songs everything sound indistinguishable and muddy, you start reaching for more volume thinking that is the solution, but nothing needs to be turned up...EVERYTHING NEEDS TO BE TURNED DOWN. Remember you can't have EVERYTHING LOUDER THAN EVERYTHING ELSE! :lol:
B) You also want lower stage volumes so there is minimal bleed through into the vocal mics and then into the wedges. Your vocalist will thank you by singing better because he can finally hear himself...turn him up without the feedback.
So here is my suggestion.
The Bass - I'd recommend using the DI out of the back and going direct into the board. The bass player could turn his rig down a bit for a stage volume and giving him a channel at the board enables him to come out of the subs. He will sound bigger and sit with the kick drum if mic'ed correctly.
The Guitars - Gibraltar Drum hardware makes some awesome products called sound shields. They are plexiglass panels that you can place in front of your amps and the drums too if you want. They eliminate bleed through into your guitar cab mic, and they eliminate the sound coming out of your cab into another mic..like the lead vocal mic. These things are lifesavers on a stage...isolation is where it's at if you want control. AND...you can still run the amps at a nice volume to keep the power tubes happy!
http://www.gibraltarhardware.com/?fa=series&sid=696&cid=35
The Mics - I know the 57 and Beta 57 are the "standard" for guitar cabs for many years. However, I have to be the only idiot who never liked the sound of a 57 on a cab. For my taste, the highs always ripped my face off, or if not too bright, it would be too muddy and not tight and defined. I know a good deal about mic placement from our studio, so I've tried many things...still was never happy. I've had better luck with a 421 or a 414, but a few years ago I found the silver bullet....the Royer 121 ribbon mic. This freakin' think is a God-send. The 121 sounds organic but brutal if you want it too. It also sounds like your cab, not too colored. For crunch guitars it totally kills! After I got a matched pair for the studio and stage, I never looked back...not interested in anything else. I get an amazing sound with minimal passes at mic placment...in 10 mins I have my sound every time. Also the FOH Guys will LOVE YOU...here are some actual FOH guy quotes from shows in regards to gigging with the Royer 121 : "Finally..someone that knows about audio and cares about his guitar sound." "Oh thank God, you guys got 121's..this is going to be an easy night for me". "Holy Sh!t...you guys got 2 121's no freaking way...NICE" "
Mic Placement - whatever mic you get, and assuming you are after a fat crunch sound that will not rip your face off with the highs or presence try the following...close mic at about 2-3 inches away from the grill cloth. Do not point the mic directly at the cone go for the edge of the speaker, unless you want it brighter. Also, angle the front of the mic a couple of inches off to the side of the grill, not directly into it---off-axis. Do this to taste.
When you get all this done and all the guitars and bass are in the board you can then pan the guitars differently to give them better separation. You will hear each guitar better and you will be in stereo too!
Remember, let the board and the PA cabs do the job they were designed for. If you get the right gear, you will sound amazing, balanced, minimal feedback, AND people will get to hear the vocals and the BOOGIES!!!!
Hope this helps and best of luck!