What you're experiencing is the age old problem of the drummer playing way too fucking loud combined with terrible room acoustics and bad EQing.
"What? Dynamics? But I'm already playing as hard as I can!"
Does the following sound familiar? You barely hear yourself while playing a song, but as soon as you play alone, you are at almost deafening levels.
The problem is that low and high frequencies build up in your room, especially when playing loud, masking everything by a horrible wash of reverb. The cymbals and kick/toms will utterly
destroy everything in the low and high frequencies and there's not much you can do about this.
Turning up the volume for the guitar won't solve this problem. As soon as you are louder than the drums, everything else will get masked up by the guitar and you have the same issue again.
All you can do is applying band-aid.
Here's what you can do:
- Get broadband acoustic absorbers and spread them across the walls around your drummer to filter out the first reflections of high frequencies. This will remove some of the cymbal wash (and no, egg cartons will not do it, as cardboard is an acoustic reflector, not an absorber... they will apply some dispersion, though, so it's still a bit better than dry wall)
- Get professional bass traps and place them in the corners of your room. Don't build your own; selfmade ones mostly don't work (
Why Your Bass Traps Don’t Work | Home Recording Blog).
... once you did that (be prepared, though... this is expensive!) you will instantly notice a huge improvement of clarity
Here is some general advice for live and rehearsal situations to improve clarity:
- apply a GEQ to your guitar; cut everything below 125Hz and above 6khz. Roll back 125Hz by 3dB and 250Hz by 2dB. Make room for the bass guitar. Add +1dB to 1khz.
- apply a GEQ to the 12-string: cut everything below 250Hz and reduce the midrange (250-1000Hz) to make room for the electric guitar; the tonal focus of the acoustic 12-string sound is in the high frequencies (2khz-6khz)
- cut the bass guitar below 70hz and beyond 1khz. Yes, I know; bass is about low frequencies, but you don't want to compete with the bass-drum here. In your setup, bass should fill the 125-400Hz range.
- get rid of
all reverb stomps/blocks. You don't need them in most live situations. Reverbs are for recording or for creating deep soundscapes. You want clarity, not depth. Every additional reverb will just take some of that clarity away. Unless you are playing outdoor or stages with line-arrays, here's the golden rule of live sound: "Delay, not reverb".
And nope, not even your singer needs reverb.
This should get you in the ballpark. Combined with some acoustic treatment, you will find yourself in tonal heaven when applying all of these rules. Don't worry that your guitar will sound like crap when isolated after applying the EQ I suggested. That's normal and you would be surprised how bad isolated guitar sounds sound even on professional recordings... it's the mix that matters.
I recommend analyzing a Foo Fighters live concert (for example, "Rock am Ring 2015") if you want to learn more about live-EQing. The foos play with 3+1 guitars on stage and it sounds MASSIVE, yet everything is crystal-clear. This is because every guitar has rigorous EQ applied to it. One of the lead guitars even sounds like it has a low-cut as high as 1000Hz applied.