I'm currently working on a project that was loaded with these kinds of issues. I recorded a band and it should have sounded really good but when I got to mixing it was awful. The guitar sounded too fat, drums sounded like cardboard boxes, and I shouldn't have had to be EQing the crap out of everything to get a balance.
I know you can only build a mix as good as the drums sound and I was sucking the life out of the guitar tone trying to make them fit into the mix with the drums, and the bass which normally needs little or no mixing wasn't anywhere near to being in unison with the kick. On top of this I knew they sounded tight as a band when I was recording them.
I did several mixdowns using every trick in the book to manipulate the sound and after two weeks I still wasn't hitting it. Then two days ago I found the solution to what was causing the drums to sound so thin. I should have known this one much sooner, but I hadn't has the issue with my own studio set in a long time. I had that set miced up to perfection and had forgotten what it took to get it sounding right. Since this drummer used his own set, I didn't get the chance to get the mics on there all working together properly.
What I eventually did was expand the wave view of the drum tracks to extreme magnification so I could see the actual sine waves the drums produced. (most daws have the ability to expand the height and length of the wave files) What I found was the signals were out of phase. I had one waveform going south, one going north and several were cross secting at various points of the sine wave arch.
The kick being the strongest sound captured in all mics through bleedover, was also the weakest limpest sounding tone in the drum mix. The drummer used a double kick and barely used the one kick drum so it got allot of bleedover from the other kick drum. Both were closely tuned so its head was resonant and the mic picked that up. Problem was, one kick drum had a wave form going north while the other was going south, so in essence, the two would cancel each other out and I was left with a kick that sounded like cardboard.
The two waveforms weren't perfectly aligned either. They were off by 120 degrees so phase reversal had only mild effects. I though it was just bad drum tuning or mic selection and EQed the crap out of them and still no bottom end.
So what I did was to drag the tracks over so the kick peaks aligned. The one kick mic was then 180 degrees out of phase with the other which was fine. I could use the phase reverse switch on it and both would be north going. I did this for the other mics too. Some were only a tad off, and their peaks weren't well defined being quite a distance from the source. The overheads I left alone. They were in phase with the one kick and snare drum. These mics also picked up their immediate source which may have been a cymbal or tom, but since the frequencies of those sources were at different frequency ranges, they didn't have a problem tracking their sources.
The result was, I had unified the phase of all the mics bleedover, caused by misplacement, so the bleedover worked in unison. This greatly reduced the phase cancellation that robs tone and it brought back the low end the mix was lacking. I could then flatten out my EQ settings or remove them all together to let all the drum tone on the tracks come through.
I was then able to remove most of the EQ I had on the guitar tracks and let them fatten up again, and the bass was punching with the kick drum the way it was supposed to. A bass has to go either north or south with the kick. When the kick is going both north and south, the bass sticks out like a sore thumb in the center and doesn't unify.
Oh, and the vocal mic had bleedover too. This was a live studio session and my studio isn't all that big. The female vocalist does better with a hand held condenser than a large diaphragm and performs best live. I will have her come back to add vocals this weekend. I thought, I'd have to dump the original vocal tracks all together due to the bleedover which is a shame because she was singing well on many of the takes. Retracking is clean but it often lacks the same energy a live band band gives a singer and they just don't pump up like they do using headphones.
The vocal mic was about 10' from the drum set. The room has no reflection so the mic only picks up the direct sound due to the walls being so highly padded for sound proofing. I went through the same phase alignment with the drum bleedover. I took a quiet passage when she wasn't singing, and temporarily normalized that part so the bleedover peaks were huge. I then placed the overhead and vocal track above and below and used my vertical time line to match the bleedover peaks when I nudged the vocal track back a little. I had to drag the vocals back because distance causes a delay so I cropped a sliver out of the intro silence to get the two aligned.
Wah lah, the drum bleedover in the vocal mic was in sync with the drum tracks and what was head on the vocal track was additive not subtractive. I had been trying to EQ the bleedover out of the vocal mic which made the vocals sound thin and unnatural. I also tried using gates and manual envelopes to silence the bleedover between vocal parts, but all this did was make an unnatural bump in in the drums coming through when the singer was singing. By aligning the phase, the vocal mic acted as a room mic when no vocals were present and having it in phase added to the ambiance of the mix.
As I said, I should have identified this phase problem as soon as I started mixing. God knows I advise others enough on this forum about such things enough and should be wise to my own advice. I should make a check list of things to check on a mix and run down the check list so It wont be missed next time.
My only excuse for missing it was I had gone a decade using the same miced set and hadn't delt with this problem in a long time. Its easily mistaken for a variety of other problems including drum tuning, mic selection, EQing and the players performance. Knowing your gear and knowing what you should get is an important part of the deductive reasoning process in figuring out what's wrong. It doesn't force you to think outside the comfortable box you often find yourself residing in.
Hopefully this may help some others. Chances are they may have some recording project stored that never mixed as well as they would have liked and were dealing with the same kinds of phase issues I was.