Some advice if you will - mixing in piano!!

First, are the notes clashing because of wrong notes or is the bass playing a completely different pattern than the piano? If the pianist is playing the correct part with their left hand, the easiest fix would be to have the bassist learn what is being played in that section, punch-in, and fix it. It will probably be a faster fix that way than to try to re-capture the magic of the piano performance. If you have already tried some surgical cutting of frequencies and it didn't work for you, this is probably going to be your only choice. Someone else?

I typically would play the left hand in a higher register so as to avoid conflict with the bass.  If your piano part is midi, that's an easy fix.  If the piano bass part is important to the song I'd consider changing the bass guitar to a root at the beginning of each measure, something simple which should get it out of the piano's way.
 
HTH
 

Thanks Paul G. Yeh. I guess that's would I should do.  I've recorded the piano part to the music. Maybe now I should go back and re-do the bass for this section, to the piano part, as I don't want to change any more of the piano notes, which sound awesome on their own.
 
I've not struggled this much with a mix before. I just can't get these two sound to 'gel'. I'll cut a new simplified bass track for this section and see if it works.
  
 
Been at this all day

What bit said. I think you can still perceive this in terms of how you would cut lows on guitars so the bass becomes the low end of the guitars if you get my drift.
I use a vst piano and real bass all the time and a HPF always works for me anywhere from around 85hz up to 200'ish depending on material. Id also consider rolling of the lows on any reverb you have on the piano as that wont be helping much. Aside from a different arrangement im not sure what else you can do. You could clone the bass part to another track....on the first track keep all the lower end, cut everything else and compress lots and use a hpf on the second track to mix in the upper mids even with perhaps a tad of distortion. That way you may be able to lower the overall bass guitar in the mix but still keep the definition. Ive used that before to good effect, but it really depends on the track.
 
You could always post your track for the chance of some more accurate suggestions from everyone.
 
Good Luck
 
Bibs

Have you tried nudging the left hand piano notes back or forward a few ticks? Given that most of the energy of a note is in the attack, it may help if the attack parts of the bass and piano notes don't coincide too much. I've sometimes done this for kick and bass notes which coincide, with varying results.

Also I wouldn't be afraid to change the piano part to make it fit better with the bass. I know what it's like to get attached to a part you feel is perfect, but sometimes it just doesn't work with the rest of the track and you have to let go. Moving some of the notes around might just result in a happy accident that you like even more - happens to me all the time.

I consider the arrangement to be the first and sometimes most important part of mixing. Sometimes I'll run around in circles trying to get two clashing parts to play nice with EQ, an in the end I'll just get them both up onto the piano roll and have them weave in an out of each other. You sometimes end up with some very engaging melodies and textures. I would even consider creating a MIDI track for the bass part using the Melodyne audio-MIDI conversion, so you have a reference on the piano roll that you can compare to the piano part.

This is all, of course, only if you really want to preserve those lower frequencies on the piano instead of cutting them as others have suggested.

Another thought depending on the song style and the feel you want at this particular section: perhaps try removing the bass part through this section - just piano, vocals, & soft drums? This might give some nice contrast and interest to the song as a whole.

Thanks et all for the advice. Just thought I would post that I have tried a lot of things mentioned here and had some good success. Pretty much a combination of all things of course, but I have essentially split the piano hands into separate tracks, applied a very small amount of side chaining to the bass piano parts from the bass line, used the multiband compressor on the bass, re-eq'd everything again, and panned until things felt right. I did re-do the bass for this section too, so it wasn't so busy, and sat more on the piano notes, plus mucked around with velocity's and attack times.
 
I think more than anything, it was the compression in the end that helped to get things under control, but I do take your point on EQ'ing Cj. I think some times you have to walk away and come back fresh, get your ears unblocked or something.
 
It's now sounding pretty good and the customer is stoked. What more could I ask for?
 
All the advice here was just great. Thanks so much.
 
Dave.

Sidroe
Sounds like you've got it whipped by now. One more thing you may consider is automating the EQ on the part that seems so offensive. Just write in some automation for the bands you need to tame for that section. If every one is happy at this point, follow the first rule of studio etiquette! "IF EVERYONE IS SMILING WHILE IT PLAYS-DON'T TOUCH IT!" LOL!!

Ha!  I like that so much I might print it and frame it up on the wall Sidroe!! Yep. Shudda auto'd the EQ. Know that now lol!!  I used new tracks and did it that way. I think I'm an old 'desk' kinda guy. Hard to knock that out of myself, but I'm trying.....
 
Thanks for your help. Appreciate.