Hi Lee, Corky
I tend to buld my sound more with a “producer’s ear” than with a “player’s ear”: as a musician, you may want your sounds to be “muscular” and “beefy”, i.e. with a healthy dose of lower mids. That holds particularly for guitarists, who have been socialized on amps blowing their sound towards the back of their knees, so they expect a sound that is heavy on the lower mids range. Also Hammonds are pretty beefy animals when standing on their own; pianos have significant energy in that range as well.
When you put all this together in a mix, it will create an unholy mess in the lower mids range, resulting in a “muddy” sound of the track - compare this to professional productions, and you will find, they’ve managed especially the range between 100 and 300 Hz very diligently - not cleaning it out wholesale but chiselling away until a healthy mix of voicings happens in that range.
All of this doesn’t matter if you simply feed your keyboard sound into an amp for your own enjoyment on stage - as @Corky wrote, as long as you don’t step on each other’s toes onstage (acoustically and otherwise), it’s not an issue. And the P.A. person will sort out the overall mix, so they may pull the low mids on the keyboard and guitar channels for the audience. In a club setting, where the instrument sound comes from the individual amps, things may be more difficult, but, hey, it’s club sound, so it’s allowed to be a bit more beefy… And usually the cymbals from the drum kit will project nicely, so that will take care of the brilliance bit; the vocals will be projected with some kind of reduced P.A., so just raise them a bit above the mud - all good…
In my main setup, we drive the whole band through the P.A., since we’re all on virtual instruments (PODs / Kempers, vDrums, Cantabile for my keys and guitars) anyways, so I aim for a more P.A.- and mix-ready sound. For that, most of the keyboard and guitar sounds have too much energy in the lower mids, so I do carve away a lot of the 200-300 Hz range on my keys.
Here’s my main piano EQ:
Looks pretty brutal, but helps the piano find its right place in a busy rock mix - you don’t want the piano in a rock mix for its mellow low end, but for its bite - that’s what it gets with this EQ. But sure, I do have some other rack presets with a more rounded EQ for ballads with the piano sitting more prominently and carrying the “warmth” of the song.
Same with Hammonds: too much bottom end will actually prevent it from cutting through in a busy mix, so I shave away on those frequencies for my “hammond layer” sounds (where the hammond acts as a pad behind the piano) and also for the lead patches that would otherwise muddy up the mix instead of shining above it. But of course there are also patches for more sparse arrangements (e.g. Green Onions) where the Hammond is allowed a bit more room - in these, I give the lower mids a bit more freedom, but not too much to get in the way of the bass…
And most synth pads definitely need cleaning out in that range - you can get away with pretty drastic cuts and still retain their character.
My absolute favorite EQ plugin is the FabFilter Pro-Q 3 - a pleasure to dial in, and it also has the ability to make EQ bands dynamic - kind of a frequency-selective compressor. That feature is great to tame some nasty screaming frequency peaks that do pop up in some organ plugins, but without eliminating that frequency altogether. Definitely worth buying!
Hope this helps!