Steven Slate shared some great tips and i'd like to post them:
- Get a slightly narrow bell eq and crank 50Hz by 6db. Then crank 1-2khz. Now send the bass to some kind of compressor with a high ratio and slam it so that the thing is almost pinned, probably around 10db gain reduction. Now, put on another eq and with a narrow notch, carve out 80Hz so your kick can breathe. You'll end up with a big humm'n deep bass sound that will sound huge on guitar palm mute stuff but will still have the upper mid growl.
Another tip:
Set up an aux and put a thick and wide chorus on it. Follow it up with an eq and put a hi pass filter at 300Hz. Send some of the bass to this aux and mix in the chorused signal while monitoring with the full mix.. what you'll hear is that the bass will have a wider, more massive presence. The reason you follow the chorus with a hi pass is because it'll muck the low end up, the chorus is mainly to spread the upper mids in the stereo spectrum.
the chorus thing works great... remember to keep it subtle, you don't want it to sound like "whoa there is chorus on the bass"... its all about getting a bit more presence and spread.. and yeah it works with guitars too. With guitars, try using a pitch shifter... Go 9cents up on one side, 9cents down on the other, delay the left 15ms and the right 30ms and add that in a bit.