Everyone pointing you in the direction of mids is spot on! Low mids are "tighter" versions of bass frequencies and high mids are "tighter" versions of treble frequencies. Find the low mid freq that has the punch you want, then find the high mid freq with the "bite" you want and you're golden. The reason mids work so well for bass is that they are the 2nd, sometimes even 3rd, octave harmonics of the fundamental note you are playing which makes them more easily heard by the human ear and able to compete with a blaring guitar. It also frees up more headroom since ur not soaking up all your amp's power trying to pump out 60Hz- sine waves
. I personally use the 80Hz low pass on the input of my preamp to really clean up my bottom end and even more precisely tune it.