I recently purchased a used Ibanez SR 4 string active bass. This bass has 2 pups and has a variety of great sounds. The problem I am having is that the low E string is louder than the other three strings. I tried fixing this with EQ with limited results. This problem occurs on several amps I have used. When I set my volume to the low E, then play on even the A string the bottom falls out of the band. I tried adjusting the pup height but moving the pup away from the E string also lowers it a little from the A string and I am back to the same problem. Does anyone out there have any suggestions?

Try a compressor between the bass and amp. I have a bass that's the same way, and a nice potent dose of compression fixed it right up.

Don't use a compressor. Find a good compromise with pickup height. And don't boost too much bass on your amp or your bass. I can suffer the same problem at home with my 51 P clone and my Fender P through my GK amp. It's mostly a matter of getting the eq right once the pickup height is adjusted correctly. Too much contour on your amp can cause the problem too.

On my Ibanez Artcore I have no problem. Because of the placement of the single pickup there's no boom, unless I deliberately dial it in on the amp.

It could be a string problem too.