So, how low and are there 1 or 2 notes on 1 or 2 strings that are buzzing or all of them?
There are several side issues that could be affecting the action on your bass, like nut height, but if you want to go very low then you're into uneven fret territory, and fret levelling is the first thing to check and fix. Everything else flows from that.
A couple of years ago I had my US Lakland set up with a fret levelling. It played like a million dollars afterwards. I cost me about £80. Worth every penny.