Bass onboard preamp amplifies but doesn't equalize. I tested a few components already, everything ok. Help troubleshoot please. : r/AskElectronics
Chinese onboard preamp for bass guitar - YouTube
What is a Bass Preamp Pedal? - Andertons Blog
On board preamps, 2 and 3 band EQ, active/passive switching for bass guitar, Bass, Treble, Mid, Passive tone, Volume, Pan controls. for sale, Bartolini, Aguilar, Delano, East, Glockenklanf, UK, EU, for sale
East UK Uni-Pre Onboard Preamp | Bass Gear Magazine