Boss GEB-7 Bass Equalizer
For your consideration, Garrett Park Guitars presents this Boss GEB-7 Bass Equalizer
From the Boss website:
The GEB-7 is a seven-band equalizer created specifically for the frequency range of the electric bass. Since the frequency range extends down to 50Hz, the GEB-7 is also great for adjusting depth and bottom end of an upright bass with pickups.