For all of you Sunn lovers out there, here's a Sunn Beta Bass preamp that I built using the original Sunn Beta Bass amp schematic to build it. It has an internal charge pump converting 9 volts DC (at the power jack) to bipolar 15 volts (+15 & -15 volts) so that it runs at the same voltages as the actual amplifier. I think that it's an awesome sounding preamp that's capable of going from absolutely clean to heavy distortion. It comes in a polished and acid etched 1590BB with a relayed true bypass with ALL top jacks. If you love Sunn amps, you'll LOVE this one!
Here's a quick soundclip of it with a P bass.
