As designer Jim Felton, of Lloyd, Florida describes it, "the amp is a 200w (100w rms) stereo automotive amp, and powers a dual voice coil 8" subwoofer (45-3500 Hz). In the upper cavity is a 25 amp Radio-Shack ac/dc power supply and a Tech21 Sansamp active Acoustic DI, with a 20db pad, phantom power, and both balanced and unbalanced lines out. The bottom shelf can support a deep cycle battery for times when commercial power is not available.
The staff is 1-1/4" oak about 4' long and at least 70 years old with straight grain and no knots. It has a Fishman piezo piano/harp pickup (150 Kohm impedance) mounted to a flat spot carved into the staff just below the string entry. The SansAmp Acoustic DI is a 3-band active tone control with a sweepable mid-range and an input impedance of 4.7 Mohms, which fully bridges the piezo and smooths it out. I run the mid-shift at about 350 Hz for the tub, and at about 750 for my guitar. I'm pretty well satisfied with the tone, and the amp has a stereo line out if I need more volume.
I don't prop up the front of the tub, since playing from a sitting position allows me to raise or lower the front of the tub at will for different effect (with no feedback issues...no mic.) I play cotton strings of my own making (never a blister) and achieve different tones and pitches by sliding my hand as a capo in conjunction with moving my feet across the top of the tub.