The amplifier (AMP) is a 2 stage Class A discrete design using 3 pairs of hand matched transistors. Envelope is usually applied to ST1/1. ST1/2 goes thru an attenuverter and can be used for envelope or modulation. ST2/1 goes to the 2nd stage, and is typically used for volume control. ST2/2 goes thru an attenuverter and is typically used for modulation.
The AMP, the 5089, and the 3003 are Class A circuits. They draw more current from the +12 rail than from the -12 volt rail. If the system power supply is under-sized, hum or buzz may be heard. In that case, larger filter capacitors and/or a larger power transformer will be needed. The 4075 draws equally from both rails, and is more immune to hum. Like our filters Boomstar Modular AMPs are hand-built entirely in the U. S. of A—just ask Rachael Herbison!
Two attenuverters and two attenuation pots control the INPUT, STAGE 1/2, STAGE 2/2, and OUTPUT, delivering smooth, detailed, and complex expression.
INPUT – Adjusts the audio input.
STAGE 1/2 – Adjusts stage 1/2.
STAGE 2/2 – Adjusts stage 2/2.
DRONE – Sustains the last note received—“Hold that Train.”
DRIVE – Final output stage overdirve/saturation.
OUTPUT – Adjusts the audio output.
INPUT – Audio input.
ST 1/1 – Stage 1/1 input.
ST 1/2 – Stage 1/2 input.
ST 2/1 – Stage 2/1 input.
ST 2/2 – Stage 2/2 input.
OUTPUT– Audio output
Size - 8hp
Depth - 39.7mm with ribbon cable attached
Power Usage - 36mA, 12mA (+12 / -12)