Electronics can be a brain-melting subject to get to grips with. It takes awhile for things to click. But after a time I learned to approach design work more scientifically; analyse tube amps using circuit simulation; implement strict audio electronic test regimes; and slowly, but surely, got a grip on how to control and blend the vital, basic ingredients that constitute good tube amp tone.
My initial enquiries focused on modern high gain amp designs, such as the creations of Randall Smith (Mesa Boogie®), Alexander Dumble and Mike Soldano’s SP-77. The creamy, saturated tones of these types of amps are addictive, but over the years I came to desire the milder, lower gain bluesy tones of a ‘pushed’ tube amplifier going into breakup. My tastes for these two distinctly different overdrive and distortion characteristics had a big influence on my first prototype drive pedal.
The prototype was completed in December 1996. The signal path was based on the SP-77′s four cascaded grounded cathode stages followed by a simple passive Fender® ‘Harvard’ style tone control. The power supply was built into the pedal housing and based on a sub-miniature high voltage transformer, which I wound by hand as none of that minuscule proportion were available. The transformers were ferro-magnetically screened from the tubes using a steel partition plate. The result was the chunky little tube pedal with warm, saturated tones, however lower gain settings were lacking robustness. Further work was needed…