Ben Easher (designer of this pedal)
The Valve Grinder concept originated around 1995, when I was working in a Portland amplifier repair shop called Entertainment Electronics. I was using silverface Fenders for a clean sound, and wanted an overdriven Marshall sound from a foot pedal. At the time there were a limited number of solid-state boxes and only a few with tubes (usually running at low voltage). My boss, Jim Flynn, helped me design a pedal with two 12AX7s running at high voltage. The last stage of the second tube functioned as a single-ended output section based on the Fender Champ. The cascading preamp was modeled after the Marshall Club and Country series because of the simplicity. The equalization was based on the silverface Twin because of the wide bandwidth.
The circuit had some problems with hum and oscillation, which led to using a double-sided eyelet board and a tall enclosure with reversed input and output jacks. Along with two prototypes, twenty units were manufactured in 1998. In retrospect, I wish we had spent more time on development first. My graphic "design" left something to be desired. The expensive paint job didn't hold up when our sole endorser, Lee Ranaldo of Sonic Youth, took his pedal on tour. (I had brought one to his gig at Club Satyricon after reading his online complaints about other models.) Oscillation remained a problem at the highest gain settings. Still, Guitar Player and Vintage Guitar gave us decent reviews. We sold some pedals to friends, one to a European recording studio, and the rest to dealers -- the last several at below cost.
In the mid-2000s, with me in Seattle and Jim in Las Vegas, we developed a MKII prototype. This time, we used a single-sided board and a sloped enclosure, and managed to solve the oscillation problem. The equalization was now a modified JCM 800 circuit. I presented the new prototype to a couple of Seattle technicians who were planning to produce a line of guitar amplifiers. They told me that Underwriters Laboratories costs made pedal-building unfeasible. They never built any amplifiers.
Which brings me to 2013. The number of pedal manufacturers has skyrocketed. Many solid-state models sound tube-like, and several high-voltage tube designs are available, some with output stages. In addition, low-wattage amplifiers and built-in attenuators have become commonplace. Valve Grinder MKI lost money. Could MKII make a profit in today's crowded marketplace? At this point, I don't have the time or space to build them, but if someone else made an offer, I would listen.