Bernard d'Uur's little lab; the docter is in!

The EHX Small Stone is next to the MXR Phase 90 one of the most known and common phase pedals out there!  The Small Stone was created in 1974 by David Cockerell, a former employee of EMS. He worked also on the EMS Synthi Hi-Fli that was released in 1971. The Hi-Fli was a multi-effects unit that became popular by David Gilmour. In this multi-effect there was a phase-shifter that mimics the basic circuit of a phase-shifter nowadays. The circuit Yet the Small Stone is different to most phase-shifters. As most phase-shifters use an opamp and a transistor / FET as a phase building block, the Small Stone uses an OTA (Operational Transconductance Amplifier) as it's main building blocks. This way of producing a phase effect was more expensive (as you needed four dedicated opamps) but the matching of parts, common in FET based phase-shifters, was not needed. The Small Stone uses EH1048 OTA's; these EH1048 are home branded OTA's (and for more info on these IC's check here ). A sh...