Electro-Harmonix Small Stone Phase Shifter Effects Pedal

Description

The origin of the Small Stone dates back to 1974, when Electro Harmonix president Mike Matthews hired former EMS engineer David Cockerell, whos first design for EH was the Small Stone phaser. The design was based on Davids previous work on the EMS Synthi Hi-Fli from 1971 - it is a rather unique design in that it uses Operational Transconductance Amplifiers (OTA) instead of operational amplifiers with variable resistors. It is a 4 stage phase shifter with one additional stage for feedback, which can be activated using the "Color" switch. The strongest rival of the Small Stone, the MXR Phase 90, uses FETs (Field Effect Transistor), which suffer from the fact that the FETs have to be matched in production. This made the Phase 90 more expensive and gave the Small Stone an edge in the market share. Soundwise the OTA based phaser will give it's unique flavour with rather strong third harmonic distortion, whereas the FET based phaser has a pronounced second harmonic distortion - the matter of which one is better is simply a matter of taste.

Throughout its history the Small Stone has had numerous revisions and modifications - all versions are OTA based, but the changes will affect the sound of the unit. Here's a short overview and comparison of the different versions of the EH Small Stone. The controls of the Small Stone have remained unchanged troughout its history - a SPEED-control, a switch labelled COLOR, which adds feedback to the circuit resulting in a deeper and stronger sounding phasing effect with many more notches added to the spectrum, an finally - the footswitch to toggle the effect on and off.