1980 Electro-Harmonix Bad Stone Phase Shifter

Model Description:

While analogue modulation, known as phase shifting, goes way back in music recording, the history of compact phase pedals goes back to about 1971 when Maestro released the PS‑1 Phase Shifter. By 1974, MXR Innovations had released the Phase 90 and Electro‑Harmonix introduced the small enclosure 4‑stage Small Stone Phase Shifter. Building on the success of the smaller effect, Electro‑Harmonix introduced its bigger brother, the 6‑stage Bad Stone Phase Shifter. For the technically inclined, the Electro‑Harmonix phasers differed from the MXR pedals – the former had a unique circuit that used Operational Transconductance Amplifiers (OTAs), while the latter used Field Effect Transistors (FETs), giving the two approaches markedly discrete sounds. The Bad Stone also has some unique features to make it a versatile effect. Whereas the Small Stone had a 2‑way ‘Color’ switch to give shallow or deep phases, the Bad Stone had a ‘Feedback’ control to vary the amount of feedback. The ‘Rate’ control also allowed or slower phase sweeps. The real difference, though, was the ‘Manual’ mode that enables the user to ‘freeze’ the filter at a set point in the range, giving exclusive tonal control unmatched by any other model. There have been various incarnations of the Bad Stone throughout the years, with the earliest ones now attracting serious money on the vintage effect market. Even the later ones, before the company went out of business in 1984 are now seeing crazy price increases. Electro‑Harmonix has also reissued the Bad Stone in ‘Nano’ form for the modern market, extending its appeal to newer generations.

Pedal Description:

Back in the day, I used to have one of these late 1970s Electro‑Harmonix Bad Stone Phase Shifter’s, owned from new. At the time, it didn’t seem to a novice guitarist that it offered much more than the smaller and simpler Small Stone, so the latter remained and the Bad Stone went. Now, a Bad Stone is back in the family and thoroughly deserves its pride of place. As with many of the chrome plated and screen printed pressed steel enclosures of the time, they are showing signs of age and use. However, this cool scruffy aesthetic belies the underlying robustness of the Electro‑Harmonix enclosure, which has actually endured well. The battery clip is a replacement but everything else is original and working very well. The LFO tips over into continuous hum at the extreme of the ‘Rate’ control, which I don’t recall the original doing, so it may need a bit of TLC at some point. The Bad Stone is a different animal when contrasted with its Small Stone sibling or the MXR pedals. The swirly sounds are typical of 1970s analogue phase pedals which, on the surface, seems to belittle its characteristics but is actually a backhanded compliment – this really is a classic of its era and rightly so. The amount of control over the effect is significant, especially compared to the Phase 90’s single ‘Speed’ knob, or even the Small Stone’s limited feedback/depth control. Modern phase effects can sound all too clinical, while these older all‑analogue pedals just seem to get better over the years, relatively speaking. Despite the faithful reissues and copies that have appeared along the way, the originals still stand up very well, if a touch noisy at times.


  • Made in New York, U.S.A. in 1980
  • The ‘Rate’ knob controls the speed of the phase modulation
  • The ‘Feedback’ knob controls depth of the phase modulation
  • The ‘Manual Shift’ knob controls the static position in the sweep when the ‘Auto/Manual’ switch is set to ‘Manual’
  • The ‘Auto/Manual’ switch controls the mode – ‘Auto’ uses the circuit’s LFO while ‘Manual’ freezes the position in the range set by the ‘Manual Shift’ knob
  • Standard on/off footswitch turns the effect on and off
  • Standard ¼” input and output mono jack sockets
  • No LED status indicator
  • 9V centre positive DC input or 9V battery
  • No battery compartment in the base of the pedal
  • Philips screws on the top of the pedal
  • No serial number

Detail Gallery:

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