The Electro-Harmonix Small Stone is an analog phaser pedal with a control panel that has barely changed in five decades: one knob and one switch. Electro-Harmonix describes it as generating "thick sweeping phase shifting with liquid transparency"1. The current reissue, released in 2006, carries forward the circuit of the classic 1970 original in a compact die-cast chassis, and according to Electro-Harmonix founder Mike Matthews it was "the biggest-selling Electro-Harmonix product of all time"21.
A phaser splits your signal, shifts the phase of one copy across a set of frequency stages, and recombines the two, producing the moving, whooshing sweep associated with 1970s rhythm guitar and funk. The Small Stone is a multi-stage phase shifter with an extra stage for feedback, which is what the Color switch engages1.
The controls: Rate and Color
Two controls do all the work, and as Pedal of the Day notes, "the controls have remained constant through the Small Stone's many iterations"3.
| Control | What it does |
|---|---|
| Rate knob | Adjusts the speed of the phasing sweep, from slow and smooth to rapid edge frequency sweeps1 |
| Color switch | Down position: a full and robust phase shift. Up position: a more pronounced phase shift1 |
| Footswitch | Toggles between effect and bypass mode1 |
The Color switch works by switching a feedback path in the circuit: the path should be disconnected with the switch disengaged and connected when engaged, which is why the switch plays such a large role in the character of the effect4. On the circuit level, the Rate pot sets the speed of the LFO (the low-frequency oscillator that drives the sweep); builders recreating the circuit on the Tagboardeffects blog found a C500K pot gives better control, with the slowest setting still slow enough4.
Power and connections
The current reissue runs on the included 9V battery or an optional 9.6VDC-200mA power adapter, which is not included1. At 10mA of current draw it is light on a power supply1. Connections are minimal: one audio input jack and one Amp jack for the output to your amplifier1. The chassis is a tough and compact die-cast box1.
History and versions
The Small Stone was designed by David Cockerell, and Premier Guitar traces the circuit "from its gestation amongst the circuitry of the EMS Synthi Hi-Fli to the very early Electro-Harmonix versions"5. The original v1 dates to 1975 and was made in New York City67. A v2 followed in 19786. A later EH-4800 issue used a slightly different layout but essentially the same circuit8.
The Russian-made green version earns particular praise from Pedal of the Day: "This green one is an absolute tank of a pedal, solid and sturdy as they come, built to last for years and years"3.
The Golden Small Stone
Common mods
The Small Stone's known weak spot, volume drop when engaged, has produced a small industry of fixes91011.
Analog Man can only perform its mods on models with black and red graphics, like the last reissue, not the earlier one with orange lettering12. Also note that Analog Man says Small Stones from 2005 onward came with true bypass, "but the volume is cut a little when ON"12.
What reviewers said
Reviewers consistently praise the sound while flagging the volume issue. On the Tagboardeffects blog, Alex wrote: "I had never played a Small Stone before but it sounds amazing and I prefer it over my Phase 90 style phaser"4. Aion FX classifies it as a classic OTA phaser13, and Function f(x) lists it among commercial examples of OTA-based phase shifting.
MusicRadar's Alex Lynham found that "particularly at slower rate settings it nails that dramatic, vintage whoosh that you've heard on countless records," while noting that "especially on vintage units, there tended to be a bit of a volume drop when engaged. Also, the footswitches were prone to breaking"9. JHS Pedals' Josh Scott goes further on the vintage question: "the vintage Small Stone actually has an issue with volume loss, so the reissue actually works slightly better"10. Guitar.com has noted that early incarnations of the Small Stone featured a volume drop, and that it is likely the vintage pedal MXR voiced its Deep Phase after11.
On the Russian version, Pedal of the Day wrote, "We love the range of the speeds you can get," calling it a vintage unit coveted by players across the world3. Guitar World's beginner-pedal guide picks the Small Stone Nano as a budget phaser, praising its tiny size and classic sound with true bypass, while conceding it is "a bit of a one trick pony"14.
General Guitar Gadgets' comparison of old and new adds a nuance for tone chasers: "the older models seem to have more 'swish' and more noise" than the NYC reissue8.
Players
Carlos Alomar, David Bowie's guitarist, used a Small Stone alongside a Mu-Tron Bi-Phase to emphasize rhythm licks on Bowie's mid and late 1970s records15.
Videos
ProGuitarShopDemos
EHX
Woven Chaos
News
Questions
Does the Small Stone take a battery?
Yes. The current reissue ships with a 9V battery included, and it can also run on an optional 9.6VDC-200mA power adapter, which is not included. Current draw is 10mA, so a battery lasts a long time at typical playing sessions.
Is the Electro-Harmonix Small Stone true bypass?
Yes, the current reissue is true bypass. According to Analog Man, Small Stones from 2005 onward came with true bypass, though the volume is cut a little when the effect is on. Older units used a Carling DPDT switch, which can be swapped for a 3PDT true bypass switch.
Why does my vintage Small Stone drop in volume?
Volume drop when the effect is engaged is a known trait of vintage units. On reissue Small Stones, General Guitar Gadgets reports that changing the feedback resistor in the input gain stage, R6, from 5k6 to 10k fixes the volume loss. Analog Man offers a mod that sets the volume the same on and off, with an internal trim pot.
What does the Color switch do on a Small Stone?
The Color switch changes the character of the phase shift. In the down position it gives a full, robust phase shift; in the up position a more pronounced phase shift. It works by switching a feedback path in the circuit, which is what gives the up position its sharper, more intense sweep.
Who designed the Small Stone?
The Small Stone was designed by David Cockerell, the British engineer who also worked on the EMS Synthi Hi-Fli. Premier Guitar traces the circuit's gestation to the circuitry of that unit before the very early Electro-Harmonix versions appeared.
What is the Golden Small Stone?
The Golden Small Stone is a limited edition of 600 pedals released in 2025 to mark the phaser's 50th anniversary. It recreates the original 70s circuit using NOS CA3094 chips, in a full-sized gold chassis with a holographic sticker, and was priced at $300. It has since sold out.
Sources (15)
- Small Stone, Electro-Harmonix (www.ehx.com)
- “Jimi was staying at a hotel in Times Square. He had his hair set in pink curlers and we would just talk band drama”: Electro-Harmonix founder Mike Matthews on befriending Hendrix, booking Chuck Berry and the birth of pedal culture, Guitar World, 2025-04-24
- Electro-Harmonix Russian Small Stone Phaser, Pedal of the Day, 2021-03-24
- Guitar FX Layouts: Electro Harmonix Small Stone, Tagboardeffects (tagboardeffects.blogspot.com), 2016-05-15
- Modulation Nation: Chorus, Phasing, and Flanging, Premier Guitar, 2018-09-20
- TONEHOME, TONEHOME
- Electro-Harmonix Small Stone Reissue, barryrudolph.com, 2021
- EHX™ Small Stone™ Phaser: Circuit Information & Schematic, General Guitar Gadgets, 2014-05-18
- 5 great phaser pedals guitar players need to try, MusicRadar, 2021-05-17
- ARE VINTAGE PEDALS BETTER?, JHS Pedals
- MXR launches the Deep Phase, a new compact two-knob phaser, Guitar.com, 2021-10-04
- aNaLoG.MaN Guitar Effects Electro-Harmonix pedals, analogman.com, 2024
- Redshift Deluxe Phaser / Blackout Whetstone, Aion FX, 2020-06-19
- Best guitar pedals for beginners: kickstart your 'board, Guitar World, 2020-12-01
- 5 Reasons Everyone Needs a Phaser, EarthQuaker Devices, 1970
