The ThorpyFX ER-2 is an all-analog Uni-Vibe pedal from UK builder ThorpyFX, designed by Adrian Thorpe and first released in June 202312. Rather than cloning the vintage circuit outright, ThorpyFX says it designed the vibe circuit "from the ground up" to cover "the best of all worlds," aiming at decade-spanning classic Uni-Vibe modulation that lets you sound like as many of the classic records that use the effect as possible34.
Like the original 1960s Uni-Vibe, the ER-2 is an optical design: its modulation comes from a pulsating lamp whose changing brightness is read by light-dependent resistors, in the original version four of them51. A second footswitch (Vib/Cho) switches between Uni-Vibe Chorus mode and Vibrato mode, which is wet signal only52.
What the ER-2 does: an optical Uni-Vibe
The Uni-Vibe is a classic modulation effect, loved by many, and ThorpyFX had wanted to do its own take on the circuit for a long time7. The key to the true Uni-Vibe sound is the optical circuitry: the original utilized four light-dependent resistors reacting to a lightbulb's changes in brightness, and Thorpy's design adjusts how the internal lamp ramps up5. The ER-2 keeps the original heart of the circuit, a lamp-powered LFO system7.
Guitar World's reviewer, Trevor Curwen, found that kicked in, the overall sound gets a useful enhancement with a sweet top-end that offers plenty of clarity to aid note articulation, with loads of subtle variations on the phasey swirl, pulse and throb the Uni-Vibe is famous for5. Guitar.com's Richard Purvis found the chorus mode "nailing that uniquely chewy swirl without any obvious coloration to the overall EQ balance"1.
"Sounds great when it's trying to be a Uni-Vibe; can sound even better when it isn't."
The controls: Speed, Intensity, Offset and Output
The ER-2 has four knobs, Intensity, Offset, Speed and Volume, plus two footswitches: On/Off and Vibrato/Chorus38. Three of the knobs are the regular controls you would expect on a vibe pedal; the fourth, Offset, is the unusual one7.
| Control | What it does |
|---|---|
| Speed | Sets the pulse / throb rate of the effect9 |
| Intensity | Sets the photocell luminosity, the depth of the effect87 |
| Offset | Changes how the internal lamp ramps up, sharpening or softening the rise and fall of the LFO curve7 |
| Volume | Sets the output level, from zero, with unity gain close to midday, leaving ample range for a useful boost5 |
| Vib/Cho footswitch | Switches between Uni-Vibe Chorus and Vibrato (wet signal only) modes5 |
| On/Off footswitch | Engages and bypasses the effect8 |
The Offset knob is the control that sets the ER-2 apart. It subtly changes the way the lamp inside ramps up, delivering a sharper or softer rise and fall of the LFO curve7. Guitar.com's reviewer found the effect is minimal except at slower speeds, where you can hear it move from smooth like a phaser at minimum to a quirky asymmetrical throb at maximum1. Guitar Pedal X's Stefan Karlsson describes it as working a little like waveform symmetry or Attack/Release times between the Lit and Unlit photocell phases, with the ultimate throb found between 2 and 3 o'clock on the Offset dial10.
On intensity, Purvis noted things can get motorboaty if you push it past noon, but the effect is powerful even at much lower settings1.
Power and build
The ER-2 runs on 9V DC, center negative, through a standard DC input, drawing 150mA; the adaptor is not supplied35. There is no battery option: ThorpyFX stopped fitting battery compartments, with Adrian Thorpe saying "We used to. We don't any more. It's a waste."11 ThorpyFX recommends a high-quality supply from GigRig or Voodoo Lab's Pedalpower series4. After release, the maker found some power supplies induce noise with the pedal and designed a dedicated Power Supply Isolator for the ER-2 to prevent it12.
The build is engineered to be robust but functional, with recessed knobs, a sloped front and top-mounted jacks37. Guitar.com found the high-walled aluminum enclosure tough, and the internal construction appears to be of equally high quality as the enclosure1. Guitar World's review of another ThorpyFX pedal notes the maker's usual solid build quality13.
Versions: original, Block 2 and Block 3
The ER-2 has gone through three versions:
| Version | Date | What changed |
|---|---|---|
| Original ER-2 | June 2023 | Optical circuit with a lightbulb and LDRs86 |
| Block 2 | November 2024 | Lightbulb and LDRs removed, circuit re-engineered without RoHS-sensitive Vactrols, retaining the original tonality; more headroom106 |
| Block 3 | September 2026 | Adds a Phase Switch, Out-of-Phase or default In-Phase modulation, plus blue knobs matching its LEDs8 |
The original ER-2 has been retired and massively re-engineered for the ER-2 Block 2, with the lightbulb and LDRs removed, which makes the output more consistent and a little louder6. The Block 3 is an evolution of the Block 2, the univibe style circuit ThorpyFX designed from the ground up, benchmarked for clarity and brightness against ThorpyFX's own Camoflange Flanger38. The Block 3 edition also adds a Phase switch, defaulting to In-Phase modulation with a switchable Out-of-Phase option8.
What reviewers said
The reviewer rated the ER-2 nine out of ten, concluding "It's not cheap, but the ER-2 is good vibes all the way"1. Guitar World's reasons to buy included its authentic Uni-Vibe sound with thoughtfully added variations5. On the Block 3, Guitar Pedal X's writer said he is still very happy with his V1 ER-2, so a Block 3 is not immediately on the cards for him, but Thorpy has given newcomers one more reason to go for one8.
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Questions
Is the ThorpyFX ER-2 true bypass?
Yes. Guitar World's review lists the ER-2 with true bypass switching, so with the effect off the signal passes through without buffering. The pedal also uses a standard input and standard output for connections.
Does the ER-2 have an expression pedal input?
No. Guitar World's reviewer notes there is no expression pedal input to recreate the actions of an original Uni-Vibe's foot treadle. Speed is set with the Speed knob rather than swept with your foot.
Why was the original ER-2 retired?
The original ER-2 used a lightbulb and light-dependent resistors, and Vactrols containing cadmium sulphide fell under an evolving RoHS hard ban. Adrian Thorpe retired the pedal in the fall of 2023, and it returned in November 2024 as the re-engineered, Vactrol-free Block 2.
What does the Offset knob on the ER-2 do?
Offset subtly changes the way the internal lamp ramps up, giving a sharper or softer rise and fall of the LFO curve. Guitar.com's reviewer found the effect is most audible at slower speeds, running from smooth like a phaser at minimum to a quirky asymmetrical throb at maximum.
Where does the ER-2 name come from?
The pedal is named after NASA's high-altitude, earth-observing ER-2 plane, which itself was derived from the USAF U-2 reconnaissance aircraft. Guitar.com's reviewer also notes the enclosure is tough enough to survive being dropped from a cruising ER-2.
Sources (13)
- ThorpyFX ER-2 review: is this the ultimate modern Uni-Vibe?, Guitar.com, 2023-09-04
- Thorpy FX’s new ER-2 offers a twist on the classic Univibe pedal, Guitar.com, 2023-06-30
- ER-2 BLOCK 3, ThorpyFX
- ThorpyFX promises Uni-Vibe perfection from the compact and easy-to-use ER-2, MusicRadar, 2023-06-30
- ThorpyFX ER-2 Uni-Vibe review, Guitar World, 2023-12-13
- Guitar Pedal X, Guitar Pedal X, 2024-06-03
- Thorpy FX ER-2 Univibe, Delicious Audio, 2024-01-08
- Guitar Pedal X, Guitar Pedal X, 2026-09-18
- Guitar Pedal X, Guitar Pedal X, 2023-12-19
- Guitar Pedal X, Guitar Pedal X, 2024-11-15
- Thorpy FX, Stompbox Book (stompboxbook.com), 2020-04-12
- Power Supply Isolator for ER-2 UNI-VIBE, ThorpyFX
- ThorpyFX Electric Lightning review, Guitar World, 2024-07-05
