The Electro-Harmonix Talking Machine is a vocal formant filter pedal: an envelope filter that uses multiple moving filters to make a guitar or bass imitate the vowel sounds of human speech. Electro-Harmonix describes the Stereo Talking Machine as a "highly customizable envelope-controlled digital vowel filter" that turns your instrument's signal into talking, singing tones1. At its heart, as Delicious Audio's reviewer Howard Stock put it, "is, at its heart, an envelope filter," one that speaks in vowels rather than the single-band sweep of a traditional wah2.
The pedal was released in 2011 as the Stereo Talking Machine and discontinued in 2022, so it is now found secondhand or as remaining stock1. It sits in a long line of Electro-Harmonix filter pedals, from the Doctor Q and Q-Tron family to the Bass Balls mode built into this very box.
What it does to your sound
Where a wah pedal sweeps one band-pass filter, the Talking Machine moves several filters at once, the way the human vocal tract shapes formants to produce "AH," "OO," and "EE." Vintage Guitar reported at launch that its nine selectable Voices deliver vowel sounds such as AH-OO and OW-EE, as well as Bassballs and wah-type dynamic filters6. MusicRadar's NAMM 2011 announcement said the resulting effects "imitate characteristics of human speech and create sounds that are both organic and harmonically rich"4.
The filters respond to your playing dynamics: the Sensitivity control sets the input volume at which the filters start moving, so a harder attack triggers the vowel sweep and a softer one leaves it still1. Delicious Audio's review adds that the speed of the sounds can be adjusted forward and in reverse, "effectively doubling your filters"2.
The controls and presets
The pedal keeps its front panel simple, with the deeper editing tucked into an auxiliary mode7.
| Control or switch | What it does |
|---|---|
| SENSITIVITY (with voice polarity) | Sets the input volume at which the filters start moving1 |
| VOICE TYPE | Selects one of the nine voice options1 |
| PRESETS encoder | Scrolls through presets; press and hold 3 seconds to save; press and release to toggle auxiliary functions1 |
| PRESET footswitch | Press and release to load a selected preset; press and hold to enter auxiliary knob edit mode1 |
| BYPASS footswitch | Toggles between Effect mode and buffered bypass; red LED indicates Effect mode1 |
Nine preset locations let you store and instantly recall favorite programs1. The pedal ships loaded with nine preset sounds, and you can overwrite these by holding down the white preset button2. MusicRadar's review notes that pressing the Presets dial puts the pedal in aux mode, replacing the standard controls with hidden auxiliary functions7. The voices themselves can be shaped with individual Attack and Decay controls, which set how quickly each vowel swells in and fades out3.
The Bass Balls mode and the voices
The nine voices break down as seven vowel sounds plus EHX's signature Bass Balls effect and an auto wah2. The Bass Balls voice recreates the classic dual-filter sweep of the original Bass Balls envelope pedal inside the Talking Machine, so a player gets that funk staple without a second box on the board. The auto wah voice covers the more conventional envelope-filter territory of pedals like the Micro Q-Tron or Riddle.
Expression pedal use
An expression pedal can be plugged into the EXP PEDAL jack for manual control of the filters, which Electro-Harmonix says enables interaction similar to a wah-wah pedal1. In practice, this gives real-time control over the filter sweeps: you rock the pedal to move the formants by hand instead of letting your attack trigger them1. Delicious Audio's reviewer confirms you can use an expression pedal to control the sweep as you would with a traditional wah2.
The Stereo Talking Machine version
The version most players know is the Stereo Talking Machine, introduced at NAMM in January 20111. As its name suggests, it has true stereo outputs3, and Delicious Audio's review notes additional features include optional stereo out plus a send/return circuit for inserting other effects into the filter path2. Everything fits in a compact 6" x 4.7" metal box2.
Premier Guitar's review recorded the street price as $215 at the time of its 2023 review5, while MusicRadar's launch announcement gave a US list price of $290 in 20114. Delicious Audio's 2025 review put the street price at $2202.
What reviewers said
Reviews were positive about the concept while flagging the learning curve. Delicious Audio's Howard Stock wrote2:
"Because of the nature of the beast (filters are complex effects) it takes a commitment of time to get the most out of the Talking Machine, but the enormous functionality combined with a solid build make this pedal a superb tool for sonic pioneers."2
His review treats the Talking Machine as a deep filter that rewards patient dialing-in rather than an instant-gratification stompbox. MusicRadar's review highlighted the hidden auxiliary functions behind the Presets dial as part of what makes the pedal more customizable than its small panel suggests7.
Power and practical notes
The Talking Machine does not take batteries and runs on its included adapter only2. Premier Guitar's review confirms the Stereo Talking Machine runs on a DC adapter only5. Electro-Harmonix ships a 9.6V DC, 200mA adapter in the box1, so check supply compatibility before substituting a standard pedal supply.
Videos
Premier Guitar
EHX
Gelb Music
Sources (7)
- Stereo Talking Machine, Electro-Harmonix, 2022
- Electro Harmonix Talking Machine, Delicious Audio, 2025-09-10
- Electro-Harmonix Announces Stereo Talking Machine, Premier Guitar, 2011-01-14
- NAMM 2011: Electro-Harmonix Stereo Talking Machine unveiled, MusicRadar, 2011-01-20
- Electro-Harmonix Stereo Talking Machine Pedal Review, Premier Guitar, 2011-08-16
- Electro-Harmonix Intros Stereo Talking Machine, Vintage Guitar magazine, 2011-06-08
- Electro-Harmonix Stereo Talking Machine review, MusicRadar, 2011-07-19
