The Electro-Harmonix Tube Zipper is a distortion pedal with a twist: it is actually two effects in one box, an envelope filter and a distortion unit, with the distortion driven by a pair of 12AX7 tubes that plug into the top of the chassis1. Released around 2000 or 2001, it was hailed by its creators as the greatest product Electro-Harmonix had introduced in over 20 years23. It is a descendant of the original E-H Zipper envelope filter, which Vintage Guitar notes is now a hard-to-find collectible1.
What it does
An envelope filter sweeps a filter in response to how hard you pick, so the Tube Zipper reacts to your playing dynamics rather than running on a fixed cycle like a phaser. The distortion stage sits after the filter, and the tubes give it a character JHS Pedals summed up bluntly: "It has two 12AX7 tubes, so it's massive"3. Because the filter and the tube distortion interact, the resulting tones shift with every small change in controls and attack, which is both the pedal's draw and its challenge.
The controls
Vintage Guitar's review laid out the front panel like this1:
| Control | What it does |
|---|---|
| Drive | Adjusts the amount of distortion after the filter |
| Resonance | Sets the center point of the sweep |
| Sensitivity | Adjusts filter sweep range |
| Envelope (ENV) | Selects the direction of the filter sweep |
| Mode | Selects Tron or Trill |
| Master Volume | Sets the overall output |
A standard on/off stomp switch, true bypass, turns the whole thing on and off1.
Tron and Trill modes
The Mode switch selects between two behaviors. In Tron, the filter sweeps smoothly, the classic envelope-follower sound. In Trill, the pedal adds what Vintage Guitar called a funky modulation on top of the sweep1. Between the mode choice, the sweep direction on the ENV control, and the Sensitivity and Resonance settings, the two modes cover a wide range of filtered and distorted textures.
Where it came from
The Tube Zipper was developed jointly by Mike Matthews, E-H's founder and the figure Vintage Guitar called its legendary stompbox guru, and Tom Barmentloo, in collaboration with E-H's engineers12. It arrived around 2000 or 2001, a period JHS Pedals described as making it something of an enigma in the company's catalog3. It carried a list price of $378 at the time of the 2002 review1.
What reviewers said
Vintage Guitar tested the Tube Zipper with a Les Paul Custom fitted with Seymour Duncan JB and '59 humbuckers plugged straight into a hot-rodded 100-watt Marshall plexi stack2. Their verdict on the experience of using it:
"It was very easy to dial up unique, inspiring effects, even if it's a bit of a challenge to remember how you arrived at"
The reviewer found the resulting tones significantly different with every slight manipulation of the controls, which made the pedal easy to explore but hard to recreate a specific sound on later1. JHS Pedals, writing decades later, counted it among Electro-Harmonix's underrated pedals3.
Videos
EHX
THE MUSICIAN NETWORK (TMNtv)
JetCityMusic
Questions
Does the Electro-Harmonix Tube Zipper run on batteries?
No. The Tube Zipper is powered by an AC adapter and does not run on batteries, which is worth knowing before planning a pedalboard around it. The tubes need more current than a 9V battery can supply.
Is the Tube Zipper true bypass?
Yes. Vintage Guitar's review describes it as having a true bypass on/off stomp switch, so with the effect off the signal passes through without the circuit in the path.
What tubes does the EHX Tube Zipper use?
It uses a pair of 12AX7 tubes, the common dual-triode preamp tube, and they plug into the top of the box rather than being hidden inside.
Who designed the Electro-Harmonix Tube Zipper?
Vintage Guitar reports it was developed jointly by Mike Matthews, Electro-Harmonix's founder and longtime stompbox figure, together with Tom Barmentloo, in collaboration with E-H's engineers.
Is the Tube Zipper still made?
The Tube Zipper was released around 2000 or 2001 and is not part of the current Electro-Harmonix lineup. As of the 2002 review it was available from dealers selling E-H and New Sensor products, but it is now a discontinued pedal.
Sources (3)
- Electro-Harmonix Tube Zipper, Vintage Guitar magazine, 2003-12-30
- Electro-Harmonix Tube Zipper, Vintage Guitar magazine, 2003-09-11
- UNDERRATED ELECTRO-HARMONIX PEDALS, JHS Pedals
