1980 Electro-Harmonix Zipper Envelope Follower

Model Description:

Exalted American effect pedal manufacturer, Electro‑Harmonix introduced the Zipper onto an unsuspecting world in early 1977 at a price of $79.99 and marketed boldly as “the guitar synthesizer”. The Zipper stayed in production for a relatively short time, up to c.1979/1980. Electro‑Harmonix was on quite a roll with envelope followers, as they also produced the smaller and simpler models, the Doctor Q and Y‑Triggered Filter (and later, the fabled Q‑Tron from the 1990s). The Zipper was the largest and most flexible of the original models, allowing greater fine tuning of the analogue filter’s response to an input signal. The effect was designed for use with guitar, bass or keyboard, hence the low pass/band pass options. At its simplest, envelope filters are often referred to as ‘auto wahs’, frequently used to produce funky wah effects without the need for constant foot control. However, as the threshold of the filter is responsive to signal strength, the Zipper is capable of more subtle analogue synth‑like sound effects. The craze for envelope followers was probably prompted by the success of the legendary Musitronics Mu‑Tron III in the 1970s, although interest had largely waned by the mid‑1980s. Apart from the Mu‑Tron, there was competition in this niche market, primarily from the BOSS Touch Wah, MXR Envelope Filter and the Ibanez Auto Filter. The controls require a bit of perseverance in order to get the most out of the pedal. Unlike some other envelope followers, the Zipper only sweeps from low to high with no option to sweep from high to low. The rejuvenated Electro‑Harmonix released an updated and more complex version called the Tube Zipper in 2001. Original vintage Zippers are now quite scarce, especially in good working condition. As the fascination with retro analogue synth technology continues to increase, the vintage market value is bound to follow the envelope (sic!).

Pedal Description:

This cool and rare 1980 Electro-Harmonix Zipper Envelope Follower is in a class of its own. To me, it is the most expressive of the envelope filter effects and my favourite of its type. I used to have one of these back in the late 1970s, so this is like revisiting an old pal. Dating Electro‑Harmonix pedals can be a bit of a minefield. Although the Zipper was on its way out by the end of the 1970s, and the feature set suggests an earlier build date, 1980 is hand written on the circuit board, so I’m going with that. It is in generally good condition with just a few scratches to the screen‑printed finish but that’s it – not at all bad considering that it has seen around four decades of use. The effect works perfectly, which is what really matters. By today’s standards and with ever more crowded pedal boards, the Zipper can take up quite a bit of floor real estate. Personally, I think it’s worth it though. Ergonomically, it is not very intuitive, as the layout and labelling of the controls don’t mean anything to the uninitiated or unwary. The best way to approach the Zipper is to experiment with it and see what it can do (NB. a fair bit) before settling on a few usable and reproducible favoured sound effects. With a little diligence, it is possible to extract some captivating grooves and spacey psychedelic filter sweeps, especially if combined with other effects like fuzz, echo and reverb. If you dig investigating leftfield soundscapes, the Zipper can be a revelation.  Say wah?


  • The ‘Range’ knob controls the frequency range over which the filter sweeps
  • The ‘Q’ knob controls the intensity of the filter relative to signal strength
  • The ‘Attack’ toggle switch actually controls the speed at which the filter sweep returns after being triggered – ‘1’ moderately fast and ‘2’ rapid
  • The ‘LP/BP’ EQ slide switch attenuates high frequencies (Low Pass) or both high and low frequencies (Band Pass)
  • Standard footswitch turns the effect on and off
  • Standard ¼” input and output mono jack sockets
  • No LED status indicator
  • 9V DC power supply input or 9V battery
  • No battery compartment in the base of the unit
  • Phillips screws on the top of the pedal
  • No box or instructions

Detail Gallery:

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