1978 MXR Envelope Filter

Model Description:

During the late 1970s and early 1980s, New York‑based pedal maker MXR Innovations was turning out some very credible effect pedals such as the iconic Phase 90 and the classic Dyna Comp. A lesser‑known model in the MXR range was the Envelope Filter, which uses the dynamics of the input signal to trigger an analogue filter sweep, resulting in an auto wah‑type effect, much favoured by funk, soul and disco artists at the time. The early first generation MXR pedals featured a ‘script’ logo and model name until about 1975/6, when they changed the design to the more common, modern ‘block’ font. What is it with auto‑wahs and the colour beige? It seemed to be the de facto colour for some envelope filters at the time, including the BOSS TW‑1 Touch Wah.

Pedal Description:

This is a real hidden gem of an effect and is very possibly my favourites of its type. This inconspicuous little dirt‑coloured stomp box was made in the USA in 1978, according to the pot codes. It is in very good all‑original condition. While the 2nd generation main box exhibits the typical block logo, the baseplate has the earlier script logo. This transition combination was quite common, as MXR worked its way through surplus components. In use, the Envelope Filer is responsive, sumptuous and well‑balanced, producing a very effective touch sensitive triggered sound. In my naïve view, although simple to use, it may even be up with the very best of the breed. The analogue circuit can be a bit noisy but, hey, used judiciously the results are well worth it. Overall, it is a much underrated and very cool little pedal. Original vintage MXR Envelope Filters are relatively rare and good condition ones are becoming increasingly sought after for those looking beyond the brand’s more familiar signature pedals.


  • Made in Rochester, New York, U.S.A. in 1978
  • The ‘Threshold’ knob controls the sensitivity to the input signal
  • The ‘Attack’ knob controls the intensity of the filter sweep
  • Standard footswitch turns the effect on and off
  • Standard ¼” input and output mono jack sockets
  • 2nd generation ‘block’ MXR and model logos
  • ‘Script’ logo baseplate
  • No LED or DC power supply input – 9V battery only
  • No box or instruction manual

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