PEDAL BENCH
by Stompbox Labs
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Modulation1976· Electro-Harmonix (USA)

Electro-Harmonix Electric Mistress

BBD analog flanger with filter-matrix sweep — Andy Summers' chime and Gilmour's swirl.

⏳
Schematic pending verification

We don't ship reference schematics until they've been hand-authored against authoritative sources (manufacturer service docs, ElectroSmash analyses, GEOFEX writeups) and reviewed in the simulator. Until then, the BOM, signal chain, controls and mod notes below are accurate, and you can still add this pedal to a project — it just won't include a circuit yet.

About

An SAD1024 (and later MN3007/3207) BBD provides a short delay that's swept by a triangle LFO. The flanging effect comes from mixing the delayed signal back with the dry, producing the characteristic moving comb-filter notch. A Filter Matrix switch freezes the LFO and lets you park the comb-filter at any setting — used famously by Andy Summers in The Police.

Signal chain preview

5 stages
Input
Input op-amp buffer
SAD1024 / MN3007 BBD short delay (clocked by an external CMOS oscillator)
Triangle LFO modulates clock frequency (Rate + Depth)
Filter Matrix switch: bypasses LFO and lets manual Range pot park the delay
Wet+dry mixer with feedback path for resonance
Output

Quick facts

  • David Gilmour's 'Run Like Hell' rhythm tone is an Electric Mistress into a clean Hiwatt.
  • Andy Summers used Filter Matrix mode for the static 'flanged' shimmer on 'Walking on the Moon'.
  • Original Mistresses are noisy; the Deluxe (1979) and Stereo (1996) reissues lowered the noise floor and added stereo outs.

Controls

  • Rate
  • Range (manual sweep)
  • Color (feedback)
  • Filter Matrix switch

Mod recipes Pro

3 mods
  • Noise reduction

    Adds a compander pair to clean up the famously noisy SAD1024 path.

    How: Insert an NE571 with the compressor pre-BBD and expander post-BBD. Trim the encoder/decoder gain to unity at 1 kHz.

  • True bypass

    Removes the buffered-bypass tone load.

    How: Rewire jacks through a 3PDT footswitch and lift the FET bypass circuit.

  • Speed range expander

    Slower ballad-style sweeps.

    How: Replace Rate pot with a 1M reverse-log instead of 500k linear; add a 'slow' switch wiring a 1 µF cap parallel to the LFO timing cap.

References