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Modulation1972· Electro-Harmonix (USA)

Electro-Harmonix Frequency Analyzer

Analog ring modulator — atonal bell tones, broken-radio textures, Vader's voice.

⏳
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

A four-quadrant analog multiplier (CA3080 OTA pair, or MC1496 in the reissue) multiplies the guitar signal by an internal sine-wave oscillator. Result is the sum and difference frequencies — neither the guitar pitch nor the oscillator pitch is heard, only their non-harmonic products.

Signal chain preview

5 stages
Input
Input buffer
Internal sine-wave VCO (triangle → sine wave shaper)
Four-quadrant multiplier (CA3080 pair or MC1496) multiplies input × VCO
Output filter removes DC and very-high products
Output buffer
Output

Quick facts

  • Used for the metallic clangs in classic horror and sci-fi scores; Vader's voice is a treated ring mod.
  • Reissued in 2008 with a Shift (oscillator frequency) and Fine control plus 9 V DC.
  • Genuinely musical only on single notes — chords through a ring mod sound deeply broken (which is the point).

Controls

  • Shift (oscillator coarse)
  • Fine (oscillator fine)

Mod recipes Pro

3 mods
  • Sub-audio LFO mode

    Use the ring mod as a tremolo (multiply by very low freq sine).

    How: Add an SPDT switch that swaps the VCO's timing cap from 1 nF to 1 µF — drops oscillator range to ~0.5-50 Hz.

  • External CV in

    Multiply by an external oscillator (synth or another guitar).

    How: Add a TS jack feeding the VCO's input directly to the multiplier's carrier port. Lift the internal VCO with a switch.

  • Dry blend

    Make the effect more musical by retaining some fundamental.

    How: Add a 50k linear blend pot mixing buffered dry with the ring-mod wet at the output buffer.

References