Electro-Harmonix Bassballs
Twin envelope filter with distortion — squelchy, vocal, slightly absurd.
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
Two parallel band-pass filters (one low, one high) modulated by a single envelope follower; the outputs sum back together, producing a vowel-like 'wow-wah' as the envelope sweeps. A pre-stage diode-clipping Distortion switch adds grit before the filters. Designed for bass but equally famous on guitar.
Signal chain preview
5 stagesQuick facts
- Frank Zappa's bassist Patrick O'Hearn used the Bassballs throughout the late '70s.
- Two-filter design is rare — most envelope filters use a single sweepable filter.
- Reissued in 2008 with a 9 V DC jack (the original was battery-only).
Controls
- Response (sensitivity)
- Distortion switch (on/off)
Mod recipes Pro
3 mods- Range shift switch
Move both filter centers up an octave for guitar use.
How: Halve the integrator caps on both OTA filters via an SPDT switch (e.g. 22 nF → 10 nF). Cleaner sweep on a Strat.
- Dry blend
Keep the fundamental intact while the filters quack.
How: Insert a 50k linear pot mixing buffered dry into the output sum stage.
- External envelope CV
Drive the filters from a synth envelope.
How: Add a TS jack summing 0-5 V external CV into the rectifier's smoothing cap node.