PEDAL BENCH
by Stompbox Labs
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Modulation1980· Boss / Roland (Japan)

Boss BF-2 Flanger

MN3207 BBD flanger — the silver Boss box behind countless '80s jet swooshes.

⏳
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

BBD-based flanger using the low-voltage MN3207 (which made it possible to run from a single 9 V supply, unlike the earlier 15-18 V analog flangers). Triangle-LFO-modulated short delay mixed with the dry signal, with resonant feedback for the deep notches.

Signal chain preview

7 stages
Input
JFET input buffer
Pre-emphasis filter + companding encoder (for noise reduction)
MN3207 BBD short delay (clocked by MN3102)
Triangle LFO modulates BBD clock
Companding decoder + de-emphasis filter
Resonant feedback path back to BBD input
Wet/dry mix → JFET output buffer
Output

Quick facts

  • Replaced the BF-1 (1977) which required 12 V; the BF-2 ran on a standard 9 V battery.
  • Used heavily by Andy Summers, Eddie Van Halen ('Unchained' intro), and The Cars.
  • Stereo version BF-2B (bass) and the digital BF-3 (2002) eventually replaced it.

Controls

  • Manual (sweep center)
  • Depth
  • Rate
  • Res (resonance/feedback)

Mod recipes Pro

3 mods
  • True bypass

    Removes the FET bypass loading.

    How: Replace the stock FET bypass with a 3PDT footswitch wiring jacks directly.

  • Slower minimum rate

    Underwater-slow sweeps for ambient work.

    How: Increase the LFO timing cap from 0.47 µF to 2.2 µF; expect minimum rate to drop from ~0.1 Hz to ~0.025 Hz.

  • Deeper resonance

    More extreme notches before self-oscillation.

    How: Increase the feedback resistor scaling — replace Res pot with a 50k log (from 25k stock). Add a 10k series safety resistor to prevent runaway oscillation.

References