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Delay1986· Boss / Roland (Japan)

Boss DD-3 Digital Delay

Sample-rate-converted digital delay with a hold function — the pedalboard standard for clean repeats.

⏳
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

Boss's first compact digital delay. Uses a Roland custom 12-bit, 31.25 kHz sample-and-process chain to give up to 800 ms of delay across three switched ranges (50/200/800 ms). Repeats stay bright and pitch-stable, unlike analog BBD delays.

Signal chain preview

5 stages
Input
JFET input buffer + anti-aliasing low-pass filter
Sample-and-hold + 12-bit ADC (Roland custom)
RAM buffer with read pointer offset = delay time
12-bit DAC + reconstruction low-pass filter
Mix wet + dry → JFET output buffer
Output

Quick facts

  • Internally nearly identical to the DD-2 (1983) but with a longer max delay and lower cost.
  • The HOLD setting (max Delay knob, range switch on 800 ms) infinitely loops the buffer — a primitive looper.
  • Production continues virtually unchanged since 1986; one of the longest-running Boss compact pedals.

Controls

  • E.Level (effect level)
  • F.Back (feedback)
  • D.Time (delay time)
  • Mode switch (50/200/800/HOLD)

Mod recipes Pro

3 mods
  • Tails mod

    Repeats decay naturally when you disengage the pedal.

    How: Re-route the bypass switching so the dry signal is true-bypassed but the wet mix stays summed at the output.

  • Analog-style filter

    Darker, BBD-flavored repeats.

    How: Reduce the cutoff of the output reconstruction filter from ~5 kHz to ~3 kHz by doubling the filter cap; repeats lose top end each pass.

  • External tap-tempo

    Tap-tempo control via expression jack.

    How: Replace the D.Time pot with a digipot (MCP41100) driven by an ATtiny85 reading a tap-switch on the expression jack.

References