PEDAL BENCH
by Stompbox Labs
← All pedals
Delay1999· Princeton Technology (TW)

PT2399 Analog-Voiced Digital Delay

The cheap, dirty, beloved 'bucket-brigade-ish' delay chip behind hundreds of DIY pedals.

⏳
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

Princeton Technology's PT2399 is a single-chip echo processor with 1024-stage CMOS delay line. Pair it with an op-amp for input/output filtering and feedback, and you have a warm, ~30-340 ms delay that degrades musically at long settings.

Signal chain preview

5 stages
Input
Input op-amp filter (low-pass at ~3 kHz)
PT2399 delay line (delay set by pin 6 resistance to GND)
Output op-amp filter
Feedback path: output sample → mix back into input via Repeats pot
Dry/wet mix
Output

Quick facts

  • Self-oscillates beautifully — push feedback past unity for runaway echoes.
  • Officially spec'd to ~340 ms; many builds push to 600 ms+ at the cost of clarity.
  • Forms the basis of the Rebote Delay, Magnus Modulus, Belton-style verbs (with three chained PT2399s).

Controls

  • Time (50k linear)
  • Repeats (100k log)
  • Mix (10k linear)

References