twotracks

twotracks · effects · schema v6

Two-reel tape loop emulator with record, overdub, scrub and Lofi character. Phase 1 ships reel A: patch stereo audio into L/R inputs, arm with the ARM gate or REC gate, and the tape records destructively (REC mode) or additively (OVERDUB mode, with a DECAY knob that fades previous passes by 0.50–0.90× per loop). A draggable blue playhead scrubs the cursor within the current window (START/END markers); rate is varispeed (1.0 = forward unity, negative = reverse, 0 = frozen). Mode toggle selects TAPE (one-shot: record one pass then play, play once then stop) or LOOP TAPE (loops continuously). Transport state is reflected by REC/ARM/PLAY/OVERDUB LEDs. Gate inputs for all transport events so gates or sequencers can drive the transport via cable. Save tape exports the current buffer as a stereo 48 kHz 16-bit WAV. Phase 2 adds reel B, EQ, and filter; Phase 3 adds Lofi saturation; Phase 4 adds CV ins and persistence polish.

A two-reel tape-loop emulator — two independent tape decks (reel A and reel B) in one box, mixed to a stereo output. Each reel records the stereo audio at its inputs onto a fixed-length 'blank tape', then plays the captured take back: you set a loop window (START / END) within the tape, a tape RATE (which slows, speeds, or reverses playback and pitch like a varispeed reel), an ECHOES feedback amount for tape-echo-style repeats, and per-reel 3-band EQ + a multimode filter to colour the playback. Recording is driven hands-free by the per-reel REC START / REC ARM / OVERDUB gate inputs (or the on-card transport), and OVERDUB layers new input onto the existing loop sound-on-sound. The two reels are blended by the global A/B crossfader, can cross-feed into each other (A→B and B→A) for runaway tape-loop textures, and a global LOFI option degrades the sound; MONITOR passes the live input through. The card draws each reel's live waveform + playhead and can export a take to WAV.

the faceplate

10 inputs · 2 outputs · 31 params

about this module

Hover a control, or open the patch panel and hover a jack.

inputs

id	cable	what it does
`audio_l_in_a`	audio	Left audio into reel A's record path. While reel A is recording or overdubbing, this is what gets written to the tape; pairs with the right input. audio signal
`audio_r_in_a`	audio	Right audio into reel A's record path, partnering the left input. audio signal
`rec_start_a`	gate	Reel A record START gate: a rising edge starts (or restarts) recording onto reel A from the head of the tape. Drive it from a clock/button to capture a take hands-free. gate / trigger
`rec_arm_a`	gate	Reel A record ARM gate: a rising edge arms reel A so the next pass (or the next REC START) drops into record — the "ready to record" toggle. gate / trigger
`overdub_a`	gate	Reel A OVERDUB gate: a rising edge toggles overdub (sound-on-sound) mode, layering new input onto the existing loop instead of erasing it. gate / trigger
`audio_l_in_b`	audio	Left audio into reel B's record path. While reel B is recording or overdubbing, this is what gets written to the tape; pairs with the right input. audio signal
`audio_r_in_b`	audio	Right audio into reel B's record path, partnering the left input. audio signal
`rec_start_b`	gate	Reel B record START gate: a rising edge starts (or restarts) recording onto reel B from the head of the tape. Drive it from a clock/button to capture a take hands-free. gate / trigger
`rec_arm_b`	gate	Reel B record ARM gate: a rising edge arms reel B so the next pass (or the next REC START) drops into record — the "ready to record" toggle. gate / trigger
`overdub_b`	gate	Reel B OVERDUB gate: a rising edge toggles overdub (sound-on-sound) mode, layering new input onto the existing loop instead of erasing it. gate / trigger

outputs

id	cable	what it does
`out_l`	audio	Left channel of the mixed stereo output — reels A and B summed per the A/B crossfader (and any cross-feed), post per-reel EQ/filter and the global LOFI stage. audio signal
`out_r`	audio	Right channel of the mixed stereo output, the partner of OUT L. audio signal

params

id	label	range	default	curve
`rate_a`	Rate A	-3..3	1	linear
`mode_a`	Mode A	0..1	1	discrete
`echoes_a`	Echoes A	1..5	3	discrete
`start_a`	Start A	0..1	0	linear
`end_a`	End A	0..1	1	linear
`overdub_flag_a`	Overdub A	0..1	0	discrete
`playhead_a`	Playhead A	0..1	0	linear
`eqLow_a`	EQ Low A	-12..12dB	0	linear
`eqMid_a`	EQ Mid A	-12..12dB	0	linear
`eqHigh_a`	EQ Hi A	-12..12dB	0	linear
`filterMode_a`	Flt Mode A	0..3	0	discrete
`cutoff_a`	Cutoff A	20..20000Hz	20000	log
`reso_a`	Reso A	0..1	0	linear
`rate_b`	Rate B	-3..3	1	linear
`mode_b`	Mode B	0..1	1	discrete
`echoes_b`	Echoes B	1..5	3	discrete
`start_b`	Start B	0..1	0	linear
`end_b`	End B	0..1	1	linear
`overdub_flag_b`	Overdub B	0..1	0	discrete
`playhead_b`	Playhead B	0..1	0	linear
`eqLow_b`	EQ Low B	-12..12dB	0	linear
`eqMid_b`	EQ Mid B	-12..12dB	0	linear
`eqHigh_b`	EQ Hi B	-12..12dB	0	linear
`filterMode_b`	Flt Mode B	0..3	0	discrete
`cutoff_b`	Cutoff B	20..20000Hz	20000	log
`reso_b`	Reso B	0..1	0	linear
`ab`	A/B	0..1	0	linear
`a2b`	A→B	0..1	0	linear
`b2a`	B→A	0..1	0	linear
`lofi`	Lofi	0..3	0	discrete
`monitor`	Monitor	0..1	0	discrete

controls

control	what it does
A→B	Cross-feed A→B (0..1) — routes reel A's playback into reel B's input/record path; with overdub this builds layered, evolving tape loops (raise carefully — it can run away).
A/B	A/B crossfade (0..1) — blends the two reels in the output: 0 = reel A only, 0.5 = both at unity, 1 = reel B only.
B→A	Cross-feed B→A (0..1) — routes reel B's playback into reel A's input/record path (the mirror of A→B).
Cutoff A	Reel A filter CUTOFF (20 Hz..20 kHz, log) — the corner of reel A's playback filter (active per FILTER MODE).
Cutoff B	Reel B filter CUTOFF (20 Hz..20 kHz, log) — the corner of reel B's playback filter (active per FILTER MODE).
Echoes A	Reel A ECHOES (1..5) — sets the feedback/repeat behavior: how many times the recorded loop re-circulates (and decays) like a tape echo.
Echoes B	Reel B ECHOES (1..5) — sets the feedback/repeat behavior: how many times the recorded loop re-circulates (and decays) like a tape echo.
End A	Reel A loop END (0..1) — the right edge of the playback window within the recorded tape.
End B	Reel B loop END (0..1) — the right edge of the playback window within the recorded tape.
EQ Hi A	Reel A EQ HIGH (±12 dB) — high-band shelf on reel A's playback.
EQ Hi B	Reel B EQ HIGH (±12 dB) — high-band shelf on reel B's playback.
EQ Low A	Reel A EQ LOW (±12 dB) — low-band shelf on reel A's playback.
EQ Low B	Reel B EQ LOW (±12 dB) — low-band shelf on reel B's playback.
EQ Mid A	Reel A EQ MID (±12 dB) — mid-band on reel A's playback.
EQ Mid B	Reel B EQ MID (±12 dB) — mid-band on reel B's playback.
Flt Mode A	Reel A FILTER MODE — off / low-pass / high-pass / band-pass selector for reel A's playback filter.
Flt Mode B	Reel B FILTER MODE — off / low-pass / high-pass / band-pass selector for reel B's playback filter.
Lofi	LOFI degradation (0..3) — a global tape-degradation amount that adds wow/flutter/bit-grit character; 0 = clean.
Mode A	Reel A MODE (LOOP vs ONE-SHOT) — whether the reel loops continuously or plays its take once.
Mode B	Reel B MODE (LOOP vs ONE-SHOT) — whether the reel loops continuously or plays its take once.
Monitor	MONITOR (on/off) — passes the live input signal through to the output so you can hear what you're about to record (input monitoring), independent of playback.
Overdub A	Reel A overdub state flag (0/1) — the persisted on/off of overdub mode (the button form of the OVERDUB gate); when on, new input layers onto the existing loop.
Overdub B	Reel B overdub state flag (0/1) — the persisted on/off of overdub mode (the button form of the OVERDUB gate); when on, new input layers onto the existing loop.
Playhead A	Reel A playhead position (0..1) — the live read position on the tape; scrub it to jump within the take (the card draws it on the waveform).
Playhead B	Reel B playhead position (0..1) — the live read position on the tape; scrub it to jump within the take (the card draws it on the waveform).
Rate A	Reel A tape RATE (−3..+3) — playback/record speed and direction; 1 = normal, fractions slow it down and pitch it lower, negatives play the tape backwards.
Rate B	Reel B tape RATE (−3..+3) — playback/record speed and direction; 1 = normal, fractions slow it down and pitch it lower, negatives play the tape backwards.
Reso A	Reel A filter RESONANCE (0..1) — emphasis at reel A's filter cutoff.
Reso B	Reel B filter RESONANCE (0..1) — emphasis at reel B's filter cutoff.
Start A	Reel A loop START (0..1) — the left edge of the playback window within the recorded tape (you can't drag it past the playhead while rolling).
Start B	Reel B loop START (0..1) — the left edge of the playback window within the recorded tape (you can't drag it past the playhead while rolling).

source

twotracks.ts on GitHub.