Output Matrix for Elektron Octatrack

Turn the headphone jack into a third assignable output pair and pick each track's outputs with CUE + LEVEL.

Module version 0.1.0-experimental. Base firmware: 1.40C.

About this module

Adds MATRIX beside NORMAL and STUDIO in PROJECT > CONTROL > AUDIO (the box stock calls CUE CFG, titled OUT CFG with the module). In MATRIX, LEVEL sets a track's level and CUE + LEVEL chooses where it plays: MAIN, CUE or PHONES as stereo pairs in any combination, or a single mono jack of the six (track L+R summed at half each, so a centred sound keeps its level). The choice is stored in the Part, so it survives SRC page resets, Part reload and project save. The MIXER's MIX knob becomes the PHONES output level. Inputs keep their stock DIR routing to MAIN.

• Three stereo output pairs: MAIN, CUE and the headphone jack.
• Per track: any combination of MAIN, CUE and PHONES, or one mono jack (MAIN L/R, CUE L/R, PHONES L/R).
• Routing lives in the Part: SRC page resets and track clears leave it alone.
• With MASTER TRACK on, tracks routed to MAIN feed the master and track 8's destination picks where the master plays.

How to use it

1. PROJECT > CONTROL > AUDIO: select OUT CFG > MATRIX and press YES.
2. On a track, hold CUE: the LEV box shows the destination. Turn LEVEL to change it.
3. In the MIXER, MIX (labelled PHN) sets the PHONES output level. Choose NORMAL or STUDIO again to return to stock behaviour.

Compatibility notes

• Builds with the stock DSP code built in and takes a given-up stock effect's program memory on core 0. The builder chooses it: SPRING REV first, then PLATE REV or DARK REV when other modules also need room. The given-up effect leaves the FX2 menu.
• The MATRIX mixdown costs core 0 up to about 210 more instructions per sample than stock (every track on ALL, MASTER on, bus levels moving); every track on MAIN adds about 20.
• Switching to or from MATRIX rewrites every Part's LEVEL and cue bytes (and, into NORMAL, the project's cue settings) by documented rules; save to keep it.
• A MATRIX project opened on a stock OS loads as STUDIO with tiny cue levels; switch to NORMAL or STUDIO before flashing another OS.
• Changes core 0's mixdown and headphone crossfade; other modules that hook those sites are refused by the ledger.
• Not yet combinable with Analog BD, whose builder places DSP code only beside a reviewed list of effects.

Test evidence

The image gate passes 117 checks under the ColdFire port: every destination, mono sums, MAIN against stock, the level law, MKII, MASTER, mute, DIR, the declick, every mode-conversion rule by the keys (including track 8 as the master and the power-cycle copies), CC 51 out and a power cycle. On an MKII the author tested routing, levels, the MIXER, everyday flows, saving and power and the conversion (functional report, 7–9 Oct 2026). No timed stress run, no chip timing.