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Elektron OT & A4: MIDI CC, NRPN and OSC map

The Elektron OT & A4 as named OSC addresses — 36 CC, 33 NRPN — ready to use from Claude (MCP), SuperCollider, Sonic Pi, TouchDesigner or any OSC app via osc-bridge.

Device Elektron OT & A4
Vendor Elektron
OSC prefix /ot_a4
Source 🎛️ Derived from an Electra One community preset
Revision per Electra preset
Upstream electra-preset
Driver file devices/elektron/ot_a4.json

Not tested on the device yet

This driver comes from documentation or community data and has not been checked on real hardware. If you own one, a quick test and a pull request promoting it helps everyone — see CONTRIBUTING.

How do you control it?

Find the MIDI ports, then start the bridge with this driver:

osc-bridge detect        # prints the ready-to-run line for what is plugged in
osc-bridge run --device devices/elektron/ot_a4.json --out-port <N> --in-port <M>

Then send OSC to 127.0.0.1:7777, for example:

osc-bridge osc-send /ot_a4/tr1_lfo_speed 63

From Claude or any MCP client, the osc-bridge mcp server exposes this driver as ot_a4: ask “what can the Elektron OT & A4 do?” and it reads this map with list_routes. See the MCP guide.

MIDI CC and NRPN parameters (69)

OSC address CC NRPN (MSB/LSB) Range Nature Section
/ot_a4/tr1_lfo_speed 28 0–127 continuous
/ot_a4/filter_lp 34 0–127 continuous
/ot_a4/reverb_mix 45 0–127 continuous
/ot_a4/filter_lp 34 0–127 continuous
/ot_a4/delay_time 40 0–127 continuous
/ot_a4/arm 52 0–127 continuous
/ot_a4/tr1_lfo_depth 31 0–127 continuous
/ot_a4/filter_hp 35 0–127 continuous
/ot_a4/reverb_time 40 0–127 continuous
/ot_a4/filter_hp 35 0–127 continuous
/ot_a4/delay_fb 41 0–127 continuous
/ot_a4/delay_send 45 0–127 continuous
/ot_a4/delay_time 40 0–127 continuous
/ot_a4/delay_fb 41 0–127 continuous
/ot_a4/delay_send 45 0–127 continuous
/ot_a4/filter_lp 34 0–127 continuous
/ot_a4/delay_time 40 0–127 continuous
/ot_a4/arm 52 0–127 continuous
/ot_a4/filter_lp 34 0–127 continuous
/ot_a4/delay_time 40 0–127 continuous
/ot_a4/arm 52 0–127 continuous
/ot_a4/filter_hp 35 0–127 continuous
/ot_a4/delay_fb 41 0–127 continuous
/ot_a4/delay_send 45 0–127 continuous
/ot_a4/filter_hp 35 0–127 continuous
/ot_a4/delay_fb 41 0–127 continuous
/ot_a4/delay_send 45 0–127 continuous
/ot_a4/tr5_mute 49 0–127 continuous
/ot_a4/tr6_mute 49 0–127 continuous
/ot_a4/tr7_mute 49 0–127 continuous
/ot_a4/aux_3_4_mute 49 0–127 continuous
/ot_a4/aux_3_4_cue 51 0–127 continuous
/ot_a4/tr3_mute 49 0–127 continuous
/ot_a4/tr4_mute 49 0–127 continuous
/ot_a4/request_all 61 0–127 continuous
/ot_a4/rec_arm_t5 53 0–127 continuous
/ot_a4/f1_frq 1 / 40 0–16383 continuous
/ot_a4/f1_res 1 / 41 0–16256 continuous
/ot_a4/f1_ovr 1 / 42 0–16256 continuous
/ot_a4/f1_trk 1 / 43 0–16256 continuous
/ot_a4/f1_dep 1 / 44 0–16256 continuous
/ot_a4/reverb 1 / 57 1024–16256 continuous
/ot_a4/f2_frq 1 / 45 0–16383 continuous
/ot_a4/f2_res 1 / 46 0–16256 continuous
/ot_a4/f2_trk 1 / 48 0–16256 continuous
/ot_a4/f2_dep 1 / 49 0–16256 continuous
/ot_a4/delay 1 / 56 0–16256 continuous
/ot_a4/f1_frq 1 / 40 0–16383 continuous
/ot_a4/f1_res 1 / 41 0–16256 continuous
/ot_a4/f1_ovr 1 / 42 0–16256 continuous
/ot_a4/f1_trk 1 / 43 0–16256 continuous
/ot_a4/f1_dep 1 / 44 0–16256 continuous
/ot_a4/reverb 1 / 57 1024–16256 continuous
/ot_a4/f2_frq 1 / 45 0–16383 continuous
/ot_a4/f2_res 1 / 46 0–16256 continuous
/ot_a4/f2_trk 1 / 48 0–16256 continuous
/ot_a4/f2_dep 1 / 49 0–16256 continuous
/ot_a4/delay 1 / 56 0–16256 continuous
/ot_a4/f1_frq 1 / 40 0–16383 continuous
/ot_a4/f1_res 1 / 41 0–16256 continuous
/ot_a4/f1_ovr 1 / 42 0–16256 continuous
/ot_a4/f1_trk 1 / 43 0–16256 continuous
/ot_a4/f1_dep 1 / 44 0–16256 continuous
/ot_a4/reverb 1 / 57 1024–16256 continuous
/ot_a4/f2_frq 1 / 45 0–16383 continuous
/ot_a4/f2_res 1 / 46 0–16256 continuous
/ot_a4/f2_trk 1 / 48 0–16256 continuous
/ot_a4/f2_dep 1 / 49 0–16256 continuous
/ot_a4/delay 1 / 56 0–16256 continuous

Performance MIDI

Notes, pitch bend and any CC are also available: /ot_a4/note/on <note> <velocity>, /ot_a4/cc/<number> <value>, /ot_a4/pitchbend <0-16383>, /ot_a4/program_change <n>.

Limitations

Imported from an Electra One community preset. The mapping reflects the preset author's editorial choices: parameter naming, ranges, and which params are exposed. Untested on hardware in this repo.