Written from devices/oberheim/ob_xa.electra-mravitz.fw-encore.jsonEdit on GitHub JSON

Oberheim OB-Xa (per Electra preset) MIDI CC chart, NRPN and OSC map

The Oberheim OB-Xa MIDI implementation: 37 CC, 1 SysEx commands, each named, for Claude (MCP), SuperCollider or any OSC app.

sourceElectra One preset
firmwareencore
real unitnot yet checked

Not checked on a real Oberheim OB-Xa yet. Own one? Load a sound or send a control, and tell us whether it worked.

Maker: Oberheim
Version: per Electra preset
Source: Electra One preset
OSC prefix: /ob_xa

Use 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/oberheim/ob_xa.electra-mravitz.fw-encore.json --out-port <N> --in-port <M>

Then send OSC to 127.0.0.1:7777, for example:

osc-bridge osc-send /ob_xa/osc_1_wave 63

From Claude or any MCP client, the osc-bridge mcp server exposes this driver as ob_xa: ask “what can the Oberheim OB-Xa do?” and it reads this map with list_routes. See the MCP guide.

MIDI controls

38 controls, each with its number, its range and the name to send

Control	CC	Range	Name to send
Osc 1 wave	102	0–127	`/ob_xa/osc_1_wave`
Osc 1 freq	28	0–127	`/ob_xa/osc_1_freq`
Osc pw	19	0–127	`/ob_xa/osc_pw`
Osc 1 sync	104	0–127	`/ob_xa/osc_1_sync`
Lfo rate	80	0–127	`/ob_xa/lfo_rate`
Lfo wave	88	0–127	`/ob_xa/lfo_wave`
Osc 2 wave	106	0–127	`/ob_xa/osc_2_wave`
Osc 2 freq	29	0–127	`/ob_xa/osc_2_freq`
Osc 2 detune	30	0–127	`/ob_xa/osc_2_detune`
Osc 2 filt env	105	0–127	`/ob_xa/osc_2_filt_env`
Lfo depth	1	0–127	`/ob_xa/lfo_depth`
Lfo depth	81	0–127	`/ob_xa/lfo_depth`
Vcf cutoff	16	0–127	`/ob_xa/vcf_cutoff`
Vcf resonance	17	0–127	`/ob_xa/vcf_resonance`
Vcf modulation	18	0–127	`/ob_xa/vcf_modulation`
Filter track	113	0–127	`/ob_xa/filter_track`
Osc 1	85	0–127	`/ob_xa/osc_1`
Osc 1	82	0–127	`/ob_xa/osc_1`
Osc 1 on off	108	0–127	`/ob_xa/osc_1_on_off`
Osc 2 on off	109	0–127	`/ob_xa/osc_2_on_off`
Noise on off	111	0–127	`/ob_xa/noise_on_off`
Filter 4 pole	112	0–127	`/ob_xa/filter_4_pole`
Osc 2	86	0–127	`/ob_xa/osc_2`
Osc 2	83	0–127	`/ob_xa/osc_2`
Vcf attack	20	0–127	`/ob_xa/vcf_attack`
Vcf attack	21	0–127	`/ob_xa/vcf_attack`
Vcf attack	22	0–127	`/ob_xa/vcf_attack`
Vcf attack	23	0–127	`/ob_xa/vcf_attack`
Filter	87	0–127	`/ob_xa/filter`
Vca attack	24	0–127	`/ob_xa/vca_attack`
Vca attack	25	0–127	`/ob_xa/vca_attack`
Vca attack	26	0–127	`/ob_xa/vca_attack`
Vca attack	27	0–127	`/ob_xa/vca_attack`
Portamento	5	0–127	`/ob_xa/portamento`
Unison	114	0–127	`/ob_xa/unison`
Split double	89	0–127	`/ob_xa/split_double`
Upper lower	90	0–127	`/ob_xa/upper_lower`

SysEx commands

Command	Arguments	Name to send
Tune	val: u7	`/ob_xa/tune`

Performance MIDI

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

JSON

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.

Other versions

The Oberheim OB-Xa is mapped in 2 versions. per Electra preset.

Frequently asked questions

Which MIDI CC controls the filter cutoff on the Oberheim OB-Xa?

CC 16 (0–127), named /ob_xa/vcf_cutoff in SynthHub's map.

How many parameters of the Oberheim OB-Xa can be controlled over MIDI?

SynthHub's map of the Oberheim OB-Xa lists 37 MIDI CC parameters, each with its number, range and a readable name; the full chart is on this page.

Can an AI agent like Claude control the Oberheim OB-Xa?

Yes: SynthHub's hosted MCP server knows the Oberheim OB-Xa's MIDI map, and its browser relay lets the agent send it parameter changes or load a sound, each sound change confirmed by you.