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  • Encodes 8 analog inputs into ADAT Lightpipe
  • Decodes ADAT Lightpipe into 8 analog outputs
  • DC-coupled outputs support both CV and audio signals
  • Selectable 44.1/48 kHz internal sample clock or external sync
  • Dual LED indication of output signal strength and polarity

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This product has been discontinued as we prepare for the launch of Optx v2, which includes multiple improvements in both performance and features. Sign up for the stock notification above, and you will be notified when Optx v2 is ready. Thank you for your interest and patience!

Straightforward ADAT conversion

Optx is a compact and bi-directional ADAT lightpipe converter for eurorack synthesizers. The module provides 8 channels of input and output expansion to many pro audio interfaces, and may be used standalone to interconnect eurorack systems.

ADAT Encoding & Decoding

Some computer audio interfaces are equipped with one or more pairs of ADAT expansion ports allowing for additional input and output channels. Optx takes full advantage of these often unused ports, providing multi-channel connections directly to and from eurorack systems.

The module accepts any 8-channel ADAT encoded digital signal at the Rx TOSLINK jack (via lightpipe optical cable) and converts it into 8 discrete analog signals available at the OUT 1-8 jacks.

Conversely, Optx accepts 8 discrete analog signals at the IN 1-8 jacks and converts them into an 8-channel ADAT encoded digital signal available at the Tx jack.


The module’s analog outputs are DC-coupled, meaning signals can be AC (audio) or DC (control voltages). So when used in conjunction with software such as Bitwig Studio or Ableton CV Tools, Optx becomes an interface for outgoing control voltages like 1V/oct pitch and gate signals, or LFOs, ADSRs and other modulators. The amount of creative potential here cannot be overstated.

Sample Clock Synchronization

The module has three options for sample clock sync, selectable using the 3-way switch.

44.1Generates and syncs to internal clock of 44.1 kHz
EXTSyncs to external clock from ADAT signal at Rx
48Generates and syncs to internal clock of 48 kHz

With the switch set to EXT, the blue EXT SYNC LED will illuminate when a valid sample clock is detected at Rx.

Signal LEDs

Optx also provides visual signal indication of the 8 decoded ADAT channels feeding the OUT 1-8 jacks. Each pair of WHITE LEDs indicates the polarity (-Ve left, +Ve right) and relative strength of the signal (± 10 V).

Audio-rate signals will generally light both LEDs continuously, whereas LFOs will alternate more apparently between the two. Gates, triggers and positive-going envelopes will generally light only the right LED (+Ve).

technical specs

  • Width: 8 HP
  • Depth: 1.5 in (38 mm)
  • Weight: 3.7 oz (105 g)
  • Resolution: 24 bit, 44.1/48 kHz
  • Max I/O Level: ± 10 V (20 Vpp)
  • Power: +12 V 78 mA, -12 V 78 mA

patch tips

CV/GATE/MOD & AUDIO RETURNS – Use CV capable software such as Bitwig Studio or Ableton CV tools to send pitch, gate, and modulation signals to Optx outputs. Patch them respectively into a 1V/oct oscillator, envelope gate input, and filter cutoff control. Then patch the audio signal(s) back to the Optx inputs to mix within the DAW software. Instrument tracks can then contain both the sequence data and audio returns for simple and powerful integration with your eurorack synth.

NOTE: 1V/oct signals will require calibration within the software.

DRUM TRIGGERS & AUDIO RETURNS – Using a drum rack in one of the aforementioned CV capable softwares, send up to 8 drum triggers to Optx outputs. Patch them into trigger inputs of drum modules, envelopes, etc. Now patch their respective audio signals back to Optx inputs to mix and process within the DAW.

NOTE: Some drum modules are responsive to varying trigger voltage. If the trigger CV output level is modulated using velocity/etc in the software, then Optx will dynamically produce trigger voltages based on velocity!



Expanding Your Audio Interface (Without Buying A New One!)