CV.OCD - A super flexible MIDI to CV box
CV.OCD - A super flexible MIDI to CV box
CV.OCD - A super flexible MIDI to CV box

CV.OCD

£119.00

Super-flexible MIDI to CV convertor

Clear

CV.OCD is a device which converts MIDI signals to the Control Voltage (CV) and Trigger/Gate signals which are used to control traditional analog synthesizers.

As well as doing this useful bit of “plumbing”, CV.OCD is designed to open up some creative options that go beyond what a simple MIDI-CV converter can usually do.

CV.OCD has four assignable “continuous” analog CV outputs and twelve assignable gate/trigger outputs

It has powerful functionality for generating clock, trigger and non-note gates from MIDI information. For controlling your analog equipment via MIDI you are probably not going to get as much bang for your buck with anything else!

Each of the FOUR analog CV outputs have 0-8V output level and 12-bit resolution and be assigned to any of

  • Note pitch (1V/octave and Hz/V)
  • Note velocity
  • Controllers (CC)
  • Pitch bend
  • Channel aftertouch
  • Fixed voltage

Each of the TWELVE gate outputs has 5V output level (Please ensure that this is a high enough voltage level to trigger your synthesizer) and can be assigned to any of

  • Note on/off
  • Note velocity above threshold
  • Controller (CC) crossing threshold
  • MIDI clock (with divider/offset and transport gate)
  • MIDI transport states/events (start/stop/running etc)

CV.OCD allows to group pitch and gate outputs to achieve configurations like

  • Play up to four monosynths together like a single polysynth by playing chords on a single MIDI channel
  • Play multiple synths cyclically with consecutive notes going to different synths
  • Implement keyboard splits to control bass and lead synths in different ranges of same keyboard

You get 12 gate outputs to play with! As well as simply gating notes you can

  • Map specific MIDI notes to specific gate outputs for triggering drum machines etc,
  • Apply velocity threshold to get an accent trigger based on the MIDI velocity or trigger different gates depending on velocity
  • Output divided and offset pulse clocks to mess with time itself!

The device is configured by MIDI system exclusive patches, which you can create using a web based configuration page. Onces installed on the device, the patch is saved during power cycles.

See the manual here Take a look at the configuration page here. If you have a question you can ask via a Tindie message or email me directly (jason at six4pix.com)

Future firmware upgrades to the device can simply be installed over MIDI as sysex files.

CV.OCD has a standard 5-pin DIN MIDI input with optical isolation. There is also a 3.5mm TRS minijack MIDI input which follows the new MMA standard. Only one of the MIDI inputs may be used at a time.

Power is 9-12V DC via a 2.1mm barrel plug with negative centre pin (This is the type of supply used with most guitar stompboxes). Use a supply with 100mA (0.1amp) or morecurrent capacity (It does not matter if the current capacity of the supply is higher). The supply must have a DC output – do not use an AC output power adaptor.

The supplies which I am re-selling as a product option are quality “wall wart” style supplies from myVolts.com. More information on these supplies is available on myVolts web site

The device comes FULLY ASSEMBLED and tested. Size approx 17.6cm x 5.5cm x 2.7cm. Approx weight 175g. Laser cut acrylic case with laser etched acrylic face plate.

Designed and hand assembled in Brighton, UK

Click below to see a nice review by Enrique Martinez

User Guide

Click here to Download: CV.OCD User Guide

Configuration Sysex Builder

CV.OCD is configured using an online form which builds a MIDI Sysex (system exclusive) file that you downline and send into the CV.OCD using your MIDI interface.

Access the CV.OCD online web configurator here

Diagnostics and FAQ

Output triggers on wrong MIDI note (For example you program CV.OCD to trip a gate in response to a D1 but you find it responds to D0 instead) Octave numbering of notes is not actually standard, for example middle C (MIDI note number 60) can be named C3 or C4 in different devices/programs. CV.OCD uses C4 for middle C – most notably, Ableton Live uses C3. In Live you’ll need to remember to sequence notes an octave higher. The actual MIDI note numbers however are always reliable, so think in terms of them if you can.

Yellow LED is not in sync with the beat MIDI clock signals are just “ticks” and do not contain any count information. Since there are 24 MIDI clock ticks for every beat, a reference point is needed so that a slave can be put in “phase” with the master (they should always be running at the same “rate”). CV.OCD needs to see a MIDI “clock start” message to get its phase synched up. Usually just stopping and starting the transport on the master is enough (as long as the master is sending MIDI transport messages). In many cases it does not actually matter if the phase is out – the exception would be if you are sending clock outputs from the CV.OCD.

Weird behaviour when controlling via CC There are four CCs which cannot be used for general control of CV/gates on the CV.OCD. These are; NRPN MSB (CC#99), NRPN LSB (CC#98), Data Entry MSB (CC#6), Data Entry LSB(CC#38). These cannot be used to control the CV and in some cases might actually cause issues by accidentally changing patch mappings. Avoid them … all other CC’s are up for grabs!

Is Hz/Volt Supported? Yes – but you may need to upgrade your firmware (see firmware page)

What is the gate voltage level CV.OCDs twelve gates are 5V (On) and 0V (Off) similar to Eurorack.

What is the CV voltage range CV.OCD’s four CV outputs can output from 0 to around 8 Volts.

What is the CV voltage accuracy CV.OCD’s four CV outputs have 12-bit DACs (Digital to Analog converters). The 12 bits are scaled over output range 0 – 8.192V giving a mininum voltage step of 0.002V. At 1V/Octave this corresponds to 2.4 cents.

Can I use one of the gates to get another CV output? No, only the four CV outputs have DACs (digital to analog converters), the gates are logic (ON/OFF) outputs – this is a hardware limitation. If you do connect a gate output to a CV input on a synth you’ll just get 2 levels (0V and 5V) – use it this way if you want to!

Can I use CV.OCD gates with an S-Trig inputs? A V-Trig to S-Trig converter would be needed. There are ways to make one yourself quite simply just using a transistor and a resistor.

Sysex load of patch fails Sysex transmission can be interrupted by any MIDI “status message” such as note on/note off/CC etc. Usually a single sending device or piece of software (e.g. a DAW) will synchronise MIDI output to avoid interruption to Sysex transmissions. However if you are using multiple pieces of software (e.g. a Sysex manager running outside of a DAW) then no synchronisation is likely taking place between the programs and Sysex transmissions might get interrupted by other MIDI activity. Avoid this by stopping playback from a DAW while uploading Sysex to CV.OCD. Also make sure you are not trying to use the firmware update mode! When you load a patch you DO NOT need to use the button. Powering up with the button held is only for firmware uploads. You send a patch to the CV.OCD in the normal play mode. Incomplete or incorrect patch function I’ve seen some USB MIDI cables/interfaces which truncate sysex blocks which can mean part of the settings contained within a patch are not sent to the CV.OCD. The CV.OCD LED indications might even show a success indication (blue and yellow LEDs on for 1 second). This can be resolved by reducing the buffer sizes for sending Sysex. In MIDI-OX you need to go to Sysex Configuration and set Low Level Output Buffers size to 64 bytes, and similar for input buffers.

Firmware Downloads

CV.OCD firmware can be downloaded as SYSEX files and programmed on to the device using a SYSEX librarian or MIDI tool (See the CV.OCD manual for information). After loading any new firmware, please reload your current CV.OCD patch via SYSEX since some firmware updates will invalidate the patch stored in the CV.OCD memory.

  • Version 5.1 BETA (25 Feb 2019) Improvements to highest/lowest/last note priority mode for improved usability with paraphonic multi-oscillator setups. Fixed stuck note gate bug.
  • RELEASE 5.0 (24 Jan 2019) Same as 4.2 beta
  • Version 4.2 BETA (10 Sep 2018) Corrected a problem where gates listening to specific MIDI notes might trigger on the wrong note when an active note input shares the same MIDI channel
  • Version 4.1 BETA (24 May 2018) Corrected a problem skipping MTC and SPP messages which could result in message misinterpretation and random outputs
  • Version 4 RELEASE (12 May 2018, previously 3.1beta) Added CV output calibration features, Tempo to BPM feature removed (to free up program memory space for calibration code)
  • Version 3 (1 Oct 2017) Same as 2.2 Beta – Renamed for general release
  • Version 2.2 BETA (20 May 2017) Added 1.2V/OCT support
  • Version 2.1 BETA (20 May 2017) Fixed a bug where negative pitch transpose did not work (could cause output at maximum CV instead)
  • Version 2 (1 Apr 2017) Same as 1.3 Beta – Renamed for general release
  • Version 1.3 BETA (12 Feb 2017) Fixes a bug where a CC assigned to a CV output would always listen on the global default MIDI channel rather than the specific channel defined for the CV output.
  • Version 1.2 BETA (28 January 2017) Adds Hz per Volt handling, up to maximum of 8 volts (for C5, MIDI note 72). Pitch bend is handled, but fractional (bent) note CV is interpolated linearly, so resulting pitch glide between whole notes will not be quite linear in Hz/V mode. Adds Transport Start/Stop gate trigger to drive sequencers that have a single gate input to toggle their running status on and off. MIDI clock START, STOP or CONTINUE will trigger the gate output in this mode.
  • Version 1 (17 October 2016) This is the original release version of the CV.OCD firmware!

BETA releases are new and have been tested but are not yet pre-installed in new devices. However feel free to try them out and let me know if you see any issues.

Source code

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