Saturday, May 04, 2013

Doepfer History: Doepfer MCV1 MIDI-to-CV Converter

In 1986 Doepfer introduced the first in a series of MIDI-to-CV interfaces, the MCV1.
The MCV1 was a monophonic MIDI-to-CV/GATE-Interface that could control other vintage analog synthesizers equipped with CV and Gate/Trigger inputs via MIDI.

MCV1 front (version 4 or 5)
MCV1 was equipped with MIDI in and Thru, one CV (control voltage) output to control the VCO's (Voltage Controlled Oscillator) and a Gate/Trigger output to control the Envelope Generators.
It was suitable for synthesizers using standardized V/Octave or Hz/V and gate voltages from +5V to +12V or switched trigger (S-Trig)

The factory setting and adjustment of the CV output was 1.00V/Octave. To change or re-adjust the scale you had to insert a small screw driver into the the hole labeled ADJUST/ or SCALE right of the CV jack and turn the potentiometer setting to the desired value.
The factory setting for the GATE output was +5V voltage gate, and if you wanted to change the setting you had to remove the cover plate.
On the PC board inside you could find a  jumper that could be set in 3 ways: +5V or +U voltage gate or SWITCH TRIGGER (S-TRIG. e.g. used by MOOG).

There was also the possibility of changing additional settings by Program Change control numbers.
The interface had no separate ON/OFF switch nor have a built-in power supply. Instead it used an external plug-in type.

Back side of the MCV1 plus external adapter
The pictures probably show version 4 or 5. 
Versions 1 and 2 were available only as kits and there was no suitable housing available (i.e. pcb only). 
Version 1 had no sockets on board. The MIDI and CV/Gate sockets had to be wired manually. 
Version 2 had MIDI and CV/Gate sockets on board. MIDI channel and other parameters were adjusted by means of a DIP switch. 
Version 3 was a redesign of version 2 so that a small standard case could be used (the case in the picture). 

As far as Dieter remembers the only difference between versions 3 and 4 was the non-volatile memory. Version 3 did not store the settings (i.e. after power off the settings for MIDI channel, reference note and other parameters were lost and the unit started with Midi channel 1 and reference note 36 after the next power on). 
Version 4 had a non-volatile memory for these parameters 

The price range of the MCV1 was from around Euro 50 (kit version without case) to about Euro 90 (ready built with case).
Approximately 500 units were sold (i.e. all versions together).

Another fun fact: The guy who programmed the firmware for the MCV1 about 30 years ago showed up at the Doepfer/Alex4 booth at MusikMesse in Frankfurt this year. They had not seen each other in more than 15 years...

Find more info at

*Special thanks to Dieter Doepfer again for all additional info