Monday, April 09, 2012

Doepfer MSY-1

MIDI-to-SYNC interface MSY1 
In 1994 Doepfer released a MIDI-to-SYNC interface called MSY1
The MSY1 was an interface that could convert MIDI realtime events CLOCK, START and STOP into the corresponding signals CLOCK and START/STOP of the SYNC standard.

The MSY1 was a nice little grey box, with only a few connections (MIDI in-Thru, SYNC out, Clock Out and Start/Stop out) and it had two LEDs that lit up when active.
It did not have a built-in power supply or an on/off switch, instead it used a simple plug-in type external power supply.

The SYNC standard (or DIN sync or sync24) was used in vintage drum computers or sequencers such as the Roland TR808 rhythm composer and the Roland TB303 bass line.

SYNC-START/STOP is a signal that indicates on the 2 possible states: START = +5V, STOP = 0V. MSY1 enables the 1:1 conversion of MIDI CLOCK to SYNC CLOCK i.e. 1 MIDI clock triggers 1 SYNC clock pulse, as well as the reduction of the tempo by dividing the incoming MIDI clock frequency by an integer factor.

SYNC-CLOCK is a periodic TTL signal (0/+5V) representing the tempo.
Inside the MSY-1 you find a 8 pole DIP switch or 8 jumpers depending upon to the type of MSY1.
With jumper 1-7 the dividing factor can be set to any value between 1 and 128.
1 corresponds to the 1:1 conversion, 128 is the maximum of frequency reduction, i.e. after 128 MIDI clocks 1 SYNC clock appears.
The last one of the 8 switches/jumpers changes the clock polarity.

The SYNC standard uses the same type of 5 pole 180ø DIN connectors as MIDI. 
But the standards do not fit as other pins are used and the signals are completely different!
So you always have to distinguish between the MIDI and SYNC connectors. 
Using a suitable cable (e.g. 5 pin DIN plug -> two 1/4" mono jack plugs) the CLOCK and/or START/STOP outputs of the MSY1 can also be used to control arpeggio, gate, trigger or other +5V/TTL controlled events of analog synthesizers via MIDI.

Find the MSY-1 manual HERE (txt)