Tuesday, 9 December 2014

EMS - Pitch to Voltage converter

A problem I constantly encounter is how to modulate or control synths
using old instruments that don't use any triggers/clocks or any other type of voltage control.
Buchla use the 130 & 230 modules for this task. ARP have their envelope followers.
Moog Modular used the 912 Envelope Follower. Gentle Electric had their Pitch & envelope follower. Roland had their SPV355 Pitch to Voltage Synthesizer. Even Korg got in on the act with the External Signal Processor that you will find on the MS-20.

I picked this up at a recent auction. It's a EMS Pitch to Voltage converter from the 1970s.
Maybe this is what I've been looking for.

Some photos:


These often come housed in beautiful afrormosia wood cases. Sadly in this case, the wood is gone (maybe it was never there). It's mounted in a standard 19" rack. It's 1.7" (44mm) high.

Four inputs, six outputs.

The P to VC converts an audio input into a DC voltage whose value is proportional to the pitch of that input signal.

The trigger outs seem on average to be about +4 to +5V.
Pitch Voltage:1V  per octave ( invertible) .This is unusual considering most EMS gear uses a 0.33V/octave standard.
Envelope Voltage: 1V per 6dB gain (log. or lin., invertible).

The control voltage output is selected by a dial to give 6 settings.
They are 2 for a pitch-following output., 2 for a exponential output, and 2 for an envelope-following (loudness) output.

There are 2 types of trigger. - Hold On & One Shot.
"One Shot" gives a 20 millisecond pulse every time the input level rises to a level set by the sensitivity dial.
"Hold On" gives an output all the time the input signal exceeds the trigger set level.

The  reference oscillator provides a test tone input. In the middle position the Osc is off.
The switch at the "f" position turns the oscillator on. The "2f" setting will to raise its pitch exactly one octave. (f=256Hz)






Connections to and from the modules can be made either from the jack sockets on the front panel or via the multi-way facilities socket at the back.










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