Re: MPU 101 pitch bend

From weareas1
Sent Tue, Sep 2nd 1997, 10:22


The reason you are not able to pitch bend from the MPU-101 is because the
MPU-101 does not add pitch bend infomation to the channel's CV output.  The
MPU's CV output will only put out the voltage for the basic note you are

In order to use the Pitch Bend output of the MPU, you will need to slightly
modify your Pro One.  You would need to install another input jack for the
Bend voltage, and route that jack directly to the actual CV summing buss of
the oscillators.   You would connect to the buss through a resistor, with its
value selected to give you the Pitch Bend range that you desire.  100k would
probably give you a +/- one octave range, and larger values would
proportionally decrease that range.  

If what I have written above does not make complete sense to you, then you
probably should consider taking the synth to a qualified technician to do the
actual work.

It should be noted that most of the more modern MIDI to CV converters, such
as the Kenton series, have the Pitch Bend data already summed into their main
CV outs.  The ones that include built-in LFO's also sum the LFO voltage into
the main CV output, as well.  This makes it possible to more easily get
expressive control from the typical synth which only has a single basic CV

It's also important to remember that the MPU-101 was primarily designed as an
accessory for the 100M modular synths.  These synths were riddled with as
many CV inputs as anyone could ever desire (well, almost anyone..), so it was
easy to route the MPU's various CV's to wherever they may have been needed.
 Roland could very wasily have included a built-in LFO and summed the pitch
bend voltage and LFO into the main CV outs, but they kept these voltages
separate because that is what the owner of a modular system usually wants.

Michael Bacich