Reason CV/Gate to Analog Synths

Friday, June 12th, 2009 | 9:00 pm and filed in Reason, Synthesizers, Gear, Tutorials.

Lately It seems like the only things I purchase from guitar cnter are connectors and jacks. Yesterday I wandered in to get (more) connectors to make some XLR to 1/8″ phone cables which would further my experiments using Reason 4.0 as a control voltage generator with some of my analog synthesizers. Surprisingly, they had some premade cables that fit the bill: Female XLR to 1/8″ mini plug!

After wiring everything up, it took about 90 seconds to find the right calibration settings and I had Reason sending Note CV and Gate CV signals out through the MOTU 896HD into an old Oberheim CPS-1 / S.E.M. module. A bit of tweaking was required to get the note cv scaling set, but after finding the right settings, I had Thor acting as a MIDI to CV converter.

With this Thor patch, it’s possible to control analog synthesizer systems (in this case the Oberheim S.E.M.) from the Reason MIDI Sequencer, Thor Pattern Sequencer, Matrix Pattern Sequencer, any LFO source in Reason, and the RPG-8 Monophonic Arpeggiator. It should also be noted that because the Reason 4.0 sequencer is sample accurate, theoretically, the synchronization should be very solid when sending CV signals through the MOTU audio interface.


This should work on Windows based computers running Reason 4.0, so PCers who are itching for Volta for windows can try this out, provided you have a proper interface. Make sure that your system meets the specifications outlined by Mark of the Unicorn on their site:

http://www.motu.com/techsupport/technotes/testing-analog-outputs-for-control-voltage-compatibility/

Disclaimer: Do not play notes into the combinator or run the song file if your system is not configured to control analog synths. The Reason file generates a DC signal directed at your audio interface which may cause problems. The CV/Gate signals are connected to the Reason Hardware Interface inputs 3 and 4. Disconnect these if you don’t know what you’re doing!

The reason song file containing the arpeggiator combinator patch is available here:

Peff - Reason CV to AudioCV.zip

The song file will not work without multiple audio outputs assigned. These should be enabled in the audio preferences. This file was calibrated for the MOTU 896HD. Other Interfaces may not be calibrated properly. You will need to adjust the KeyNote to Audio Out1 AMOUNT values on the Thor modulation matrix. Try adjusting the -29 value, and play octaves until you get a proper note division. AMOUNT Values of 79 and -17 might be more appropriate in some cases.

I have not tested this with an S-Trig system like a vintage minimoog, and I suspect that it will not work properly. As I try out new configurations, I will post updates. I’ve tested the file with an Oberheim Two-Voice and CPS-1, and an ARP 2600.

If you are using a Rewire Host application, make certain that the signal path is direct to the audio interface, and that the gain structure remains at unity.

One Response to “Reason CV/Gate to Analog Synths”

  1. Using Reason 4.0 To Control An Oberheim S.E.M. » Synthtopia Says:

    […] This is a demo of Peff using Reason 4.0 to control an Oberheim S.E.M. with CV and gate signals: I had Reason sending Note CV and Gate CV signals out through the MOTU 896 into an old Oberheim CPS-1 / S.E.M. module. A bit of tweaking was required to get the note cv scaling set, but after finding the right settings, I had Thor acting as a MIDI to CV converter. […]