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How To Run Reason With Modular Synths

Propellerhead Reason Tips & Techniques
By Simon Sherbourne

Screen 1: The Silent Way device converts MIDI and CV from Reason into modular–compatible pitch CV that you can patch via audio connections.Screen 1: The Silent Way device converts MIDI and CV from Reason into modular–compatible pitch CV that you can patch via audio connections.

We show you how to get Reason and your hardware or software modular synths speaking the same language.

Last time we looked at how to connect modulation and audio sources between Reason and software modular synths. As promised, this time we'll learn how to generate note CV signals from the Rack so that you can play and sequence modular synths (soft or hard) directly from Reason.

Notes

The main story of last month's episode was that what Reason calls CV in its Rack is not the same thing as CV in your hardware modular or virtual Eurorack plug-ins. To use Reason's CV to modulate a modular synth, you have to convert it to an audio signal. We did this using Thor's routing matrix, and Robotic Bean's CV‑O Rack Extension.

If you followed along at home you may have taken the next step and tried to sequence the pitch of a modular oscillator, perhaps connecting something like the Matrix step sequencer to a software modular. If so you'll have encountered a problem: the 'voltage' from the Reason CV is not calibrated in the same way as modular note CV. You'll hear the pitch change, but it won't track correctly. What's needed here is a way to convert precisely from Reason's note CV to a voltage signal that follows a standard modular pitch convention. For Eurorack this is 1V/octave. There is a way... a Silent Way.

The Silent Way Voice Controller

British company Expert Sleepers make a number of hardware and software products for interfacing between computers and modular synth hardware. They also sell a Reason Rack Extension called Silent Way Voice Controller (£17$17 in the Prop Shop), which we'll be using here. It's actually just one part of the Silent Way suite of plug-ins, but it's exactly the part we need.

The Silent Way Voice Controller generates note CV which you can connect to your synth via an audio connection. Just like a regular RE instrument, its input can be taken directly from your MIDI keyboard, Reason's Sequencer, or CV/gate inputs in the Rack.

But it's not just a MIDI–to–CV converter: it also uses a calibration process to automatically adjust its output to produce the correct notes on the connected instrument. Let's start with a software modular to see how it works before we look at special considerations for hardware.

In Screen 1 (above) I've connected the Silent Way RE's pitch and gate outputs to the first two audio inputs on a plug-in device hosting Voltage Modular. I've also connected a Matrix sequencer to the regular Reason CV note and gate inputs on Silent Way. Inside Voltage Modular I've connected the two audio channels from Silent Way to the pitch and gate destinations on my modular patch.

Screen 2: In this Voltage Modular plug-in patch the audio inputs from Reason are connected directly to the modules' V/oct and gate  inputs.Screen 2: In this Voltage Modular plug-in patch the audio inputs from Reason are connected directly to the modules' V/oct and gate inputs.

For the calibration process, Silent Way needs an audio signal coming back from the synth. I could have split the main output from Voltage Modular but the parallel output from its mix channel is a convenient alternative.

To initiate calibration you just click the V/oct button on Silent Way's front panel. You'll then hear a series of ascending tones as Silent Way sends voltages to the synth and listens to the results. It creates an internal map which you see displayed on the dot matrix display.

If all goes well (see the 'Calibration Tips' box later, if it doesn't) you'll now be able to play your synth via the Silent Way device with pitch tracking to MIDI correctly.

Why Not Use MIDI?

Screen 3: From the front panel you can see the calibration map and various other features of the Silent Way Voice Controller.Screen 3: From the front panel you can see the calibration map and various other features of the Silent Way Voice Controller.Why, I hear you ask, should I go to all this trouble when I could just use MIDI? With software modulars you can always use MIDI, and some hardware modulars have MIDI as well as CV inputs. If you have a modular system, you probably already have a MIDI–to–CV converter somewhere too.

Well, first this method is obviously ideal if you don't have the option to connect another way, and frees up any hardware converter you have for other tasks. But beyond this there are some juicy extra features in the Silent Way device that you don't get in your average MIDI–to–CV converter.

Looking on the front panel you'll see a set of utilities for defining the voltage ranges for gate, trigger and velocity (Screen 3). You can also adjust trigger lengths and bend range on the right-hand side. Not exciting enough? OK, you can offset the overall pitch with the coarse and fine tuning knobs, and also define how overlapped notes are treated using the priority and legato settings.

But the real gem is the Portamento section, which can generate glide in the CV output. 'Auto' will glide between all notes, while 'Fingered' will only glide overlapped notes. The killer feature for me is 'Constant Time' portamento, enabled with the 'CT Auto' and 'CT Fingered' modes. This is the classic acid glide mode and is the key to authentic 303 sounds.

There's another hidden bonus of using Silent Way and CV instead of MIDI: timing. MIDI is awesomely useful, but it can be prone to jitter, response delays, etc. With an audio signal carrying analogue control signals direct to your instruments you can approach sample accurate timing alongside your audio tracks.

Connecting Hardware

Screen 4: When controlling a  hardware modular, connect Silent Way directly to spare outputs on your compatible audio interface.Screen 4: When controlling a hardware modular, connect Silent Way directly to spare outputs on your compatible audio interface.To sequence and play hardware synths via Silent Way, you need physical audio connections between Reason and your modular (Screen 4). To do this your audio interface needs to have DC-coupled analogue outputs. There's a list of interfaces that are known to work on the Expert Sleepers website. If you have a modular and get seriously into this way of working, Expert Sleepers also have some dedicated hardware solutions. For example, they have a USB audio interface in Eurorack format, and a lightpipe to DC-coupled analogue converter that uses the often unused ADAT connectors on your interface.

The other thing you'll need is the right cables. Typically you'll need quarter-inch TRS to 3.5mm TS cables to get from your interface's outputs to the CV/gate inputs on a modular, but they should also be wired in a particular way to work properly. The recommendation is to have the tips and shields connected, but the ring unconnected. You can make these up, but I bought several for less than a fiver each. They are available from most synth shops: just search for 'floating ring cables'.

Calibration Tips

Screen 5: The calibration display shows the voltage map and where it goes out of range.Screen 5: The calibration display shows the voltage map and where it goes out of range.There are a couple of tricks for getting the best results when calibrating the Silent Way Rack Extension.

1. Use a simple, clean sound. A sound that's too complex, distorted or filtered will be difficult for Silent Way's pitch detection to accurately assess.

2. Set the sound's pitch in the middle of its range. If the oscillator's base frequency is too low or high you'll end up limiting the range over which Silent Way can map. You can see on Silent Way's calibration display where it's unable to make a linear map and starts to double back. Ideally you want to see a straight diagonal line through most of the display (Screen 5).

Once calibration has been successful you can change the sound as much as you like.

Published August 2019