Introduction to MIDI and Computer Music: Assignment 3, Part 4
The earliest analog synthesizers required you to connect different modules — oscillators, envelope generators, LFOs, filters — using patch cords. (Looking at a Moog modular synthesizer will give you an appreciation of the patch cord “spaghetti” that resulted.) Some of the patch cords carried audio signals, such as the ones connecting the outputs of oscillators to the inputs of filters. Other cords carried control voltage signals. These signals were not meant to be heard; rather, they were used to control parameters like oscillator frequency or filter cutoff.
Reason preserves some of this way of doing things, with its audio patch cords and flexible modulation features. Sections within a synthesizer — like the LFO section in SubTractor — can control another section within the same synthesizer. And, of course, patch cords route audio signals between devices. But Reason takes the analogy to analog synthesizers further by providing various CV (control voltage) connections on the back of the rack. A CV connection lets one device control some aspect of another device.
Some analog synthesizers had step sequencers, which generated a repetitive sequence of control voltages, some with as many as 256 steps. Each step stored a voltage that the user could adjust with a knob. The steps were of equal duration, and the user could change the tempo. At each step, the sequencer would emit the stored control voltage, which could be routed to control most anything, such as oscillator frequency, amplitude, filter parameters, etc. When the sequencer performed the last step, it would start the sequence over from the beginning. You can hear a step sequencer at work in the Pink Floyd song, “On the run,” played on an EMS Synthi AKS synthesizer.
Reason has a step sequencer, called the Matrix Pattern Sequencer, which can store 32 different patterns (or sequences of steps). In this part of the assignment, we’ll learn how to control SubTractor with this sequencer. Of course, the Redrum drum machine also has a step sequencer.
Please choose a patch that uses the low-pass filter, and make sure it has moderate filter resonance and a pretty low filter frequency. Otherwise, the Curve CV discussed below may not do much.
NOTE: For this assignment, we will not play the SubTractor patch from a keyboard. Instead, a Matrix step sequence will play notes on SubTractor.
This automatically makes two CV connections between the Matrix and the SubTractor: one for Note CV and one for Gate CV. Note CV sends out pitches, just as if you were playing the notes on a keyboard. Gate CV triggers notes — starts their envelopes — and provides note-on velocities. You need both connections. Spin the rack around to see the connections.
Start playing by pressing the Run button on the front of Matrix. You won’t hear anything yet, because the pattern is empty.
Then click in the main part of the window, the pattern grid, to set the values for each step. There are two sections of the grid: the upper one sets pitch (Note CV), and the lower one sets velocity (Gate CV). For a given step, you must have a non-zero velocity value, or else you won’t hear a note for that step.
The easiest way to get started is to ask Matrix to create a random pattern. Right-click anywhere on Matrix, and choose Randomize Pattern from the menu that appears. You can do this repeatedly until you get something you like. Also, try the Alter Pattern command. Then try editing the individual step values.
Change patterns when playing by pressing those buttons. Patterns change only at pattern boundaries. For example, if you’re playing pattern A1 and switch to B3 while A1 is still playing, A1 will finish before B3 starts.
This all works exactly like Redrum.
DO THIS: Create at least 3 patterns with different note content and number of steps. Store them in locations A1, A2, and A3. Use a monophonic patch in SubTractor — one that has a low-pass filter with non-zero resonance.
This changes Matrix from Keys mode to Curve mode. Now dragging across the upper section of the pattern grid creates the Curve CV that will control the filter. (The lower section still shows the velocity values.) The higher the value of a bar in the pattern, the higher the filter cutoff frequency.
DO THIS: Create a Curve CV pattern for each of your 3 note patterns, stored in A1, A2, and A3. Use this to control the cutoff frequency of SubTractor.
DO THIS: Create pattern Matrix pattern automation that includes all three of your patterns (A1, A2, and A3).