There are many examples of advanced Matrix applications in the Factory Sound Bank's Combinator patches.
To analogue synth fanatics, the Matrix Pattern Sequencer is one of the highlights of Reason 's toolbox.
When I first got Reason, I was in the middle of moving and my MIDI controller keyboard was in storage; all I had was Reason running on a laptop. This turned out to be a blessing in disguise, as for a few months I was forced to use the Matrix step sequencer as my main way of creating music. Although step sequencers can be a slower and more fiddly way of playing synths than a keyboard, they are valuable in that they tend to produce very different results and steer you toward different songwriting techniques. They free you from habitual playing patterns, chords and scales, and introduce unpredictability. You often start by setting a few random notes and seeing what happens. You can then store pattern variations and chain them on the fly to make an arrangement.
Step sequencers are also popular tools for live electronic music, as they allow you to leave the arrangement more flexible than with a full song sequence, and free the hands for shaping sounds rather than playing notes. The Matrix is not just an alternative way to play notes, however; it can also be used to generate versatile tempo-sync'd modulation sources that can be connected to many parameters on other devices using Reason 's virtual CV system.
Matrix Basics
If you add an instrument (such as Subtractor) to the rack, followed by a Matrix Pattern Sequencer, Reason will automatically create two connections (as shown in the screens at the top of the page opposite). The Matrix 's Gate CV output will be connected to the instrument's Gate input, and the Note CV output will be connected to the instrument's CV input. All Reason 's synths and samplers have a Sequencer Control section on the back panel with these inputs. A third output (labelled Curve CV) on the Matrix 's rear panel is left unconnected at this stage. If you press play at this point, or click the Run button on the Matrix, you will hear the synth play back a series of middle Cs at 16th-note intervals, which is the default pattern.
It's fairly easy to intuit how the Matrix works in this configuration. The main central grid represents a sequence of notes, as indicated by the keyboard display running up the 'Y' axis. The 'X' axis of the grid represent units of time, and when the Matrix is playing back you can see a red marker running along the top of the grid showing the current step. Below the note grid the vertical bars represent gate events (note triggers in this case) with the height of each bar determining the velocity. The Resolution knob sets how long each step lasts (how fast the pattern plays back), and the buttons above this set how many steps are active (how long the pattern is). The default setting is 16 steps with 16th-note resolution: a one-bar pattern.
Note Sequencing
The screen at the top of the page opposite shows a typical Matrix note sequence. Notes have been added by clicking in the main grid, with corresponding triggers added underneath in the gate track. The first thing to note is that the grid only shows a range of one octave at a time. The five-position switch to the left of the keyboard graphic lets you view different octaves, giving a total range equivalent to MIDI notes C1 to C6. You'll also see that some of the gate bars in the picture are as wide as the grid step, and some are only half-width. The double-width gates are 'tied', meaning that the note is held until the next step. The half-width gates are held for half the length of the step, which of course varies with the Resolution setting. Unlike some traditional step sequencers, Matrix can't alter the gate length of each step beyond this.
A bank of Matrices makes a fast and visual way to program Redrum patterns. Try making a snare build like this using Redrum's built-in sequencer!
Reason has a few built-in functions for helping you with step sequences, some of which we've looked at in previous issues in relation to Redrum 's sequencer. Firstly, you have the various Shift Pattern commands, accessed from the Edit menu or by right-clicking the Matrix. Shift Left and Shift Right move the current pattern forward or backward by one step. This is really handy for changing where the perceived downbeat of the pattern occurs with respect to other tracks. Shift up and Shift Down transpose the current pattern in semitone steps. The other two specialised functions are Randomise Pattern and Alter Pattern. Alter Pattern makes subtle random changes to the current pattern. Both the Gates and Notes are altered, but the resulting pattern will only contain the same notes as the original, so the new pattern will stay in key with the song. Randomise Pattern completely randomises the notes and gates, and usually produces a pattern with notes spread across all five octaves. More often than not these patterns are not usable, but if you are in need of inspiration you can use Randomise repeatedly until it generates the seed of an idea.
The Pattern Bank works in exactly the same way as the one in Redrum that was explained in detail in the June 2006 issue of SOS. You can store up to 32 patterns in four banks of eight. To change pattern, just click the corresponding button. If you have to change bank, click the bank button first and then the pattern number. Pattern changes are quantised so that the pattern will not change until the start of the next bar. The Edit menu has four functions for managing patterns: Cut Pattern, Copy Pattern, Paste Pattern and Clear Pattern. A pattern can be copied from one storage 'slot' to another by choosing Copy Pattern, then switching to a new pattern number and choosing Paste Pattern. The Resolution, Steps (number of steps) and Shuffle settings can be different for each stored pattern.
Patterns can be chained together to create song arrangements by recording pattern changes into the master sequencer.Again, everything that applied to the Redrum pattern sequencer applies to the Matrix when it comes to recording or drawing pattern changes into Reason 's master sequencer. Each Matrix track in the main sequencer has a dedicated Pattern Automation lane where you can record, edit, and view sequenced pattern changes (as in the screen below). The simplest and most immediate way to chain together your patterns into a sequence is to record the pattern changes on the fly. All you need to do is record-arm the Matrix track, start recording from the master transport, and change the patterns in the arrangement. The pattern changes are displayed as gold bars with tabs indicating the pattern number. Your recorded arrangement can then be edited and adjusted as required, and you can write patterns in directly with the Pencil Tool. Again, the article in the June 2006 describes a number of editing techniques for approaching this task, and is available on the SOS web site. Finally, you can use the Convert Pattern to Track command if you need to generate MIDI data from any pattern, or use the Convert Pattern Track to Notes command to convert an entire pattern arrangement into MIDI.
Ahead Of The Curve
Step sequencing is not just for notes: it can also be used for modulating and triggering many of the parameters on Reason 's devices. This is commonly achieved using the Matrix 's Curve CV output. The Curve CV is controlled by a completely different sequence stored in each Matrix Pattern. You can flip between the Note and Curve sequences using the front-panel Curve/Keys switch. A single Matrix can be connected to both Note and Curve destinations, controlling both at once. Curve sequences are drawn like graphs on a single display page: the octave display switch has no effect in Curve edit mode. 
Here, the second Matrix's Curve CV output is being used to modulate the synth's filter. Using more steps at a higher playback speed results in a smoother curve.
The screen at the bottom of page 185 shows an example use of the Curve CV. In this case, a separate Matrix is being used to modulate the Filter Frequency of the Subtractor synth. Using a second Matrix allows you to use a longer pattern with a higher resolution than the note sequence. In this case both the note and curve patterns are one bar long but the curve is smoother than it would have been with a 16-step sequence.
Curves can be set to unipolar or bipolar mode using the switch on the back of the unit. The default unipolar mode sends values from zero upwards and is appropriate for most controls. However, some parameters have a default position of zero, with negative and positive values in two directions. Examples of this are the pitch wheel on most instruments, and pan pots on the mixers. In these cases you can use the bipolar mode, which has zero at the centre of the graph and positive and negative values above and below. As well as these specific cases, bipolar curves are actually really useful for all controls, because they make it easy to modulate a parameter up and down from its panel setting. Unipolar graphs can only adjust parameters upwards from their current position. The type of graph to use depends on what you want to achieve. If you want to have the Matrix Curve control the absolute value of a parameter, set the parameter to minimum and use a unipolar graph. If, on the other, hand you want the Matrix graph to act more like a LFO, set the parameter to a particular level, then use a bipolar graph to modulate it up and down relative to this position.
All the modulation inputs found on Reason 's devices have a trim knob, which lets you adjust the intensity of the modulation. When the knob is in the default centre position the parameter will have a one-to-one relationship with the graph. In other words, a sweep from top to bottom on the graph will modulate the parameter across its entire range, or from the top of the range to the current position if it's a unipolar graph. Turning the CV trim knob to the left will scale down the effect of the CV input, and turning to the right will exaggerate the effects of the modulation.
Curve sequences can be drawn like curves for smooth modulation, but you can also create staccato and rhythmic effects by drawing erratic sequences. Curve sequences can be used to create LFOs of any shape, from smooth triangles to square waves, or random sample-and-hold type shapes. There is a built-in editing function for drawing smooth straight lines. Hold down Shift, then click and drag the mouse across the grid. All the bars in each step will be drawn to meet the line between where you clicked and where you drag to.
Gates
If you're a seasoned Reason user, this much is probably fairly familiar to you, so let's look at some more adventurous uses of the Matrix. First off, you can use Gate signals for more purposes than triggering notes. Many Reason devices have extra Gate inputs on their rear panel. All the synths and samplers have Amp Env and Filter Env gate inputs, and Subtractor also has a gate input for its general purpose Mod Env. These allow you to use a gate signal to trigger the envelopes independently of notes. A typical example of this would be using a Matrix to trigger the filter envelope to create a rhythmic pulse to a sound while you hold a note. The Combinator means that you can save configurations of this kind as a patch, and many of the Combi patches in the Factory Sound Bank use tricks like this (see the screen at the start of this article).
This CV signal is being split to two separate destinations, allowing you to both modulate the filter frequency and trigger the filter envelope from a single Curve sequence.Each of Redrum 's channels has a gate input that can be triggered from a Matrix, and also responds to the velocity level. Using a bank of Matrix sequencers may be a faster and more visual way to program drums than using Redrum 's sequencer, and gives much improved dynamics compared to the three basic velocities Redrum offers (see top screens on page 185). Gate signals can also be used with some Reason effects. For example, the Envelope Controlled Filter has a gate input for triggering its envelope, and the RV7000 's gate can be triggered from an external source.
A little known Matrix trick is generating gate signals from the Curve sequence. Any step in the curve graph that is preceded by a step set to zero will act as a gate. The configuration in the screens above is an example of how you can use this. The Curve CV signal is being sent to both the Filter 1 Frequency modulation input and the Filter Env gate input via a Spider CV splitter box. The Curve graph then becomes a single modulation source that be used to modulate the filter and trigger the filter envelope at various intervals. When you play a chord on the Subtractor, the Matrix chops up the sound into a moving rhythm riff. Combine this into a Combinator and you have a unique-sounding patch.
In a final twist, you can create the same patch using just the Gate output split to the same two destinations. The Gate's CV value, which is normally used for velocity when triggering notes, is no different to that of the Curve. This is a testament to Reason 's flexibility and the possibilities that flow from the fact that all the devices share a compatible CV system. Just as with traditional analogue modular synths and sequencers, there are always new sounds and tricks to be discovered by experimenting with new patching combinations.
