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Reason 4: Advanced Arpeggiation

Reason Notes & Techniques By Simon Price
Published April 2008

Delving beneath the surface of Reason 4's new RPG8 arpeggiator reveals a treasure trove of rhythmic modulations and variations.

This is what we'll be working towards: the final patch, with the RPG8 triggering notes and Thor's own sequencer, generating an 'arp within an arp'.This is what we'll be working towards: the final patch, with the RPG8 triggering notes and Thor's own sequencer, generating an 'arp within an arp'.For years, an arpeggiator module has been one of the features most frequently requested by Reason users. No surprise, then, that when the Props finally responded they delivered something that goes well beyond the basics. As is often the case in Reason, you can use the RPG8 at two levels: you can let it connect itself to an instrument directly, and just start playing and adjusting the front panel controls. Then, for the tweakheads, there are many less-obvious possibilities for experimenting with advanced settings and creative CV connections. The main purpose of this article is to look at some of the latter, but as this is the first time we've covered the RPG8, let's start with a quick look at its main features.

RPG 101

If you select an instrument in the Reason rack, and then add an arpeggiator (Create / RPG8 Monophonic Arpeggiator) the RPG8 will be auto-cabled to the instrument. The RPG8 will also automatically become the live MIDI device in the sequencer, so will immediately start receiving input from your keyboard. The arpeggiator translates your played MIDI notes into an arpeggiated performance, which is sent to the connected instrument by means of CV and Gate signals. As well as the Gate and CV signals, you'll see that there are also Pitch and Mod Wheel connections between the RPG8 and its associated instrument. This is simply to pass through these controller sources, because your MIDI keyboard is no longer pointed directly at the instrument.

The main panel controls are mostly quite easy to understand, especially if you experiment with them to see what their effects are. The central Arpeggiator panel houses familiar controls found on most arpeggiators. The Mode knob selects the order in which order the held notes are played: Up, Up and Down, Down, Random, or Manual (which plays the notes in the order in which they were first played). The Octave buttons let you choose how many octaves the sequence will be extended to.

The Insert buttons change the pattern of played notes. 'Off' results in traditional arpeggiation, with the notes cycled in the order set by the Mode knob. 'Low' produces a sequence that alternates between each held note and the lowest note held; 'High' is the opposite of this; and '3-1' and '4-1' create sequences that transpose each cycle, following a 'three (or four) steps forward, one step back' pattern that rises or falls depending on the Mode. These last two are particularly good when the Random Mode is selected, as the result is an ever-changing sequence.

The Rate control sets the speed of arpeggiation, which can be sync'ed to the song tempo, or switched to Free mode. Gate Length sets how long each note in the sequence is held.

Modulation Only?

Once you've experimented with using RPG8's CV outputs as modulation sources, it's a natural step to consider using them purely for modulating an instrument, without using the notes generated at the same time. For example, you might want to use a synth polyphonically, playing pad chords for example, while still using an RPG8 to modulate the synth based on the notes you are playing. This presents the same technical challenge we've encountered before with vocoding, because you're trying to connect your MIDI keyboard to two places at once. The solution is the same: put both devices into a Combinator, which can receive the notes and pass them on to both the arpeggiator and the synth at the same time. You'll need to make sure that note CV is not connected between the RPG8 and the sound source, and that Receive Notes is checked for both devices in the Combi Programmer panel.

Pattern Recognition

While the Mode and Insert sections determine the melody of the arpeggiated sequence, the Pattern section lets you vary its rhythm. The display in this section, which looks like a miniature, multi-octave version of the Matrix device, is always active, showing a visual representation of the sequence that is playing. To use the Pattern function you need to switch it on with the small grey button at the top of the section. The 16 step buttons and pattern length controls create a rhythmic pattern of On or Off steps. The important thing here is that the note sequence is independent of the Pattern; the pattern adds rests cyclically, but doesn't restart the note sequence each time the pattern loops.

RPG8 Trickery

As I said, the best way to grasp the basic arpeggiator functions is to play with them rather than read about them, so let's move on to some more unusual tricks you can try with the RPG8. First, let's get an RPG8 running with the new Thor synth. Simply create a Thor, then create an RPG8, and everything will be set up for you. In the following examples, I'm using a Thor patch called Analogue Lead, which can be found in the Synth Lead folder in the Reason Factory Sound Bank.

The CV connections used in our patch example. The Spider CV Splitter is used to send the Pitch and Gate signals to multiple destinations.The CV connections used in our patch example. The Spider CV Splitter is used to send the Pitch and Gate signals to multiple destinations.The simplest trick with the RPG8 is to send the Pitch CV to other destinations on the connected instrument. To start doing this you'll need to split the CV signal, using a Spider CV Merger and Splitter (as in the screen below). The auto-cabling system splits the CV and Gate signals for you, assuming this is what you want. For now, we're only interested in CV, which appears on Split 'A'. As we've seen in previous articles, Reason's CV system is all normalised, so CV signals are interchangeable between different parameters, including note values. Thus if we send the Note CV to the filter we can control the full range of the filter from MIDI notes. In the picture below I've actually connected the CV to Thor's Rotary 1 input, as this control is mapped to the filter over a predetermined range set by the patch.

Now, the filter frequency will change with the notes as the arpeggiator plays. Try altering the CV input trim and using a large octave range for the arpeggiation, to create a more dramatic result. But couldn't this have been achieved with Thor's Modulation Matrix? Well, yes, up to a point, but if you try it you'll find it has a limited range and different characteristic to using the CV method. This way is also quicker and saves Modulation Matrix slots, which we'll need shortly.

Before moving on, take another CV split of the note output to Thor's Rotary 2 input. The Resonance now changes with the notes of the arpeggio, too, with pleasing results.

Trigger Happy CV

Next, we'll add some rhythmic interest using a Gate signal. Connect the 'Start of Arpeggio Trig Out' port on the back of the RPG8 to the CV1 input on Thor. This output sends a Gate signal every time the arpeggio starts a new cycle. As we've connected the signal to one of Thor's general-purpose control inputs, we'll need to use the Modulation Matrix to route the Gate within Thor. Open up Thor's Programmer Panel and locate the first empty slot in the Matrix. In the Source field, choose CV Input / 1. For the destination select Global Env / Gate, and set the Amount to 100. Now, add a Low-pass Ladder Filter in the Filter 3 slot, and set it up as it is in the screen above. Each time the arpeggio restarts, the Global Filter's envelope will be triggered. This instantly creates more movement, as both the indivdual notes and the overall melodic loop have independent filters.

The adapted Thor patch, with Filter 3 triggered by the arpeggiator, and LFO 2 triggering restarts of the arpeggio sequence.The adapted Thor patch, with Filter 3 triggered by the arpeggiator, and LFO 2 triggering restarts of the arpeggio sequence.A lot of sonic variation is available in this patch. Use the Global Env Hold, Decay and Release sliders to alter the movement within the arpeggio. Vary the RPG8's Octave range and the number of keys held down to change the length of the sequence and how often the filter envelope triggers. Varying the filter frequency, resonance and envelope amounts for Filters 1 and 2 all create different results that interact with one another.

One thing this patch highlights is that arpeggio sequences vary in length, depending on how many notes are held and the number of octaves set for the range. Sometimes it's preferable to have an arpeggio with a regular cycle, regardless of these factors. In the above example, this would create a regular, rhythmic pulsing as Filter 2 is triggered. It's easy to force an RPG8 to do this, by re-triggering the arpeggio from an external source. In the picture on page 175 you can see a connection from the CV1 output of Thor to the 'Start of Arpeggio In' port on RPG8's rear panel. I've used the Modulation Matrix to send LFO 2 to the CV 1 output. Finally, I've set the LFO to a pulse wave, and sync'ed it to tempo. Now, the LFO can re-trigger the arpeggio at any division of the tempo. In this example I've used the LFO from the instrument connected to the RPG8, but there's nothing to stop you using any other gate signal, such as drum triggers from a Redrum, to re-trigger the arpeggio in other rhythmic ways.

Patterns Within Patterns

The last trick this month is to use both the RPG8 and Thor's step sequencer to create a double pattern effect. The RPG8 will play an arpeggio at a moderate speed, and the step sequencer will play multiple notes for each note triggered by the arp. First you need to connect the RPG8's Gate output to Thor's sequencer. The Gate should already have been split via the CV splitter when you first connected it. Simply take another of the split outputs from 'Split B' on the back of the CV splitter and connect it to the 'Gate In (Trig)' port on the back of Thor. Now set up the front panels as in the screen on the first page.

The RPG8 has a slow rate (quarter notes). Each note triggers Thor's step sequencer, which is set to 16th notes, and has its first four steps adjusted to play a simple rising sequence. The resulting sequence is a combination of arpeggio and step sequence — like an arpeggiated arpeggio! For the best results, set a long arp gate length so that all the step sequence notes are triggered, and reduce the LFO 2 rate so that the arpeggio has a chance to play before being reset. You will also need to switch on the Step Seq button in the Trigger section of Thor's main panel.

Hopefully the examples here show that the RPG8 offers unique modulation possibilities that could not be achieved with Thor's internal sequencer or a Matrix step sequencer. This is largely because the arpeggiator generates step sequences in real time that change every time you play different notes and chords. What's more, the modulation is directly related to the note sequence that is being generated, creating engaging sequences with bags of natural movement. 

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