Chord Generation

1: Reason 7's new-found flexibility allows for third-party MIDI processors like Pitchblende's AutoTheory. It is shown here generating chords for a little orchestral stack, alongside melody patterns for a lead synth sound, all from just a two-note live MIDI input.

We look at how chord–generating Rack Extensions in Reason could help you out of a musical rut.

In last month’s Reason column we looked at how the RPG8 arpeggiator and Matrix Pattern Sequencer, along with a couple of third–party Rack Extensions, can expand your options for generating notes and patterns. They can be a great choice for developing certain styles of music, and for providing inspiring and unexpected discoveries, especially if you always find you gravitate towards the same old chords, riffs and patterns when playing in real time.

A few third–party Rack Extensions take the concept even further. AutoTheory (€32$39) and AutoArp (€29$35) take note input and generate new chords and patterns in response. They can prove useful no matter if you’re a non–keyboard player, a music theory novice or an expert musician looking for new inspiration. And there are still other similar gadgets out there too, as we’ll discover this month.

Autobahn

Let’s start with AutoTheory. This RE takes note input, played in real time or from a sequencer track, and remaps it to generate musically coherent chords and scales. The new note data is then used to drive an instrument (or, as we’ll see, more than one instrument) via rear panel CV connections. AutoTheory itself doesn’t generate audio.

With a freshly created instance of AutoTheory in your rack, create a polyphonic instrument of your choice nearby, and then flip the rack to see the rear panel connections. As you’ll see, AutoTheory’s musical, note–based CV outputs are grouped into two sections: Chord and Melody. For now just hook up Chord CV Output number one, connecting both Gate and Note to the corresponding sockets on your instrument. Then flip the rack back round and make sure AutoTheory’s sequencer track is selected, so it’s receiving MIDI from your controller.

You should already have a working setup. Play some single white notes (lower than C3 — we’ll see why in a minute) and you’ll hear whole chords from your instrument. You’ll also see parts of the keyboard–shaped display in the Chord Generator section light up. Each key is already labelled with the chord that it generates, so you’re kept pretty well informed about what you’re getting up to musically.

Of course, the next step is to tweak AutoTheory to match your musical intentions, or the existing harmony of your song. Most important of all are the Key and Scale knobs at top left, because these dial in all the important musical settings elsewhere. It helps here to have a little theoretical background knowledge, or at least a willingness to explore the characters of the seven scales and modes on offer. With this RE though, that’s not difficult.

By way of illustration, in screen 1 I’ve chosen the ever–popular, serious–sounding D Dorian for Key and Scale. What you’ll notice is that seven chords which work great in this tonality are now mapped across the keyboard, from C upwards. Yes, that’s right: pressing note C generates a D minor chord. It’s a bit unexpected, how AutoTheory decouples the pitch of the notes you play from those that it generates, but in practice it feels interesting and inspiring.

Next, you’re not bound to use the exact chords that AutoTheory chooses for you. You can momentarily change the chord generated by each white note by also holding down a black note ‘modifier’. Again, the keyboard display prompts you, with all the black keys labelled with alternative chord types. So if you want a ‘sus4’ chord, hold down the G# key just a fraction of a second before playing the next white note.

You can also make permanent changes to the palette of chords that’s offered in each Key/Scale combo. Let’s say I always want a funky–sounding F minor chord in my D Dorian setup, rather than the F major that’s provided by default. I could just use the minor key modifier each time, but a more permanent way to dial in the one note that’s different (a flattened third of the chord) would be to mouse to the upper bank of sliders for chord III, and pull down the one marked ‘3’ by one click, to the flat position. The label is instantly updated to confirm I’ve made a minor chord — neat!

2: Distributor fires note triggers and other data around to any devices connected to it via CV. It can turn a stack of monosynths into a potent polysynth, and much more besides.

Likewise (and this is another one for theory nuts...) not every chord has to be in root position, nor closely voiced. The lower bank of sliders underneath each chord type dial in octave transpositions for each chord’s component notes. So if you want a first inversion chord (where the 3rd is the lowest sounding note) grab the slider for ‘1’ (the root) and drag it up to raise its pitch by an octave. Just as easily, notes can be disabledby dragging their sliders to the lowest ‘off’ position. And chords can have their 7ths, 9ths, 11ths and 13ths turned on, to create extended, jazzy-sounding harmonies.

AutoTheory is, then, a pretty flexible tool, and it’s works very well for generating big chordal textures for pads, orchestral strings and wind, amongst other things. Those additional rear panel Chord CV outputs are mirrors of the single one I described hooking up earlier, so it’s easy to drive multiple instruments simultaneously. It’s also possible to have output number four generate just the root note of the chord, and use it to drive a dedicated bass sound. You have to enable that from the front panel, towards the bottom right, with the Root Separate button. The nearby knobs also control octave transposition and velocity for each of the chord outputs — almost like having a little on–board mixer.

We’re still only seeing half the picture too. Above the note C3 (or any other C, chosen with the Keyboard Split knob on the rear panel), AutoTheory generates melody notes, ‘quantised’ to the key, scale and chord in use from moment to moment, and sent from the rear panel Melody CV outputs to instruments of your choice. Four different ‘melody lock’ mapping modes present lots of possibilities, again with the apparent pitch you play sometimes quite different to what’s generated; only Absolute mode retains a fixed, standard pitch layout. For the other modes the upper, smaller keyboard display keeps you in touch with what’s going on.

Distributor

What can you do when you have a strictly monophonic instrument (like the RE synths Viking or Tres Mono) but want to play chords on it? Grab Blamsoft’s €15$19 Distributor and do a bit of rear panel patching!

This little Rack Extension is yet another that accepts MIDI input from its own sequencer track, and in turn drives other instruments via CV connections. Its basic role, then, is to break up all incoming MIDI data into individual monophonic note triggers and ‘distribute’ them amongst its eight CV outputs. So to achieve, in effect, a polyphonic Viking synth you’d create up to eight instances of the synth, patch them individually to Distributor, and then play Distributor.

3: Far more than just another arpeggiator, AutoArp is a deep and sophisticated note processor with its own unique capabilities and programming system.

The front panel controls are really straightforward. Turn the knob in the Voices section to Auto and Distributor will figure out itself how many instruments you’ve patched in. Then set the slider beneath to Single, unless you deliberately want more than one instrument at a time to respond to each new note (which can work well for basic layers and ambitious stacks). The Order knob lets you decide in what order the CV outputs are utilised, whether positive (working from the number chosen in the Start section upwards), negative (from that same downwards), pos/neg (a sort of ‘crab’ motion) or randomly.

You’re not limited to using mono synths with Distributor, of course. Polyphonic instruments work great too.Also try patching up lots of different instruments with deliberately varying or even wildly different timbres. Then when you play chords or note sequences you’ll get strange, shifting, semi–chaotic textures and patterns that would be extremely laborious (and a lot less fun) to achieve in other ways.