London Crime Theme

Introduction

Click on the play button below to listen to an mp3 recording of this patch.

Click on the button below to download the .voltagepreset file then open it to launch Voltage Modular with the patch ready built.

Downloading presets

The idea behind this patch was to come up with something that might be suitable for a TV police drama title sequence so a dark GUI seemed appropriate. The image below uses the classic skin so it’s far more obvious which parts of the patch are LSSP modules.

The patch produces a very short theme tune so doesn’t have much in the way of song structure. It consists of three parts – an intro, a main part and a fade. So there are three Song Part modules.

Chord progression and lead melody

The most obvious feature is a very slow four note (D, F Bb, A) lead melody based on the root notes of the eight bar long chord progression which is repeated six times…

i	\	III	\
VI	\	V	\

Or using chord names…

Dm	\	F	\
Bb	\	A	\

The \ symbol indicates that the chord doesn’t change.

The chords are supplied by the Diatonic Triads module and sequenced by the Progression module.

Note that the Progression module is set to run at 2 chords per bar, not because the chords change so fast but simply to make the sequence last 8 instead of 16 bars. It just makes the wiring a bit simpler as there’s no need to patch the chord progression twice.

The Progression module’s V/BAR IN socket is fed by all three of the Song Part V/BAR OUT signals but as the progression repeats all the way through the song a single connection from Song Control’s GLOBAL V/BAR OUT would work just as well. The slightly inefficient wiring is just a hangover from how the patch developed.

An Inversion module is used to modify the i chord so that the root note is raised by an octave as shown by the Note Watcher modules in the image below.

Inversion is a very useful compositional technique as it allows one to maintain a chord’s harmonic function while adjusting the pitch range. Try adjusting the Inversion module’s knob to 12 o’clock to hear why it’s used.

The Progression module’s CHORD OUT signal feeds into an arpeggio section that is explained later.

The BASS OUT signal from the Progression module is used to control the pitch of the lead melody voice. Note that the “bass” note of the i chord is raised an octave due to the inversion.

The voice is just a single oscillator but depth and complexity is added by making the pitch Glide and by using a Delay and then a Chorus module to expand the simple sawtooth wave into something more interesting. It’s supposed to be a reference to a police car’s siren and also a nod to Delia Derbyshire.

The slow melody is patched to channel 5 of the upper mixer. It’s a drone voice so there’s no envelope generator or VCA involved. The amplitude of the voice is only controlled by the Dual VCA next to the mixer which fades it (and everything else) out at the end of the song.

Drums

The Drum Sequencer modules in this patch are mostly used to drive the arpeggiation covered later but they also trigger kick, snare and closed hi-hat sounds.

For the intro though a Beats module is used to trigger a very simple two beats per bar kick. This sets up an expectation that things are going to be pretty dull so when things change in the ninth bar there is a heightened sense of satisfaction. Also the intro is supposed to represent the crime while the main section represents the hero springing into action in response.

The V/Bar sequencing is pretty simple. The Beats module is driven by the V/BAR OUT of the first Song Part while the Drum Sequencers are made to play an AAAB pattern by the use of a Time Split Fills module connected to the V/BAR OUT sockets of the second and third Song Parts.

Time splitting is covered in the LSSP 101 Tutorials.

Probability modulation is used to add interest to the snare pattern of the “A” (left-hand) Drum Sequencer and to the hi-hat pattern of both sequencers.

Track 8 of the Drum Sequencer, labelled “solid” is used to provide a solid beat as described here.

So in the A pattern the solid beat is…

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The A snare pattern is…

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The snare’s probability is modulated by the solid beat pattern so that we end up with one of the following four outcomes being selected at random…

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Because beats 5 and 13 always occur (as they are “solid”) with only beats 10 and 12 being random the snare pattern hangs together well. The probability of beats 10 and 12 firing is set fairly low so the result is just the occasional extra snare hit being added for a touch of variation.

A similar thing happens with the hi-hat pattern with only every other 1/16th note being allowed to randomly drop out.

In the “B” (right-hand sequencer) fill pattern the snare’s probability is 100% as every hit is desired. The solid beat pattern is inverted though so this causes the hi-hat pattern to apparently shift by a 1/16th note later in time to add a little contrast.

Arpeggiation

In other tutorials we’ve looked at quantization where a control voltage is adjusted to fit in a chord or scale but another approach is to directly select individual notes from the current chord. This approach is explored in this patch.

A chord (or scale) signal in LSSP is carried by an S-Poly connection where the first channel represents the number of notes and subsequent channels represent the pitches in standard 1 V/Octave form.

So in a triad (a three note chord) channel 1 will be 3 volts, channel 2 will be the pitch of the root note, channel 3 will be the pitch of the third and channel 4 will be the pitch of the fifth.

It’s easy to access these pitch voltages by using an S-Poly to Mono module.

So at the bottom of the patch there are four Vintage Oscillators wired to the outputs of an S-Poly to Mono module that is fed with the CHORD OUT signal of the Progression module.

The first oscillator is connected to the 2 output – so its pitch is that of the root note of the current chord.

The second is connected to the 3 output – so its pitch is the third.

The third is connected to the 4 output – so it’s pitch is the fifth.

The fourth oscillator is connected to the 2 output but it’s set an octave up – so its pitch is the root raised an octave.

Each oscillator has an associated AHR Generator module that provides VCA and envelope generator functionality. Each of these AHR Generators is connected to a separate GATE output of the Drum Sequencer chain.

Track 1 controls the root, Track 2 the third, Track 3 the fifth and Track 4 the octave. So setting patterns on the first four tracks of the Drum Sequencers enables us to create arpeggios. Note that by setting more than one step on at a time we have the flexibility to create polyphonic arpeggios.

I assigned the tracks in a way that you might find counter-intuitive as the lower pitched tracks are at the top so it’s sort of upside-down but you can of course have the higher pitched tracks at the top instead.

So in the bottom cabinet of the patch we have a simple four voice polyphonic synth with each voice consisting of a VCO, VCA and envelope generator. The outputs of these four voices are fed to a stereo mixer so that we can pan each voice to a different position for a nice stereo effect. Also for a little added colour the oscillator waveforms used for each voice are varied a little.

As we have four AHR Generators that ought to operate pretty much in unison their RATE and SHAPE are voltage controlled by a pair of Scratch modules. Their sliders can be used to modify the settings of all four AHR Generators at once. Note that each AHR Generator has a minimum RATE and SHAPE setting and maximum attenuvertor setting to make this arrangement work.

OK so the lower mixer is outputting a stereo image of the arpeggiation but it’s a rather clichéd overly clean sound and this is supposed to be music to accompany a gritty drama so the signal is passed through a pair of Distortion modules to make things dirty. This also gives the next modules in the stereo signal path something to work on. These are a pair of Ladder Filters.

You may have expected each of the four voices to have its own VCF and envelope generator but a nice trick is to use filters down stream with their cutoff frequency controlled by an Envelope Follower. This is computationally cheaper as half as many filters are required but it also benefits from a little extra “bubbling” character caused by the envelope follower producing a peak when more than one note at a time is playing. The filter cutoff modulation has much more complex movement than those generated by simple envelope contours as shown below.

Note that the Envelope Follower is tracking the pre-distortion signals as these have a wider dynamic range than the post-distortion ones.

To add a tiny bit more movement, a Mini LFO module is used to slowly modulate the left and right filters’ cutoff frequencies at different rates but the effect is very subtle.

Final stages

The slow melody, drums and stereo arp signals feed the upper stereo mixer with the following channel assignments…

1. Arpeggio
2. Kick
3. Snare
4. Hats
5. Slow melody

The outputs of the mixer pass through a Dual VCA module that’s used to add a fade out using the fade signal from the final Song Part module. Its LPF buttons are engaged so as the volume decreases at the end of the song low pass filtering is applied. Therefore higher frequencies fade out much faster than lower ones. This makes it sound like the distance between the listener and sound source is increasing and adds a subtle spatial effect to the fade out that’s more interesting than a mere volume fade.

Finally the signals pass through a Reverb module to add a sense of space that’s pretty much essential in electronic music.

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