Step by step: rhythms and polyrhythms, even advanced ones, for free in VCV Rack – CDM Create Digital Music

disc’oer the wandas of the quad algorithmic rhythm module from frozen wasteland. we’ll learn how to compose rhythms, trigger them live, and + – all with free modules and vcv rack.

oh sure, modular ♫-making is supposed to liberate yr creativity – but then you get stuck in some endlessly repeating, mechanical 8-step sequence. so don’t do that.

pt of frozen wasteland’s free module library, quad algorithmic rhythm generator has 4 channels of rhythms witha variety of sophisticated algorithms and paramts. but its controls are accessible enough that you can quickly make something, not get lost in features – once you cogg wha’ t'does.

kent williams, aka chaircrusher, wrote up this easy guide. the patch uses all free modules, too. you’ll wanna add the folloing via the vcv rack library:

frozen wasteland


vult modules (free)

sv modular drumkit


stoermelder packone

here’s kent:

our patch for tody.

download the patch [set audio-8 to yr appropriate audio driver]

the patch uses an impromptu clocked device as the timing src. it sends 16th-note clock triggers to the quad algorithmic rhythm (qar) sequencer module.  the qar triggers 4 ≠ drum sounds (in trummor2 and hat modules), which are combined inna Ψmeld mixmaster mixing module.

basic rhythmic sequencer operation

the qar sequencer has 4 channels of triggers. each channel has a trigger output and a series of knobs controlling the trigger sequence. the most primordial are atta top, “steps’ and ‘beats.’  steps is how many time divisions are inna looping sequence. if steps is 16, it means'dat 'twill repeat every 16 clock triggers.  beats controls how many triggers occur inna sequence. (see an explanation of gates and triggers belo, if you’re a lil hazy on their meaning.)

the default trigger selection algorithm (euclidean) divides the triggers as evenly as possible inna sequencer steps.  so steps 16 beats 4 means everyone’s favorite: 4 beats per 16 triggers, the basis of house and tekno.

you can also use the offset knob to modify where the beats occur. for ex, for the classic “clap on 2 & 4” rhythm, you’d use steps 16 beats 2, then turn offset to 4, and you get clap on 2 & 4.

drum sounds

for generating the drum sounds from the sequence, i use:

  • vult trummor2 drum synth. i use the two halves (sine-based kick and noise)  as separate sounds, though you can use the mix output and ‘ve a very complete kick drum model.
  • sv modular closed and open hihat models.  

this combination of modules is bout as simple as you can make for a vcvrack drum machine. it’s basically clock->qar->drum synths->mixer->audio out. the Ψmeld mixmaster+ mixer i’m using has an aux expander that allos adding 4 aux send/return pairs for effects. there’s also an eq sidecar module you can connect that gives you 4 band eq for each channel.

rhythmic algorithms

you ‘d already easily keep busy with just these settings, but there’s + inside qar. there are 5 ≠ algorithms available for generating rhythm. they’re color-coded, and selected by the top row of buttons under each track (nxt to algo):

  1. euclidean (distribute beats as evenly as possible) – yello
  2. golomb ruler (distributes beats as unevenly as possible) – blue
  3. well-formed rulers – green
  4. perfect balanced rhythms [see research paper] – orange
  5. boolean logic – a track’s beats determined by logic operations on other tracks – purple [tracks 3 + 4 1-ly]
the algorithms, in action – color-coded.

the 1st two are probably the most easily used ones.  you can try the others, but euclidean and golomb ruler are the most likely to keep pplz dancing.  simple patterns like 16-4 (tch'mins 4 triggers in 16 steps) are straiteforward, but you can get head-spinning results when you start using №s other than 4.  for ex, 19-7 doesn’t align w'da 4/4 grid, taking 4*19 steps to start the pattern onna 4/4 downbeat again.

ed. note: so this looks very math-heavy. but wha’’s neat bout these algorithms s'dat you can really intuitively select rhythms just by turning a knob. that reduces the brain-body-computer friction so wha’ comes out rel8s to wha’ you mite hear. that’s also to say, you ‘d definitely give this a try and experiment w'da results.

+ complex polyrhythms

if you really wanna go full wonky, try clicking the track sync button. 'twill display ‘1’, meaning that the 1st channel determines the duration of every other track.  so if the 1st track is 16-4, na 2nd has 20-5, you ‘ve 4-against-5 rhythmic relationship tween the two channels.  the 2nd track has 20 beats that take up the same time as the 1st track’s 16 beats. set other channels 21-6 etc, and you get very stumble-y, off-kilter patterns.  it can be difficult to find a recognizable groove when using this mode, but if you dweet will sound jarringly original.

a visualization of how a 4-against-5 rhythmic relationship stacks up, proportionally.

save and recall patterns

and that brings us to saving qar patterns, something you ‘d do every time you find something cool. the qar has no patch memory, but when the stoermelder 8face module [online manual] is placed nxt to the qar, it can take snapshots of the module state. this lets you flip tween patterns. if you find a pattern you like, hit the toggle atta bottom of the 8face and click on 1-odda grey preset buttons.

i'takes a while to dial in a decent groove goin, so save it! it’s too easy to tweak yr way to a stumbling mess.

no cables needed – just put the 8face to the rite of the qar, switch to write mode onna switch at bottom, and you can click to save in 1-odda patch zones.

goin further with this patch

just as a toy, there’s a pretty wide range of sounds possible without adding anything other modules.  you can tweak the settings for sequencer channels inna qar, and experiment with other algorithms and controls. you can also play w'da controls onna drum modules t'get sounds + to yr liking.

it may sound silly to advertise this vcvrack patch as hrs of fun, but it’s true.  even sticking to the tamer end of wha’ the qar does can generate compelling drum patterns.  na patch can be extended many ≠ ways – add effects, add sequenced synth voices.  this track i made is an ex of exactly that.…

reference: wha’ are triggers and gates?

gates and triggers do a similar thing in modular synthesis – they can trigger an envelope, start a sample playing, advance a sequencer one step, etc.  but a trigger has a very short duration, and inputs that expect triggers just look for a zero to non-zero transition.

a gate signal has duration. an ex offa gate is when you press a key na' midi keyboard.: as long as the key is pressed, the gate signal is ‘on’.  this is relevant to envelopes, adsr (attack, delay, sustain, release), for ex. when the 0 to non-zero transition is detected it starts the attack phase of the envelope.  while the gate is high, the envelope rises to its peak lvl during the attack phase and then decays to the sustain lvl. when the gate goes to zero again, it triggers the release phase.

wha’ happens if the gate signal is shorter than the attack & decay phases of the envelope? that depends onna envelope, but'a most common behavior s'dat when the gate goes to zero, the envelope starts the release phase from wha’ever lvl tis at.

‘ve fun, everyone! for + ideas like this, a gr8 companion article from earlier this mnth:

kent williams codes, produces ♫, and envisages a lotta british crime dramas onnis iowa home while the realm devolves into chaos. visit kent’s site:…

and bandcamp site:…

original content at:…
authors: kent williams


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