DASYRAC and DASYsideRAC in situ watched over by one of the many residents.
DASYRAC (Digital/Audio System Yielding Retro Auditory Coolness) is my voltage-controlled audio mad science lab, containing sixty or so Eurorack synthesiser modules. I started putting it together in early 2017 partly as a 40th birthday present to myself and partly as a practical introduction to electronics. Once I figured out what I wanted from a modular synthesiser setup and how to solder, there was very little to stop me. 🙂
Eurowhat?
Eurorack is a Eurorack modules have a standardised height of 3U – that’s 133.5mm to the rest of us. The widths of the modules is measured in horizontal pitch (HP for short). 1HP is equal to 5.08mm. My smallest module is all of 2HP and my widest one is 22HP.
DASYRAC is housed in a 9U (= three rail) 104HP Synthrotek Cheeks Of Steel open rack, a 104HP Tiptop Z-Ears + Z-Rails rack and an 84HP Tiptop Happy Ending kit rack for a total of 500HP. The modules are powered by one Tiptop uZeus power supply and two 4ms Row Power 30 supplies. The modules connect into shrouded IDC power connectors at the back; the Row Power 30s are daisychained to run off a single 90W laptop power supply, and the uZeus runs off a 2A power pack.
There’s a list of modules on this site or you can see how those modules are set up on Modulargrid: DASYRAC main rack, DASYRAC side rack.
External instruments
Most of these instruments talk to DASYRAC using voltage control.
It’s been 5 to 11 November 2017 and it’s been an extremely synthesiser-centric week!
Beepity boop boops
Sunday was showing a friend around my modular synth to show her Eurorack in the flesh and get her pumped for her upcoming electronic engineering degree. That seems to have set the tone for the whole week.
On Monday evening, I got my parcel of DIY kits from Thonk and soldered together a Horstronic Arcade Button…
…then on Wednesday evening, I spent time testing out said modules which I had no time left for on Tuesday, resulting in this strangely pleasant noise..
On Thursday evening I spent putting together a particularly big order to Thonk, and on Friday evening I was testing out sample playback on the Disting Mk 4 and creating lovely crunchy triplet beats.
And finally today (Saturday) I started mindmapping an overview of analogue vs digital voltage control sequencers to see if it’s worth following up. There’s a surprising amount to talk about for little circuits that just eat pips and spit out voltages.
What’s behind the dots? Wouldn’t you like to know…
So that’s pretty much been my week, which leads neatly into..
The last of the weeklies
After 3 1/2 years of weekly blogs (since May 2014 when I started “A moment in the sun”), I’m going back to a less frequent posting schedule again. Without a consistently active production to talk about, touching base every single week has begun to feel strange and perfunctory. There’ll be posts here in the future, but only when I have something worth saying. 🙂
It’s goodbye then to “see you next week” – so see you ’round! 🙂
The Mutable Instruments Clouds is one of the most popular Eurorack modules ever. It was intended to be a “texture synthesiser”, an instrument which uses granular synthesis in order to extract a texture from an incoming signal.
Granular synthesis is just the “default” mode, however. There’s other ways of extracting texture from sounds and sure enough, buried on secret firmware number 4 is a happy little phase vocoder! Rather than explaining how it does what it does, take my word for it that it can smear any dynamic sound into a static timbre using complicated maths which gives engineering students lifelong PTSD. I was using this trick to create drones back in 1999 by “misusing” the noise removal feature of Cool Edit Pro.
Anyway – sound goes in, drones or whooshes or wibbly noises or crackles come out. Here’s what it sounds like.
There is no actual synthesiser in this recording aside from Clouds – I played a D5 chord in on the electric mandola (2200 if anyone’s keeping score) and froze the timbre in place to create the drone. Then I played in some other notes live over the top. Add a bit of delay to smooth it out and that’s all there is to it!
Despite its popularity, the designer of Clouds discontinued it earlier this month, citing disappointment that “feedback and reverb got stuck to the maximum setting, resulting in a never-decaying smudgy howl of hype”. This is part of the reason I avoided it for so long, because I didn’t want to.
DASYRAC is my voltage-controlledEurorack modularsynthesiser. It’s a synthesiser because it creates positive and negative voltages which turn into vaguely musical positive and negative sound waves when they’re sent through a speaker coil. It’s modular because it’s built up from modules and instruments which each have a specific role to perform in the process of synthesis. It’s Eurorack because the modules use Doepfer’s Eurorack specfications for size (3U) and voltage (+/- 12V & +5V supply rails, plus gate and pitch CV buses which only Doepfer’s modules seem to use).
Finally, it’s voltage-controlled because the modules are connected by patch cable and signal one another using voltages. Signal types include:
triggers – a very short pip of steady positive voltage used trigger a modulation source or function generator, reset a sequence, etc
clocks – a series of short triggers used for timing, usually evenly spaced
gates – a sustained steady positive voltage which is held “high” for the length of a note or other event
modulation – a non-steady voltage which is used to control module functions
pitch – a voltage which is used to represent the pitch of a note, where one volt corresponds to one octave (1v/oc); usually steady, but not always
audio – a varying voltage which rapidly swings positive and negative and is intended to be heard at some point
Because they’re all made of the same stuff (flowing electrons), these signals can play one another’s roles – audio and gate signals can both be a modulation source, sufficiently fast clocks can be an audio source, audio can also be a clock source, pitch can be a modulation source, modulation can be a pitch source, and triggers can even be an audio source as long as you’re into snaps and clicks. Part of the fun of modular synthesisers is just seeing what happens when you connect modules together in unconventional ways.
Here’s a recent photo of a cable-free DASYRAC with colour-coding to show what the different modules do. If a module has more than one function, it gets more than one colour.
A rainbow of possibilities!
The multicoloured thing at the bottom left is a Make Noise 0-Coast synthesiser – it’s not a Eurorack module itself, but it can patch into and out of DASYRAC just fine. As you can see, it’s like a tiny self-contained modular system in and of itself. There’s also an ARP Odyssey floating around somewhere.
Everything starts with a supply of tasty electrons from two power supplies (in red). All the active modules connect to the two power supplies at the back by ribbon cable.
Middle row: 4ms Row Power 30
Bottom row: Tiptop uZeus
Maybe I’m being too specific about what makes noises…
The green modules are audio sources. They speficially create oscillating voltages which are intended to be heard aloud at some point. Some are more fully featured than others – the green module in the centre top row is an entire self-contained instrument – it’s a recreation of the clap sound from a Roland TR-909. Audio sources which produce a musical tone – oscillators – have a 1V/Oct socket which takes a pitch voltage. The green module at the top left is a sound playback instrument.
Top row: Music Thing Modular Radio Music (digital sample player); Music Thing Modular Turing Machine (noise source); Mutant Clap (TR-909 clap instrument)
Middle row: Befaco Even VCO (saw-core analogue oscillator)
Bottom row: Doepfer A-110-4 QZVCO (through-zero quadrature sine wave oscillator); Befaco Crush Delay (crackly lo-fi digital noise); Bastl Instruments Noise Squared (digital square oscillators and noise sources)
Tabletop: Make Noise 0-Coast (triangle and square oscillator)
Not shown: Korg ARP Odyssey (fixed-architecture synthesiser which can be run as a plain CV-controlled dual oscillator if need be)
The blue modules are “non-audio” voltage sources and include function generators like the Rampage, step sequencers like the SQ-1, procedural sequencers and clock sources like Tuesday, and random voltage generators like Turing Machine. Their job is to provide discrete or continuous voltages which can drive melodies, rhythms, filters, or whatever else accepts voltage control. If they’re running fast enough, voltage sources can also be used as oscillators in their own right.
Top row: Befaco Joystick (gate source and fun voltage generator); Music Thing Modular Turing Machine (random voltage & trigger generator); Hexinverter Galilean Moons (two slope/attack-sustain-release generators)
Middle row: Befaco Rampage (dual complex function generator); TINRS Tuesday (procedural phrase sequencer and clock source)
Bottom row: Sonic Potions Mal-2 (random smooth voltage generator)
Tabletop: Make Noise 0-Coast (MIDI-to-CV converter; low frequency oscillator source; clock generator; stepped random voltage generator; simple slope function generator; attack-decay-sustain-release envelope generator); Korg SQ-1 (simple sequencer)
Not shown: Arturia Beatstep Pro (complex sequencer with 2 x gate, modulation and pitch channels, 16 x trigger channels, clock source, etc); Arturia Keystep (keyboard with gate, modulation and pitch out ); Korg ARP Odyssey (gate, trigger and pitch source)
Many of these blue things make excellent audio sources in their own right..
If the voltage sources put out voltages which aren’t quite right, that’s where the orange modules come into play. These modules are for manipulating voltages in different ways.
Top row: Befaco Joystick (adds/subtracts incoming voltage); Befaco Dual Attenuverter (multiplies incoming voltage then offsets it)
Middle row: Worng Electronics 3×3 mult (routes incoming voltage to multiple places); Thonk AT-AT-AT (triple signal attenuator to make things quieter); Befaco Rampage (turns gates into attack-sustain-release slopes); Erica Synths Pico Input (dual signal amplifier to make things louder); Mutable Instruments Links (makes exact copy of incoming voltage and sends to multiple destinations); Doepfer A-151 Sequence Switch (voltage controlled signal router); Befaco Slew Limiter (limits the rate of change of incoming voltage)
Bottom row: CMF Half-Wave Rectifier (splits off positive and negative halves of incoming voltage); Befaco Sampling Modulator (samples and holds incoming voltage when triggered); Sonic Potions Penrose (quantises incoming voltage to equally tempered steps); Worng Electronics 3×3 mult
Tabletop: Make Noise 0-Coast (signal attenuverter and summer)
The yellow modules are the effects and filters. Filters in particular make the incoming sound quieter at particular frequencies and also colour the sound in characteristic and desirable ways. They are “voltage controlled filters” (VCFs) because they take an input voltage to control their cutoff frequency, which is the frequency where the filters take effect. There’s also some effects modules for even more retro colour. Many of these modules can be made to create noises of their own without any input, which also makes them audio sources in their own right!
Top row: RYO Aperture LPG (low pass gate, also usable as a VCA); Music Thing Modular Simple EQ (two-band EQ and EQ “tilter”)
Middle row: Befaco Chopping Kinky (dual wavefolder); Doepfer A-106-6 XP VCF (state variable voltage controlled filter based on the Oberheim Xpander); Doepfer A-199 Spring Reverb (mechanical reverberation effect)
Bottom row: Vintage Synth Lab VCF-74 (serial highpass and lowpass filter based on the Korg Minkorg 700s); Befaco Crush Delay (circuit-bent delay effect)
Tabletop: Make Noise 0-Coast (integrated wavefolder and waveshaper)
Not shown: Korg ARP Odyssey (switchable vintage low pass filter with CV cutoff control via the pedal input)
Violet modules are a special thing called VCAs – voltage controlled amplifiers/attenuators. A VCA takes two signals – an input and a modulating signal – and outputs a quieter/louder version of the input signal with amplitude/volume tracking the modulating signal. VCAs are where a long steady beeeeep sound is contoured into a short pip or a long mournful wail. Even better: a quadrature VCA can invert the incoming signal – chuck a sine wave into it as a modulator and you’ve got Dalek voices.
Top row: RYO Aperture LPG (also usable as a VCF); Hexinverter Galilean Moons (with integrated envelope generator)
Bottom row: Befaco A*B+C (dual full quadrature VCA with offset, also usable as a mixer); Bastl Instruments Skis (character VCA with integrated envelope generator)
Tabletop: Make Noise 0-Coast (VCA stage including overdrive)
You can never have too many VCAs..
The last set of modules in indigo is for combining signals together. The modules can mix audio as well as control voltages.
Top row: Bastl Instruments ABC (dual three channel mixer); Worng Electronics LRMSMSLR (left-right to mid-side encoder/decoder)
Middle row: Doepfer A-138a linear mixer (four channel mixer with CV source on channel 1); Mutable Instruments Links (two channel unity gain mixer; three channel mixer)
Bottom row: Doepfer A-185-2 Precision Adder (for combining pitch signals together, e.g. to transpose them)
Overall, DASYRAC is an eclectic system with features from the mainstream East Coast school (character filters, rich saw/pulse oscillators), the artier West Coast school (waveshapers, function generators, sequencers, low pass gates), old timey classics (spring reverb, shift register noise) and fun new possibilities (digital audio playback).
