Tag Archives: eurorack

Modules 36, 45 and 53 – Music Thing Modular Turing Machine Mk II with Pulses and Voltages expanders

  • What kind of thing is it? The Turing Machine is a clock-driven stepped random voltage and trigger generator. Clock-driven means you have to hit it with a pip of voltage to make it do something, and stepped means that the voltage output switches instantly from one voltage to the next instead of transitioning gradually. You can also set the randomness to zero and use the write switch to turn it into a binary step sequencer. The Pulses expander is a cascading trigger source which uses the Turing Machine’s voltages to send out triggers, and the Voltages expander uses that same set of voltages to create a stepped random voltage output which is truly analogue instead of quantised to eight bits like the Turing Machine’s main out. There’s also a random noise generator which is always going.

voltages is voltages! love them little blinky slider pots ๐Ÿ™‚ #Eurorack #diy

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  • How is it useful? Random voltages can be used as the basis for the pitches of notes, a non-repeating modulation source, etc. The randomness can be controlled either by using the big friendly dial and by a control voltage. If you feed it an audio-rate clock source like a pulsewave from an oscillator, it can act as a randomising waveshaper, or you can use it as a graphic oscillator with the Voltages expander. Random triggers meanwhile can be used to set off drums or other instruments. It also looks very impressive with all its blinky lights.
  • How does it work? Inside the Turing Machine is a shift register. A register’s job is to accept and maintain values (in this case, ons and offs), and a shift register can shift those values when commanded, kind of like they’re on a conveyor belt. Every time the module is triggered, the values all move along one spot BUT there’s a certain probability (set by dial or CV) that the outermost value of the register could change from on to off (or from off to on). The Turing Machine’s shift register’s state then feeds into a digital-to-analogue converter where it’s turned into an 8-bit voltage, and out it comes.

a short informational video on what the Turing Machine's blinky lights actually mean

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So is it analogue or digital? Both. The Turing Machine is analogue in the sense that it doesn’t have a fixed sample rate, but digital in the sense that its workings are driven by discrete values (on/off) and the output is an 8-bit voltage (one of 256 possibilities). If by “digital” you mean “it has a CPU”, it’s analogue. But if by “analogue” you mean “it doesn’t contain a DAC and the output voltage isn’t stepped in any way”, it’s digital. The Voltages expander sends each step through a slide potentiometer which makes it a bit more analogue than the main Turing Machine module.

  • Whose YouTube demo convinced you to buy it? Mylar Melodies made a strong case, but Divkid’s demo sold me when he ran it at audio rate at around 22:25 – that was my breaking point. ๐Ÿ™‚

  • Does it work well? For sure. Being able to control randomness with CV is super good fun when the module is clocked at audio rates, although if it doesn’t have a 50% duty cycle at high audio rates it sometimes doesn’t clock properly. It’s possible to switch the randomness off entirely and use it as a binary sequencer with careful use of the write switch. The Turing Machine’s Noise output is handy but needs amplifying to be useful.
  • Are you still using it? Absolutely. The Turing Machine is one of those go-to modules that epitomises Eurorack’s cool factor for me – it has blinky lights and does many useful things with tech that’s been around for ages (in this case, 4000-series CMOS chips). Not for nothing does it show up in so many racks.
  • It’s a kit – how easy was it to build? The main module was easy, although this was the 23rd Eurorack module kit I’d built and that includes far more complicated builds like the Befaco Rampage and the Hexinverter Mutant Clap. The Pulses Mk II expander has SMD components which I’m still getting used to working with, so that was the more memorably difficult build! And the Voltages Mk II was easy-peasy, as promised.
  • Surprises/disappointments? I researched this one pretty well so there hasn’t been anything too surprising or disappointing aside from the quiet noise out.
  • Who makes it (and where?): Music Thing Modular, kits sold by Thonk out of the United Kingdom.
  • Stats: Turing Maching Mk II is 10HP, Pulses Mk II is 4HP, Voltages Mk II is 12HP again.

ModularGrid: Turing Machine, Pulses, Voltages (all Mk II)

Module 4 – Erica Synths Pico INPUT

  • What kind of thing is it? It’s an amplifier that takes two mono signals or one stereo signal and amplifies them from line level (1.23Vpp) up to modular level (~5Vpp).
  • How is it useful? It lets me bring audio signals in from normal gear to use in the modular. With this, I can run the Odyssey’s audio out or a guitar pedal into DASYRAC at the right volume. It’s also great for raising the volume of native modular signals which are too damn quiet, and thankfully there’s volume knobs to control the amount of gain.
  • How does it work? It’s an amplifier so it’s got amplifying circuitry in it, the stereo routing is (probably) done with switched jacks, and I’m not experienced enough to guess the rest ๐Ÿ™‚
  • Does it work well? Yes. It’ll take a stereo signal at the top and break out the left and right to the two outputs, or it can take two mono signals too. There’s a green LED for when the signal is the right volume and if the signal gets too loud there’s a red LED to warn you of clipping. It all comes in a petit 3HP package like the rest of Erica’s Pico module range.
  • Are you still using it? Now that I’ve got a Drumbrute with individual outs for each drum channel I can see myself making much more use of it.
  • Surprises/disappointments? The automatic stereo splitting was a very nice surprise – no need for a Y cable! Hooray! The harsh clipping is a bit disappointing though.
  • Who makes it (and where?): Erica Synths of Latvia.
  • Stats: 3HP.

Modulargrid.

Modules 5 and 16 – WORNG Electronics 3x3x3 Passive Mult

  • What kind of thing is it? A passive multiple. A mult lets you send whatever signal is travelling down a cable to multiple different destinations. Using a passive mult, the signal weakens the more places you send it to but for on-off signals like triggers and clocks, that doesn’t matter so much.
  • How is it useful? You can send one signal up to six new places, three signals out to two new places each, and with two signals you can send one to four other places and one to two other places. Here are some pictures with captions.

The 3x3x3’s input jacks all have a gold ring around them. Here it is fully connected. Yellow’s signal is going out to the pinks; green’s signal is going out to the whites and blue’s signal is going out to the reds.

Now we only have two inputs. Yellow’s signal still goes out through the pinks. Green’s signal goes out through the whites, and since there’s nothing plugged in under the whites it goes out through the reds too.

Yellow’s signal is still going out through the pinks, but since nothing is plugged in under pink, the white cables also carry yellow’s signal. The blue cable’s signal is carried down the red cables.

With no other input voltages, the yellow cable’s voltage (at the top) is being sent out to pink, yellow and red all at once.

  • How does it work? By joining switching audio jacks together on a circuitboard. Seriously, that’s all there is to it. They don’t come much simpler.
  • Does it work well? Definitely. This was the first module I ever got two of, even.
  • Are you still using it? I’ve replaced one of these with some Befaco six-way mults which live in the cable spaghetti. The other one is still racked up for now until I get some more six-way mults.
  • It’s a kit – how easy was it to build? It’s inexpensive to buy, safe and simple to build as an early DIY project and very useful – an ideal first DIY Eurorack module, I think! The only build problem I had was attaching the panel upside-down but that was easily rectified. ๐Ÿ™‚
  • Surprises/disappointments?ย It works even better de-racked and living in cable-space!

The white cable is carrying a repeating falling voltage used to make a kick drum. Sent through the mult, the pink leads use the same signal to make the oscillator go PEW and also reset its sync to avoid clcks on some triggers and not on others because of interactions between the oscillator’s phase and the amplifier’s envelope. Without the mult, I’d need two separate envelope generators. Bargain!

  • Who made it (and where)? WORNG Electronics (Australia)
  • Stats: 3HP, passive (no power requirements)

Modulargrid.

The DASYRAC approach

Eurorack is very easy to blow the bank on. Not for nothing do people call it Euro-crack. There are hundreds of different modules which do all kinds of different things and it’s very easy to run around like a kid in a candy shop buying anything with pretty blinky lights that makes a vaguely cool sound.

I knew this going in and I wanted to be smarter.

It helps to focus on achieving a particular goal. In my case, I wanted a voltage controlled, chaos-infused mad science lab – something that has minimal overlap with the tech already on my computer. I came up with the following guidelines to help me stay the course.

Analogue signal path wherever possible

Why? I’ve got loads of digital sounds on my computer already. No need to add even more! Analogue gear behaves in more interesting unpredictable ways than digital when pushed and digitisation can add nasty artefacts.

But… pure analogue circuitry can be annoyingly unstable, imprecise and generally fiddly, even when it’s well-behaved and recently built. Re-patching a sound perfectly is nigh-on impossible.

And so I’ve got sample playback (Radio Music and Disting Mk 4), digital delays (Chronoblob, Crush Delay – the Crush is very lo-fi though) and a digital processor (Clouds). The Disting has a nice high sample rate which helps things.

Digital timing for precision, analogue handling for fidelity

Why? DASYRAC needs to be able to hold a tempo for multitrack recording, and digital clocking is steadier. Analogue is generally still better for audio-rate modulation – the sample rate of digital can easily misinterpret or distort rapid signal changes that analogue circuitry deals with perfectly capably.

Surface controls only, preferably with CV

Why? Automation is cool, menu diving without a mouse sucks and multi-functional knobs are too much effort to remember.

But… menus can hide complexity & reduce the module size, leaving room for more modules.

And so… I have the Tuesday procedural sequencer Tuesday, the multifunction Disting mk 4, the clock manipulator Little Nerd, and the texture synthesiser Clouds whose clunky UI so annoyed its inventor that he discontinued it. All of these CPU-based modules require some menu-diving and/or have modes and other stuff. As long as they’re useful and limited in number, they’re fine.

Decoupled from the PC and MIDI-based control

Why? I’ve looked at a screen to make music for 25 years and I’m utterly bored with it. Also being able to separate gate from pitch is awesome. You can’t really do that with MIDI unless the individual instrument lets you. It’s absolutely possible to inject MIDI and computer-controlled CV into Eurorack – I just don’t want to.

And yet… recording and mix is all digital because using analogue recording media as well is pointlessly limiting when it comes time to compile something.

Ephemerality over reproducibility (no presets!)

Why? I am tired of preset surfing and I’m not on anyone’s clock.

But… patching manually is slower, even when you know exactly what you want. Either I record that cool sound or lose it forever, and disk space is ultimately still finite.

And so… Tuesday has hard-coded scale presets, Disting mk 4 has some presets in there too, and Little Nerd can be preset but I don’t use it like that.

Keep single module spend less than A$250 where possible and don’t spend more than A$500 on a single instrument

Why? Eurorack is cumulatively expensive enough as is, let alone high-end Eurorack. Second hand modules are fine too.

But.. in keeping my module selection low cost, I miss out on some very shiny stuff. Really shiny.

And so… The Tuesday, the Make Noise 0-Coast and Korg ARP Odyssey were all north of half a grand. Clouds, Chronoblob, Fluctuations Magnetiques and Deflector Shield were all more than $250 each. None of the DIY modules have been more than $250, though some have come pretty close. ๐Ÿ™‚

DIY if it’s feasible, cheaper and equal quality

Why? It’s cheaper – the cost of assembly is a big chunk of the sticker price! It’s doable if not always simple. I get to learn about electronics. Also, soldering on my back patio is a lovely way to pass the time.

But… DIY needs equipment and if a DIY module breaks, I have to fix it myself.

The one time I bailed was.. Clouds! It’s possible to get DIY kits because Clouds is open-source hardware, but it involves a lot of surface mount component soldering. I do not like surface mount component soldering.

Modular components over contained black boxes

Why? Black boxes with no control points are just less fun. If something is part of a system, I prefer it to allow that system to alter what it does instead of just doing its job.. because you never know what you might get it to do. If there’s just an in and an out, well, it had better do something pretty awesome…

But.. black boxes mean less of your system is tied up and you can do more cool stuff at once. It’s a trade-off.

And so.. The Little Nerd doesn’t accept anything except for a clock, but it does cool enough stuff with that clock that it’s OK. The 106 Chorus only has an in and an out but it sounds fab. And the Ladik Waveform Animator.. well.. it’s 4HP of black box yumminess.

Multi-function over single function

Why? A versatile module means you can do more with your system. I’ve noticed that the analogue modules tend to be more versatile in what they can be used for while the digital modules seem to be designed with a specific purpose in mind. A function generator like the Befaco Rampage can do so many things that it beggars belief, which is why it and its better known cousin Maths are in nearly every Eurorack setup there is.

But.. a really versatile module has more chance of being used early in a patch, which means choosing which of its many tricks it will perform for you. The Disting mk 4 has almost 70 different modes, for instance, but I only have one of them so I can only have it do one of those seventy things at once. Maybe I should get another one…

And yet… I don’t mind the odd one-trick pony like the Feedback 106 Chorus or the Ladik Waveform Animator in my rack because they do their job so nicely.

Unpredictable/chaos-guided systems over explicit/periodic instructions

Why? It’s more interesting to build a patch which shape chaos in interesting ways than building up intentional order from nothing. It’s also way quicker to carve away the notes you don’t want with a quantiser than program in the exact sequence of notes you do want. Just saying.

But.. building a nice chaos-taming patch requires more experimentation than plugging notes into a sequencer.

Monophonic over polyphonic

Why? Polyphony means doing more than one thing at once, and that cost more money than just having one thing going at once then multitracking it. Also, years of listening to chiptunes has taught me pretty much every trick in the book when it comes to getting bang for buck out of a single oscillator. And there’s always the option of smearing arpeggios into a drone with a bit of delay or spring reverb.

But.. it makes performing complicated things live much harder. Not that I do live stuff on my rack. It also means a lot more patching.

And so… multitracking isn’t the only answer to this. I can also use samples from DASYRAC itself courtesy of the Radio Music or the Disting Mk 4, both of which have sample playback.

DASYRAC – the whole story!

Note: This article will be updated with new information and links over time.

DASYRAC (Digital/Audio System Yielding Retro Auditory Coolness) is my voltage-controlled audio mad science lab, containing fifty 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. ๐Ÿ™‚

The Eurorack bit

A quick jargon-buster: Eurorack modules have a standardised height of 3U – that’sย  133.5mm to the rest of us. The widths of the modules varies wildly and 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 a relatively whopping 22HP.

DASYRAC is housed in a 9U (= three rail) 104HP Synthrotek Cheeks Of Steel open rack and an 84HP Tiptop Happy Ending kit rack for a total of 396HP. The modules are powered by two 4ms Row Power 30 supplies yielding a total capacity of 3A on the +12V power rail, 1.5A on the -12V power rail, and 1A on the seldom-used 5V power rail. The powered modules connect into shrouded IDC power connectors at the back and everything runs off a single 90W laptop power supply.

The actual Eurorack modules

Each module is listed with a “rack-up” date. All the dates are for 2017.

The majority of DASYRAC’s modules were built from DIY kits as sold by stores like Thonk (UK), Befaco (Spain), Noise Kitchen (Czechia) or by individual vendors like Sonic Potions (Germany) and WORNG Electronics (Australia). All the kits were supplied with all the necessary through-hole components unless otherwise stated.

Over time I want to build up a commentary about what each module does and how it does it, why I wanted it in the first place, what surprised/disappointed me, whether it actually does the job, sound demos, etc. Since that’ll take a while, the [modulargrid] link will take you through to the module’s entry on Modulargrid where you can read about it while I get my act together.

  1. Doepfer A-138a linear mixer (27 March – 16 November) [modulargrid]
  2. CFM Bipolar Half-Wave Rectifier (kit, 27 March – 6 October?) [modulargrid]
  3. Tiptop uZeus power supply (27 March – 6 October?) [modulargrid]
  4. Erica Synths Pico Input dual amplifier (30 March) [modulargrid]
  5. WORNG Electronics 3x3x3 Passive Mult #1 (kit, 5 April – 16 November) [modulargrid]
  6. Thonk AT-AT-AT triple attenuator (kit, 11 April – 16 November) [modulargrid]
  7. Befaco A*B+C dual quadrature VCA (kit, 15 April) [modulargrid]
  8. Doepfer A-199 SPRV Spring Reverb (18 April) [modulargrid]
  9. Doepfer A-106-6 Xpander VCF (18 April) [modulargrid]
  10. Doepfer A-151 Sequential Switch (18 April) [modulargrid]
  11. Mutable Instruments Links buffered multiple & mixer (24 April) [modulargrid]
  12. Befaco VC Slew Limiter (kit, 29 April?) [modulargrid]
  13. Befaco Rampage dual function generator (kit, 30 April) [modulargrid]
  14. T.I.N.R.S. Tuesday procedural sequencer (8 May) [modulargrid]
  15. 4ms Row Power 30 power supply #1 (22 May) [modulargrid]
  16. WORNG Electronics 3x3x3 Passive Mult #2 (kit, 26 May) [modulargrid]
  17. Bastl Instruments Noise Square waveform generator (kit, 26 May) [modulargrid]
  18. Bastl Instruments Skis dual decay/VCA (kit, 28 May) [modulargrid]
  19. Vintage Synth Lab VCF-74 low pass filter (30 May) [modulargrid]
  20. Befaco Sampling Modulator sample and hold (kit, 10 June) [modulargrid]
  21. Sonic Potions Penrose pitch quantiser (kit, 15 June) [modulargrid]
  22. Doepfer A-185-2 Precision Adder voltage summer (15 June) [modulargrid]
  23. Sonic Potions Mal-2 source of chaos (kit, 16 June) [modulargrid]
  24. Doepfer A-110-4 QZVCO Quadrature Through Zero VCO (21 June) [modulargrid]
  25. Befaco EvenVCO (kit, 24 June) [modulargrid]
  26. Befaco Crush Delay (kit, 25 June) [modulargrid]
  27. Befaco Chopping Kinky dual wavefolder (kit, 25 June) [modulargrid]
  28. Befaco Joystick (kit, 2 July – 21 August, re-rack 18 November) [modulargrid]
  29. Befaco Dual Attenuverter (kit, 7 July) [modulargrid]
  30. Bastl Instruments ABC mixer (kit, 7 July) [modulargrid]
  31. Hexinverter Galilean Moons dual EG/VCA (kit, 14 July) [modulargrid]
  32. Hexinverter Mutant Clap (partial kit, 21 July) [modulargrid]
  33. WORNG Electronics LRMSMSLR stereo/mid-side processor (pcb/panel, 1 August) [modulargrid]
  34. RYO Aperture LPG low pass gate/VCA (kit, 1 August) [modulargrid]
  35. Music Thing Modular Radio Music sample player (kit, 1 August) [modulargrid]
  36. Music Thing Modular Turing Machine mk II stepped random voltage source (kit, 2 August) [modulargrid]
  37. Music Thing Modular Simple EQ (SMD kit, 3 August) [modulargrid]
  38. Ladik L-010 Waveform Animator (7 August) [modulargrid]
  39. Synthesis Technology E560 Deflector Shield frequency shifter/phaser (17 August) [modulargrid]
  40. Eowave Fluctuations Magnรฉtiques quadruple VCF (21 August) [modulargrid]
  41. Expert Sleepers Disting mk 4 swiss army knife (1 September) [modulargrid]
  42. 4ms Row Power 30 power supply #2 (6 October) [modulargrid]
  43. Alright Devices Chronoblob digital delay (6 October) [modulargrid]
  44. Mutable Instruments Ears contact mic/amplifier (6 October) [modulargrid]
  45. Music Thing Modular Pulses mk II random trigger source (SMD kit, 13 October) [modulargrid]
  46. Transient Modules 8S Sequencer (kit, 14 October) [modulargrid]
  47. Bastl Instruments Little Nerd clock manipulator (kit, 14 October) [modulargrid]
  48. Mutant Instruments Clouds texture synthesiser (20 October) [modulargrid]
  49. Horstronic Arcade Button trigger/gate (kit, 6 November) [modulargrid]
  50. RYO VC Sequencer (kit, 7 November) [modulargrid]
  51. RYO TrigXpander trigger source (kit, 7 November) [modulargrid]
  52. 2hp Euclid euclidean rhythm generator (13 November) [modulargrid]
  53. Music Thing Modular Voltages mk II graphic random voltage source (kit, 27 November) [modulargrid]
  54. RYO Optodist overdrive (pcb/panel, 27 November) [modulargrid]
  55. Bastl Instruments ABC mixer #2 (kit, 28 November) [modulargrid]

Pending

  • Feedback 106 Chorus (partial kit) [modulargrid]
  • Befaco A*B+C dual quadrature VCA #2 (kit) [modulargrid]
  • Music Thing Modular Spring Reverb mk II (kit) [modulargrid]
  • Fonitronik Cascade attenuverter/mixer (kit) [modulargrid]
  • Doepfer A-124 Wasp VCF [modulargrid]
  • Polaxis Talko linear predictive coding speech synthesiser (kit) [modulargrid]
  • Ornament and Crime digital swiss army knife (kit) [modulargrid]

Patch pals

Patch pals are mini-circuits which live out in “cable space”. They don’t need a power supply to do their job.

  • Befaco 6-Way Mults (23 June)
  • Mystic Circuits 0hp OR gate (kit, 26 October)
  • Mystic Circuits 0hp AND gate (kit, 26 October)
  • Mystic Circuits 0hp Vactrol VCA/LPG (kit, 26 October)
  • LMNTL 6-way mults (27 November)

External instruments

Most of these instruments talk to DASYRAC using voltage control and are where it all started, long ago in the ancient times of January 2017.

  • Korg ARP Odyssey synthesiser (23 January)
  • Korg SQ-1 sequencer (24 February)
  • Arturia Beatstep Pro uber-sequencer (3 March)
  • Arturia Keystep keyboard/sequencer (7 March)
  • Arturia Drumbrute drum machine (28 November)

Beepboops take over!

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…

The Horstronic Arcade Button is not just a #diy #eurorack button, though it definitely is that too.

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…then on Tuesday evening I soldered together two RYO modules, the VC Sequencer and the TrigXpander…

Most of a #diy #eurorack RYO VC Sequencer… panel comes next!

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…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. ๐Ÿ™‚

It’s goodbye then to “see you next week” – so see you ’round! ๐Ÿ™‚

Jam of the day: Not your dad’s vocoder

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.

Introducing DASYRAC!

What’s a DASYRAC then?

DASYRAC is my voltage-controlled Eurorack modular synthesiser. 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,ย  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).

If you want to hear the sounds I’ve been making with it lately, check out my SoundCloud.