Freebie of the Month: VCV Rack

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Can this be true?  Not just a module or two, but a complete Eurorack-style patchable modular synth environment for Mac, PC or Linux – and it’s FREE.


by Warren Burt, Jan. 2018


In the past year, we’ve seen a number of makers release analog synth style emulations for the computer, some based on classic hardware (Arturia’s Buchla Easel V), and some based on newer Eurorack modules (Softube Modular).  So far, these have all been commercial products.  Now, however, along comes not just a single manufacturer, but a whole community of developers who are building, for free, a patchable, open source analog synth emulation environment, it’s cross-platform as well – PC (64 bit only), Mac (10.7+), and Linux (64 bit only).  It’s one of the most exciting new systems I’ve seen in quite a while. 

Andrew Belt is the developer who, about a year ago, began developing a free open-source cross-platform virtual modular system called VCV.  He approached some Eurorack module developers, such as Audible Instruments and Befaco, to see if he could get permission to emulate their designs in software.  To his delight, they said yes, and a basic set of modules based on Belt’s designs and their own designs soon became reality.   On top of this, a whole community of developers began adopting the VCV standards to make their own additions to the system – VCV calls these “plugins,” and with the release of the latest version (0.5.1), there is now a page on the VCV website called Plugin Manager where you can download a number of these free plugins to add to your system.  Some of these plugins are just one module, but some are rather large packages of both familiar and non-familiar modules, each of which has its own feature set and characteristics.

Let’s start by looking at the “rack” which makes the VCV Rack work.  Here we see the blank rack, which appears when you start the program (providing you haven’t exited the program with modules on the screen – it always remembers your last setup), along with the Add Module menu, which appears when you right-click (this may be different for Apple users) into an empty place on the screen.

In the Add Module menu, you see from left to right, a list of manufacturers and then a list of modules from that manufacturer.  Click on one of these to place it in the rack.  On the right is a column with more information about the module, and links to directories, manufacturer’s websites, and on-line manuals.  These vary from maker to maker.  On the top of the rack, left-to-right, is a file menu (new, open, save, save as, quit); a sample rate selector (which goes up to 192kHz; cable opacity and cable tension controls; a zoom control, which can resize the screen from 25% (7 rows of modules) to 200% (great for folks with vision problems); Manage Plugins (which takes you to the Plugin Manager page on the VCV Rack website); Update Plugins (which, when the program reaches version 1.0, will allow you to upload the latest plugins); and Log out or Log in (which requires your email address and password, should you choose to register the software in order to download free plugins, or purchase new modules).  It’s very early days for the project, and the Update Plugins facility is in a state of flux.  Current plans (as of mid-January) are for it to be fully operational by version 1.0.  In the meantime, all free plugins are accessible from the Plugin Manager page on the website.  I’ve been watching the progress of the system for about six weeks now, and improvements and bug fixes are appearing almost daily.

Next we see a zoomed out screen with four rows for modules and a selection of miscellaneous modules in the system.  From left to right, these are the Core Audio Output; Autodafe Square and Tres Amigos Oscillators; Arable Instruments Neil – a granulator; Bidoo dTrOY Sequencer; Bidoo Moire – a set of sixteen settable, recallable control voltages; Julien Eres Simple Wave Folder; Julien Eres Ring Modulator; JW-Modules Bouncy Balls; Hora Music Spectral Processor (this one is payware, but only €19 EUR); and Nonlinear Instruments Quadratic Iterator.  You can see from this fairly random selection, the variety of modules that are already available in this, a project which is just getting started.

Turning to the basic operations of the system, let’s look at the Core modules – the ways that you interact with the rest of the world.

From left to right, there is the Audio Interface; the MIDI to CV; MIDI Clock to CV; MIDI Trigger to CV; and MIDI CC to CV modules.  All of these can be customized to match your patch needs.  For example, the MIDI Trigger and CV modules can be set to any MIDI numbers you desire.  Not here yet, but appearing with Version 0.6.0 in mid-late January will be a Bridge module.  VCV Rack will not be a VST or AU plugin, but the Bridge module will allow sending and receiving signals from VCV Rack to any DAW environment.  And there will be as many bridges available as your DAW and CPU can handle.  Even as a stand-alone system, VCV is incredibly powerful.  Once the Bridge module is released, its power will increase enormously.  (I, for one, am eager to use GRM Tools and Melda plugins in conjunction with this system.)

The basic VCV modules (developed by Andrew Belt and Grayscale) are shown here.

These are interesting “bread and butter” modules (mostly) that will provide a central starting point for your patching.  From left to right, VCO-1 (there is also a VCO-2); VCF; VCA; LFO-1 (there is also an LFO-2); Delay; ADSR; VC Mixer; 8Vert (eight control voltage processors); Mutes (good as on-off switches); SEQ-3 (a sequencer); and two Sequential Switch modules.  There are others, like a Scope, but the figure gives you the idea.

Coming with the basic Fundamental modules are sets of modules from Audible Instruments, Befaco, Grayscale and E-Series.  Here below are shown the Audible Instruments modules, which are based on Audible Instruments Eurorack modules: Macro-Oscillator (a very versatile multi-wavetable oscillator); Modal Synthesizer (a physical modelling module); Tidal Modulator (an advanced LFO); Texture Synthesizer (a granulator); Meta-Modulator (a ring modulator and a wave shaper); Resonator (a highly resonant bandpass filter); Mixer; Bernoulli Gate (a module which randomly switches an input to one of two outputs); Quad VC-polarizer (four-control voltage processors); Quad VCA (four VCAs); and Keyframer/Mixer (a very sophisticated control generator which can morph between preset “scenes” which are sets of control voltages.

Befaco is a Spanish company which makes DIY Eurorack modules.  Their contribution to the project is a series of modules representing assembled versions of their products. You can see these in the top row of modules in the illustration below.  Their offerings are Even VCO; Rampage (highly controlled ramp generator); A*B+C (ring modulator and mixer, among other uses); Spring Reverb; Mixer; Slew Limiter; and Dual Attenuverter.  Grayscale, in addition to their work on the Fundamental modules, also contributes Algorhythm (a pulse sequencer) and two Binary modules (which do various kinds of binary arithmetic).  Finally, there is E-Series Cloud Generator, based on Synthesis Technology’s Eurorack module of the same name.

So with all these modules, what could be missing?  Lots, it turns out, and many other plugin makers are contributing things to the project.  For example, at least three different makers have available various kinds of sampling modules.  Like chaos, or random control sources?  At least four or five makers have various kinds of random voltage generator or chaos mathematics modules.  Need to record your output?  I’ve seen at least two different recording modules.  Need to quantize voltages?  A number of makers have different kinds of quantizers.  Etcetera.  (One thing that’s missing is a quantizer that would accept Scala files for microtonal quantization.  I asked Andrew Belt about this and he said that he would suggest it to one of the plugin makers who is currently making a versatile quantizer.  Stay tuned (microtonally, of course) for more information.

One of the strengths of a project like this is that so many people are working on it, so the variety and quantity of modules available increases far more rapidly than one person, or one organized team, could.  There are lots of makers listed on the plugins page.  Just to mention a few – NYSTHI has a lot of interesting emulations of control signal generators.  For example, I’ve seen several emulations of classic Buchla and Serge modules in their set. Sonus Modular; cf; and Strum’s Mental Modules are all very powerful collections of control and audio modules.  In terms of originality, there’s plenty to be found by browsing through the list of plugins.  In terms of imitations, there are both function-alike modules (where the developer is trying to emulate a classic module, function for function), and sound-alike modules.  These are harder, as Arturia, who specialize in circuit emulation, will tell you.  But still, if the module does similar things to an existing module, but has its own unique audio characteristics, that to me is a plus, and not a minus.  The stable of modules from any one of these makers would merit a future article on its own.  Undoubtedly by the time this article appears on the web, there will be more makers, more modules, and more updates.

One of the bases for this project is that it is open source.  I’ve opened up some of the code on the relevant github sites, and yes, it is legit C++ code.  I haven’t done C++ programming for at least 25 years, if not more, so I’m not going to comment on the code (sorry for the programmers pun there!).  On the plugin manager page, in fact, there are several makers who only offer the source code – if you want to use their modules, you have to compile the source code yourself.  Since I’m not at that level of programming skill anymore, I’ll have to pass on those modules.  But the source is readable, and changeable.  For example, Arable Instruments offer two plugins which are developments of the Audible Instruments Texture Synthesizer.  Why have just one version of a module when you can have three?

Some of the makers offer not only free modules, but payware modules as well.  And of course, many of the freeware makers will accept donations.  The payware modules seem to be very reasonably priced.  In research for this article, I bought VCVs Console (an elaborate mixer module) and Pulse Sequencers; the Hora Music Spectral Processor; and the Four Track Looper and Looper Expander from Sonus Modular – each was between $10 and $25 USD, and all seem well worth the price.

Installation of the plugins can sometimes be tricky.  The basic thing to remember is to place your plugin in a single folder in the plugins folder which is in the Rack folder in your documents file. (This for Windows – Linux and Mac users consult the manual for instructions for your operating systems.)  I made the mistake of unzipping one plugin, for example, and in the unzipped folder were three folders, labelled Mac, Win and Linux.  I placed the entire folder in my plugins folder and – nothing.  Only on writing to the maker did I find out that I had to take the Win folder (or the one relevant to my operating system) out of the unzipped folder and place THAT in the plugins folder.  Once I did, sweetness and operation.  With other plugin makers, unzipping the zip folder produces the proper kind of folder to place in the plugins folder.  So for each maker, you’ll probably have to make sure that the installation is taking place properly.  Once the plugins are installed properly, however, I’ve had no problems with them – they all seem to work properly.  Of course, I haven’t had a chance to use them all, so I can’t make a blanket statement here.

So now, to the best of my knowledge, I know of three different modular computer-based systems which all are emulating Eurorack modules: VCV, Softube Modular, and Native Instruments Reaktor Blocks.  To the best of my knowledge, none of these system can interact with each other.  However, I haven’t tried interconnecting them, so I’m withholding judgement on that.  VCV Rack, being the least proprietary of the lot, would seem to have the most room for expansion.  As the FAQ says, it’s still early days, and there are still teething problems with the software, but for a project this young (well less than six months old), the results so far have been very impressive indeed.

Way back when, when I was teaching analog synthesis to people, I would emphasize to them that they should take a methodical one-module-at-a-time approach to learning a system, building up one’s knowledge slowly and incrementally.  This was, of course, in the days when each module would cost the equivalent, at least, of several week’s groceries or a car payment.  Suddenly, when faced with the abundance of a project like this, what is one to do?  My first impulse is actually buy a small paper notebook, to keep track of the many new modules, and reconstructions of old ones, that are now available.  Other than that, once again, slow and methodical exploration might be the order of the day – or maybe fast and superficial initial looks, followed by later slow and deep explorations.  In any case, this system has enough power to keep one occupied for quite a long time.  And if one were to combine it with other MIDI based control programs, such as Algorithmic Arts MusicWonk(Win only), or PD, one would have an incredibly powerful system that could work on just about any current computer system, and which, except for the cost of the system, would cost you nothing.

In closing, here’s a look at a simple patch I put together with the program.  In this patch, a simple piano loop is frequency modulated and wave-shaped, with parameters of the loop playing and wave-shaping controlled by a sequencer, with the speed of the sequencer controlled by a random sample and hold circuit.  Modules used include cf’s Player; AS’s WaveShaper and 16 Steps Sequencer; ML’s Sample and Hold; BogAudio’s Noise generator, and all other modules from the Fundamental set of VCV modules.  It’s a very simple patch, but it shows that, even at a scratching-the-surface level, this is a system that is capable of great compositional flexibility.  And the price is right.  So for those of you who are oriented toward exploring possibilities of sounds and control systems, what are you waiting for?

For more information or to download, go here:


VCV Rack is mostly free but some payware modules are also available.




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