ADDAC System are responsible for some completely wild and off‑kilter designs, but also for numerous modules so nuts‑and‑bolts that they could capably unite to form the most utility Eurorack system imaginable. Although if you get excited about modules like the ADDAC200RM power‑rail monitor, then I take my hat off to you. All ADDAC System’s modules are named and decorated in a similarly sober fashion, meaning that when a highly inventive module with masses of creative excitement is presented, it’s done so with less of a fanfare of bright colours and loopy graphics and more of a wry smile.
The ADDAC511 VC Stochastic Voltage Generator can somehow fall into both categories, depending on the way you think about random voltage. A four‑channel distributor of all manner of unpredictability, no matter the scope of your stochastic ambitions, this module has you covered down to the most meticulous degree. If, on the other hand, you’re unsure of how much a (very) healthy dose of randomness can benefit your patching then read on: the ADDAC511 is waiting to bestow exactly that on your system, and with not a little finesse.
In case it needed clarifying: ‘stochastic’ simply means that something is analysable but not predictable. In this case, that means that far from simply spitting out random voltages at, erm, random, the ADDAC511 operates according to a raft of finely tuneable conditions for its behaviour. If you’re familiar with 2013’s ADDAC501 Complex Random then much of this will feel redolent of that module, only hugely expanded. It has four separate channels, each with its own CV and gate output, and within each of these, three separate ‘states’ which can be recalled at the touch of a dedicated button. That’s 12 different, instantly recallable channel states, which is mightily useful.
As for what each channel actually does; in a nutshell they can be set to generate continuous voltages, envelopes or be used as a quantiser for incoming CV. Each channel’s parameters fall into two broad categories, Voltage and Time, with each subcategory within these accessed and edited via an OLED screen and two encoders. The screen is of good resolution, and ADDAC have done their level best to avoid menu‑diving with a maximum of two screen layers per parameter. While things can still feel a tad labyrinthine (long presses on buttons, highly detailed screen parameters and so forth), I can’t in good faith imagine any further streamlining of the ADDAC511’s workflow, so we’ll allow it.
The Voltage section has six subcategories: Voltage, Quantization, Gate Out, Probability, Distribution and Smooth. At the risk of strangling any excitement out of these by listing functions, it’s very much worth illustrating just how creative these can be. The Voltage screen presents the main Mode parameter for switching between envelope and continuous voltage generation, alongside parameters like polarity (positive or bipolar) and minimum and maximum voltage values, which can also be range‑locked to allow that range to be swept up and down the spectrum — with external CV if desired.
Next up, Quantization, which can set CV to adhere to one of several scales, or a custom scale. Transposition is also possible across a range of values — particularly useful when tonal CV destinations are working together chordally. It’s possible with this page to further tune things, with individual note probability easily adjusted. Have that major third pop up just every now and then, or take out the root note entirely. Clever stuff! The Gate Out screen allows adjustment of gate size and probability, as well as of step skipping. The Probability screen, aside from the obvious, includes a visual linearity curve for weighting the distribution probability of random voltage to one end or another of the overall voltage range, while Distribution further endows its own overall distribution curve with a distribution peak of variable position and width. Walk mode allows for ‘drunken walk’ behaviour around previously triggered values. Finally, the Smooth page essentially amounts to a very finely tunable slew limiter, with adjustable resolution so that it can move in steps if desired. The Time section operates similarly, with its own Time, Distribution and Clock screens adjusting things in that domain. The Lock screens allow things to be locked into a sequence of up to 32 steps, if you want to return to some predictability.
See what I mean? There’s a lot more to random than random would have us believe. And a lot more to this module than I can fit into this review. There are four separate clock inputs — these can correspond to each channel if you want them to; or they can be assigned any which way, meaning multiple channels can draw from the same clock source. Eight CV inputs can each be assigned to any parameter on the output channel: use external modulation sources to expand and contract ranges, shift probability weighting, you name it. The three logic outputs also add a layer of pseudo‑predictability to things, comparing any of the CV inputs, clock inputs, CV outputs or logic outputs according to AND, NAND, OR, NOR, XOR or XNOR logic functions. As I explored the ADDAC511, it occurred to me how rich it is to compose with probability as a raw material, and this module iterates and accommodates that with aplomb.
The ADDAC511 can be a highly useful source of subtly tuned variation, quantisation, logic function and so on, but time and time again I found it unlocking new avenues of creativity and performability...
I should point out that on more than one occasion, when using fast clock speeds and ambitious continuous voltage ranges, I managed to crash the module completely, prompting a power down and up. Hopefully this will [raises eyebrows] be addressed in a future firmware update. Needless to say, in the ADDAC511 the aforementioned poles of ADDAC System — dour utility and effusive creativity — are both manifest. The ADDAC511 can be a highly useful source of subtly tuned variation, quantisation, logic function and so on, but time and time again I found it unlocking new avenues of creativity and performability, be it by endowing just about everything with an extra dimension of movement and life, or constituting a compositional approach from the ground up.