Zorx Electronics
Persephone  -Expert Sleepers

Persephone -Expert Sleepers

by Ian Rapp

I’m a big fan of Expert Sleepers line of analog modules, and we reviewed three of them favorably [Beatrix, Lorelei, and Ivo] back in issue #7, and Pandora in this issue. They’re well made, attractive, easy to read and navigate, and they do what they advertise quite well. Persephone was released a little after the initial three and I was happy to have it alongside the rest of the gang to check it out.
Persephone is a JFET based VCA, which rounds out the mixture of functions with the other three quite well. Really, a couple more modules [see the Pandora review in this issue] and Expert Sleepers will have a great analog system at their fingertips. Throw in a couple of Distings [or the Super Disting] and you’ve got all you need for a small, powerful system.
Like the other three modules in this particular ES lineup, Persephone is 100% analog in its signal and CV path, though it uses a digital logic chip for a sample and hold zero-crossing detection circuit, which I’ll get into in a moment. At the top of the module are two CV Ins—one with a dedicated attenuator—and a summed output of the two, which is a great way to grab an extra modulation source to throw into your patch. You can never have enough modulation sources, especially those with unique and patch- related waveforms. Patching two somewhat slow moving LFOs into the CV Ins and using the summed CV out to modulate a filter cutoff while inputting a synced up melody line as Persephone’s lone input—which was being fed into the filter—brought some cool beat-savvy formant style sounds. Feeding the same summed CV Output into either of the FM inputs on Lorelei spat out some odd rising wiggles.
In the middle portion of the module are two mini-toggles, one for turning the Zero Cross Detection circuit on and off, and another to do the same with Asymmetry. The Asymmetry switch makes it so that the positive and negative parts of the input signal are affected differently by the VCA. I was never able to predict exactly what would happen with the switch engaged, but I could definitely hear the difference with it on or off, and overall, it’s another way to alter your sound. In between the toggles is a Clip indicator LED that lights up when the output goes over ±10V.
The Zero Cross Detection is really what sets Persephone apart from the crowd. While there are plenty of VCAs out there, Persephone stands tall amongst the flock, and perhaps the biggest reason why is how it takes on a major issue that can sometimes be encountered with VCAs: the dreaded popping and clicking [that sounds like a breakdance move gone wrong] when a bipolar CV wave crosses the zero threshold. This is a common enough problem, and there have been times when I’ve had to embrace clicking in certain large patches I’ve created, when I had no viable patch options left to try and circumvent the problem, and decided that the clicking was just part of the patch, part of the special sauce. I wish I could say that it worked, that I was able to trick myself and put the clicking out of my mind, but I would be lying. VCA clicks [and pops and…] can, and usually do, drive me nuts, which is why I am so into Persephone. It utilizes a unique zero-crossing detector, a S&H circuit, that can end the pop/click nightmare when the CV/envelope is fast moving. This is huge. How many times have you wanted to pull your hair out standing in front of some amazing patch you’ve got going, and only able to hear some super annoying clicks? We’ve got the technology to fix this, right? Expert Sleepers does.
The bottom half of Persephone finds two inputs, one with a dedicated attenuator, that sums to one output with Pre and Post controls to sculpt the overall volume and tone of your signal/s at different stages of the signal chain. Various combinations yield different results and using the PRE on top of just finding the right balance to make sure you do or don’t overload the VCAs input, along with using Post to recalibrate the output level to taste you can get all manner of fattening and harshening up of your signal.
Running a kick through Persephone with nothing going in Input 2, and tweaking the Pre and Post knobs, I was able to get a pretty natural, acoustic sounding bass drum, albeit with a sort of 8-bit haze dragging on its tail. Changing the two output settings and fuzzy blow outs were happening. Even though I admitted to pulling hairs out due to VCA clicking, there were some moments with Persephone where I actually turned the Zero-Crossing circuit off because I liked the fast clicking, as it added to my sound a kind of a futzy, metallic girth that, while usually unpleasant for the most part, was in this instance a bit pleasing. I’m quite certain that the next time I play in a public park and want to annoy passersby, something I’ve unintentionally done before, I will be utilizing this, again…um…unintentionally. The zero-cross circuit really does clean the sound up quite well, and in the case of the kick drum going through, it was night and day. Circuit on, and it sounded full spectrum and like a good acoustic kick. Circuit off, and the low end was gone and so was most of the definition. It really highlighted how Persephone, apart from being used as a typical VCA, can also be utilized to sculpt sound.
Messing around with the Pre and Post conatrols is where you can really detail your sound, and I was able to go from some nice saturation to full on static-y chaos. There is also some interesting interplay between the Pre and Bias controls that can be had, which lets you really dial in when the VCA opens, the sound of the signal passing through, the strength of the opening, etc. The controls are nice and the ability to be precise with the amount of distortion is much appreciated, especially as this isn’t always the case in a lot of modules. So many times with other distortion types of modules the slightest knob tweak can have your sound go from 0 to 100 with practically nothing in between, no range at all and a lot of dead space on the control. None of the ES modules in this line are like that. They’re all really well done, everything works like it should, and there are no caveats to any of the functions or controls. I let a friend borrow a small rig to get his feet wet in the modular landscape and I made sure to include these modules knowing I wouldn’t have to explain anything about the modules themselves, just what synthesis is, what CV is, what V/Oct is, etc., and that they would serve him well. Indeed they did as he took the bait and dove in head first into the Eurorack rabbit hole.
Persephone has some really excellent features and might just well set the standard for how a VCA sounds and acts, and it makes it so that VCA pop/clickin’ can be a thing of the past. Unless, of course, you like that sort of thing.

8 HP +12v 36mA -12v 29mA
Price: $189