Packing 6 VCAs + mixer in an 8HP DIY Eurorack module

The Zlob VnIcursal Vca is a 6 channel 8hp ota-based linear vca with an additional mix output that sums any of the 6 outputs when they are not patched.  The module is 35mm deep so it will most likely fit your skiff case. The panel is made of laser cut acrylic.

A fully built Vnicursal is $260 directly from Zlob, which is not bad considering you get 6 VCAs and a mixer.  I was feeling adventurous and opted for the cheaper $30 PCB+panel.  I say adventurous here not so much because you have to solder together the module, but rather because finding all the right parts is a bit of a scavenger hunt.  There are a couple of revisions of this module, and some of the information regarding the parts for these updates are scattered throughout the website and forums.  Nevertheless, Zlob replied promptly to a couple of questions via email and was very helpful. The DIY build ran me less than $100 in parts.

The dark royal blue laser-cut faceplate design looks pretty cool--it screams satanic cyber metal-head relic.  There is a lot of detail and the laser-cutting is very nicely executed, however, the acrylic panel itself is too think which makes it stick out just a little too much and later became slightly problematic when screwing on the 1/8" jack rings.  The picture below shows the faceplate with the protective tape layer still on.  You have to peel off this layer to see the deep-blue panel, but I left it on because I liked the look of it, almost stone-like (that didn't last too long).

The circuit boards are very impressive because of how tightly packed they are designed.  The labels are tiny and not too easy to read, but they are all there, which is really the important part.  This circuit board here is the main-board, which holds most of the components including the ota amps.

The control board pictured below looks a bit more spacious, but once you install the pots you realize that it also leaves very little space to spare.

This is how the control board looks once all of its components have been mounted.  Needless to say this was the easiest part of the project apart from the fact that I initially got the LED polarity wrong on a couple of LED's (I didn't know LED's were polar).

This is the back part of the control board once soldered.  The rows of pins will help assemble the main board, which has female connection points.  Notice the screw in the middle which is there to fasten a rod that allows the faceplate to be secured.

The main board is really a work of art in its design and it take a lot of patience as the through-hole components are tightly fitted.

When looking at the back of the completed main board one can appreciate the amount of geek grease put into soldering these components.  I didn't even bother counting the solder points, but I will mention that I completed this with a cheap Radio Shack soldering iron which I had to sharpen on the sidewalk a couple of times...  true Neanderthal soldering methods went into this, but hey, it worked out fine.  The potentiometers at the bottom help you calibrate the knobs on the front side.  Also, this is only my 2nd DIY module, so if anyone is up for a challenge I say go for it.

Just a side-view of the main board giving you a slightly different angle of how the resistors coexist.

I had to be careful that none of the components were touching each other, but it was hardly an issue.  Again, the design is tight, but very well implemented.

Once both of the PCB's have been fully soldered you can sandwich them together and slap on the faceplate. Notice anything strange? Yes, I forgot to solder the power connector pins, which I realized as soon as I was ready to test the module.  Even worse, I had forgotten to order the part all together--talk about an anti-climatic ending.  Nevertheless, a local hardware store had the part, admittedly for 10x the cost vs. online, but I HAD to get it the same day to test it or I would loose my witts.

This is the complete module with the tape protection still on.  It lasted a few days, then I couldn't help peel it off, mostly because the 1/8" ring screws were barely hanging on due to the unusually thick acrylic panel..  Notice the black hex screw in the middle--I liked the aesthetic of it for this design much more than what's pictured on the website.

The Vnicursal VCA is now a central piece in my eurorack rig.  It is very tight to use in the patch section and the knob numbering order is, um, "interesting"? but the knob spacing is actually not bad at all.   I use it for virtually every patch I make, and for the money, I would highly recommend this module, especially the DIY version.  Just be ready to dig around for the right parts.

tags: 
audio production, gear, tech

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