Tag: synth DIY guy

Erica Synths Polivoks VCO – DIY Build

Erica Synths Polivoks VCO - DIY Build

ES VCO - Boards 1

Erica Synths have been around for awhile and while most of their previous offerings in the modular world were fully built modules, they do have some DIY kits. The Erica Synths Polivoks VCO or Voltage Controlled Oscillator is one of those modules. 

The core of this VCO is borrowed from the famous Russian synth Polivoks VCO, and original matched transistor IC is the same of that was used in Polivoks. These two things give this VCO a very well rounded and beefy sound. (We liked it so much we have 2 of these). 

The gang over at Synthrotek have made these kits available in all their entirety. They have several options available to purchase (links below), including a fully assembled module if you do not feel like building anything. We opted for the full DIY Kit as usual and began warming up or irons!


Erica Synths SWAMP – DIY Build

Erica Synths SWAMP - DIY Build

The Erica Synths SWAMP is a random CV and audio generator inspired by the famous Wiard Wogglebug module; it’s often the heart of self-generating patches and brings controllable randomness to any modular system.

Synthrotek did the world of DIY builders a solid by putting together these hard to find discontinued kits, and we have been wanting to get our hands on the SWAMP for a long time…and now you can too!

Purchase Quick Links: 

Erica Synths SWAMP – DIY KIT

Erica Synths SWAMP – Fully Assembled

Erica Synths SWAMP – Panel/PCB/IC

Before hoping straight into the build, let’s take a step back and highlight what separates this module from the original Wobblebug. 

The Erica Synths SWAMP module introduced numerous modifications and improvements to extend the potentiometer range. It added an audio input, which, when connected, replaced the internal Tone oscillator, and the expensive dual vactrol.

The S&H (sample and hold) circuit was build around the Riga S&H IC (AS1100CK2) and ES added audio waveform selection switches, CV output configuration jumpers and much more. All of these are reasons to have just one in your rack!

To sum everything up, the Erica Synths SWAMP is an advanced multi-level kit that can pose a few challenges for even the experienced builder. Packed and distributed by Synthrotek, the entire DIY line of modules is now available for you to take on! (so we had to)


Erica Synths Dual VCA II – DIY Build

Erica Synths Dual VCA II - DIY Build

Completed Rear - Dual VCA II

On with the build....

Fresh off the build table comes Erica Synths Dual VCA II. The module itself is apart of the open source DIY kits that are available via the Erica Synths Github.

Our friends over at Synthrotek have painstakingly taken it upon themselves to part out these kits and package them up to make them accessible by all DIY enthusiasts. VCA’s or voltage controlled amplifiers are modules that every rack contains.

This module is a Polivoks-inspired VCA that is 35mm deep, skiff friendly, has solid mechanical construction and doesn’t require wiring.  Who could pass this one up? We couldn’t! 

In the end, the Erica Synths Dual VCA II is like all other kits in that the BOM is comprised of the basics … resistors, diodes, capacitors, pots and jacks. There might be a few other surprise components in there, but all in all, these are what make up the kit.

Start by laying out all of the components and the x3 boards. This kit contains a control board and a logic board so you will be going back and forth between the two boards when placing components. Resistors, diodes and ferrite beads are first up.

Diodes have polarity so prior to tacking these down, you have to make sure they are placed in the correct orientation. We used top down soldering to make quick work of these. 


Zlob Modular Diode Chaos – DIY Build

Zlob Modular Diode Chaos - DIY Build

Tailgating off the Triple Chaos, we decided to pick up the Zlob Modular Diode Chaos due to the uniqueness of this module. The Diode Chaos is a 3HP analog low frequency voltage generator that is packed full of chaos. The module is based on a circuit from a paper called “A Simple Chaotic Circuit With Light Emitting Diode” written by Volos, Wang, Jafari and Kapitanik. 

What makes this module really unique is its “Trig Out”. The trigger is not a standard “trigger out” in that it has an exponential rise and fall to its peak. This means that it cannot trigger every module out there because some modules are looking for a perfectly squared off edge in their rise. 

An example of this is if you pair the Diode Chaos with Maths. Maths cannot handle the trigger coming into the Trig In, but it can accept the signal into its Gate In. Unusual? Yeah, we thought so too. It was time to get on with the build!

About the kit ...

Zlob Modular provides some really great documentation via their website which is always a plus when taking on a new build. The components were also individually labeled which shows how much time the company puts into their product. This also made it easy to sort things out when cracking the kit open.  

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