Tag: random

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)


Synthrotek VCO – DIY Build

Synthrotek VCO - DIY Build

As you get more and more involved in the modular world, you will hear the statement “you can never have enough VCO’s” We have found that this statement is very true and it was time to add another to our rack… the Synthrotek VCO from their slider series of eurorack modules. VCO’s or otherwise known as Voltage Controlled Oscillators are a must have for any modular artist as they are often used for drones or other audio sources.

Compact and backed by the Curtis CEM3340 reissue chip, the Synthrotek VCO is an analog voltage controlled oscillator with a wide frequency range and 8 trackable octaves. Let’s get onto the build…

The Build...

One thing you will notice with the Synthrotek VCO kit is that it is a partial kit and not a full on DIY kit. A “partial” kit usually means that most of the tiny stuff has been already soldered and you only have to solder the bigger hole-through components; this kit is just that.

Please note …. this doesn’t mean that the kit is for beginners though!


Erica Synths Modulator II – DIY Build

Erica Synths Modulator II - DIY Build

Completed Front - Modulator

Following our last build of the Erica Synths Mixer II module, we decided to go back to back by taking on the Erica Synths Modulator II. This DIY module is essentially an LFO with simultaneous triangle and square wave outputs. It is a clockable S&H module with external CV input and noise source. It is also one of the new kits currently being offered by the gang over at Synthrotek.

Apart of the DIY series from Erica Synths, the Modulator II is unique in that it not only has one noise source, but two. Noise sources come in the form of “backpack” PCBs that one can swap for different tones of noise. You have the choice of transistor-based or Zener diode-based noise generator for massive, full spectrum white noise.

As you start this build, it can easily feel overwhelming upon cracking open the kit being that there are multiple PCBs and a bunch of components. Synthrotek did a great job on this kit by providing a clear BOM which we have scanned and linked below. They also separated all of the components for each backpack PCB so that the parts could be located quickly and partnered with the correct board.

IMPORTANT: Before we jump into the build, take note that this is not a build for novice builders. This is due to the very tight soldering pads, poor layout of the silkscreen and one’s ability to read a BOM. You do not want to go into this build not knowing how to read or build from a BOM, being that there is little to no step by step assembly instructions.

The Erica Synths assembly guide is really generalized compared to most DIY build guides we have seen from other companies (but hey, thats why we are writing this up and recording our videos).