Tag: Synthrotek

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. 


Erica Synths Output – DIY Build

Erica Synths Output - DIY Build

As the world of modular continues to grow, there is one module that is a must for any rack or system…. the output module. How else are you going to get your amazing performance to your speakers or interface to record? 

Erica Synths have been around a long time and their eurorack kits give DIY enthusiasts a chance to build their amazing modules. Their open source modules were previously discontinued and hard to come by until recently.

Packed and distributed by Synthrotek  the entire DIY line of modules is now available for you to take on! The Erica Synths Output module is a quick and easy build and is an essential module for any system. 

Before we jump right in...

Erica Synths Output - Completed Front

Since you are dealing with two PCBs on this build, we highly recommend reading the assembly guide when you are putting this module together. Things can get tricky because there are multiple things going on here.


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).