Month: December 2018

Fonitronik Ps3100 Triple Vactrol Resonator – Time Lapse Build

Fonitronik Ps3100 Triple Vactrol Resonator - Time Lapse Build

In our latest build we take on the Fonitronik Ps3100 Triple Vactrol Resonator – A clone of the lovely triple resonator from the rare 1977 Korg Ps3100 polyphonic modular.

What we have here is basically a module combining three bandpass filters (vactrol based filter core from the PS3100) with a simple resettable LFO and some clever CV and signal routing.  The LFO is normalized to the common CV input, which is normalized to the 3 single CV inputs. the 3rd CV channel can be inverted.

Play Video

The build itself was a timely one and it took great patience and a skillful hand to complete.  As they stated in the description “Not for the beginner”, remained true.  We don’t recommend this kit to anyone just getting started in the Eurorack DIY realm as it can easily be overwhelming and a simple soldering mistake can cause feelings of anxiety and let down. 

Now, if you successfully complete the module as we did, the module itself can be a prize possession in your rack.  The triple vactrols do exactly what they say they will do and resonate some of the warmest sounds from the 1970’s.  Hence, another reason why this module is special.  The warmth of the analog audio is something that is rare to find in today’s Eurorack systems.  

If you are down for a challenge and are needing some much provided warmth in your rack, this might just be the perfect module for you!

Fonitronik Ps3100 Triple Vactrol Resonator Specifications:

Module Description:

– 3 single audio inputs + a common audio input,

– 3 single audio outputs + sum audio output

– 3 single CV inputs with attenuators + a common CV input

– LFO output, LFO reset input

Module Dimensions:

Height – 3U

Width – 20HP

If you have comments or questions about the Fonitronik Ps3100 Triple Vactrol Resonator, please feel free to contact us!


Nonlinear Circuits Vactrol PiLL – Time Lapse Build

Time Lapse Build: Nonlinear Circuits Vactrol PiLL (NLC Vac PLL)

Violent Behavior PCB

In this build, we take on the Nonlinear Circuits (NLC) Vactrol PiLL module. While the build itself wasn’t a difficult one, it did take some patience when it came to soldering the LED after mounting the panel. With most of the components already mounted, we recommend you use a very fine time on your soldering iron to be able to get to the LED solder points.

Also, make sure you don’t have a lot of coffee or caffeine in your system when it comes to building this module… save that for when you are done!

Play Video

The name is drawn from the two main components that define the function and characteristics of the module. One is the vactrol which is a light controlled resistor, these have an interesting effect whereas there is always a time delay whilst the resistor changes its value – this is a good thing and has been exploited by many synth designers, notably Don Buchla.

The PiLL is from a PLL – phase locked loop, this is a special purpose IC which contains number of subcircuits and usually used in radio and digital control circuits. It contains a VCO, logic gate and a phase detector meaning all fun stuff!  

You will notice that our panel is very different from the normal NLC panels. We opted for the White Magpie from Magpie Modular for its unique look and excellent print quality.  

Module Specifications:
Height – 3U
Width – 4HP

Panel:  White Magpie Custom

If you have any questions about the module, the build or functionality please feel free to drop us a line and we will get back to you as soon as we can!

If you are interested in purchasing the DIY kit, head on over to Modular Addict and let them know that fiN Studios sent ya!

~ f i N


error: Content is protected !!