Polivoks

Some audio examples of the great Shruthi-1 equipped with the Polivoks filter board. All the demos make use of the filter overdrive for extra nastyness. The "clean polivoks sound" (= without overdrive) lies somewhere in between those samples and the sound of the default smr4 filter.
And honestly: The screaming filthyness of this filter is the real deal for this unit - so why demo anything else?

Recording chain: Shruthi-1 into Firefly808. No post production.

Shruthi-1 Polivoks Filter - Demos with overdrive

The first test of my recently arrived Doepfer A-199 Spring Reverb and The Harvestman Polivoks filter.

The primary sound is the Polivoks VCF self-oscillating and being run into the A-199. An MMG is in the reverb feedback loop and a Serge Res EQ and Deflector Shield are on the main outs. Just the tiniest hint of delay from the Eventide Space (and actually, I turned it on and off while recording and you could barley tell the difference!). So this ended up very much as a sci-fi sounding feedback patch.

A-199 & Polivoks First Test

First test run of a Diy polivoks filter clone. (LP mode)
The volume in the beginning is quite low but I had to turn it down to not get clipping when I increased the resonance.
Mind your ears, there is some serious screaming resonance in the middle.

Input is three saw oscillators, two in the same octave an one octave below.
(The fade out on the end is done by lowering the mix of the oscillator)

The cutoff is controlled by a envelope, triggered by a LFO. 
The same envelope also controls the output VCA. -> mixer -> converter

20110221 polivoks clone

Some audio examples of the great Shruthi-1 equipped with the Polivoks filter board. All the demos make use of the filter overdrive for extra nastyness. The "clean polivoks sound" (= without overdrive) lies somewhere in between those samples and the sound of the default smr4 filter.
And honestly: The screaming filthyness of this filter is the real deal for this unit - so why demo anything else?

Shruthi-1 Polivoks Demo (Processing External Audio)

Shruthi-1 Polivoks Demo

Quick test/demo of my modified Erica Polivoks VCF (kit from https://soundcloud.com/ericasynths ), a recent clone of the VCF from the classic Soviet synthesizer.  It's a state-variable filter built around K140UD12 programmable op amp chips, which are themselves Soviet clones of the American µA776.  Persons looking at the schematic diagram of this filter have been known to ask "What?  Where are all the capacitors?  Is this a joke?"  The trick is that these op amps have slow, and controllable, slew rates.  In this circuit they are adjusted so that their slew rate is especially low, down in the audio range, and that makes them function as integrators to build a state variable filter.  The capacitors are effectively inside the op amps.  It was, like many old Soviet electronic designs, a way to make the most of the available parts in a time and place where hobbyists and even commercial manufacturers couldn't just send off an order to Mouser.  Nowadays, we can do that, but we can't so easily get the authentic chips; I ordered mine from a colleague in Latvia who (as I understand it) made an arrangement with a local semiconductor factory where they still have the original tooling from the old Communist days.

Very basic patch with a clean sawtooth wave going into the VCF, then a VCA; separate ADSR envelopes on the filter cutoff (CV1) and the VCA; sine wave LFO into the filter's CV2 input for most of the track, but that one unplugged around the 2:40 mark to demonstrate one of my mods, see below.

I modded the kit by (among other things) removing all the aluminum electrolytic capacitors from the signal path, replacing the low pass/band pass switch with a potentiometer to smoothly interpolate between the two modes, and normalling the CV inputs to the internal LP and BP signals.  That last was a suggestion from user "SydHeresy" on the Muffwiggler Forum; it means that when there are no cables plugged into those inputs, the knobs for them can be used to add extra chaotic distortion.  You can hear its effect from around 2:40 to 4:40 in the recording, when I unplug the LFO, especially around 3:30.

Also take note of the arpeggio-like things right at the start.  Those are just single long notes, with the filter set on the edge of oscillation and slowly sweeping upward.  That makes it pick out the harmonics in the sawtooth wave one by one, so each note splits into a whole sequence.  Quite an appealing effect, I think, and one I haven't been able to reliably achieve with the other filters I've tried.

Erica Polivoks VCF demo

I brag about this module to folks all the time and figured I probably ought to have something to back it up.  Uoki Toki is a guy on Muff Wiggler that sells these super cheap modules made from NOS soviet parts and they sound spectacular.

Started with a saw from the Analogue Solutions VCO Sub going through the Polivoks VCF and straight into recording.  The sections are ordered as follows:

1.  Low pass filter sweep, input at half, resonance at zero.
2.  Low pass filter sweep, input at half, resonance at half.
3.  Low pass filter sweep, input at half, resonance at 90%.
4.  Low pass filter sweep, input at half, resonance at maximum.
5.  Low pass filter sweep, input at full (overdriven), resonance at zero.
6.  Low pass filter sweep, input at full (overdriven), resonance at half.
7.  Low pass filter sweep, input at full (overdriven), resonance at 90%.
8.  Low pass filter sweep, input at full (overdriven), resonance at maximum.
9.  Band pass filter sweep, input at half, resonance at zero.
10.  Band pass filter sweep, input at half, resonance at half.
11.  Band pass filter sweep, input at half, resonance at 90%.
12.  Band pass filter sweep, input at half, resonance at maximum.
13.  Band pass filter sweep, input at full (overdriven), resonance at zero.
14.  Band pass filter sweep, input at full (overdriven), resonance at half.
15.  Band pass filter sweep, input at full (overdriven), resonance at 90%.
16.  Band pass filter sweep, input at full (overdriven), resonance at maximum.
17.  Screwing around:  Switch oscillator to Akemie's Castle modulated by Oberkorn,  Peaks, Gailean Moons, and Maths, filter modulated by Maths, and processed by Aeverb.

Uoki Toki Polivoks VCF Demo

I'm a student of Mechatronics in Germany and I make music since I'm 7 years old. I uploaded some of my stuff here on soundcloud.

I'm always looking for new inspiration! So if you like ambient, melancholic or dreamy music, radiohead, the monome, synthesizers or complex sound scapes - then please leave me a comment or send me one of your tracks! I'd love to meet other hobby musicians for mutual inspiration!

Have a great day!

Shruthi-1 Polivoks Demo

The Slow Growth