Pole mixing filter

I’ve posted some things about pole mixing filters. Here, finally, is a post about an actual pole mixing filter. I don’t have the final front panel yet, but this module seems to be working: It’s a multimode VCF based on a (partial) design by Electric Druid. I made a number of modifications but the basic design is […]

Pole mixing cancellation redux

Amazing what a good walk will do for your thought processes. I’d hardly set foot on the trail when I realized the pole mixing problem isn’t as serious a problem as I thought. The thing about the gains depending on the control voltage is they’re correlated. All four gains change about the same amount in […]

Pole mixing on the breadboard

Electric Druid shows a pair of partial designs for a pole mixing filter, one based on the V2164/AS2164 filter chip and one using the AS3320. I’ve been breadboarding a circuit based on the latter, and my results have… not been encouraging. There are a couple of errors in the Electric Druid schematics. There should be […]

Pole mixing

A while ago I mentioned pole mixing in a post about my all pass filter module. Pole mixing is a technique of combing the outputs of different poles in a filter with the input signal to get different kinds of frequency responses. For instance, suppose you have a simple 1-stage (or 1-pole) low pass filter. […]

Another rung

I built another module the other day, got around to starting to test it last night. Right away there was a problem, no +12 V on the board after the protection diode. Today I touched up the diode connections and all was well. It’s a VCF. (And yes, I am out of large knobs for […]

VCF, grounded

Last May Day I wrote: I don’t think the VCF is working as intended, though. It’s definitely not working the way I expect. I thought it was better when I built it but right now, no. It does do some sort of low pass filtering, the filter cutoff changes with the knob, and the resonance […]

Twofer

Two new modules in one day! Well, one of them hardly counts. Still. Back to Kosmo format. Here’s the Sallen-Key VCF from Barton Musical Circuits. The board was designed with Eurorack in mind. It’s small, and rather densely packed. Still, no problems assembling it and it went together quickly. As designed the pots are all […]

OBG VCF TLA OMG (part 4)

Capacitors in and new, corrected panel PCB installed; it’s done. New video up:

OBG VCF TLA OMG (part 3)

The VCF front panels from JLCPCB, my first PCB front panel order, arrived last week: What looks like white streaking in the black areas really is light reflecting off the not entirely smooth texture of the surface. It looks better in person. Not the highest quality panel ever made by any stretch of the imagination, […]

OBG VCF TLA OMG (part 2)

I got the VCF boards from PCBWay: Even though I ordered them two days earlier, I have not received the boards from JLCPCB: Sigh. Not that those boards matter, really; I don’t intend to use them. But then there are the panels also ordered from JLCPCB, shipped but at last report (five days ago) still […]