You Can DIY! Building a Guitar-Controlled Synthesizer: VCA & VCF

Ethan Winer offers his fifth Guitar-Controlled Synthesizer article where he describes how to make two key modules needed by every analog synthesizer: the Voltage Controlled Amplifier (VCA) and Voltage Controlled Filter (VFC). This article explains two different VCA circuits, with a simpler one that works fine for one-off projects where precise unit-to-unit repeatability isn’t needed, and a second circuit similar to the VCA in the original Moog synthesizers. This article was originally published in audioXpress, August 2022.

In this article for audioxpress, Ed Simon writes: "There seems to be controversy over what testing means in audio. Measuring a difference does not mean you can hear it. On the other hand, if my ears tell me there is a difference between two audio chains and I cannot measure it, that does not mean it is not there. Probably, I'm just using the wrong method to determine audio differences." And after trying to measure all sorts of things to compare which ones sounded fine - or not - he decided the next step would be to build a dedicated more sensitive measurement. This article was originally published in audioXpress, November 2009.

A great solid-state project where National Semiconductor’s (since 2011, a part of Texas Instruments) LM4702 meets up with Renesas lateral MOSFETs, this article by Jack Walton was originally published in audioXpress July 2007 and it is still cited as a reference today. An ideal project for the DIY enthusiasts.