I’ve been working on some DIY audio projects for some time now that are finally far enough down the line, that I wanted to share them.

One of the more interesting projects ( and difficult…. ) is restoring some old designs, like the Moog Minimoog Model D circuits, from scratch, using new and readily available parts, yet still keeping as close as possible to all of the aspects of the original designs that made it sound “good”.

Luckily I have a very clever and resourceful friend ( whom also happens to be a brilliant photographer: talsit ) who is currently doing a lot of this DIY type stuff, and hence, I have a lot of very good help.

The first piece of work I had to do was source the original circuit diagrams, which I found here: fantasyjackpalance

Next, I had to source the parts, or, at least, extremely appropriate equivalents, which I’ve managed to do with the following supplier ( whom are also incidentally Australian, which is quite useful since I live in Sydney 😉 ): element14

Then I used LTSpice to simulate these circuits, and make any necessary improvements to them including accounting for changing the component types, or fixing poor performance based on circuit measurements.  Here is a screenshot of the VCF ( voltage controlled filter ) design I’ve been recently adapting to build ( quite a few of you will notice the unmistakable topology of this circuit, and notice it’s a Low Pass 24dB transistor ladder filter from the Minimoog Model D ) along with a simulation that exercises a bunch of different resonance values:

From there a transpose this schematic into Eagle:

Then from there I piece together a board layout for the parts:

And the next step is to actually build these projects.

Stay tuned, more to come soon….