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The Fathom-Sound Project

This is a project is about building a midi controlled synth. I will be going through experimentation and planning of such a project. It will be written from my viewpoint, but I will be open to people making suggestions.

Project Log

The primary goal of this project is to document my journey in building a synth. I have not seen a whole lot of midi controlled synths projects out there. At least not one that documents both the progress and the failures encountered along the way. I always wanted to build something that I could be proud of. I thought why not a midi controlled synth. With time I hope to start documenting my progress on my Youtube channel FathomisticFantasy.

Your first Experiment

I found that the most important thing you need to consider is how you will be controlling the voltage input of your voltage controlled oscillator (VCO). The next thing to consider is your capacitor values. These values will determin your range in frequency. You cannot just use one value because either the voltage is too low for the VCO to produce sound or it will be too high to produce sound. In some cases you can damage the transistors by doing that. So the first experiment you should do is to test many different values.

Below is the image of the oscillator that I am currently experimenting with. These will be the values I will be testing. Also, yes I know these transistors are obsolete. They are still sold on ebay and they are what I have on hand right now. Always disconnect power before switching out components.

Q1-s9014 C1-0.01-10 micro-farads
Q2-s9015 R3-330ohms


In the next picture is a voltage divider. These will be the values in which I will be testing. While testing you should either have an oscilloscope and or an instrument tuner to read frequency and suggest a note value such as middle C. I will allow you to decide on what increments to advance on, but remember to check values with a multi-meter. Also potentiates will be difficult to predict so, make sure to use real resisters.

R1-1-20 kilo-ohm
R2-100kilo ohm - 1mega ohm


Special notes:
Make sure to write down your findings and keeping a journal of what your thinking. This will help you limit your emotions from causing frustration. Always know where your limits are and when to take a break. Sometimes waiting for the next day is just the thing to clear things up. Most importantly this is a work in progress so, expect errors. I will be sure to eliminate them for a final pdf that I hope to make available to anyone who wants it. I am not making any money doing this so, please be considerate when making suggestions or spotting errors.

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