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Old 2013-02-06, 20:52
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bassiclife bassiclife is offline
Join Date: Jan 2007
Posts: 36
Ring Modulation Nation

Hello again Everyone,
up late again trying to save the universe! I've got a special treat for you all tonight. Ring Modulation. As a few of you have heard, I now own a Moog MF-102. I've been trying to research how players use this pedal, or others that function in the same schematic. To be honest, it's been rather rough, trenching through the internet looking for settings, tips, tricks, anything and coming up with enough of the picture that I figured out how to fill my gaps.

So this all starts off with basic addition and subtraction. Whatever frequency (or pitch) you input will be added to and subtracted from the carrier frequency (the one you set with the Freq. knob on the bottom left), which gives you two new frequencies. Now, using the mix knob on the top right you can blend your original signal with the new one, combining to three pitches coming out. If I playA4 @ 440 and set the frequency knob to C6 @ 1040 we hear F#6 @ 1480 and a rather sharp D5 @ 600, which could be interrupted as a D major triad with it's fifth (A) in the bass. Where it gets crazy is when you play notes other than A, the two "new frequencies are going to move because of the moving relationship of your source and the frequency knob.

Throughout my searches in forums I found it interesting that just about everyone referred to the Ring Modulator as it's own instrument being triggered by yours, and that thinking about it like this yields more musical results. There are a few things to take into account when playing with an instrument like this:

It is a numbers game. If you tune your frequency knob to close to a perfect unison, it could sound rather hollow, because x-x=0, so some distance between the two is a good idea. Additionally, because of the equations nature, it doesn't take into account that the amount of Hz between pitches increases as you move up through the spectrum. What this can yield is a much more stable set tones, that act more like drones, moving in 2nds instead of 5ths and 6ths. Another common production is that your descending line will have more motion, because of the nature of the spectrum.

Just for a clear example, moving up 180 Hz from 914 yields what we hear as a Major 2nd (Bb5 to C6), where as moving down 180 Hz from 653 yields what we hear as a Major 3rd (E5 to C5)

Another thing to keep in mind, you will find negative results in the subtraction side of the algorithm. What happens here is that it will fall further and further into the negative side of the spectrum. What the pedal, and additionally our ears translate this as, is it's inverse. If you cross 0, you will hear two rising pitches. If I understand correctly, it will happen when your source is playing a higher frequency than the frequency knob is set to.

So I just finished using Excel to create a pitch to Hz spreadsheet and a series of equations displaying the output pitches of two major scales. They are listed below for you to look at, along with the frequency chart. I also posted a video I found helpful on youtube. It's a 3 part series, and it's heady, but I found it helpful.

This is going to be a rather extensive research, so keep a look out for more.


Thanks PSMProjectVids, I found this very useful!

Here is another helpful video I found on the web. Thanks!
Attached Images
File Type: jpg RM C1.jpg (84.9 KB, 7 views)
File Type: jpg RM C2.jpg (87.2 KB, 4 views)
File Type: jpg RM E1.jpg (82.8 KB, 1 views)
File Type: jpg RM E2.jpg (81.7 KB, 3 views)
File Type: jpg RM3 Freq Chart.jpg (116.3 KB, 1 views)
"Without music, life would be a mistake." - Nietzsche