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opinions wanted please: how should I retrofit an analog synthesizer to be computer controlled.

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I would like some opinions please if you dont mind. I have one of those new, small analog synthesizers (Behringer Model D). It has a bunch of potentiometers, and switches, etc. to control the sound manually with hands/fingers. In my dream, I want to be able to control the sound manually with hands/fingers, as well as being able to have a computer/arduino control the components to change the sound. So while changing the sound with hands/fingers, then the computer could record the settings (possibly in a real time sequence) to be used later, either in a real time sequence playback, or just to have the computer recall the sound settings as preset sounds and change the controls on the analog synth without me touching the synth.

What level of difficulty is a project like this? Im basically an electronics noob, but have soldered together a few simple kits. Im a software developer for my day job, so I can handle any of the programming necessary for the computer/arduino (or whatever you suggest). I took a couple of electrical engineering classes back in college.

What do you think? Obviously I need to do some reading to get caught up on basic electronics, which Im doing now. Is this a crazy first project for a noob? Or is this doable?


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Sounds crazy to me for a first project to me, and unwieldly no matter how much of an expert you are because you'd have to retro-fit like motors and motor controllers to each pot as well as a feedback circuit so the computer knows what the pot position should be.

If instead of manually turning the pots with motors, you connected a digitally controlled pot that the computer could use, then you'd have to work into the synthesizer alongside every manual pot and a switchover mechanism to use the digital pots instead of the manual ones (which might also change the sound since it's a completely different pot being used). You'd still need a feedback mechanism for every manual pot so the computer would know the position of the manual pot
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I want to be able to control the sound manually with hands/fingers, as well as being able to have a computer/arduino control the components to change the sound.
What functions can the MIDI IN control?
What level of difficulty is a project like this? Im basically an electronics noob,
Assuming the MIDI IN can't do what you want, it would be a monumental task, even for a seasoned electronics hobbyist.


Active Member
J-P-G : Take a look at this project


It's a little bit more difficult that this. :)

Here's a motorized fader.

As you can see, they're about $20 USD. They have a touch track so that you know when the user "pushes" the fader.

You could use an ADC to read the value from the fader (0..+5V or 0..+3.3V)
You would then drive the motor (perhaps pulse it?) until the value matches the incoming MIDI value (0..127)

It's a big and expensive job, depending on how many faders you have.

Good Luck. :)



I will suggest that first get the Technical manual for the Behringer Model D.
Once you get it you should consider adding Optoisolators (LDR-LED) to selected nobs. The LDR will go as substitute of potentiometers . Then with the proper circuit you can control the LED intensity which in turn will change the LDR resistance. Arduinos can do PWM to control the LED brightness.

I will not try to do ALL pots. Experiment with a few to check if this idea is possible

As suggested by Alec_T you should check if via MIDI IN you can control the pots (parameters) . Check the System Exclusive message available for the Behringer. This idea might be better on the long run.



New Member
Hello J-P-G:
Here's another project example of a (relatively) small analog synth (the PAiA Fatman) that a user 'computerized' using an Arduino:

This synth began as a kit, so it might have been easier to get at the internals, but he did an excellent job on this! Including some really great software features.

Cheers and good luck hacking ;)



New Member
on other forums, people have suggested that I just sell the Behringer Model D and get a Roland SE-02, which does more of what I want. but instead, I sold the Behringer Model D, and bought a multimeter, a soldering iron, some tools and this kit:


and the book that goes with it:

most of which is also here: http://musicfromouterspace.com/analogsynth_new/NOISETOASTER/NOISETOASTER.php

I have assembled the kit, and I have it 75% working. so Im on my way to learning more about electronics and sound synthesis

thanks everyone for all of the replies. they're great ideas that will keep me busy for years to come.


New Member
HA! Excellent move!
I have that book, and it's fantastic. Ray Wilson is the man (RIP). I've built a couple noise/drone boxes (including the WSG ;) It's a great way to break in to synths. His electronics explanations are some of the very best I've read.

Here's a great list of DIY resources compiled by SyntherJack: https://syntherjack.net/how-to-start-synth-diy/

Helpful books (printed / online)
  • Ray Wilson – “Make: Analog Synthesizers”
  • Craig Anderton – “Electronic Projects for Musicians”
  • Reed Ghazala – “Circuit-bending – Build your own alien instruments”
  • Thomas Henry – “Analogue synthesizer for the 21st century”
  • Thomas Henry – “Electronic Drum Cookbook”
  • Hal Chamberlin – “Musical Applications of Microprocessors”
  • Sergio Gonzalez – “Intro to Lunetta CMOS Synths“
  • Thomas Henry – “Noise Generator Cookbook”
  • “Electronotes – Newsletter for the musical engineering group”
Forums (specialized in synth DIY only)
Great resource if you have any problems or are looking for inspiration. But read carefully, there are lot of untested circuits!
Online resources
Keep melting solder!

Cheers, Spot


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Most Helpful Member
Jeepers, those are expensive! But having seen them, it looks like you could easily hack a standard <$10 R/C model servo to do the same knob-twiddling job.
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