OK, here's what I'd like to achieve: I want to "robotize" my guitar amp so that I can record and recall each potentiometer's positions (i.e. volume, tone, reverb, etc.).
Why is that? Because I don't want digital voltage controllers to interfere with the signal path within the tube amp, hence the need for a mechanical actuators for each potentiometer.
I already have some designs in mind, but I would like to know what kind of parts I should get (i.e. what kind of servo, what kind of optical shaft encoder).
I'm looking forward to read your advices
I’m not sure if a servo
I’m not sure if a servo would work or not. Most servos give you a bit more than 180 degrees of rotation. The knobs sometimes go beyond that depending on the amp. They are still probably the easiest way to go though.
All you need are the servos
If you can control a servo, which in turn controls a pot on your amp, all you need to do is adjust it until you get the sound you want. Then simply save the servo setting. A cheap ($10) HS311 servo should work to turn the knobs on a guitar amp and a picaxe can control them.
> Most servos give you a bit
> Most servos give you a bit more than 180 degrees of rotation
Pricesely. So what ? Step-motor ?
And how do I “record” the
And how do I “record” the knobs’ positions ?
A simple gear ration of 1:2 would give you full 360 degrees. Pots don’t need much torque, they are designed to be turned my the feeble digits of a Macaulay Culkin.
When you’re this concerned about the quality of your signal then you must absolutely give your robot (both logic and actuators) a seperate power supply. Seperate from the amplifier.
Or you could skip the servo and go for a motorized pot. Recording the pot positions could be done on an EEPROM that Chris the Carpenter has experimented with in various posts, including recording movement routines for Walters head.
Note that you mighht check whether you need an audio taper or linear taper pot.
To the original poster, Did this idea ever happen? i joined up today because of this post. I have been looking for an idea for a control device to turn the knobs on an amp. Musician Neil Young designed a device called the whizzer which does exactly what im talking about. look it up if curious… if anyone has built something similiar, please get in touch.