Casio SA-20 keyboard - guitar signal processor?

Thread Starter


Joined Jul 15, 2010
Hello -

My friend recently suggested turning a working Casio SA-20 keyboard into a guitar/whatever signal processor. I told him that the keyboard had no input, and even if it did, it would be for a "toy" mic that would bypass the signal processing area.

So, I got to thinking... what if you soldered one wire of a 1/4 female plug into the input on the chip - Its a M6387 (I still need to find the datasheet to see if there is an input option) - and the other wire to the ground trace?

Basically the goal of the project would be to select one of the 100 presets for the keyboard, and that effect would be mixed with the guitar signal, and outputed to the speakers.

This M6387 IC is the second chip in the signal path. The other chip is on a small board containing the AC power input and the 1/8 output for headphones, and a few other caps, etc.

Is this a crazy idea? Please let me know if this "might" work. If it does, it would provide insane sounds on the cheap for guitar, bass, vocals, drum machines, etc.



Joined Dec 8, 2006
I've looked for the chip you are talking about and can't find a datasheet. That being said this sounds like it won't work at all. Most of these keyboards play their tone from a database or recorded sounds or generate the tone based on digital information (what keys have been pressed). I don't think you are gonna get something that is as simple as a square-triangle wave converter and the like out of this chip. Not to mention your voltage levels will probably be way off, and your impedances may be horribly setup depending on the output resistance of the guitar.

You want something that takes the raw tone of the guitar and generates the required harmonics and whatnot to produce the sound of another instrument.