I am learning how to play the guitar. One of the things I enjoy doing when I play is to listen music and try to play along with it. This becomes difficult when I am playing my electric guitar and the volume of the guitar overwhelms the music. Also, being able to practice late at night with headphones is one advantage of an electric guitar over an acoustic, but piping in music into the headphones AND my guitar was difficult.
The 2 channel audio mixer was then built out of necessity. The circuit is a voltage summing op-amp with variable input resistance. The values of the input potentiometers and feedback resistor were chosen to give me a variable gain for each channel of ~ -6 db to + 6 db. This would allow me to "mix" the music and the guitar to my liking. I figured I would use this circuit alot, so I put it in an enclosure with a power switch and audio input/output jacks. In the last photo in the above series you can see the mixer in action. It has a 1/8" stereo input jack (for a CD or MP3 player), a 1/4" mono input jack (for the guitar) and a 1/4" mono output jack.
I feel I should explain my statement on the previous page. This little monster is a tone-sucking beast. when I play through this little guy, all my stuff sounds thin. I hate it. I will probably scrap the whole thing and make another one. The other sucky thing I just realized, I did not write down the schematic for this "suck" circuit, so for those of you who really wanted to crank up the "suck", I apologize.
