Brief
Make a small mixer for use with things like the Korg Volcas and other tiny synths. I wanted something I could just grab and use on the sofa with minimal hassle setting up. Ideally it should contain;
Spec
A compact mixer with between 3 to 6 inputs
Fits in a 1590BB guitar pedal enclosure
Possible Effects section
Not be too expensive
Keep reading to see the prototypes…
Version 1
An early prototype of the mixer section, 4 channels;
This version is using a cd4049 hex invertor, using just one invertor per audio channel. Audio quality was excellent, however I want the gain to distort at higher levels so a revision was needed.
Version 2
Here is a version with gain and volume pot that reaches into fuzz (using two channels of the chip and feeding it back into itself) on each of the 4 mixer channels. I also added a delay and a basic plate reverb. It was actually sounding pretty good but there was a couple of problems that appeared;
1. The battery ran out while testing. The two PT2399 chips used in the delay and reverb are known to be pretty thirsty for power (not too sure the combined CD4049s?), but to continue using this version I’d probably need to add a power jack, which leads to the next problem;
2. It’ll be a struggle to fit all the into a guitar pedal enclosure.
A rethink was needed, however I may revisit this design at a later point to make some sort of multi-effect unit. To make a smaller version I’d have to either lose a few features or input channels. It might be possible to stack two pcbs on top of each-other, but then the cost would increase. At this point I started to think what would be cool if it could run without batteries, just a simple passive mixer;
Version 3
Version 3.1
