I want to create a passive "mixer", with which I can connect two of my guitars to one amplifier, so basically one with two 6,3" input jacks and one for output.
For passives without a transformer as far as I know I have two options:
Connecting them parallel or series.
simulate this circuit – Schematic created using CircuitLab
Which one should I use and why? If there is no specific, what are the advantages of each?
Won't parallel produce too much voltage and damage my pre-amp or amp?
(PS: I know that the volume knobs will affect both guitars, but that doesn't matter for me.)
Best Answer
If this is two separate guitars, pretty much your only option is a parallel connection That's because these are unbalanced, hi-impedance signals. If you were in fact to wire these in series, touching any of the metal associated with the top guitar's wiring(metal connector shell, etc) would cause hum and other noises.
Pretty much any of the passive audio mixers that I've seen just connect the hot signal from each guitar to the top end of a potentiometer with all of the ground connections connected together and to the bottom end of each pot. The wiper connections of each pot go to a summing resistor (about 100k for guitar signals) and then to the output. Pot values for a passive guitar mixer would be somewhere between 100k to 1 Megohm, audio taper.
A passive mixer such as I have described has a lot of flaws but they do work. And they will allow you to adjust the level from each guitar individually.