DIY high impedance 4 output mixer

  • Thread starter Thread starter walrus123
  • Start date Start date
W

walrus123

New member
Hi there,

I'm attempting to build a simple mixer that would allow me to route 4 high impedance guitar inputs to 4 different outputs.

each channel would look like this:

INPUT JACK
POT OUT1
POT OUT2
POT OUT3
POT OUT4

so it would be like a 4 x 4 grid of pots allowing me to send this guitars to 4 different guitar amplifiers.

could I just wire each input to four 500k jacks, and each jack to its corresponding output ?

or should I do something to prevent bleeding?


I'm not too concerned about getting SOME noise due to it being passive. however, if you think i will get TOO much noise, and there's a simple way to avoid this (say, making it active and just buffering the 4 inputs), I could do that.

Well, hope you can give me some advice...

thanks !
javier
 
Javier,

You will be losing signal due to mismatched impedance.

4 - 500k pots wired in parallel will result in a 125k ohm load on the guitar/pickups. This will reduce output level and skew frequency response as well as introduce noise through the needed gain make up.

My recommendation is not to do it.

You can purchase active distribution amps pretty cheaply. Any quality of DA would be a major improvement over what you have planned. :P

Or you could build an FET buffer amp which will drive 4 passive pots to the amps. - THAT would work great. Let me know if you want a design. ;)

Cheers,
John
 
Hey john, thanks for ansering me...


yes, i would love to get a design for that !

would i just need to put a FET on each of the 4 inputs? or at each pot ?

one thing I forgot to say, I want to add a kill switch to each pot...

the idea is to be able to send any guitar to any amp, every guitar to every amp, and everything in between...


( I haven't found any cheap commercially available gear that will do what I want.)


thanks!
 
wow, thanks for drawing that up for me.!


but it seems I may not have been clear: want to be able to set the send of each guitar INDEPENDENTLY to each output.

i see that in your schematic each input has 1 pot, my idea was to have 4 pots at each channel, so i could select where to send each guitar.
 
This is a composite of a couple of my designs... So instead of summing, you will have selector switches to send to the amps of your choice.

If you understand electronics, you should be able to modify this to suit your function. ;)

Cheers,
John
 
MMM let's see...

You are telling me I could replace the resistors that you have there just after the potentiometers of each? and use variable resistors instead?

I have some electronics knowledge, but not too much... what size would these pots need to be ?


thanks!
 
Each FET buffer has a level (voltage divider) on the output feeding 4 busses.

You would not replace resistors with more pots... you would either; 1. put switches in line from the wiper of the pot that goes to the buss resistors. or 2. instead of one pot feeding the buss resistors, use 4 - 50KA pots, each feeding one buss resistor per input channel.

Cheers,
- John
 
You must log in or register to reply here.
Back
Top