[sdiy] mixer

[Scott Bernardi]

If you use a high input resistance (>10K or so) you shouldn't have to
buffer.  For a mixer, you'll probably want a log taper pot on each input to
set individual channel levels, then another for the feedback loop of the
summer (to set master gain). (Say 50K log for input level, 100K resistor to
summing node, 1M log in summing amp feedback loop).
If you want to be fancy, use two summers with a Pan pot so you can have
stereo out. Voltage controlled Pan is fun. A headphone jack is also very
useful.
Here's an old design of mine; I wouldn't do it quite the same way today, but
you can get some ideas.
http://members.home.net/sbernardi/elec/mixer.html

matti wrote:

> It's time to make mixers; I'm thinking 4 in 1 out or so, driving andbeing
> driven by synthesizers and effects mostly. So, some questions  :
>
> is it enough to simply sum all of the inputs with a summing amp, or must
> each be buffered?
>
> must all outputs be bufferes (in the case of more outs), or is the one
> summing amp enough?
>
> thanks.
>
> -
> the chatter has stopped. oh joy. achmed, yon achmed, make my felt.

--
Scott Bernardi
sbernardi at home.net