[sdiy] mixer

[harry bissell]

Hi Matti

--- matti <matti at devo.com> 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?

Buffers are used to reduce the load on the source...
The summing resistor will look like that valuse
resistance connected to ground... maybe 100K ? Can you
accept 100K to ground. If you use input level pots...
that might be even lower....

If it gets too low, you use a buffer.
> 
> must all outputs be bufferes (in the case of more
> outs), or is the one
> summing amp enough?

How much drive do you need ? If all inputs being
driven
are like 100K ??? then just the summing amp will be
OK.

You also need to consider what you will drive with the
mixer... for audio a little gain error is OK... for
CV (like keyboard) NO gain error is OK. Then you may
want to use a buffer.

H^) harry
> 
> thanks.
> 
> 
> -
> the chatter has stopped. oh joy. achmed, yon achmed,
> make my felt.
> 
> 
> 


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