[sdiy] Passive/simple stereo to mono circuit?

[Seb Francis]

Lower resistors would increase the load on the output stage.  The 
effective impedance that has to be driven is in the worst case (left and 
right channels out of phase) 1/(2/R + 1/Ri) where Ri is the input 
impedance of the next stage.

I think I got the maths right here!  Effectively the input impedance is 
paralleled with 0.5*R.  For left * right channels in phase in mono, the 
input impedance would be unaffected.


HL-SDK Synths wrote:
> What would the possible downside of using low value resistors?
>
> On 5/1/07, *Seb Francis* <seb at burnit.co.uk <mailto:seb at burnit.co.uk>> 
> wrote:
>
>     2 series resistors into a relatively high impedance input should work
>     ok.  Try 10K.
>
>
>     Altitude wrote:
>     > Is there a simple way to do a sum to mono from a stereo L/R
>     pair?  From what
>     > I read so far there are many issues but I really just need
>     something simple
>     > and usable.
>     >
>     > Cheers.
>     > Raph
>     >
>     >
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