[sdiy] Multiples - passive vs. active?

[David G. Dixon]

> >> Is there any reason or advantage - other than cost and PCB space -
> that someone would choose a passive multiple over an active/buffered
> multiple? Is it always one is better than the other - or is there a
> time and place for both - or it really matters not in the real world?
> 
> > Multiples are passive, an active "multiple" is a unity gain mixer /
> amplifier.
> 
> > If the destination(s) is(are) high impedance, passive multiples will
> work, however modules with a lower input impedance will load the
> source hence the need for active mixing.
> 
> To clarify - by 'active' I meant 'buffered'.
> 
> So for peace of mind on impedance issues - it's active/buffered.
> 
> Any other takers?

I don't think there is a single output in my system which isn't
low-impedance (i.e., emanating from an opamp output, with or without a 1k
output resistor), nor a single input which isn't high-impedance (typically
100k).  Hence, I would only ever require passive multiples.  When it comes
to buffered multiples, I wouldn't waste the opamps, but would rather have
attenuators and attenuated mixers, preferably bipolar (i.e., optionally
inverting).