Eeyore wrote:
TonyL wrote:

Here's a problem that is causing me some grief. I'm rusty with
electronics these days, perhaps the experts in here can give me some
pointers ?

I want to combine the audio outputs of an unspecified number of
op-amps, say 2-20. A simple mixer would do the trick...except I need
the resulting summed audio level to be constant as outputs are
connected to and disconnected from the system.

Absolutely constant ? You need a thing called a hard limiter on the
mixer output.


Not absolutely...reasonably. Limiting has occurred to me but I wanted to
explore other options before I looked at active limiting. Hoping there was
some clever trick that would keep the levels constant such as an adaptation
of the virtual ground idea.


I know a virtual ground is the standard method to mix audio but
there's another wrinkle here. I also need to send the summed audio
signal to an unspecified number of outputs, between 2 and 20.

You need a distribution amplifier for that.

All readily available off the shelf for a price.


A DA would work if all of the outputs were to branch from a single location.
In the proposed setup, outputs were to be taken from various locations along
a single conductor.

The unexpected difficulties may force me to reconsider the "daisy chain"
configuration (which had lots of practical advantages) and go for a central
mixer/distribution amp instead.