A good observation Karl.

In theory a well balanced source fed into a well balanced input
should offer good immunity to such induced noise.

So from experience a C460 fed into a Sonosax balanced opamp input was OK
and I found that a C480 fed into the same mike line and mixer was not OK

I've just examined the circuit of the C480 to find that is in fact an
unbalanced feed and not even floating!!

The live phase (pin 2)is fed from a push-pull output driver and
the return phase (pin 3) is connected to ground through a T network (and
an electrolytic capacitor to hold off the 48v phantom on that line)
which I guess is there to stop RF getting back into the mike circuit.
Pin 1 is also earth and case.

Hence the problem with C480 - pretty unfortunate for such a good mike!

Mike
www.mikewestgatesound.webnz.co.nz

Mike, thank you for your explanation and observation.

Do I understand that the Sonosax mixer's inputs do not have transformers
and
therefore prefer microphones with output transformers?

Here's the answer to Mike's findings about the innards of a C 480.....:

A good observation Karl.

In theory a well balanced source fed into a well balanced input
should offer good immunity to such induced noise.

So from experience a C460 fed into a Sonosax balanced opamp input was OK
and I found that a C480 fed into the same mike line and mixer was not OK

I've just examined the circuit of the C480 to find that is in fact an
unbalanced feed and not even floating!!

The live phase (pin 2)is fed from a push-pull output driver and
the return phase (pin 3) is connected to ground through a T network (and
an electrolytic capacitor to hold off the 48v phantom on that line)
which I guess is there to stop RF getting back into the mike circuit.
Pin 1 is also earth and case.

Hence the problem with C480 - pretty unfortunate for such a good mike!

Mike
www.mikewestgatesound.webnz.co.nz

What is differently solved with our (and also with many of our competitor's
products) is the following:

Instead of a true AC output symmetry we (as well as other manufacturers)
have a phantom symmetry - that means only pin 2 outputs audio and pin 3 does
not have an opposite phase signal, but no signal and is therefore only the
reference for the signal.

We (again like other manufacturers) have been using this variant of a
transformer-less output stage since more than 18 years with the C414 B-ULS
as well as the TL/TL II, and also with the C480 B and many other
transformer-less designed AKG microphones.