[Phil Allison[_4_]]

Paul wrote:



So it's normal to NOT see any signal on the input differential pins 2
and 3, right?

** Depending how the inputs are driven ( one, the other or both) you may or may not see any signal on op-amp pins 2 and 3.

I was driving only pin 2, from the unbalanced RCA input. But
there didn't appear to be any signal on either pin 2 or 3.


** Pins 2 and 3 stay near identical in normal operation.

If you had driven XLR pin 3, op-amp pins 2 &3 would both have half the signal voltage on them.


My sig gen signal only appeared before R20, and on the output pin 1.

I recall learning about virtual ground in this topology.


** Yes, that is what you had.



..... Phil