MOTM

If you are careful to match the input resistors can't you get
good common mode rejection with active balancing? Attached
is a small GIF with a schematic from Midwest Analog.  I notice
in the lower corner he makes note of the "subtle" challenges of making
this circuit referring to an article from Poly mag.  Anyone have
that article or would care to comment?

Having said all that, I normally use the pre-packaged transformers sold
by many of the microphone manufacturers that have the connectors
built onto a case with the transformer inside.  I even used the ones
RS sells and have no problem with them except the ground is tied 
across so you have no "lift" switch.

Larry Hendry

----- Original Message ----- 
From: <ivancu@...>
Active balancing doesn't provide isolation, and quite often
is not properly balanced to provide true Common-Mode
Rejection.


  If you can afford them, GOOD 
(Jensen) transformers are the way to go.

Ivan