ABSTRACT
There are only two electrical output terminals for an unbalanced output—signal and ground. Active crossover output stages may incorporate level trim controls, mute switches, and phase-invert switches. Both the unbalanced outputs have series output resistors to ensure stability when driving cable capacitance. This increases the output impedance and can lead to increased crosstalk in some situations, notably when different signals are being passed down the same signal cable. Ground-cancelling (GC) separates the wanted signal from the unwanted ground voltage by addition at the output end of the link rather than by subtraction at the input end. A non-inverting GC stage must be fed from a very low impedance such as an opamp output to work properly. The transformer measured was a Sowter 3292 1:1 line isolating transformer. Sowter are a highly respected company, and this is a quality part with a mumetal core and housed in a mumetal can for magnetic shielding.
