Rane MS1S MS1S Mic Stage Manual - Page 20

Floating, Pseudo, and Quasi-Balancing During inspection, you may run across a ¼" output called floating unbalanced, sometimes also called psuedo-balanced or quasi-balanced. In this configuration, the sleeve of the output stage is not connected inside the unit and the ring is connected (usually through a small resistor) to the audio signal ground. This allows the tip and ring to "appear" as an equal impedance, notquite balanced output stage, even though the output circuitry is unbalanced. Floating unbalanced often works to drive either a balanced or unbalanced input, depending if a TS or TRS standard cable is plugged into it. When it hums, a special cable is required. See drawings #11 and #12, and do not make the cross-coupled modification of tying the ring and sleeve together. Winning the Wiring Wars • Use balanced connections whenever possible, with the shield bonded to the metal chassis at both ends. • Transformer isolate all unbalanced connections from balanced connections. • Use special cable assemblies when unbalanced lines cannot be transformer isolated. • Any unbalanced cable must be kept under 10 feet (3 m) in length. Lengths longer than this will amplify all the nasty side effects of unbalanced circuitry's ground loops. Summary If you are unable to do things correctly (i.e. use fully balanced wiring with shields tied to the chassis at both ends, or transformer isolate all unbalanced signals from balanced signals) then there is no guarantee that a hum-free interconnect can be achieved, nor is there a definite scheme that will assure noise-free operation in all configurations. 20