Rane CP 52S, Installation Manual

Interconnection-5

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, not-quite balanced output stage, even 

though the output circuitry is unbalanced.

Floating unbalanced often works to drive either a bal-

anced or unbalanced input, depending if a TS or TRS stan-

dard 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 bal-

anced connections.

•   Use special cable assemblies when unbalanced lines can-

not 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 bal-

anced 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 intercon-

nect can be achieved, nor is there a definite scheme that will 

assure noise-free operation in all configurations.

References

1. Neil A. Muncy, “Noise Susceptibility in Analog and Digi-

tal Signal Processing Systems,” presented at the 97th AES 

Convention of Audio Engineering Society in San Fran-

cisco, CA, Nov. 1994.

2. 

Grounding, Shielding, and Interconnections in Analog 

& Digital Signal Processing Systems: Understanding the 

Basics

; Workshops designed and presented by Neil Muncy 

and Cal Perkins, at the 97th AES Convention of Audio 

Engineering Society in San Francisco, CA, Nov. 1994.

3. The entire June 1995 AES Journal, Vol. 43, No. 6, available 

$6 members, $11 nonmembers from the Audio Engineer-

ing Society, 60 E. 42nd St., New York, NY, 10165-2520.

4. Phillip Giddings, 

Audio System Design and Installation

(SAMS, Indiana, 1990). 

5. Ralph Morrison, 

Noise and Other Interfering Signals

 (Wi-

ley, New York, 1992).

6. Henry W. Ott, 

Noise Reduction Techniques in Electronic 

Systems

, 2nd Edition (Wiley, New York, 1988).

7. Cal Perkins, “Measurement Techniques for Debugging 

Electronic Systems and Their Instrumentation,”  

The Pro-

ceedings of the 11th International AES Conference: Audio 

Test & Measurement,

 Portland, OR, May 1992, pp. 82-92 

(Audio Engineering Society, New York, 1992).

8. Macatee,

 RaneNote

: “Grounding and Shielding Audio 

Devices,” Rane Corporation, 1994.

9. Philip Giddings, “Grounding and Shielding for Sound and 

Video,”

 S&VC

, Sept. 20th, 1995.

10. AES48-2005: 

AES standard on interconnections —

Grounding and EMC practices — Shields of connectors 

in audio equipment containing active circuitry 

(Audio 

Engineering Society, New York, 2005).

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