Hardware & signal path
Balanced and unbalanced
A balanced connection carries the signal twice, once inverted, and cancels anything picked up along the way. An unbalanced one carries it a single time, so interference picked up by the cable stays in the signal.
In practice
Balanced cancels what the cable picks up, so it only matters on the long run out of the booth.
Use balanced outputs for anything leaving the booth and do not worry about it for the short hops inside one. XLR and TRS jacks are balanced; RCA and TS jacks are not, and a TRS-to-TS cable quietly unbalances the connection without anything indicating it. If a long run is humming or picking up interference, moving it to balanced is a more reliable fix than shortening it or re-routing it. Keep audio cables away from mains cables where they run alongside each other, and cross rather than run parallel where you cannot.
XLR and TRS
Balanced connectors
RCA and TS
Unbalanced connectors
Long runs only
When it matters
Where these come from: Connector and wiring convention, not catalog figures. For what we can measure, see the connectors themselves.
Why it matters
The difference only shows up over distance. On a half-metre patch cable it is irrelevant; on the ten metres from a booth to an amplifier rack it is the difference between a clean feed and one carrying hum, lighting buzz and radio.
It is also why a booth has two kinds of socket. Players and mixers usually offer unbalanced RCA for the short runs inside the booth and balanced XLR or TRS for the long run out of it, and using the wrong one is a decision made at install time that everybody lives with.
Frequently asked
Is balanced audio better than unbalanced?+
Over distance, yes — it rejects interference the cable picks up. Over a short run inside a booth the difference is not audible and either is fine.
Is a TRS cable always balanced?+
The cable is, but only if both ends of the connection are. A TRS output into a TS input is unbalanced, and nothing warns you.
Does balanced audio fix hum?+
It fixes interference picked up by the cable, which is most long-run hum. A ground loop is a different problem and needs the power and earthing addressed.
Related terms
RCA and XLR
RCA is the unbalanced two-channel connector on players, turntables and consumer gear. XLR is the balanced three-pin connector used for long runs and microphones, and it locks into place.
Ground loop
A ground loop is a hum caused by two pieces of connected equipment being earthed at different points, so current flows through the audio cable's shield. It sounds like a steady low buzz at mains frequency.
Line level
Line level is the standard signal strength equipment sends between devices — a player into a mixer, a mixer into an amplifier. It is far stronger than a microphone or turntable signal, which need preamplifying first.
Audio interface
An audio interface converts between the digital signal inside software and the analogue signal a mixer or amplifier accepts. In a timecode rig it also converts the other way, digitising the control signal coming off the turntables.
Explore: Mixing guides · Audio interface · Gain · All DJ terms