Every audio cable is either balanced or unbalanced. The difference decides how well the cable rejects noise, how long you can run it, and which gear it belongs on.
| Balanced | Unbalanced | |
|---|---|---|
| Conductors | Two signal conductors plus a shield | One signal conductor plus a shield |
| Noise Rejection | Cancels noise picked up along the run | Relies on the shield alone |
| Run Length | Long runs stay quiet | Best kept reasonably short |
| Common Connectors | XLR, 1/4" TRS | 1/4" TS, RCA |
| Ghost Cable | Ghost Analog, Ghost Analog/Digital | Ghost Instrument |
Unbalanced Cables
An unbalanced cable has one signal conductor and a shield. The shield also carries the return path. A 1/4 inch TS plug, with a tip and a sleeve, is the most common unbalanced connector.
The shield blocks a lot of interference, but anything that gets through ends up in the signal. That is why unbalanced runs are best kept reasonably short.
Guitars, basses and many keyboards have unbalanced outputs, so an instrument cable is an unbalanced cable.
Balanced Cables
A balanced cable has two signal conductors plus a shield. The two conductors carry the same signal in opposite polarity. At the input, the gear flips one back and adds them together.
Noise that gets into the cable lands on both conductors the same way, so it cancels out at the input. The signal adds up and the noise drops away. This is called common-mode rejection, and it is why balanced cables can run much longer and stay quiet.
XLR and 1/4 inch TRS, with a tip, a ring and a sleeve, are the common balanced connectors. Microphones, preamps and most interfaces, outboard gear and studio monitors use balanced connections.
How to Tell Which One Your Gear Needs
- Check the Manual: It will say whether an input or output is balanced.
- Look at the Plug: A TRS plug has two black rings. A TS plug has one.
- XLR: Almost always balanced.
A TRS jack can also be used for a stereo signal, such as a headphone output, or for an insert. Those are not balanced connections even though the plug looks the same.
What Happens If You Mix Them
A balanced cable plugged into an unbalanced jack usually works, but the connection runs unbalanced and you lose the noise rejection. A TS cable in a balanced jack also works, unbalanced. For the quietest result, match the cable to the gear on both ends.
Why Guitars Stay Unbalanced
A passive pickup has a high output impedance and an unbalanced output. That makes the cable's capacitance the thing to watch, more than noise. Read why capacitance matters in an instrument cable.
Which Ghost Cable Is Which
- Ghost Analog: Balanced, for microphones and line level, with XLR and TRS ends.
- Ghost Analog/Digital: Balanced and 110 ohm, for AES/EBU and analog runs.
- Ghost Instrument: Unbalanced and Hi-Z, with TS ends, for guitar, bass and keys.