Pro Audio Cables: Signal Level Decides the Construction
Quick answer / TL;DR: Short answer: use balanced twisted-pair with an XLR or TRS for mic and line level, and an unbalanced TS cable for instruments. Star-quad construction rejects interference on long mic runs. Check connector locking and strain relief before comparing conductor specs.
Four audio lines: balanced XLR, TRS, unbalanced RCA, and speaker cable.Pro audio is not one cable type. A microphone lead, a line-level patch and an instrument cable carry different levels and different impedances, and each has a construction that suits it.
This guide maps the signal path to the cable.
Level Determines the Cable
| Signal | Typical level | Cable | Connector |
|---|
| Microphone | Millivolts | Balanced twisted pair | XLR |
| Line | About 0.8 to 1.2 V | Balanced twisted pair | XLR or TRS |
| Instrument | Tens of millivolts, high impedance | Unbalanced coax-like | TS jack |
| Speaker | Volts to tens of volts | Two-core, heavier gauge | Speakon or binding post |
Using a mic cable as a speaker lead is a common and expensive mistake: the conductor area is far too small for the current.
Star Quad and Interference
Star-quad puts four conductors in a quad geometry so the two signal pairs sit closer to the centre. It raises rejection of magnetic interference, which is why it is standard for long mic runs near lighting dimmers.
- Balanced connection cancels common-mode noise
- Pin 2 is hot on XLR by convention
- Ground the shield at one end only for long unbalanced runs
- Keep cable runs away from dimmer racks
Real-World Applications
A venue running 30 m mic lines past a lighting bar will specify star-quad. A studio patch bay uses short balanced TRS or XLR patch leads, where the priority is connector density and reliable latching rather than interference rejection.
Standards and Verification
| Reference | Relevance |
|---|
| IEC 60268 | Audio system reference |
| AES14 | Professional audio connector practice |
| RoHS / REACH | Material compliance |
Specific attenuation figures for a given star-quad cable are not provided in the knowledge base. Request measured data if the run is critical.
Practical Notes
Label both ends of every lead with its length. In a rack, the shortest lead that reaches is the one that fails first and the label saves the diagnosis.
Related reading: audio cable — blogs/news/audio-cable
Related reading: toslink audio cable — blogs/news/toslink-audio-cable
Related reading: rca audio cable — blogs/news/rca-audio-cable
Frequently Asked Questions
Can I use a mic cable for speakers?
No. The conductor area is far too small for loudspeaker current.
What does star-quad do?
It improves rejection of magnetic interference on balanced runs.
XLR or TRS for line level?
Either, provided the connection is balanced. Pick by what the equipment offers.
Sourcing cables for a project, a store, or a private-label line? Contact our B2B sales team for specifications, certification evidence, and volume terms – FOB and CIF options available. Request a quote or sample.
