What causes signal loss in cables?

Signal loss comes from three sources: conductor resistance (converts signal energy to heat), cable capacitance (rolls off high frequencies) and connector losses. Balanced cables (XLR, TRS) reject noise far better than unbalanced (TS) cables over long runs.

How long can I run an XLR cable?

Balanced XLR cables can typically run 100+ metres with negligible loss. The CMRR (Common Mode Rejection Ratio) of balanced connections cancels induced noise. For critical recording, keep runs under 50 m for the lowest noise floor.

Why are instrument cables limited to short runs?

Guitar/bass instrument cables (TS) are unbalanced and have high source impedance from passive pickups (~10kΩ). Combined with cable capacitance, this creates a low-pass filter that dulls the tone. Keep TS cables under 6 m for best tone.

Does cable gauge matter?

For speaker cables, gauge is critical because high current flows through low impedance. Use thicker cable (lower AWG) for longer runs and lower impedance speakers. For mic and line cables, standard 24 AWG is fine for runs under 30 m.

AudioCalcs

Cable Loss Calculator — Signal Loss Over Cable Runs

Calculate signal loss, noise floor impact and impedance for audio cable runs.

Cable TypeBalanced (XLR/TRS) rejects noise over long runs; TS is unbalanced and short-run.

Cable Length

Total run length, end to end.

Signal LevelSets source impedance — Hi-Z pickups suffer most from cable capacitance.

Cable GaugeLower AWG = thicker = less resistance; matters most for speaker runs.

How We Calculate This

Signal loss = resistance loss + capacitance loss + connector loss

Resistance loss (dB) = −20 × log10(1 − R_loop / (R_load + R_loop)), where R_loop = 2 × R_per_m × length (current flows through both conductors).

HF −3 dB point = 1 / (2π × R_source × C_total)

Cable capacitance creates a low-pass filter with the source impedance. This effect is most pronounced on unbalanced cables with high-impedance sources (guitar pickups ~10 kΩ), and negligible with low-impedance line/mic sources. Characteristic impedance (75 Ω coax, 110 Ω AES3) only matters for digital audio.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates based on standard formulas. Always verify results for critical applications.