ToolsElectronics, cables & data
Cable capacitance & high-frequency loss
How long cables and high source impedance roll off the treble.
Ω
Passive guitar pickup ≈ 5–20 kΩ at resonance; line outputs 50–600 Ω.
pF/m
Typical instrument cable 80–150 pF/m.
m
- Total capacitance
- 0.6nF
- −3 dB frequency
- 26525.8Hz
- Longest cable keeping 20 kHz within −3 dB
- 7.95775m
The source impedance and the cable capacitance form a low-pass filter. It matters for high-impedance sources (guitars, some vintage gear); low-impedance line outputs can drive long cables easily.
How it works
Every cable has capacitance between its conductors. Together with the source impedance it forms a low-pass filter. Guitars with passive pickups are affected most, which is why cable length audibly changes their tone.
Formulas
- C = c′ · ℓ
- f_c = 1 / (2π · R_source · C)
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