1. What is Characteristic Impedance of Cable?

The characteristic impedance (Z_cable) of a transmission line is the ratio of voltage to current in a wave travelling along the line. For speaker cables, it's determined by the cable's inductance (L) and capacitance (C) per unit length.

2. How Does the Calculator Work?

The calculator uses the characteristic impedance equation:

Where:

• \( Z_{cable} \) — Characteristic impedance (Ω)
• \( L \) — Inductance per unit length (H/m)
• \( C \) — Capacitance per unit length (F/m)

Explanation: The equation shows that impedance increases with higher inductance and decreases with higher capacitance.

3. Importance of Cable Impedance

Details: Matching cable impedance to source and load impedances minimizes reflections and power loss, especially important for high-frequency audio signals and long cable runs.

4. Using the Calculator

Tips: Enter inductance in henries per meter (H/m) and capacitance in farads per meter (F/m). Typical values for speaker cables are in microhenries (μH/m) and picofarads (pF/m) ranges.

5. Frequently Asked Questions (FAQ)

Q1: What's typical impedance for speaker cables?
A: Most speaker cables have characteristic impedance between 50-100Ω, but this differs from the nominal speaker impedance (usually 4-8Ω).

Q2: Why does cable impedance matter?
A: Impedance mismatches can cause signal reflections, affecting high-frequency response and transient accuracy.

Q3: How do I measure L and C?
A: Use an LCR meter at audio frequencies (typically 1kHz) to measure inductance and capacitance per meter.

Q4: Does cable length affect impedance?
A: Characteristic impedance is independent of length, but longer cables make impedance matching more critical.

Q5: What affects cable impedance?
A: Conductor size, spacing, insulation material, and geometry (twisted pair, coaxial, etc.) all influence L and C values.