Understanding Capacitance in Microphone Cables: Why It Matters for Sound Quality

2025-10-18

What Is Capacitance in a Microphone Cable?

Every microphone cable has a certain level of capacitance, which is the ability of the conductors and shield to store a small electrical charge.
This property is measured in picofarads per meter (pF/m) and determines how much charge the cable holds across its length.

When connected to a microphone, the microphone cable capacitor interacts with the microphone’s output impedance to form a mild low-pass filter. This can slightly reduce very high frequencies as the signal travels through the cable.

The key question is: does this affect what we actually hear?
The answer depends mainly on cable length, impedance, and capacitance value.

Low vs. High Capacitance: What’s the Real Difference?

Capacitance affects how much the high frequencies roll off as the signal passes through the cable.
Below is a simple overview of how different capacitance levels behave in real-world use.

Capacitance Type	Typical Range	Effect on Audio Signal	When It Matters Most
Low Capacitance Cable	30–60 pF/m	Keeps high frequencies clear over long distances. Slightly higher cutoff frequency, so less treble loss.	Useful for very long runs (over 50–100 m) or for high-impedance sources (e.g., guitars).
High Capacitance Cable	90–150 pF/m	Can slightly soften or reduce high frequencies over long cable runs.	Acceptable for typical studio or stage use under 30–50 m with low-impedance microphones.

Effects of Low Capacitance

Maintains better high-frequency clarity on very long runs.
Reduces signal loss for weak or high-impedance sources.
Typically used in precision or measurement applications.

Effects of High Capacitance

Can cause minor high-frequency roll-off in long cables.
May smooth or dull brightness in extreme lengths.
For normal microphone lengths, usually inaudible.

Most professional low-impedance microphones have output impedances around 150–200 Ω.
Even with cables at 100 pF/m and lengths under 50 m, the resulting cutoff frequency remains well above 100 kHz — far beyond human hearing.

That’s why, in practical recording and live sound use, the mic cable capacitance value rarely changes how the signal sounds.

When Does Cable Capacitance Become Audible?

There are only a few cases where capacitance plays a noticeable role:

Very Long Cable Runs
The longer the cable, the more total capacitance it accumulates. Once lengths exceed 50–100 m (160–330 ft), even low-impedance microphones can show measurable high-frequency loss. In these cases, using a low capacitance cablehelps maintain clarity.
High-Impedance Instruments
Passive guitars, basses, or some vintage equipment have much higher impedance. Even short cables can change the sound by rolling off treble or altering the resonant peak. This is why guitar cables often advertise “low capacitance,” while microphone cables do not.

Should Capacitance Be Tested Before Shipping?

In most professional workflows, capacitance is not measured on every cable before shipment.
Manufacturers keep capacitance consistent through precise design, geometry, and materials.
Minor variations — for example, ±5 pF/m — make no audible difference in typical use.

Instead, production testing focuses on:

Mechanical durability(bending and strain resistance)
Shielding quality(hum and noise rejection)
Connector reliability(solid, low-resistance contacts)

These factors directly affect signal integrity and performance, while small capacitance variations do not.

Summary

Every microphone cable has capacitance — it’s an unavoidable electrical property.
The microphone cable capacitoraffects high frequencies only under specific conditions (long lengths or high-impedance sources).
For most setups under 50 m, even a “high” mic cable capacitance valuewon’t change what you hear.
A low capacitance cablecan be helpful in specialized cases but isn’t essential for standard low-impedance microphones.
Focus on build quality, shielding, and connector reliability — those factors make the biggest real-world difference.

Citations

Rane Commercial. Cable Capacitance and Frequency Response. https://www.ranecommercial.com/legacy/note145.html
Audio Systems Group, Inc. Understanding Cable Capacitance. https://audiosystemsgroup.com/CableCapacitance.pdf
GRAS Acoustics. How is the Length of a Cable Affecting My Measurement?https://www.grasacoustics.com/fileadmin-gras/FAQ/Microphones/How_is_the_length_of_a_cable_affecting_my_measurement.pdf
Star-Quad Cable. https://en.wikipedia.org/wiki/Star_quad_cable
Instrument Cable Myths and Realities. https://www.ovnilab.com/articles/cables.shtml