Electrical Conductivity: Understanding Conductive Materials in Audio Cables

Electrical conductivity is a key parameter in the world of audio cables, determining how efficiently a material can transmit electrical signals. In audio equipment, conductivity affects signal clarity, resistance, and overall sound quality. To evaluate conductivity, engineers use annealed copper (pure copper that has undergone heat treatment) as the benchmark, assigning it a value of 100% IACS (International Annealed Copper Standard).

In this article, we will explore the concept of electrical conductivity, its measurement methods, and compare the conductivity of various materials used in audio cables, connectors, and electronic components.

What Is Electrical Conductivity?

Electrical conductivity (σ) is a material’s ability to conduct electric current. It is measured in Siemens per meter (S/m) and is the inverse of electrical resistance. The higher the conductivity, the lower the resistance, meaning the material allows current to flow more easily.

The International Annealed Copper Standard (IACS) is used to compare the conductivity of different materials. According to IACS:

Annealed copper (Cu) has a conductivity of 100% IACS (~58 MS/m).
Other metals are compared to copper as a percentage of its conductivity.

Conductivity of Common Materials Used in Audio Cables

Below is a comparison of the conductivity of different metals commonly used in audio cables and connectors:

Material	Conductivity (% IACS)	Properties & Usage in Audio
Silver (Ag)	105%	Best conductor, used in high-end cables and connectors.
Copper (Cu, annealed)	100%	Standard reference material, widely used in audio cables.
Gold (Au)	70%	Corrosion-resistant but lower conductivity than copper. Used in premium connectors.
Aluminum (Al)	61%	Lightweight and cost-effective but higher resistance.
Tellurium Copper (TeCu)	93-95%	Used in premium connectors for enhanced durability.
Phosphor Bronze (CuSnP)	15-20%	Strong but significantly less conductive, used in some connectors.
Brass (CuZn)	23-37%	Used in connectors but less conductive than copper.
Beryllium Copper (BeCu)	45-60%	Strong and durable, commonly used in high-quality audio pins.

Why Conductivity Matters in Audio Equipment

Higher conductivity means lower resistance, reducing signal loss and distortion in audio cables. Silver, with 105% IACS, is the best conductor, but its high cost makes copper the optimal choice for balancing conductivity and affordability. Gold, despite its lower conductivity, is used in audio connectors due to corrosion resistance, while silver, though prone to oxidation, remains highly conductive. Some materials, such as beryllium copper and phosphor bronze, are used in connectors and pins because they provide enhanced mechanical strength with a slight loss in conductivity. The choice of material depends on the priority between maximum conductivity, durability, and mechanical resilience.

It is important to note that in audio cables for headphones, where the cable length is relatively short and the currents are low, the difference in conductivity between copper and brass is not critical. Even though brass has only 23-37% of copper’s conductivity, this does not make it a poor material. In short-distance, low-current applications, signal loss due to higher resistance is minimal and has virtually no impact on sound quality. Therefore, when selecting materials for audio cables and connectors, it is essential to consider not just absolute conductivity values but also specific usage conditions, where relative differences may be insignificant. The optimal balance of conductivity, strength, and corrosion resistance ensures the best choice for both cables and connectors, delivering clear, detailed, and long-lasting sound quality.