There’s Gold in them there connectors!
Shiny, attractive and expensive looking it may be but that’s not the technical reason Gold is used for audio connectors. So why do audio companies go the extra expense of the shiny coating we see on the plugs of posh audio cables?
First, lets dispel a myth:
Gold is a good conductor isn't it?
No! Gold does conduct electricity but not that well. Copper and Silver are far better electrical conductors and, despite the recent hikes in the cost of Copper, they’re cheaper too.
So now we have the myths out of the way why do audio manufacturers use Gold at all?
- Gold doesn’t oxidise
Anyone who’s worn a Copper bracelet for a period will tell you that Copper, when exposed to air, starts to gain a green outer layer. This is because Copper reacts with Oxygen in the air to form Copper Oxide (that’s the green stuff). While Copper is a great conductor, Copper Oxide isn’t and the Copper Oxide layer adds electrical resistance (and other nasty sound degrading effects) to your signals. Clearly that’s not good. Gold is used as a coating for the Copper parts to prevent them from oxidizing over time and thus maintaining signal quality and preventing your connectors turning green.
- Gold is soft
To maintain a tight, low resistance connection audio (and other) electrical connectors operate what’s called an “interference fit”. That is the two parts are slightly too tight to fit together easily and thus, as they are pushed together, something has to give allowing them to stay together and permanently connect. In the case of audio connectors what gives is a small amount of the Gold coating allowing a nice tight fit and a good electrical connection.
- Larger surface area
Because the electrical connection is formed by the interference fit mentioned above the surface gains small scratches consisting of peaks on one component and corresponding valleys on the other. The net result of these peaks and valleys is a larger surface area for the connection which has lower resistance and therefore higher signal transmission efficiency.
- It’s shiny
I know, we said that wasn’t the reason but truth is the marketing chaps like the fact that Gold connectors are nice and shiny. Customers associate the shiny finish with good value and, over time, they’ve come to expect on their audio cables.
So there you have it. Gold is used for good reason on audio connectors but maybe not for the reasons you thought!