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The Benefits of Plating in Rhodium and other Precious Metals

By Graham Nalty, proprietor of Black Rhodium

The plating of metal surfaces in both wires and connectors has been very common in electronics for a number of practical reasons. The plating offers higher performance in terms of the superior properties of the plating metal, but without the high cost that would be incurred if the whole wire or cable was made out of the superior metal.

At Black Rhodium, we have been plating out high end connectors in rhodium for over 25 years. We do this as it not only enhances the sound quality of the system, but it also maintains that same high quality of sound over the connection for a long time. We have also plated wires in rhodium in the past, but we now prefer to use pure palladium wire when we wish to achieve ultimate performance levels in sound quality.

Black Rhodium plates our connectors in rhodium for a number of reasons

1. The plating does not tarnish with prolonged use
2. There is an audible improvement to the sound quality

Rhodium plating reduces tarnishing

If you look at the any audio connector that has been in use for a number of years, you will notice that its surface has become dull with age. This is called tarnishing. With many metals, continuous exposure to the air causes the forming of oxides and other impurities on the surface of the metal as the air and metal combine. This oxidised layer over the metal surface does not conduct electricity as well as the pure metal and will exhibit non-linear electrical characteristics. The effect of any non-linear electrical conduction on the complex electrical signals that convey musical information is to distort the sound.

We are all familiar with the need to polish silver ware on a regular basis and with regular polishing, you can reduce the distortion caused by tarnished connectors. However this is not always convenient and we find the modest extra cost of rhodium very worthwhile for mainataing the ‘as new’ visual effect of our plated connectors. Plating in Rhodium,and other similar precious metals, eliminates the need for regular polishing.

The pictures above show the rear of two amplifIers which I manufactured at around 1990. The left picture shows one of the standard models of the amplifier which sold at a basic price point. This amplifier used the same mass produced connector that was very common in amplifiers at the time. The right picture shows the ‘high end’ version of the same aplifier made using much higher specification resistors and capacitors, and connectors that were specially plated in rhodium for us. A simple inspection of the pictures shows how te rhodium plated connectors have maintained their  shine over a long period of time.

Rhodium plating improves sound quality

Over the years we have conducted very many tests in which we have auditioned the sound quality of systems in which we have compared a cable using a rhodium plated connector with an identical cable using a similar connector that has been lated in gold or not been plated. Every time we test a rhodium plated connector we have heard an improvement in sound quality.

On occasions when we have been able to change the mating connector to a rhodium plated version of the same connector, we have heard a further improvement in sound quality.

Polishing and plating for even better sound

Many surfaces of connectors are not smooth. This particularly applies to the UK 13A mains plugs whose surface is not smooth.

Polishing a connector surface prior to plating in rhodium  further improves sound quality.

The process of polishing the metal surface of an audio connector creates a flatter smoother surface on the connector. This assists the flow of electrical current between the connectors, resulting in a further improvement in sound quality, that more than justifies the hand polishing.

Polishing and plating of the 13A UK mains power connector further improves sound quality and brings you closer to the musicians in your music.

Plating in other precious metals

Rhodium is not the only precious metal which can be used to deliver the sonic benefits of precious metal plating.  Silver, palladium and platinum are also used for audio. One test carried out by Black Rhodium was the plating of wires in rhodium, ruthenium, palladium and gold. We built a simple interconnect from each and we found that the rhodium plated wire performed best, the palladium and ruthenium wires were next and the gold plated wire least good. The level of performance correlated very closely with the price we paid for the plating in the different metals.

The plating of audio connectors will grow due to the growing demand for improved sound quality and the range of precious metal plated connectors will grow to meet this demand.