IACS Ratings of Metals

The different metals conductivity is sometimes not understood well and gets confusing. Often metals that look very similar are thought to operate the same way or because it has a plating on it that again it somehow it will not matter. For many years Brass and Bronze has become very popular metals to make various audio connectors from for a very good reason. Both Brass and Bronze are excellent at machining while relativity inexpensive to buy. While wonderful looking connectors can be made from these materials it does not mean that you will get a wonderful sound as the audio signal has to pass through them.

To get a better understanding of what is bad, good, and great the IACS rating is a great place to start. It was set up to understand the conductivity of different metals and alloys through a percentage rating. Copper was setup up as a comparison and given a rating of 100% as a comparable comparison for all to be judged by.

Material IACS % Conductivity  

Silver 105%
Copper 100%
Gold  70%
Aluminum 61%
Nickel 22 %
Zinc  27%
Brass 28%
Iron 17%
Tin 15%
Phosphor Bronze 15%
Lead  7%
Nickel Alum. Bronze  7%
Steel 3 to 15



So as you tell all metals and alloys are less conductive than Copper except for one, that is Silver. You also can tell that Brass and Bronze are both not very conductive and this have an influence on the sound as it passes through these Alloys.

So why are they used? I stated earlier machining is one factor as they can provide a stiff solid platform to machine products from. Cost is another as they are used in such larger amounts then when foundries make so much of course this can reduce the cost. If they both had the capability to be far better at conducting like Copper then we would all be in a very happy place. Another issue that arises when using Brass is that while pure Brass is not magnetic when it is formed pure from a foundry for the first time, so much Brass now days is recycled so is remelted and mixed with other recycled batches which causes various impurities to be in the forming process of rods to be machined and is magnetic! It is quite easy to know how pure Brass products are by waving a magnet to them. If they attract you then know. If you find that the magnet is attracted then that is only one problem as most likely the conductivity is even worse than in the IACS Rating due to the impurities.

This is why ETI-Research we use either Copper or Silver for our products as we really do care that you get an Audio signal from a source to your ears with as little changes in the process as possible.

When we plate the Copper ETI-Research will only use Gold or Silver without any Nickel in the middle. The reason that Nickel is used so often is when you apply it to Copper then put Gold or Silver plating on, it really makes the plating shine and glisten. It looks great but can add harshness to the sound. Look at the IACS rating to see how poor Nickel is at conducting. Rhodium while also can look very shiny it is also a very poor conductor and will also add an element of harshness to the sound.

When you are looking at improving the sound in your system, getting the right metal can make all the difference.

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