The IACS Rating of Metals and Alloys

ETI-Research IACS Rating

IACS Rating of Metals and Alloys will give a better indication of the quality of material used in connectors.Over the years when buying Audio Equipment and Cables we focus on the great designs and materials  they are made from and ignore the basic connection material used to bring the music to our ears. Cables will have the most state of art Copper and Silver wire in various well thought out meticulous  designs only to finish with a connector that may look nice but may have less conductivity than the actual wire.

Audio Equipment will have pure Copper/Silver traces in the circuit boards or high quality wire in point to point designed only to have connections to connect to again that may have less conductivity than the what the audio signal is traveling on inside.

The chart shows the IACS rating of some common metals and alloys and beside the Alloy box is the pure metals IACS rating that we have discussed in previous post


                          Alloy                    IACS               Comments
C10100                    101% Oxygen Free Electronic Grade
C10200                 100 to 101% Oxygen Free
C11000                  100 to 101% Electrolytic Tough Pitch
C14500                  93% Tellurium Copper
C17500 Beryllium Copper                  45% Commonly used in situations that the Copper needs t o be able to “Spring”
C31400 Leaded Bronze                  42% These Alloys below are commonly used for manufacturing because of cost and very easy to machine
C17530 Beryllium Copper                  38%
C37700 Forging brass                  27%
C36000 Free Cutting Brass                  26% C3600o is the most common of the Brass used
C17300 Beryllium Copper                  22%
C54400 Phosphor Bronze B-2                  19%
C53400 Phosphor Bronze B-1                  15%


Material Resistivity   nOhm-m Conductivity  109S/m           IACS
Silver               15.87                0.0630           106%
Copper               16.78                0.0596           100%
Gold                22.14                0.0452             76%
Rhodium                43.3                0.0231             39%
Nickel                69.3                 0.0144             24%
Platinum                105                0.0095              16%
Paladium                 105.4                0.00095             16%


















Silver IACS rating is based upon 99.99% purity which may seem common but today it is harder and harder to verify the purity. That is why  ETI-Research Pure Silver products state that the Silver comes from a foundry in England that makes our specific size rods for machining and  supplies a Assay Report of the 99.99% purity. Most Silver today is mostly 99.9% at the best and most likely worse as price and where the Silver is sourced  comes into play when purchasing for manufacturing. To make Silver  rods of 99.999% or 99.9999% purity would be extremely costly and very few foundries will want to pursue this. We would suggest when in doubt to ask for verification of the claim.


ETI-Research uses Tellurium Copper  in certain designs as it provides the hardness needed for machining and durability. In the designs that will allow then we use Harden Copper such as C11000.


When you see a product that has a very shiny Gold or Silver plating most likely it has Nickel applied to the surface before the plating occurs. All of our products apply the plating directly to the Copper as we know the effects that Nickel has on the sound.

Free Cutting Brass without a doubt is the most common material used for connections. It is cheap and very easy to machine however the conductivity of it is very poor and the IACS rating is based upon clean forged Brass. So much Brass nowadays is recycled and this has even worse conductivity due to the other material in the mix. ETI-Research will use Brass for Housings that do not touch the Copper or Silver as Brass is very good at EMI/RF rejection and also very good at vibration damping.

At Eti-Research we believe that the connectors we make should have as little impact on the sound as possible.That is why we prefer Copper and Silver not Brass or Bronze.  After all if Brass which is commonly used was really that good then why isn’t the wire also made from Brass?




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