HOLLAND LINK is pleased to present cables made from single crystal OCC copper or silver. Such cables feature an average crystal size of 125 meters (410 feet)! Compare this to the average crystal size of Oxygen Free Copper (OFC), which is .02 meters (3/4").

OCC is actually a special type of high purity Oxygen Free Copper (OFC) or silver, in which the whole wire is composed of a single metal crystal. There is no "crystal boundary" between crystals, which would reflect and refract the signal to produce distortion and signal decline. Therefore, it will provide extremely high signal transmission.

UP-OCC or HP-OCC copper and silver are considered the ultimate in copper and silver conductor technology today because of this faster transfer of electrical signals, with less distortion than ordinary OFC and silver wires. All of these features make pure OCC copper and silver cables the state-of-the-art components in the audiophile world.

OCC is short for Ohno Continuous Casting, which process is patented by Japanese Dr. Atsumi Ohno.

Harmonic Technology, Furutech and Oehlbach are certified manufacturers of this type of cables and offer a wide range of different UP-OCC speaker, interconnect, S-Video and power cord cables in the medium to high performance class.

Read more on cable technology in this Furutech paper (PDF)

And this is what Sowter England, maker of high-quality transformers writes about it:

WHAT IS OCC WIRE?
In 1986 the Ohno Continuous Casting (OCC) Process was developed by professor Ohno of the Chiba Institute of Technology in Japan.  The wire made by this process is claimed by our manufacturer to be 99.999 % pure and in our thinnest wire size (50 micron) that it has one crystal boundary per 6.5 km on avearge.  Normal wire has a number of contaminants particularly Oxygen, Sulphur, Lead, Antimony and Aluminium and is typically 99.97% pure and has a cristal boundary perhaps every 10 mm.

BACKGROUND
We have been asked many times over the years if we can wind transformers with Silver, Ultra high purity ("oxygen free") copper or OCC wire.  We have always resisted the idea because we don't want to make exaggerated claims which we cannot justify.

Recently we made some transformers using OCC wire for one of our highly respected customers who wanted to try them them in his products. He did a side by side comparison of a stereo system which used 3 transformers per channel in the signal path. His conclusion was that there was an unmistakable improvement in the sound from the amplifiers using the OCC wire. The improvement was most noticable in the reproduction of transients.

We do not consider this single result to be significant evidence to make any claims whatsoever as to the benefits or otherwise of OCC wire. This is particularly so because the listening test was not a scientifically valid experiment and as yet we have not been able to make any electrical measurements to back up the observations.
However we feel sure that other customers will wish to make their own experiments and we are delighted to be able to offer versions of some of our standard  products made using OCC wire.  The wire is of course, much more expensive but for smaller transformers we are able to offer this option for a price uplift of around 20%.

HOW COULD IT WORK?
Perhaps our hearing can respond to "super-sonic" (i.e. frequencies above say, 20 kHz) frequency components present in transients.  Perhaps the amplitude and phase of these components can be affected by the wire purity and crystal structure. It would be very interesting if somebody could devise a method of measuring the distortion of transients in music which could be applied to a comparative test of transformers. Transformers use quite a length of wire, so if there is an audible effect it should be possible to measure it.