Hookup wire for tube amplifier?

The issue is break-in and longevity.

Copper seems to take longer to break in than silver does. If handled correctly they both get to the same place.

You have to be careful with silver- don't go with silver-plated copper and you have to be careful to use the right solder too. Silver wire usually has a Teflon insulation.

Copper works fine but you have to be careful with the insulation. Teflon will not block air from the wire, and the wire can't get oxidized! In addition the extrusion process runs at a high temperature so unless very special provisions are made the result will be that Teflon-coated OFC will not be OFC once inside the Teflon.

BTW, there are no wires that have more than 99.99% purity. If more than that is claimed either the supplier is misinformed or they are lying. I remember that there was a craze for '6-nines' copper a few years ago; when it was found out that such a thing does not exist, the various manufacturers that were making such claims quietly stopped doing so.

To retain its OFC status, the insulation has to be able to seal the wire; its helpful if it melts a little near the solderjoint. If it does that correctly it will be fine for decades.

Ralph, you are claiming the three licenced manufactures of OCC (Neotech, Furukawa, and the other Japanese company) copper wire are lying about the purity? Can you direct me to an article or website where their claims were disproven?

I swear Cardas also claimed 6 nines copper wire being drawn and coated in oxygen free atmosphere.

These are not suppliers but actual manufacturers of the wire.

You mentioned using the right solder for silver wire. Do you mean solder that contains silver?

Ralph makes some good points. The OCC is a casting process, not a ranking of purity. The other point many will make is, "does it matter" whether it is OCC? The Jupiter wire is CDA-101, which is thought to be the highest purity - it is 99.99 percent pure copper. Measurements show the conductivity of ETP copper is the same as OFC or OFHC copper. I certainly don't have the answers, but I can say the Jupiter wire (in the configuration I use for IC's) sounds very good in my system against some other well regarded wires. I suspect dielectric material and surface condition of the wire, along with other factors, could all play a part in the sonic performance of wire/cables. I particularly like the following from one of the attached links;

Copper of extremely high purity, or with large crystal size are also available, sometimes at a high price. Whether they have any value in such applications as audio speaker cables is at best unproven, there being no measurable improvement, and some negative results from subjective blind tests. (Not to mention claims of positive results from non-blind tests where dramatic differences were invariably described for what were believed to be known different cables, when in fact the cable was never changed.) Blind testing is sometimes dismissed as too intimidating by believers in 'cable effect', and yet the language used to describe cables suggests gross effects easily audible, e.g. someone claimed that his wife rushed through from the next room to find out what had happened when a cable was changed, the effect was so dramatic. This does not suggest some minute effect only audible under ideal conditions.

Links:
http://www.angelfire.com/ab3/mjramp/ofc.html
http://www.angelfire.com/ab3/mjramp/wire.html
http://en.wikipedia.org/wiki/Oxygen-free_copper
http://www.sequoia-brass-copper.com/alloy_101_ofe_copper.htm
http://www.6moons.com/industryfeatures/caelin/caelin_2.html
http://www.southerncopper.com/metals.asp?

I don't think any generalizations about wire hold true. There are good examples of all kinds of wire. I have never heard Audionote silver wires to sound overly bright in any of a number of tube systems I heard them in, my own included.

The only way to know how any cable will sound in a particular setup is to actually try the cable. Most dealers allow for auditions, and there are on-line companies that have a "library" of cables that they offer for home trial.

If anyone has compared OCC copper vs silver wire, please chime in.