speaker wire

There could be (and possibly is) internal filtering on your monitor but my guess is the manufacturer was trying to save a few cents/pennies. It is certainly more 'usual' to see them fitted at each end particularly in the case of long speaker wires.

I missed the staff meeting but the minutes show Dave Hinz wrote back on 24 Feb 2005 19:49:56 GMT in rec.crafts.metalworking :

Umpty eleven years ago, I went with my Dad to buy a stereo. Went to Japan, and I doubled his "duty free" amount. [Hmmm - half that stereo was mine.] He'd been talking to the audiophiles, and they basically told him "if you got a hundred dollar ear, buy the hundred dollar stereo. If you have the fifty dollar year, buy the fifty dollar stereo." (Tells you hold long ago this was). His response was "I've got a ten dollar ear ..."

So I got a week in Japan with my Dad, as he shopped around. Lots of fun for a twelve year old kid.

tschus pyotr

I do know that all gold-plating is not the same. Trompeter (the connector guys) understand that you cannot strike with nickel first under the gold, like many folks do.

You actually can see the distortion from that.

Jim

At audio frequencies?

That's an interesting observation. If you don't know, the reason the nickel is plated to begin with is to prevent migration of the gold to the base metal. In my years of refining I discovered it was pretty much common practice to find nickel under gold plating when stripping. Sir T.K. Rose concluded long ago that gold and silver have an affinity for certain metals and will migrate to them when in close proximity, and they need not be molten or even hot. Ingots of pure silver and pure gold end up transferring to one another when in contact, for example. Nickel prevents the migration. If what you say is correct, unless gold is plated quite thick (I have no idea what that may mean) , there is likely no benefit in using it at all, because, over time, and it's not long, it simply vanishes. One problem gets replaced with another. Comments?

Harold

Trompeter makes a lot of their stuff on my machines.

So does Maury Microwave

It's better to be a red person in a blue state than a blue person in a red state. As a red person, if your blue neighbors turn into a mob at least you have a gun to protect yourself. As a blue person, your only hope is to appease the red mob with herbal tea and marinated tofu.

(Phil Garding)

Transition metals are commonly used as both diffusion barriers and as adhesion layers. (Ti, Ni, Mo, W, etc)

The first prevents the plated, or deposited, layer from diffussing into the the substrate. This is a real issue in semiconductor processing, where it's important to keep layers of metal (wiring) on chips from being contaminated by the layers adjacent. This is especially important because some of the processing is carried out at elevated temperatures. A layer of, say, Ti, that is about 200 atomic layers thick will suffice to keep the layers of the cake from smearing out.

Adhesion layers are another issue. This is why nickel strikes are used under gold plating as a rule.

Adhesion is a peculiar thing - what makes one thing 'stick' to another? At atomic levels this question is a) of considerable practical interest and b) not entirely well understood. There's a lot of research being done on the fundamentals.

I can recall desperately trying to figure out some way to deposit copper on sapphire stubstrates - but it would *not* stick. The common trick is to put down a Ni adhesion layer, but nickel is magnetic and for our work that was unacceptable.

That company I mentioned (trompeter) makes rf connectors for low level, high freqency applications. All of the other connectors I investigated were magnetic because of the ni strike in the plating process. Because they build for the small-signal rf market - mostly satallite communications gear - they understand that distortion of the rf signal can occur from any magnetic materials in the connector, so they use something they call a "pulse plating" process to eliminate the Ni strike beforehand. This is specifically to replace an *adhesion* layer, not a diffusion barrier.

Does the gold diffuse through into the brass metal underneath?

I honestly don't know. They may use some other kind of diffusion barrier, but I've never seen them degrade over the 20 or so years I've been using them. I will look up in their catalog at work and find their spec for plating thickness.

Jim

Jim, I sincerely hope that you don't seriously expect to see any distortion at audio frequencies resulting from the plated layers found in connectors.

Maybe at X-band but ...

Ted

Yeah, and I've seen a few examples of it through the years, but just a few, obviously something that was done rarely. Almost everything I processed with cyanide had nickel underneath. Without the nickel strike, the gold layer would start oxidizing, but only because it had been absorbed by the base metal. As you well know, it's not lost, but is no longer providing a barriers because it has diffused too much, leaving the base metal unprotected, and it's the base metal oxidizing, not the gold. The gold is recovered in refining, assuming you dissolve the base metal, not strip it, so long as nothing is discarded. I found that by filtering with a well clogged filter, or allowing the solution to settle well before decanting, I would end up with the gold, although it certainly didn't look like gold at that point. When the base metal is dissolved, the gold, for all practical purposes is down to what might be considered a colloid, (go easy on me here, Jim, I'm not a chemist) perhaps? Very finely divided particles, clusters of atoms, nothing you can really see, but you do see the affect, a purple color. Various processes before dissolving the gold allow complete recovery.

That varies according to need, and one pays accordingly. I supplied a modified connector to Univac on several occasions, where four were made from one, a Cinch wire wrap connector. This was prior to May of '83, when I closed the doors on my shop permanently. I purchased them directly from the mfg. and modified them to Univac's specs. They specified a given depth of plating, under a tenth, 80 millionths as I recall, but one had options as need required. At least that's the way I remember it. It was interesting to see the pricing schedule and gold adder, considering I was machining at the same time I was refining and by then had a firm understanding of the amount of gold in question. Need I tell you the price of the gold adder was quite lucrative for the manufacturer?

I did have one very interesting experience, the opportunity to strip some micro-wave gear that hailed from what must have been WW II equipment. The plating on it was so heavy that it was in thousandths, not millionths. There was no barrier under it, which made stripping with cyanide very difficult because there was nothing to prevent the base metal from dissolving along with the gold (done electrolytically). Nickel does just that. Some of this gear was one of the rare times I recall seeing gold oxidize, but only one part in particular. It was a brass casting (wave guide? dunno!) that was heavily plated, but still managed, some areas much worse than others. The gold had obviously been absorbed. A sulfuric process would have been far better suited to stripping that stuff. It doesn't attack the copper base, but removes the gold quickly. I would have to wonder if the diffused gold would have been recovered, though.

Harold

Those were microwave connectors Ted. The distortion winds up as intermodulation products, trompeter makes so many different kinds of connectors I think they just decided to make their plating standards for gold avoid nickel for *all* their connectors.

For me this was good because I had to obtain miniature triax connectors with very low remanent magnetization. They were the only folks I found who could do this.

Jim

FYI this intermod effect was noticed with a 100 Watt 450 MHz transmitter which was connected to an antenna that was also used for receiving (with a diplexer)

Replace the connectors with Silver and all was OK.

Bill K7NOM

You can forget about skin effect at any frequency my dog can hear.

Sounds good.

That's great for typical PA systems but I have yet to see a transformer that would meet my specs for a high quality system and I've been messing with this stuff for more than 55 years. I was SO glad when serious silicon was able to go direct into a speaker.

Yup. If the amp is in LA and the shop in NY, this is a _very_ serious consideration. Calculate what fraction of a wavelength 100' is at 20KHz.

Ted

Skin effect problems generallly start above 100KHz and that is why your example needed the higher conductivity across a connection that the silver on both terminals of the connector became needed. Gold has a higher resistance than silver but it can be better as it molds better to the contact.

-- Why isn't there an Ozone Hole at the NORTH Pole?

You have received lots of good advice here. Now here are some links for your amusement.

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

On Thu, 24 Feb 2005 16:29:05 GMT, Bruce L. Bergman vaguely proposed a theory ......and in reply I say!:

remove ns from my header address to reply via email

I have to say here that any transformer will cause more trouble than it saves. They are OK for a sprts meeting, with long long runs, high power and low quality, and to keep wire costs down etc. But the impedance, oscillation, and frequency response problems of a tranny are huge, compared to transistors and good wire of sufficient size.