Nac A5 corrosion?

Hi, my first post here so please be gentle!!

I have gradually changed and upgraded my system over the years, moving from NAC 92 NAP 90 to my now NAC 82, Supercap, NAP 135s driving SBLs. All the time I have used the same lengths of NAC A5. I was having a poke about the other day… as you do and looking at the wire behind the black sleeving it is very green, verdigris is clearly there, this goes at least 15cm up the cable, probably more, I didn’t look any further. Is this normal and will it be degrading the sound? It can’t be seen unless you look for it but it just doesn’t seem right to me.

No, that isn’t normal and will most certainly degrade the sound.
I wouldn’t bother stripping back any further, you have gone far enough. Time for some new cables I think. :+1:t2:

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What I thought Popeye, ever heard of it happening before, I guess it must be about 15 years old

How are they terminated and are they oxidised at all ends?

Naim plugs both ends, inside the plug is clean and solder is good, oxidisation occurs under the black sleeving. I have some 30 year old A4 and it hasn’t gone like this at all

This is a quote I just found on the net, can’t comment if it’s accurate but interesting.

“it’s caused because over time and exposure to environmental variables such as temperature, the PVC degrades to form hydrogen chloride as one of the decomposition by-products. The reaction product, copper chloride, is green.”


That makes sense, I wonder if it is something Naim are aware of and whether it happens regularly or this is a strange one off. Thanks for posting that.

If it were me, I would cut them back to where there’s no verdigris, or else get a new set of cables.

Yes, that was my thought, but I would have to cut them back so much they would not connect the speakers to the amp!! Sadly, sounds like new cable time. Have you heard of this happening before Richard? Thanks for your advice.

I have heard of it (IIRC there was a post about it on some cables many years ago on one of the old forums) but I’ve never actually ever seen it. I’ve got lots of runs of A5, some vey old indeed, and they look fine.

If the PVC is breaking down ultimately it’s days are numbered.

Interesting. According to Wikipedia, “In a fire, PVC-coated wires can form hydrogen chloride fumes” but says nothing about normal temps. I guess the hydrogen chloride would indeed react with copper to Copper(II) chloride, which looks like this:

On the other hand, “surface embrittlement and microcracking” due to normal degradation of PVC according to, so maybe not impossible that it’s air and with it humidity getting through

It’s probably not possible but I wondered if electrolytic reaction is possible with certain dissimilar metals used at the speaker binding connections?

These effects of metal mixes with different whateveritiscalled occasionally reappear and it’s maybe expected as most people who take any kind of chemistry in school hear about it. And certainly there are situations where it is an important considerations but I am not aware of it ever bearing out in home electronics situations. I remember around the early nineties there were stark warnings against putting RAM with gold connectors into sockets with a different material (forgot what it was) and vice versa. However, in 30 years in the home and business desktop computing industry I never came across an issue from it, and remember to have read an article maybe ten years ago saying that it had been all hogwash, with some chemical reasoning.

I’ve known of it in car restoration when different metals get put together and react but all it has been in contact with is Naim plugs and solder, plus amp and speaker, very weird.

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Just get new cables. A lot of older designed cables did this. Monster cable was notorious for this. I hate to say this, but this can also happen to internal wiring . I hear a lot of folks here loving the Witch Hat cables might give those a try.


Is the room very humid, or is there damp in the floor or walls in the vicinity of the cable? I have seen corroded copper in a cable that had lain for years along the floor edge, and investigating revealed damp in the wall. Whether that was definitely the cause wasn’t proven, but seemed a possibility, and anyway pointed to some remedial work needed.


That is a really good point. Wall is not damp though or humid, however, one length runs through my garage, will have to check if the length that doesn’t is also corroded.

Being a plumber and using copper, obviously. I would say that damp has caused this.
Either its got wet at some point, or been in humid air.
It would have crept down from the un shielded ends between the copper and plastic.

Copper goes green, naturally, ever seen a house with a light green roof, thats a copper roof, copper pipe the same, starts of nice and shiny, but soon dulls of, add in condensation on the pipe surface and it will start to go green

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Thanks for your thoughts. So you think damp more probable than PVC breaking down, do you think it would have to to have been more than damp in the air in the cooler garage? Thinking about it can’t see how damp would get into the sealed wire. Condensation possibly, but again it is sealed.