Precious Metals

Alan

When it comes to plugs, most I/C cables, speaker cables, and amp/speaker terminations are gold plated. Why is this?

My limited (and fragile) understanding is that gold isn't the best conductor to plate onto these terminations. Indeed, even dull, lustre-lacking unexciting, plain old nickel plate ought to be a more sensible choice. Is this just too boring? Not enough bling to justify a higher price perhaps?

I have also been looking into mains plugs just recently for a DIY project, and I see all the different options out there (gold plate, siver plate, rhodium plate, plated on brass, plated on copper....), so again, what are the merits to each combination? - And lack thereof?

I always thought silver or silver plating would be the last thing to use in a mains application, as it is so good at transmitting HF, this would surely invite RFI to be a problem.

Please, feel free to tell me why I am wrong.

uglymusic

Col's your man, I think. We talked about this (amongst other stuff) when we met the other week.

Brain_Dead

The problem is:-

1) Dissimilar metal set up a small voltage between them this is effected by heat, and chemicals and changes the voltages. 

2) Gold, and a few others because of there chemical stability do not. Gold will amalgamate with the likes of Mercury and Copper, Copper will absorbed the Gold if plated directly on to it so barrier metal are plated first to the Copper before the Gold is plated.

3) Metal such as Silver oxidise very quickly in air and in damp atmospheres and this then increases the voltage differences.  A good conductor when clean and connected to another Silver connector.

4) As this voltage and then as the area of conduction and voltage increase more small currents are available.

These small batteries will add or subtract from a DC supply but when a AC signal or supply is used it will cause distortion. 

So Gold is this best to resist this distortion but Silver will give less loss (very very small).

I hope this helps a little Alan.

PAC

What Col said plus:

Gold is actually a pretty good conductor too.  Relative conductivities of some of the top 10 metallic conductors are given below (in relation to silver each is given as a % or relative conductivity to silver):

Silver (100% = 1.63 Ohmcm)

Copper (95);

Gold;  (72)

Aluminium (60)and;

Rhodium (33)

Brass (varies from 23% to 40% depending on the alloy)

Gold is commonly used because it does not tarnish (is inert) and maintains it's surface electrical conductivity. Silver is a better conductor though.

Rhodium is often used over silver because it is far harder wearing than gold or silver and more conductive still than many brass alloys, hence "high grade" electrical plus for hifi tend to be Rhodium plated. Like gold, Rhodium will not tarnish nor react with nasties in the atmosphere.

Silver whilst not oxidising due to the presence of oxygen in air will tarnish readily to silver oxide in the presence of sulphates in the air, particularly in humid atmospheres.  Silver oxide is still conductive, but less conductive.  Silver shouldn't oxidise where the electrical contact is good enough to displace the air but signal connections should still be periodically cleaned and preferably treated with electrical contact lube to prevent airborne oxidation occurring. 

Bare copper also oxidises readily in air to copper sulphate (those suilphates again) so that's why it's usually plated with nickel (for the reasons Col gave) then gold. 

Thick nickel plating, depending on how the plating was achieved can be electro-magnetic and for this reason it is believed that it isn't the best choice for sensitive signal connections as it can give rise to small electromagnetic currents which modulate the signal, albeit to a very small amount.  Its also not as conductive as silver, gold, copper or rhodium.

Brass on its own is not the best conductor as you can see but the reason that so many connectors are made from it is a) that it is cheap and easy to machine or cast and b) that the input impedance of amplifiers is in the order of KOhms, so the additional impedance value of brass when compared to other better conductors shouldn't matter...but it does for one very simple reason.  The signal connection (positive) of an unbalanced connection (single ended like RCAs) may be connected to a high impedance circuit so only need a tiny voltage to drive the very small current, but the ground connection needs to be as low an impedance as possible for two reasons:

Firstly, the lower the ground (shield) impedance, the greater the signal to noise ratio (ie low noise floor) of the connection and secondly, to dump unwanted noise to ground, the conductor ideally must not be connected to a high impedance source.

The connector bodies on RCA's usually act as continuity of the shield in the cable, so these made from copper, or copper alloy (not brass, but a less ductile alloy of pure copper) are usually preferable (which is why I'm fond of using Furutech RCA connectors).

Hope this helps.

PAC

Double post...sorry!

uglymusic

No worries!

You should be able to delete your own posts, I think, Paul.

Alan

Thanks for the lesson chaps, I appreciate it. It seems gold is pretty stable and inert, I can see why it is used.

Sometimes I wonder at all the different materials used in a simple cable and wonder if the fewer, the better?

Brain_Dead

KISS nearly always works but some times a good cake needs Pepper. (my Grandma saying)

KISS = Keep It Simply Stupid

Alan

One of the things that bugs me is the crappy sockets on my pre, on my amp, and just as crappy on my I/Cs. I wonder if there's much point in re-terminating my I/Cs without changing the sockets to something that matches?

(They match at the moment, being equally crappy. I don't want to upset the balance of crappiness I currently enjoy)

Docfoster

There was a small company called 'precious metal' or 'precious metals' that made interconnects wasn't there...?
Obviously not what the thread's about, but it has reminded me...

Alan

Dunno mate? It seems ironic to me that there may be more precious metal in a lot of nutter's HiFi looms than has been bought for said HiFi nutters wives...

uglymusic

One of the things that bugs me is the crappy sockets on my pre, on my amp, and just as crappy on my I/Cs. I wonder if there's much point in re-terminating my I/Cs without changing the sockets to something that matches?

(They match at the moment, being equally crappy. I don't want to upset the balance of crappiness I currently enjoy)

I, for one, would be very interested in the results if you do go changing the sockets on your amps - I'm assuming yours are similar to mine for obvious reasons.

uglymusic

Dunno mate? It seems ironic to me that there may be more precious metal in a lot of nutter's HiFi looms than has been bought for said HiFi nutters wives...

As it should be
:-j

Alan

Dunno mate? It seems ironic to me that there may be more precious metal in a lot of nutter's HiFi looms than has been bought for said HiFi nutters wives...

As I am eternally ashamed to admit may be the case.
:-j

Fixed for you.

Honestly, reading the posts around here it's like a Peter Kay comedy, Phoenix nights sort of thing. We're lucky we even have wives...

uglymusic

b-(

PAC

Funny you should bring that up Alan.  I'm chaning the sockets on a few amps and DACs for customers for similar reasons you mentioned.  Changing plugs can most certainly be very worthwhile if the cable is a decent design and decent quality to begin with.  Why some manufacturers insist on cost cutting with plugs is beyond me.  A really decent set of plugs can be had for less than £45 and the mprovements over poorly designed and badly fitting plugs can be considerable.  I've also seen some kit costing £1000's using sockets which were worth pennies and made from (poorly) plated brass rather than decent gold plated copper affairs.

uglymusic

Sound of Dave putting two TDSs into a Jiffy bag and sending them off to Paul :-)

Alan

Can you recommend a decent set of plugs and sockets that match? I may like you to do my lightspeed attenuator for me in a while - and perhaps supply a set for my power amp project?

PAC

)

Mind you, I've never seen two turbo-diesels squeezed into a jiffy bag...should be interesting...soz...that's TDi's 

@-)

Alan

TDIs are more economical than TDS's, I should imagine.

uglymusic

I'd have to put them in the twin-turbo Subaru :-)

PAC

link to a short article I scribed on RCA's a while back if of interest:  http://referencefidelitycomponents.co.uk/why-high-quality-connections-matter/

no diesels involved...

Brumjam

Can you recommend a decent set of plugs and sockets that match? I may like you to do my lightspeed attenuator for me in a while - and perhaps supply a set for my power amp project?

Hi Alan,

I used Furutech FI-10 inlet sockets on my power amps. They are rhodium plated and cost about £26 each. Screw down terminals so no soldering required. Furutech do a range of inlet sockets from the wallet friendly to the downright insane (imo).

PAC

+1

great quality sockets.  Match them with FI-1363R plugs and that's a great quality combination with decent electrical contact.

uglymusic

link to a short article I scribed on RCA's a while back if of interest:  http://referencefidelitycomponents.co.uk/why-high-quality-connections-matter/

no diesels involved...

Thanks for that Paul.

We don't like diesels at Ugly Towers :-(

PAC

link to a short article I scribed on RCA's a while back if of interest:  http://referencefidelitycomponents.co.uk/why-high-quality-connections-matter/

no diesels involved...

Thanks for that Paul.

We don't like diesels at Ugly Towers :-(

Something very odd has happened and you, being a gentleman of (ahem) more experienced years may be able to help here:  I am a confirmed petrol head...97Ron ran in my veins (you do Ron Ron... ), and despite being married with children, still mess about on an Aprilia RSVR Mille.  I had a what every petrol head should at some point until very recently, a 6-pot Bimmer but looking outside the window now, there's an S60 D5 sat on the drive.  Is it just me?  Is there hope for me? Does a D5 count and will my left foot drop off from lack of use now as it's also a geartronic auto?  I apologise in advance for my dieselnessness...

uglymusic

I have what every family man and petrol head should have, if you can find one - a Subaru Legacy GT-B Twin Turbo Estate in the automatic flavour. It'll swallow around the same number of people and their stuff as your Ovlov, and out-accelerate a Porsche Boxster S (I know, I tried it yesterday on a long hill on the A27).

Fast estates are a wonderful thing, IMHO, and autos fit with their character perfectly.

Oh, it also requires 99Ron petrol from messrs Shell or Tesco because as a Japanese grey import, it was weaned on 102Ron.

PAC

The Legacy may well have the legs on the Ovlov in some areas Dave.  Chipped, mine has 230BHP and 400ft-lbs torque (that's HUGE), and also swallows most over-stated two seaters in the 40-80mph stakes!  However, on a long run carefully driven I still get to see 50mpg :P

uglymusic

They're about the same BHP-wise, then (the Legacy is rated at 260, although on 99Ron?). I haven't got a clue on the torque.

Petrol consumption? You've got me beat! The Legacy consumes the expensive stuff at about twice the rate of yours :-(

Alan

Hi Alan,

I used Furutech FI-10 inlet sockets on my power amps. They are rhodium plated and cost about £26 each. Screw down terminals so no soldering required. Furutech do a range of inlet sockets from the wallet friendly to the downright insane (imo).

Hi James

Thanks for that tip, very kind of you. Whether or not they make audible differences, my OCD tendencies are telling me to get a gold plate version to match the gold plate IEC plug.