Gold-plated contacts ...
For centuries we know that all metals can conduct electricity; i.e. electrons can flow through metals and we call this effect 'conductance' which is in turn a distinctive property of all metals.
Another distinctive property of metals is the property to build oxydation products if they react with oxygen on the surface - rust with iron, verdigris with copper just to name the most popular. These oxydation products are bad conducters or cannot conduct electrons at all.
Among metals there are two candidates that do not or do not much suffer from oxidation at all:
Gold & Nickel (and it's shiny brother Chrome-Nickel [NiCr] which is in fact an alloy). Some other alloys like bronce come into account - but their conductance is far bellow the before mentioned. Brass is a really good candidate for gold-plating, since its specific resistance is even better than that of Nickel.
|Chrome nickel||NiCr (alloy)||12||8,4||-|
From the table above it can be seen, that gold is the first metal that does not suffer from high oxidation - but not only this ...
Gold ... not just for the beauty ...
The conductance of gold is about 300% higher than that of Nickel. Since resistance is the reciprocal value of conductance this means that the resistance of Gold is just 1/3 as that of Nickel.
But what does that electronically mean?
From article "Good cables, bad cables" it could be taken, that every piece of cable is comprising a (passive) "low-pass-filter" - which is in fact the very same as a (passive) "high-cut-filter"; i.e. regarding to its quality an audio cable cuts trebles which are in the high-end of the overtones that make out the sound characteristics of a high-grade acoustical instrument. The resistance of the contacts ('transition resistance') adds to the implicit cable resistance - and that on both ends of the cable.
So the formula changes significantly ...
Instead of the plain cable (without connectors) the cable with connectors on both ends adds 2 times the 'transition resitance' of the connectors to the total resistance (...+ 2Rc) - and it is not just 'tripple' ...
As we all know: the bigger the value under the line the smaller the result; i.e. the signal is cut-off at a smaller frequency and yet more overtones are down the drain ...
The other way around: with better connectors that have much lower resistance the overtones are much better preserved. This is why pro-audio cables consequently use gold-plated contacts on the connectors.
And what does that technically mean?
In a technical context spoken: Having contacts with far better conductance (which is the very same than having far lower resistance) this means, that one gets much lower 'connection crackling' when plugging-in and -out. This is for the relief of the speaker(s) in the amplifier or the speakers of a PA system.
With gold-plated contacts 'connection crackling' is a lot lower and can reach 'not hearable'
And what does that musically mean?
The overtones from a musicians play get through as he arranged his playing for this. In particular this relates to harmonics that are played. At the end of the day the signal comes clear and crisp from the speakers or PA system if overtones are preserved by using high-grade connectors and cables - and the audience can hear it ...
All your endeavours at the instrument get through to your audience ...