Binding posts Brass vs Copper : does really makes differences ?

in that little lenght does brass really degrade sound quality ?
Assuming equal clean contact area there will be no "sound degradation" from either material.

In the real world, deformed and dirty contacts can add resistance, robbing some power from the speaker that is turned to heat in the connector.

Brass is more resistant to deforming, and tarnishes less than copper, making it a better connector material.
silver is the best electrical conductor. Its oxide 'tarnish' is conductive.

Brass is also a good conductor, and its oxide is also conductive.

Which oxide in turn is the best conductor i couldnt say without rifling thru a book or two. Coppers tarnish, in contrast, isnt a good conductor.

Gold is only really worth the cost due its almost untarnishing surface. I really dont think resistance is much to worry about. Platignum and rhodium are perhaps choson for the same reason?

I.e. Plate any Cu binding post with Au, Rh or Pt and it is a good conductor regardless since it wont tarnish, AND it will look pretty.

Silver plate Cu would conduct well, even when the bright silver has blackened and SWMBO wants to polish them shiny again.
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in that little length does brass really degrade sound quality ?

This depends on your own hearing, and the rest of the system.

As far as the system: the poorer the quality of the system to reproduce fine-detail, the less likely that there will be a noticeable difference.

On the other hand if you have a minimalist system (composed of few parts and connections, along with a loudspeaker driver grouping and loading that has low damping at very low excursion levels with few high-quality parts used in a passive crossover), then it can actually be quite noticeable - enough that even a casual listener would easily identify a difference.
Originally Posted by diypass
in that little length does brass really degrade sound quality ?

It's irrelevant.
Resistance of of a 2mm length, 8 mm diameter path through any of those metals is non-existent compared to, say, the resistance present in 2 to 6 meters of 1 or 2 mm diameter copper speaker cables.

Not forgetting that you also have many other resistive/lossy paths inside the amplifier itself, plus soldering (ugh!! dissimilar metals :eek:) or even worse, unsoldered physical contacts (connectors/terminals/capacitor legs/etc.)
And if the amp is a tube one, you have tens of meters of fine copper wire in series with the signals.
And the tubes will not be soldered but pushed into sockets.
And so on and on and on.

So in due perspective, worrying about that little and easy path compared to all others, sounds like a little too much.

Of course, keep the surfaces clean and the contact pressure tight.
electrical conductivity of metal oxides is a complex topic, e.g. PbO is an extremely good conductor (a car battery easily can supply 100A and more) but TiO is an isolator, having the same crystallographic structure.
concerning rhodium: manufacturers use massive silver, coat with 100 microns of gold (costs nearly nothing, looks good, they can say it's gold plated), coat that with 20 microns of rhodium, which is very hard, to prevent the gold from beeing scratched und the silver from shining through after plugging/unplugging several times. They do the same thing with electrical components and with jewelry. Many cheap "gold" rings are made that way.
When I was designing amplifiers at McIntosh one of the amplifier engineers looked at the speaker terminals we were using and gave me some grief. It was some ferrous material and he said he wouldn't be allowed to use it on the amplifiers. It would prevent them from getting to .0001% distortion or whatever. He was serious that it would have a measurable impact on distortion.

Of course, on a speaker it would be absolutely undetectable relative to the typical driver distortion (even with LD/HP).

David S.
hi dave,
please, could you explain better ?

Not really:D

My recollection was that it was a slightly magnetic material and so had a magnetic hysteresis loop. So it would be a slightly nonlinear resistor in series with the output. This was a vanishingly small nonlinearity but the amplifiers were so linear that it would make a measurable difference in output distortion and make it difficult to hit the intended spec.

This was Ron Evans, one of the chief designers and a solid engineer, so I would take his word for it.

David S.