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Ok, how bad really are magnetic materials in binding posts?

Nat said:
Doesn't the voice coil operate in a very strong magnetic field? Beats me why whatever inductance/reactance would be created in the half inch or two of conduction in steel connectors would be close to the the effect of the magnetic field on the bazillion wires of the voice coil. And yes, I know that the voice coil wires may not be ferrous, but they are diamagetic or paramagnetic, copper and aluminum being the obvious possibilities. So there is interaction with the magnetic field - not much, but when we are getting the heebie jeebies about a binding post, let's go whole hog.
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The voice coil's electromagnetic field reacts to the speaker's permanent magnet. That is how it converts electrical signals to mechanical ones. The phono cartridge does the same (in reverse—mechanical energy into electrical).

This is one of those Maxwell-Faraday things. ;)
 
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Solder or braze up a bunch of steel coat hangers to make speaker wires and see if you can hear a difference. I think it's been done and it sounded the same. I can't believe the nuts you use are measurably or audibly different. Copper is great but it makes terrible binding posts. It's soft, weak and prone to galling. Tellurium copper machines better and has fewer problems, but the conductivity is less. IMO, the lugs you use don't matter either. Never use tinned wire in binding posts as it loosens over time.
 
I made a few hundred interconnects to tease out the sound of metals as an audio signal conductor.

Fascinating experiment that took over 18 months~!

Copper (Every possible shape, size and configuration including stranded),
Pure Platinum,
Pure Silver,
Pure Gold,
Steel,
Nickel,
Nichrome,
Niobium,
Lead,
Beryllium copper,
Gold plated steel,
Silver plated copper,
Copper plated steel,
Platinum plated steel,
Constantin,
Ferroniobium,
There is a few more, Will have to think on that...
Will write up some documentation on what we experienced and learned.

Picture of my current interconnects using Cardas RCA's and come in three flavors.
Pure Platinum, Pure Silver or Pure Gold as signal conductor.

0P6f0ku.jpeg
 
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audiotemp said:
That's not really a correction so much as a counter myth.

It's true that silver sulfide tarnish is often/usually more prevalent than silver oxide tarnish but saying that silver oxide doesn't form at all at room temperature is overstating the case.
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It is not a counter myth. It is a scientific fact that pure silver films will not readily form silver oxide (Ag2O) under ambient conditions. I studied the surface chemistry and electronic structure of silver films extensively using a variety of surface sensitive spectroscopies. These experiments were all done in an ultra high vacuum system on pure clean silver films with controlled exposure to a variety of gases. The silver films were vacuum deposited and alternately argon-ion etched followed with high temperature annealing until a 100% pure silver surface was obtained. The silver films were then exposed to controlled amounts of O2 gas (pure O2 and O2 + water vapor) at room temperature and analyzed with Photoelectron Spectroscopy. No evidence of Ag2O formation was observed even after hours of exposure. However, low concentrations of physisorbed O2 were observed. For dissociative chemisorption to occur, it required heating the silver film to several hundred degrees C, in which case the formation of Ag2O was observed. In comparison, similarly prepared metal films of Cu, Al, and Ni all formed an oxide layer within seconds of exposure to O2 gas at room temperature. Exposure of the silver films to controlled amounts of hydrogen sulfide (H2S) gas (pure H2S and H2S + water vapor) resulted in a Ag2S layer within minutes of exposure at room temperature. The presence of water vapor increases the reaction rate considerably.

I would like to clarify that silver in it bulk form is not readily reactive with O2 but in its atomic form it is very reactive. For example in silver nanoparticles, a large portion of the silver atoms at the surface of the nanoparticle are not fully coordinated (they have atomic-like properties) and are very reactive. This is the reason that silver nanoparticles are widely used as catalysts. It is possible that a poor silver film with a lot of defects at the surface could have silver atoms that are not fully coordinated and could react with O2 at these defect sites.

audiotemp said:
Also, statements made about semiconductors and bandgaps are also largely misplaced here because "the bandgap" does a lot of funny things in a thin film or at the interface with another material---enough that the bulk material bandgap doesn't, by itself, explain much of anything at the surface.
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The statement regarding Ag2S being a semiconductor is only to dispel the myth that the surface remains as conductive after the formation of the Ag2S layer. This is obvious when analyzing the silver surface after exposure to H2S gas and observing the formation of a layer of Ag2S on the silver surface. Analysis of the Ag2S layer with Photoelectron Spectroscopy and Low Energy Inverse Photoemission Spectroscopy, illustrates that the surface electronic properties change from a conductor to a semiconductor and the surface becomes less conductive.
 
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I'm way too lazy to do this, but... tin/bismuth/silver solder is readily available from Digikey. Not even terribly expensive. It has a low melting point and relatively terrible conductivity. It's also very brittle. OTOH, it can make nice joints and doesn't thermally stress components. It meets RoHS. It would be interesting to build some audio stuff and see if it sounds any different. If it didn't, that would negate a lot of argument over solder joints and types.
 
ConradH said:
I'm way too lazy to do this, but... tin/bismuth/silver solder is readily available from Digikey. Not even terribly expensive. It has a low melting point and relatively terrible conductivity. It's also very brittle. OTOH, it can make nice joints and doesn't thermally stress components. It meets RoHS. It would be interesting to build some audio stuff and see if it sounds any different. If it didn't, that would negate a lot of argument over solder joints and types.
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I have my opinion on this. ;)
 
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