"ScottW" wrote in message
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Robert Morein wrote:
"ScottW" wrote in message
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Robert Morein wrote:
"Sander deWaal" wrote in message
...
"Robert Morein" said:

If it's Arny Krueger's ABX box, it was constructed with
inadequate
relays.
IME, this can easily mask subtle differences between amplifiers.
Even
if
it
was not constructed by Krueger, that does not make it immune from
criticism.


Dunno about Arny's soldering skills, but the relays in my preamp
(gold-plated gasfilled OMRON types) sure as hell don't add or
subtract
anything in the signal.

Now, if one's to ABX gear with a 4066, that's another matter :-)

The inadequate size of the relays was noted in a Stereophile article
that
predated the current acrimony.

I built a remote control AB box using garden variety P&B relays with
plated
palladium/oxide contacts.

Palladium doesn't oxidize, thats why its used.. however it's
conductivity is poor so it isn't used in high current (5 A) apps.

http://relays.tycoelectronics.com/app_pdfs/13c3236.pdf

Even with brand new relays, there was clearly a
degrading effect. All those days of wasted fabrication!

From the change in the sound, I think there was something nonlinear
going
on, ala rectification.

I'm sure Arny used better relays, but the Stereophile comment
remains,
specifically challenging the power handling capacity.

You mean current handling. If the relay is dissipating power, you
f'd
up.
Relays dont care if you're delivering 10V and 1A but they sure might
care if your delivering 1V and 10A.

ScottW

No, I don't mean current handling.

Then Stereophile meant current handling and you repeated their error.

ScottW

Probably.
Ever since the cat's whisker detector, it has been known that mechanical
junctions have effects.
When the purpose of a mechanical junction is to supply power, or a digital
signal, methods of contact design, such as bifurcation, have been
practically successful.
But "dry" contacts, that must pass a delicate analog signal that dips to
millivolts near the crossover, are, like audio, an electronic backwater. Is
gold-on-gold with sufficiently low resistance sufficient? Silver oxide is
quoted as having excellent conductivity, but what about junction effects
that would not be noticed in power applications?
And what about changes in the mechanical interface, caused by local heating,
that occur on the time scale of the signal? This means that for me, cannot
be accepted without examination for comparator construction.