On Wed, 24 May 2006 13:46:17 +0100, Nick Gorham
wrote:

Don Pearce wrote:
On Wed, 24 May 2006 13:10:40 +0100, Nick Gorham
wrote:


Jim Lesurf wrote:

In article , Nick Gorham
wrote:


Serge Auckland wrote:


I'll accept that pots, capacitors, resistors etc. sound different when
I see objective measurements that indicate that there should be a
difference and the results of properly conducted double-blind tests
that show that there was a difference.



http://members.aol.com/sbench102/caps.html


I've only had a quick look at the above, and the pages linked to it.
However they don't seem to me to be particularly relevant to the question
of capacitors normally having a 'sound' in normal use.

The first thing that struck me about the page was the following which I
quote:

"The signal level was held constant at about 70 volts RMS at 600 Hz across
the capacitors. (for about 26mA signal current). This is probably more
than you would normally expect,..."

My reaction to the last phrase was,,, "indeed!" :-)

I can't recall ever building or using an audio amplifier or tuner that had
anything like this large an *audio voltage* across any of the *capacitors*.
Note the above is 70v RMS *between the capacitor terminals*. i.e. not just
an input where most of the voltage appears elsewhere. I have certainly
built (and use!) amps which have audio voltages this large inside them, but
not between the terminals of any of the signal capacitors.


The fact you may not have built such a thing, doesn't mean they do not
exist. Using a coupling cap between a driver and the grid of a 211 would
have this sort of voltage, as will most driver valves. a 845 would have
a much higher voltage.

A even more extreme example could be a cap used in a parallel feed
output stage, that could have 1kv or more across it.


You appear to be confusing DC conditions with signal voltage.

d


Maybe, ok, in both cases there will be a DC voltage, but there will also
be the signal voltage of the magnitude we are talking about.

Are you sure? In normal use the signal across a capacitor is very
close to zero. The scenario he has presented is one which simply
doesn't exist in an audio circuit.

Are you perhaps confusing signal level at a point in the circuit with
potential difference across the coupling cap at that point?

d

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