Digital volume control question....
 

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

--
Pearce Consulting
http://www.pearce.uk.com

Digital volume control question....
 

"Keith G" wrote in message

"Jim Lesurf" wrote in message
...
In article ,
Keith G wrote:

"Serge Auckland" wrote
in message
...
Keith G wrote:

I think the nub of your response is that people
"believe" things sound different. It's the same mental
process that have people believing in God, the Tooth
Fairy and Santa Claus. They don't have a shred of
objective evidence that things sound different, just
their faith.


Let's say they *perceive* things to sound different.

OTOH lets *not* say they "perceive" things since that
then opens up all the
ambiguities and misundestandings where people use the
word 'perceive' in different ways and argue at
cross-purposes... :-)

What word would you prefer then? They have to perceive to
believe, do they not?

A little apparently much-needed Psychology 101:

There are two kinds of perceptions:

Illusory or unreliable
Veridical or reliable

Audiophiles are well-known for confusing the two.

Digital volume control question....
 

"Nick Gorham" wrote in message

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 stupid problem associated with doing a stupid thing.

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.

But, it won't appear across the capacitor's dielectric.

Digital volume control question....
 

On Wed, 24 May 2006 14:29:02 +0100, Nick Gorham
wrote:

Don Pearce wrote:



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


Ahh, I see the point you are making, as you say, the other side would
need to grounded for the voltage to be across the cap.

Well, I am happy to admit when I am wrong.

No prob.

d

--
Pearce Consulting
http://www.pearce.uk.com

Digital volume control question....
 

Don Pearce wrote:



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


Ahh, I see the point you are making, as you say, the other side would
need to grounded for the voltage to be across the cap.

Well, I am happy to admit when I am wrong.

--
Nick

Digital volume control question....
 

"Arny Krueger" wrote in message
...
"Keith G" wrote in message

"Jim Lesurf" wrote in message
...
In article ,
Keith G wrote:

"Serge Auckland" wrote
in message
...
Keith G wrote:

I think the nub of your response is that people
"believe" things sound different. It's the same mental
process that have people believing in God, the Tooth
Fairy and Santa Claus. They don't have a shred of
objective evidence that things sound different, just
their faith.


Let's say they *perceive* things to sound different.

OTOH lets *not* say they "perceive" things since that
then opens up all the
ambiguities and misundestandings where people use the
word 'perceive' in different ways and argue at
cross-purposes... :-)

What word would you prefer then? They have to perceive to
believe, do they not?

A little apparently much-needed Psychology 101:

There are two kinds of perceptions:



Actually, four....

http://dictionary.reference.com/search?q=perception


Illusory or unreliable
Veridical or reliable


....none of them based on factual accuracy, as I perceive it....

:-)

Digital volume control question....
 

"Keith G" wrote in message

"Arny Krueger" wrote in message
...
"Keith G" wrote in message

"Jim Lesurf" wrote in message
...
In article
, Keith G
wrote:
"Serge Auckland" wrote
in message
...
Keith G wrote:

I think the nub of your response is that people
"believe" things sound different. It's the same
mental process that have people believing in God,
the Tooth Fairy and Santa Claus. They don't have a
shred of objective evidence that things sound
different, just their faith.


Let's say they *perceive* things to sound different.

OTOH lets *not* say they "perceive" things since that
then opens up all the
ambiguities and misundestandings where people use the
word 'perceive' in different ways and argue at
cross-purposes... :-)

What word would you prefer then? They have to perceive
to believe, do they not?

A little apparently much-needed Psychology 101:

There are two kinds of perceptions:

Illusory or unreliable
Veridical or reliable


Actually, four....

http://dictionary.reference.com/search?q=perception

Different issues.


...none of them based on factual accuracy, as I perceive
it....

:-)

Obviously true for you, Keith.

Some of the rest of us are mostly interested in veridical perceptions.
Illusions are fun, but that's about it for them.

Digital volume control question....
 

In article , Keith G
wrote:

"Jim Lesurf" wrote in message
...
In article , Keith G
wrote:

"Serge Auckland" wrote in message
...
Keith G wrote:

I think the nub of your response is that people "believe" things
sound different. It's the same mental process that have people
believing in God, the Tooth Fairy and Santa Claus. They don't have
a shred of objective evidence that things sound different, just
their faith.


Let's say they *perceive* things to sound different.

OTOH lets *not* say they "perceive" things since that then opens up
all the ambiguities and misundestandings where people use the word
'perceive' in different ways and argue at cross-purposes... :-)


What word would you prefer then? They have to perceive to believe, do
they not?

Depends what you wish to describe. If the situation is that there is no
clear or reliable evidence either way that the physical soundfields differ
in a way that could be audible, then a term like 'believe' seems OK as it
allows that the idea may or may not be well-founded in physical reality.
However this is a difficult area for the reason I outline below.

The problem is that 'perception' can be taken by some people to mean
"something which I can perceive/sense' hence implying that a perceived
difference *must* be based on a physically real one being sensed. Whereas
others may assume it means the 'impression' people have even if it due to
imagination, error, wishful thinking, or some other factor completely
different to that being discussed.

If the evidence gives reason to think the idea *is* simply misguided or
incorrect, them something like 'impression' might be better.

Depends on the details of the case.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Digital volume control question....
 

In article , Nick Gorham
wrote:
Jim Lesurf wrote:
In article , Nick Gorham
wrote:



"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.

I agree. Hence the question I asked at the end of the posting you have
quoted, but which you snipped. :-)


However from the discussion which followed I now think you misunderstood
what I was saying. Hence can we now take it that in practice we can
regard it as unlikely that any amplifiers *do* require their signal
capacitors to endure such large ac voltages?

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Digital volume control question....
 

In article , 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.

I was trying to provide information relating to the "I see objective
measurements that indicate that there should be a difference" part, not
the "sound" as such.

Ah. So you point was that types of capacitors may well differ in ways that
we have no particular reason to think have any effect on the audible
results when they are used appropriately in audio equipment? :-)

Serge: Was what you wrote above intended to be dealing with that point? I
read the above to mean "objective measurements", etc, that support the
argument that they would lead to a "different" sound in use...

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html