Arny Krueger wrote:
"Rob" wrote in message

Arny Krueger wrote:

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

Wrong.

Google finds upwards of 100,000 references to this phrase.


The phrase? More like 15,400. 'Marxist reality' get over 15 million
references. Context is all :-)

Let your Objective World of Audio go!

My world? it's an objectivist/subjectivist blend.

I think you lean rather heavily in favour of objects.

Rob

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

Arny Krueger wrote:

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

Google finds upwards of 100,000 references to this phrase.



Wrong.

15,300 actually.....

;-)

(Google Tip: Use "----" to restrict the results to those containing the
*exact phrase* only...)


Ha - it's gone up since you checked - it's all Arnie's fault!


Let your Objective World of Audio go!
My world? it's an objectivist/subjectivist blend.


Of course - what else could it be?


It's the healthy balance that makes the difference :-)

Rob

On 2006-05-25, Jim Lesurf wrote:
In article , John Phillips
wrote:

I noted, BTW, that the integrator used in the test setup employs another
capacitor which must be assumed to be linear for the test to work. ...

... my reaction was to feel the above didn't matter once we'd
established that the actual conditions of the test were of dubious
relevance. No point in worrying about details if the test situation was
orders of magnitude different to those which are of actual interest to us.

I agree that in the case of a coupling capacitor the ideal design drops
a negligible *signal* voltage across it. The article and its test are
of dubious relevance there.

However, consider the case of a single-pole RC filter. In the pass-band
substantially the full signal voltage appears across the capacitor.

So I suspect there can be relevance in measuring capacitor non-linearity
with significant AC signal level. I am not sure if in a valve amplifier
this may happen inter-stage with the sort of signal level the article
uses for the test, though. As an input RC filter the signal voltage
across the capacitor will be somewhat smaller than that used.

--
John Phillips

On 26 May 2006 10:22:30 GMT, John Phillips
wrote:

On 2006-05-25, Jim Lesurf wrote:
In article , John Phillips
wrote:

I noted, BTW, that the integrator used in the test setup employs another
capacitor which must be assumed to be linear for the test to work. ...

... my reaction was to feel the above didn't matter once we'd
established that the actual conditions of the test were of dubious
relevance. No point in worrying about details if the test situation was
orders of magnitude different to those which are of actual interest to us.

I agree that in the case of a coupling capacitor the ideal design drops
a negligible *signal* voltage across it. The article and its test are
of dubious relevance there.

However, consider the case of a single-pole RC filter. In the pass-band
substantially the full signal voltage appears across the capacitor.

So I suspect there can be relevance in measuring capacitor non-linearity
with significant AC signal level. I am not sure if in a valve amplifier
this may happen inter-stage with the sort of signal level the article
uses for the test, though. As an input RC filter the signal voltage
across the capacitor will be somewhat smaller than that used.

But do remember that in a low pass filter, the opposite situation
applies. In the passband, the capacitor looks to all intents and
purposes like and open circuit, so it still doesn't matter what the
dielectric is doing. Now, at the top of the passband, where the
capacitor is starting to matter, some of this might happen, but at
that point the filtering action is going to attenuate any products. Of
course they will probably be outside the audio band as well.

d

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

On 2006-05-25, Jim Lesurf wrote:
In article , John Phillips
wrote:
Also I would point out that I believe the hysteresis observed is not,
per se, a linearity issue. I think hysteresis will arise from parasitic
series inductance or resistance, and also from dielectric absorption.
These may well be defects from ideality but in spite of the article's
title are not capacitor linearity issues.

Indeed. And may also in practice be orders of magnitude less significant
than implied by the curves when we move to a more relevant set of
conditions of use.

This is certainly true of the linear effects of dielectric absorption
(DA). I see audio cable and capacitor sales literature pronouncing
that energy storage in DA and its later release "smears" transients.
Well, if it's a linear effect [1] it does cause ripples in the frequency
response so it may do what's stated. However the magnitude of the effect,
when I plug in some real numbers for DA, is several orders of magnitude
below what should be audible [2].

If there are audible differences between capacitors there's no evidence
yet that DA is the (or even a) culprit.

[1] The DA models are all linear, but I have searched occasionally
for any evidence of non-linear effects arising from DA. These may
be audible if big enough. However the one mention I found was for
semiconductor-insulator (e.g. Silicon - Silicon Nitride) boundaries but
it provided no details and no references to follow up.

[2] Based on reported levels of audibility arising from frequency response
differences. However, recently I have become interested in the human
sensitivity to audio arrival time differences. Detectable differences
as reported seem to be smaller than implied by 20 kHz hearing limits.
I am looking out for more evidence on this.

--
John Phillips

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



OK, this is difficult.

I'd agree. So bear in mind I'm not quibbling for the sake of trying to
nit-pick with you or find fault. I am just trying to 'raise awarness' as
we
have to say these days that these things can be hard to discuss since
people may use the same words or phrases in critically different ways.
With
that said, I'll continue... :-)


OK, you don't need to qualify your responses to me, but see below...



Put simply:

If someone jacks his kit up on cubes of coconut husk or whatever (don't
dismiss that as impossible, btw) and tells me it has *improved* the
sound, I say he perceives a difference (real or imagined) and therefore
believes there's an improvement. OTOH, in the time-honoured ukra way
(*unheard*) I would not believe it - unless I heard the kit before and
after and could perceive a difference myself?

Does that help?

Not sure. :-)

The problem is that some people might react to the statement that he
"perceives a difference" as meaning that he physically sensed a difference


Yes, that's how I would see it. (Perceive it? ;-)


- e.g if we could have attached some measurement kit to his ears it would
have produced a changed output. Others might take it to mean that his
impression was that there was a difference.


OK. This is where it hangs. If someone says he 'perceives' (can see,
discern, determine, tell &c.) a difference, then I take it that he is under
the impression there is a difference - effectively the same thing, IOW...


When you say "could perceive a difference myself" we have a similar
difficulty. I'd say that if a set of tests were done which could reliably
establish that - by sound alone - you/he repeatedly showed you could tell
the difference, then you did 'sense' or 'detect' a difference, but if such
tests showed no such result then you have 'believed' it.


Sure. The fact that someone says he perceives a difference in no way means
there is one. The proof of that pudding is in testing, as you say. Until
disproved, his belief is based on his apparent perception.



FWIW I'd agree that even 'belived' is difficult in such situations. Hence
my preference is to try and use language that is more based on
evidence-linked statments like those above. The snag is that these can get
long-winded, and may still be problematic....


OK, see below....



It is just that my impression is that I've seen many arguments which were
simply based on those involved not all using the same meaning for terms
like 'perceive'. Hence they argued at cross purposes, or in a way that was
futile. My interest then tends to be to ask what the nature and detail of
the evidence may be.


OK, see he

One of the reasons I am glad English (in its various forms) is becoming the
global language* (despite a tendancy toward homophony - which many
foreigners find difficult to master, apparently) is not so much because of
the exact precision possible with it (especially in the written form) or its
brevity compared with many other languages (record sleeves and multilingual
instruction manuals for example) but because of the high degree of
flexibility (and adaptability) it possesses. In the spoken form, 'fuzzy
English' is very often capable of transferring a clear and precise meaning
while appearing to sound like gibberish, if you catch my drift...?? ;-)

Thus I could flag down passing motorists (say) and get them to listen to a
couple of bits of kit and would be able to ask them if they could determine,
perceive, tell, see, hear, discern &c. any 'difference' between them or I
could ask if they could 'split them', 'pick one', 'rate them', grade them'
and so it goes on - all with much the same outcome. (FWIW, I have found that
if I ever phrased an instruction or question with precisely correct wording
it was invariably queried or I was asked to repeat it!!)

Now, you either get that or you don't!! (If you don't dig it, it's no skin
off my nose!! ;-)

While you are not wrong *per se* to persue a high degree of accuracy in the
words used by people to say that they can [any of the above] differences
between bits of kit, or before and after tweaks/substitutions I do think the
context in which the phrases are used should be be borne in mind.
Understanding the concept is more important than understanding the question
(sign language?) and provided that the word used/misused is generally
understood by all others concerned, I have no problem with the use of the
word 'perceive' in the context we have discussed here - for instance, I'm
often seeing the words 'religion/faith/belief' being confused and misused
here, but it does not matter because I can usually per***** the concept that
is being referenced!! ;-)


*The reason French was never going to make it as the true, long-term global
language (despite being favoured by the Royal Courts in Europe at one time
and being fairly, if thinly, widespread) is because a) There are official
movements to rigidly control the language and the use/meaning of words (from
what I gathered from a proggie on the box recently) and b) French women
don't shave their armpits. The world at large doesn't view either of these
practices favourably....

(Proggie on the box? - Woss 'e me mean, the telly or the wireless? ;-)

In article , John Phillips
wrote:
[snip]

I agree that in the case of a coupling capacitor the ideal design drops
a negligible *signal* voltage across it. The article and its test are
of dubious relevance there.

However, consider the case of a single-pole RC filter. In the pass-band
substantially the full signal voltage appears across the capacitor.

Yes. Three cases had occurred to me after continuing to think about this:

1) Something like a Baxandall arrangement when the tone was set well away
from 'flat' sic. Here quite noticable ac levels could appear across some
of the caps without being cancelled in effect by that on another cap.
Although in most control amps in my experience this would be or the order
of a volt or less - far less than the 70v RMs used in the page we were
discussing.

2) 'Miller' shunt caps between the base and collector (or equivalents for
other types of device) as used in some designs across the output devices.
Here the voltage swings seen by the caps could be almost 'rail to rail'.
Hence they could easily be 70v RMS in some cases. However the cap values
would normally be small, and within a loop, and shunted by the device
(whose own capacitance may be far more nonlinear!) I doubt anyone would be
using an electrolytic for this! I've never noticed such a design giving
noticable distortion from this, but it is something I would avoid applying
anyway, so have not investigated it.

3) The C of the series RC of a 'Zobel'. As (2) this could see rail-to-rail
ac. However this should be gripped fairly tightly by the output impedance
of the amp, so although it may ask the power amp to deliver a nonlinear
current through the Zobel, it should have little effect on the output as
seen by the loudspeakers.

There are other examples like the C of an input LP RC roll-off filter to
prevent an amp being driven into slewing. However in most cases like this
I'd expect the level of the ac to be well below 70v RMS.


So I suspect there can be relevance in measuring capacitor non-linearity
with significant AC signal level.

Yes. That was why I was asking in an earlier posting for some examples to
see if there were any. I haven't really encountered any that seem
comparable and relevant, but for all I know they may exist, e.g. in some
valve designs. The above all occurred to me as 'in principle' areas where
an effect might show, but in each case I've never seen/heard anything
significant as a result in practice.

I am not sure if in a valve amplifier this may happen inter-stage with
the sort of signal level the article uses for the test, though. As an
input RC filter the signal voltage across the capacitor will be somewhat
smaller than that used.

Yes. In a twin-rail amp using SS devices I tend to expect caps to only
appear in a few places like an input dc block, or the block on the feedback
to reduce the dc gain. In these places the ac levels seen in normal use
should be generally relatively tiny.

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

In article , John Phillips
wrote:

[1] The DA models are all linear, but I have searched occasionally for
any evidence of non-linear effects arising from DA. These may be
audible if big enough. However the one mention I found was for
semiconductor-insulator (e.g. Silicon - Silicon Nitride) boundaries but
it provided no details and no references to follow up.

I'm familiar with nonlinear dielectric effects in terms of using bulk
material effects for things like frequency conversion in optonics devices
or Bragg cells. But the actual field levels and d/dt levels in such
applications tends to be high in order to get useful levels of
nonlinearity, and the materials chosen specifically for their nonlinear
properties.

I recall a colleague who used to build non-linear pulse lines for pulse
compression/peaking. He found some HV caps by a given maker that had truly
'awful' levels of dielectric nonlinearity when hit with multi-kV pulses.
His comment was that their slogan should be, "Don't take the **** out of
our capacitors: it spoils their usefulness!" ;- The point being that
most well-made caps simply didn't do this to such a level.


[2] Based on reported levels of audibility arising from frequency
response differences. However, recently I have become interested in the
human sensitivity to audio arrival time differences. Detectable
differences as reported seem to be smaller than implied by 20 kHz
hearing limits. I am looking out for more evidence on this.

I'd also be interested in that. However it does not surprise me. The
sensors for a given frequency band may have response interactions whose
timings have nothing to do with the physical limitation of the ability of
the upper HF sensors to detect 20kHz. The processes are distinct, I assume.

FWIW I have a recollection of reading about the above somewhere. I think
there may be a reference to it in one of the papers I refer to in the
articles on hearing on my Audio Misc pages. Can't recall, though, as I did
that some years ago...

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

In article , Keith G
wrote:

"Jim Lesurf" wrote in message
...
[snip]


OK. This is where it hangs. If someone says he 'perceives' (can see,
discern, determine, tell &c.) a difference, then I take it that he is
under the impression there is a difference - effectively the same
thing, IOW...

[snip]


Sure. The fact that someone says he perceives a difference in no way
means there is one. The proof of that pudding is in testing, as you
say. Until disproved, his belief is based on his apparent perception.

[snip]

While you are not wrong *per se* to persue a high degree of accuracy in
the words used by people to say that they can [any of the above]
differences between bits of kit, or before and after
tweaks/substitutions I do think the context in which the phrases are
used should be be borne in mind.

I agree. (And with what I snipped above.)

Understanding the concept is more important than understanding the
question (sign language?) and provided that the word used/misused is
generally understood by all others concerned, I have no problem with the
use of the word 'perceive' in the context we have discussed here - for
instance,

Overall, yes, that seems fine to me. However the snag is that some people
may have not followed the context. What you said above makes sense to me,
but we have the situation where we may have to re-explain this context to
avoid confusions. Plus my impression that the use of 'perceive' in
situations like this has more than once led to arguments at cross-purposes.
Indeed, once people start to get 'emotional' about this they may become
unwilling to accept this has happened once the fuse has been lit. :-)

Hence my reaction to pop up a 'warning flag' that this can occur. I'd agree
though that my wish for more 'precise' language can, itself, get in the way
of some discussions. With 'fuzzy' real languages like English you can't
always get clarity without some fuss first...

I may be more sensitive than usual to this as I am currently reading the
'answers' perhaps sic in exam papers. Noting how some people seem to
misunderstand what most have found perfectly clear!

I suppose that the reality is that whatever words or explanations you use,
the diversity of human minds, and the fuzzness of language, means that some
will not understand what was actually meant. All you can do then is to try
alternative approaches until sufficient pennies have dropped. :-)

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

On 2006-05-26, Don Pearce wrote:
On 26 May 2006 10:22:30 GMT, John Phillips
wrote:

On 2006-05-25, Jim Lesurf wrote:
In article , John Phillips
wrote:

I noted, BTW, that the integrator used in the test setup employs another
capacitor which must be assumed to be linear for the test to work. ...

... my reaction was to feel the above didn't matter once we'd
established that the actual conditions of the test were of dubious
relevance. No point in worrying about details if the test situation was
orders of magnitude different to those which are of actual interest to us.

I agree that in the case of a coupling capacitor the ideal design drops
a negligible *signal* voltage across it. The article and its test are
of dubious relevance there.

However, consider the case of a single-pole RC filter. In the pass-band
substantially the full signal voltage appears across the capacitor.

But do remember that in a low pass filter, the opposite situation
applies. In the passband, the capacitor looks to all intents and
purposes like and open circuit, so it still doesn't matter what the
dielectric is doing. Now, at the top of the passband, where the
capacitor is starting to matter, some of this might happen, but at
that point the filtering action is going to attenuate any products. Of
course they will probably be outside the audio band as well.

Good point. However even if the current in the capacitor is low, the
RC product and therefore the -3 dB point may be modulating with the
voltage amplitude. I will have to think if this effect is negligible.

--
John Phillips