how good are class D amplifiers?
 

In article , Serge Auckland
wrote:


"Jim Lesurf" wrote in message
...


Well, I've used both 'traditional' THD+N kit that works by nulling or
filtering the test sinusoid, and a specan/generator that autofinds the
harmonics and works out THD. The second didn't seem at all 'tedious'
to use as it automated the process. It was also faster than the old
distortion kits I used to use that took some seconds to null down for
low distortion.


When I was designing audio equipment, I never had the luxury of an
autofinder, the one I used was a Marconi Instruments meter which in
effects was a highly selective filter and meter, and to use it, one
found each harmnic individually, measured its level, then worked out
the THD by algebra. As I said, tedious in the extreme.

Jings! Yes, I think I'd have thrown it out the window. :-)

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

how good are class D amplifiers?
 

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


"Jim Lesurf" wrote in message
...


Well, I've used both 'traditional' THD+N kit that works by nulling or
filtering the test sinusoid, and a specan/generator that autofinds the
harmonics and works out THD. The second didn't seem at all 'tedious'
to use as it automated the process. It was also faster than the old
distortion kits I used to use that took some seconds to null down for
low distortion.


When I was designing audio equipment, I never had the luxury of an
autofinder, the one I used was a Marconi Instruments meter which in
effects was a highly selective filter and meter, and to use it, one
found each harmnic individually, measured its level, then worked out
the THD by algebra. As I said, tedious in the extreme.

Jings! Yes, I think I'd have thrown it out the window. :-)

Slainte,

Jim


It didn't last long! I bought the Radford combination as soon as I could.
However, it did have its uses in development in identifying individual
harmonics, but I always worked on the principle that it the total of all the
harmonics and noise was comfortably below 0.1%, and in the circuits I was
designing at the time, it was around 0.01%, then what the individual level
of any harmonic was mattered not a jot.

S.
--
http://audiopages.googlepages.com

how good are class D amplifiers?
 

"Don Pearce" wrote in message

On Tue, 22 May 2007 16:12:32 +0100, Jim Lesurf
wrote:

In article , Don Pearce
wrote:
On Tue, 22 May 2007 09:19:09 +0100, "Serge Auckland"
wrote:

Indeed, and in my previous post of the criteria, it
was stated that THD should be measured at all
frequencies 20-20k and refers to all powers and all
loads for which the amplifier was designed. In
practice, the measurements are actually THD+N as this
is what distortion meters actually measure. Of course
the use of a harmonic analyser for distortion
measurement won't pick up the +N component, but as a
practicing engineer, I found the use of such an
instrument to be tedious in the extreme, and
unnecessary when an overall THD+N figure was so easily
achieved.

S.


The problem becomes more complex when you use an FFT
analyser, as I suspect most are these days. You then
need to consider the number of points in the FFT, and
the way they display noise. Discrete signals are easy -
whatever you do with the FFT, they look the same size,
but the "+noise" bit will change with the number of
points.

Erm. It should be the total noise in the audio range.
This means that however many bins it was divided into
becomes irrelevant as they are then summed. Although I'd
agree that a small fraction of the noise will be in the
input signal bin and would be 'lost'.

In recent years I've tended to use a Stanford
Instruments unit that combines a test waveform generator
and an FFT specan, and 'automates' the process as you
wish. The trick, of course, is to know what process to
specifiy and to understand how to interpret the results
- especially when the spectrum on the screen isn't
simple. :-)

The noise floor problem is more significant when reviews
simply display the floor value in terms of the per-bin
level without having any clue what resolution bandwidth
they are using. In those cases your comment does indeed
apply, and makes the floors shown in some magazines
worthless. Having tried discuss this with one or two
people I fear that this issue whooshes over the head of
some of them. Although there are others who clearly
understand it, but don't use such meaningless plots.


Exactly - although the maths is very easy - just add 10
log (audio bandwidth / (bin bandwidth * windowing ratio))
to the noise level in dB. But as you say, this appears to
be beyond most people.

The problem is that you must do this to the noise, but
not to the discrete signals, and it can get tricky
sometimes separating the one from the other.

Are there many distortion analysers any more that
simply null the fundamental and display the sum of the
rest?

Dunno. The last one I used a lot was the Sound
Technology 1000A about two decades ago. This was very
nice, but took a few seconds to settle into a null, etc,
whenever you altered anything. Worked down to about
0.002% though, IIRC. I think that part of the delay was
for the light bulb in the oscillator to settle when you
changed frequency. ;-

I still have a couple of those tiny bead thermistors in
vacuum tubes that are really good at stabilizing Wien
Bridge oscillators. Better than light bulbs, I think.

I've experimented with all of the common means for stabalizing the output of
Wien Bridge and State Variable oscillators.

Light bulbs, thermistors, and CdS cell approaches all work, but suffer
because they are limited by the response time of their sensitive elements.
In the case of the light bulbs and the thermistors, the response time is set
by the thermal properties of the device.

CdS cells respond far faster. You end up slowing their response down with
electrical circuits, but you can control the response of the electrical
circuit with a lot more flexibility than having to accept the "pig in a
poke" response time characteristics of the light bulb or thermistor. This
allows you to tailor the settling time of the oscillator more ideally.

The other three common means of controlling the response time of the
oscillator are a FET, a VCA, and a analog multiplier, which of course the
VCA is a special case of.

In the end, the distortion of an analog oscillator is dependent on the
sharpness of the frequency selectivity of the filter that is used to make
the oscillator, and the linearity of the means used to control its output.
A state variable filter and a VCA or analog multiplier seemed to be the best
alternatives.

However, the most practical means for producing a sine wave is a table of
numbers that describe a sine wave, read out of storage and convtered to a
signal through a DAC. Now that we have inexpensive ADCs with upwards of 130
dB dynamic range, it is really hard for analog generators to compete.

how good are class D amplifiers?
 

Jim Lesurf wrote:
In article , Rob
wrote:

I simply don't get this. I've been using 5 SS amps of late (Quad 405,
Rose power amp, Cambridge AV, Behringer A500, and that within a Pure
mini system), as well as others on and off over the years, and I feel
each has 'a sound of its own'.

The problems with the above are as follows:

1) Many people have formed such views as a result of simply using various
amps. I've also repeatedly changed from one amp to another and thought it
made a difference. But then later on I changed my mind when I listened
again. The problem here is partly one of control - e.g. not level matching
- and partly that human hearing varies with time, etc. So each time you
listen your ears/brain may simply respond slightly differently.

2) Yet when people do level-matched comparisons and avoid obvious snags
like clipping *and* have only the sound to rely upon, the result is often
that they can't reliably tell one amp from another.

FWIW A number of tests have also shown that people tend to hear
'differences' even when the same system is used in the same way.

The above does not mean that all amps produce the same results. Nor does it
mean that they all produce different results. But it means that people form
views that may simply be mistaken, and often fail to do comparisons which
help prevent well-known mistakes from occurring.


Yes, I agree. DBT is not a trivial thing though, and surprisingly (to
me) there doesn't seem to have been many rigorous tests to underpin the
'little if any difference' thesis.

how good are class D amplifiers?
 

Don Pearce wrote:
On Tue, 22 May 2007 21:10:47 +0100, Rob
wrote:

Don Pearce wrote:
On Tue, 22 May 2007 20:45:32 +0100, Rob
wrote:

Don Pearce wrote:
On Tue, 22 May 2007 19:11:40 +0100, Rob
wrote:

Dave Plowman (News) wrote:
In article ,
Keith G wrote:
Yep, why waste time *listening* to a bit of kit when you could just
stick a meter on it....??
Indeed. A doctor with a stethoscope beats a MRI scan every time.

Why look at (with your eyes?!) a picture when you can digitally analyse
it? Why go for a walk when there's perfectly good GIS profile of your
route? Why listen to music when ... :-)
But the measurements aren't a substitute for listening - they are
designed to make sure your equipment is not going to mar your
pleasure.
It strikes me that measurement fixation *does* affect listening. For
some, a measured anomaly would take away some of the listening pleasure
even if it was inaudible.

Would it take you that way? Not me, that is for sure. ANd by now I
have a very good idea of what is audible and what is not. Add to that
the fact that it is trivially easy these days to make equipment with
errors many orders of magnitude below audibility, and the situation is
really pretty relaxed.

Well, yes it has affected my listening pleasure for a time. Maybe I'm alone.

The fact that audio design engineers have measured every aspect of
your favourite amp, and slaved assiduously to make sure that it is as
good as it can possibly be has adversely affected your listening
pleasure? That actually sounds a little ungrateful to me.


No. If someone tells me a measurement is awry, it can affect my
enjoyment. I've had all manner of techie types tell me that
such-and-such is off-centre, and while it's highly unlikely to make any
real world difference I think about it. That is until I forget about it :-)

But I appreciate that, fortunately, everyone is not like me.

A bit like making sure the glass on the front of your
picture is nice and clear... Of course there are those who like
cloudy glass with a coloured tint, but not those who want to see the
whole of the picture.

d

Some people like their glass 'distorted' so they can see the bigger
picture.
No, you never see the bigger picture through distorted glass. You
always see less - no choice there, I'm afraid. And of course you have
not the slightest chance of seeing the details.

Try telling my wing mirrors :-)

You have distorting wing mirrors? I don't count gain or attenuation,
of course ;-) Objects seen in this mirror are fatter than they look,
heh?



Ah, lost me again! I'm pretty sure the wing mirrors on my car give me a
wider field of view than a flat mirror might - or at least I was.

how good are class D amplifiers?
 

Jim Lesurf wrote:
In article , Rob
wrote:
Don Pearce wrote:
On Tue, 22 May 2007 19:11:40 +0100, Rob
wrote:

But the measurements aren't a substitute for listening - they are
designed to make sure your equipment is not going to mar your
pleasure.

It strikes me that measurement fixation *does* affect listening.

However not all interest in using measurements and understanding their
meanings would be a 'fixation'.

No I know, just a bit of fun.


For some, a measured anomaly would take away some of the listening
pleasure even if it was inaudible.

So far as I know, there is no law requiring you to read any of the specs or
measurements for any equipment you buy and use. :-)


Surprised it's not in this group's charter :-)

However if you actually *understand* the measurements you can easily make
up your mind if any 'anomaly' matters. Indeed, reading and understanding
'measurements' might save you from wasting time money buying a lemon.

A bit like making sure the glass on the front of your
picture is nice and clear... Of course there are those who like
cloudy glass with a coloured tint, but not those who want to see the
whole of the picture.

d

Some people like their glass 'distorted' so they can see the bigger
picture.

Indeed. However it can be useful for them and others to know the cause and
effect involved. This would then give them info useful when they and others
decide what other 'glass' to choose for specific purposes, or to get
results they would feel are a further improvement.

Interestingly, your analogy also implicitly assumes the 'people' know
that the result *is* being 'distorted' by the 'glass', rather than
assuming that what they see is what they'd get if the glass were absent
and their view was direct. The snag in audio is that many people may
have no such awareness, and indeed, no chance to do the equivalent
of seeing the view directly.

Another snag is that in the case of audio there may be many thousands
of different 'pictures' to 'view' and you might like some 'distorted'
by a specific 'glass', but other 'distorted' in other ways. So perhaps
this is simply another attempt at analogy that falls apart once you
try to use it at more that a trivial level. ;-


May well. My point was to emphasise that 'distortion' is a concept, and
not a single or pejorative (in the context of valves discussions say) fact.

More generally...

The problem with wilful ignorance is that it gives you no guide if you ever
need to change anything. Similarly, it is no help to anyone else who is
interested in the results you got. Nor does it tell anyone if what is
claimed is for the reasons claimed, or is even real rather than delusional.

I suppose I am old-fashioned. I prefer education and understanding to
ignorance, and I prefer views based on reliable evidence. Indeed, I seem to
get a lot of enjoyment and satisfaction out of learning, understanding,
etc. My experience thus far is that this has helped me to design/choose/use
equipment to allow me to enjoy recorded and broadcast music. I have also
repeatedly found that ideas presented in claims by people have no
foundations, so would probably have wasted my time and impeded my being
able to get to where I have in terms of enjoying the results if I hadn't
had the old-fashioned approach of using measurements, understanding, etc,
to try and find my way though the claims. In my experience this has
complimented listening very well.

So, no, I'm afraid I am not personally a great fan of wilful ignorance as a
policy of choice.


That's fine in the main, of course - it's your world and it suits you
(and probably many others). I'm not so happy, though, with lumping
enthusiastic commentary and enquiring minds in with 'wilful ignorance',
which I'm afraid is how I read the essence of what you seem to be saying.


Slainte,

Jim

how good are class D amplifiers?
 

"Rob" wrote in message


Yes, I agree. DBT is not a trivial thing though, and
surprisingly (to me) there doesn't seem to have been many
rigorous tests to underpin the 'little if any difference'
thesis.

What would constitute many?

I've done DBTs of several dozen hi fi power amps, and found near-total
support for the "little if any difference" thesis.

how good are class D amplifiers?
 

"Arny Krueger" wrote in message
. ..
"Rob" wrote in message


Yes, I agree. DBT is not a trivial thing though, and
surprisingly (to me) there doesn't seem to have been many
rigorous tests to underpin the 'little if any difference'
thesis.

What would constitute many?

I've done DBTs of several dozen hi fi power amps, and found near-total
support for the "little if any difference" thesis.


Sure, of course - and it would be stunning if it weren't for the fact
that, in a domestic environment, most people couldn't tell the
difference between two pieces of kit after a couple of goes back and
forth - even if *they* were making the switches fully sighted!!

how good are class D amplifiers?
 

In article ,
Keith G wrote:
Sure, of course - and it would be stunning if it weren't for the fact
that, in a domestic environment, most people couldn't tell the
difference between two pieces of kit after a couple of goes back and
forth - even if *they* were making the switches fully sighted!!

That's a remarkable change of tune from you?

--
*When I'm not in my right mind, my left mind gets pretty crowded *

Dave Plowman London SW
To e-mail, change noise into sound.

how good are class D amplifiers?
 

Arny Krueger wrote:
"Rob" wrote in message


Yes, I agree. DBT is not a trivial thing though, and
surprisingly (to me) there doesn't seem to have been many
rigorous tests to underpin the 'little if any difference'
thesis.

What would constitute many?


Many for me would be any that I come across. I flip through the hifi
press every so often, and I think I'm not far off correct in saying
there's hasn't been a single example in the mainstream media?! Which?
(UK consumer mag) do blind tests, but not with the rigour you require,
and they frequently report differences in amps (and CDPs come to that).


I've done DBTs of several dozen hi fi power amps, and found near-total
support for the "little if any difference" thesis.


Yes, we've done this, and I set out a few problems I had with your
methodology and method. Even so, and FWIW, I found your tests
interesting and valuable, if not entirely persuasive.

how good are class D amplifiers?
 

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


Yes, I agree. DBT is not a trivial thing though, and
surprisingly (to me) there doesn't seem to have been many
rigorous tests to underpin the 'little if any difference'
thesis.
What would constitute many?

I've done DBTs of several dozen hi fi power amps, and found near-total
support for the "little if any difference" thesis.


Sure, of course - and it would be stunning if it weren't for the fact
that, in a domestic environment, most people couldn't tell the
difference between two pieces of kit after a couple of goes back and
forth - even if *they* were making the switches fully sighted!!


Indeed - you've/I've caught me out on more than one occasion :-)

There's no easy way to explain the whole thing - I just find listening
to music a very different experience to listening to electrical equipment.

how good are class D amplifiers?
 

In article , Rob
wrote:
Jim Lesurf wrote:
In article , Rob
wrote:

I simply don't get this. I've been using 5 SS amps of late (Quad 405,
Rose power amp, Cambridge AV, Behringer A500, and that within a Pure
mini system), as well as others on and off over the years, and I feel
each has 'a sound of its own'.

The problems with the above are as follows:


[snip]

2) Yet when people do level-matched comparisons and avoid obvious
snags like clipping *and* have only the sound to rely upon, the result
is often that they can't reliably tell one amp from another.

FWIW A number of tests have also shown that people tend to hear
'differences' even when the same system is used in the same way.


Yes, I agree. DBT is not a trivial thing though,

I was not specifically referring to DBT methods. Just to ones which have
sensible test conditions - e.g. level matched - and where the listener was
having to rely upon the sounds alone.


and surprisingly (to me) there doesn't seem to have been many rigorous
tests to underpin the 'little if any difference' thesis.

You would need to clarify what you mean as I am unsure of the point you are
making.

The situation as I understand it is that appropriately performed tests
often show no sign of the listener being able to distiguish. In some cases
they do throw up various effects which may be due to methodology flaws. The
tests I have in mind were not to see if the differences were 'little', just
to see if those listening could actually show any relable signs of being
able to hear *any* audible differences.

I am therefore unsure what purpose the tests you refer to would have. Is it
to simply establish that two units *do* produce different results at a
level so small as to be inaudible? If so, I'd suspect that simple
measurements would confirm that differences exist in many cases. Just that
people show no sign of being able to hear them when tested.

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

how good are class D amplifiers?
 

"Keith G" wrote in message

"Arny Krueger" wrote in message
. ..
"Rob" wrote in message


Yes, I agree. DBT is not a trivial thing though, and
surprisingly (to me) there doesn't seem to have been
many rigorous tests to underpin the 'little if any
difference' thesis.

What would constitute many?

I've done DBTs of several dozen hi fi power amps, and
found near-total support for the "little if any
difference" thesis.


Sure, of course - and it would be stunning if it weren't
for the fact that, in a domestic environment, most people
couldn't tell the difference between two pieces of kit
after a couple of goes back and forth - even if *they*
were making the switches fully sighted!!

Yet another irrelevant statement from a member of the "great unwashed". The
relevance problem here is that the evaluations I'm talking about have been
vastly more extensive than "a couple of goes back and forth".

how good are class D amplifiers?
 

In article , Rob
wrote:
Jim Lesurf wrote:
In article , Rob
wrote:


Another snag is that in the case of audio there may be many thousands
of different 'pictures' to 'view' and you might like some 'distorted'
by a specific 'glass', but other 'distorted' in other ways. So perhaps
this is simply another attempt at analogy that falls apart once you
try to use it at more that a trivial level. ;-


May well. My point was to emphasise that 'distortion' is a concept,

The word is actually used in audio in at least two ways.

One is referring to a property of a system which is rooted in a suitable
form of non-linerarily and thus causes a non-linear relationship between
the input and output of a system/unit.

The other is to the consequential alterations caused by the above property.

The results may be both measurable and audible, depending on the details.

Is that simply a 'concept'? I would have regarded it as a description of
something which arises in physical reality. 'Concept' seems to me to be a
term which sounds more like it was an abstract idea.


and not a single or pejorative (in the context of valves discussions
say) fact.

Pejorative would be 'in the ear of the belistener' I guess. :-)

The reality, though, is that if the output has a nonlinear relation to the
input then it is a 'fact' that the result is being distorted according to
the relevant definitions. This can be measured, and may be audible,
depending on circumstances.

Whether someone likes or dislikes (or can even tell the difference) the
results is up to them. Of course, I'd like them to be able to make an
'informed' choice - hence my previous comments. But that isn't
compulsory... ;-

More generally...

The problem with wilful ignorance is that it gives you no guide if you
ever need to change anything. Similarly, it is no help to anyone else
who is interested in the results you got. Nor does it tell anyone if
what is claimed is for the reasons claimed, or is even real rather
than delusional.

I suppose I am old-fashioned. I prefer education and understanding to
ignorance, and I prefer views based on reliable evidence. Indeed, I
seem to get a lot of enjoyment and satisfaction out of learning,
understanding, etc. My experience thus far is that this has helped me
to design/choose/use equipment to allow me to enjoy recorded and
broadcast music. I have also repeatedly found that ideas presented in
claims by people have no foundations, so would probably have wasted my
time and impeded my being able to get to where I have in terms of
enjoying the results if I hadn't had the old-fashioned approach of
using measurements, understanding, etc, to try and find my way though
the claims. In my experience this has complimented listening very well.

So, no, I'm afraid I am not personally a great fan of wilful ignorance
as a policy of choice.


That's fine in the main, of course - it's your world and it suits you
(and probably many others). I'm not so happy, though, with lumping
enthusiastic commentary and enquiring minds in with 'wilful ignorance',
which I'm afraid is how I read the essence of what you seem to be saying.

Why are you assuing that enthusiam and enquiry mean wilifil ignorance? I'd
have said the exact opposite. I'm afraid that you are reading into what I
wrote something that I neither said not meant.

An 'enquiring mind' would seek to *understand* what they experience - and
also seek to check if their impressions or ideas have any reliability or
are errors. Enthusiam is one of the things that can drive this.

FWIW The main reason I've spent decades studying, building, testing, etc,
audio amplifiers and other kit is that I am largely driven by my enthusiasm
for the results - being able to enjoy the music. My point, therefore, was
that measurements, etc, are very valuable (if you understand them), and
allow you to make more progress.

Being able to make measurements and analyse designs, etc, does not prevent
you from also listening to the results. There is no inherent dichotomy
here. If there is a problem it is in the area I referred to.

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

how good are class D amplifiers?
 

"Dave Plowman (News)" wrote in
message

In article ,
Keith G wrote:

Sure, of course - and it would be stunning if it weren't
for the fact that, in a domestic environment, most
people couldn't tell the difference between two pieces
of kit after a couple of goes back and forth - even if
*they* were making the switches fully sighted!!

That's a remarkable change of tune from you?

Not at all - Keith is sneering down his nose at the quality and sincerity of
such the evaluations I was talking about. Since they don't agree with his
prejudices, they couldn't have been any good.

how good are class D amplifiers?
 

"Rob" wrote in message

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


Yes, I agree. DBT is not a trivial thing though, and
surprisingly (to me) there doesn't seem to have been
many rigorous tests to underpin the 'little if any
difference' thesis.
What would constitute many?

I've done DBTs of several dozen hi fi power amps, and
found near-total support for the "little if any
difference" thesis.


Sure, of course - and it would be stunning if it weren't
for the fact that, in a domestic environment, most
people couldn't tell the difference between two pieces
of kit after a couple of goes back and forth - even if
*they* were making the switches fully sighted!!

Indeed - you've/I've caught me out on more than one
occasion :-)
There's no easy way to explain the whole thing

Speaks to the knowlege, intelligence, and expressive powers of the person
doing the explaining.

I just find listening to music a very different experience to listening
to
electrical equipment.

So how do you listen to electrical equipment without playing music through
it?

how good are class D amplifiers?
 

"Rob" wrote in message



Yes, we've done this, and I set out a few problems I had
with your methodology and method.


I've reviewed the last 100 or so google summaries of your posts here, and
can't find any such thing. Can you give me a range of dates or something?

how good are class D amplifiers?
 

In article ,
Arny Krueger wrote:
Sure, of course - and it would be stunning if it weren't
for the fact that, in a domestic environment, most
people couldn't tell the difference between two pieces
of kit after a couple of goes back and forth - even if
*they* were making the switches fully sighted!!

That's a remarkable change of tune from you?

Not at all - Keith is sneering down his nose at the quality and
sincerity of such the evaluations I was talking about. Since they don't
agree with his prejudices, they couldn't have been any good.

Still an about face. Everyone who hears *his* system - dustman to doctor -
immediately goes home and throws out their Krell, begging Keith for one of
his SET amps. Or have I read him wrong?

--
*Ambition is a poor excuse for not having enough sense to be lazy *

Dave Plowman London SW
To e-mail, change noise into sound.

how good are class D amplifiers?
 

Arny Krueger wrote:
"Rob" wrote in message


Yes, we've done this, and I set out a few problems I had
with your methodology and method.


I've reviewed the last 100 or so google summaries of your posts here, and
can't find any such thing. Can you give me a range of dates or something?


6 Nov 06 - here's a snippet (I keep changing my email 'code' for
reasons unknown):

Steven Sullivan wrote:
In rec.audio.tech Arny Krueger wrote:
"Jim Lesurf" wrote in message

In article , Rob
wrote:
Jim Lesurf wrote:
In article ,
Rob wrote:

What exactly is the ontological and epistemological
basis of the 'virtual reality' methodology? I have
to be absolutely clear on these points to accept
what you say.
Nice job of raising the bar to impossible heights.
I've seen this technique used many times before and
I'm not playing.

Well, it's your ball :-)

how good are class D amplifiers?
 

Arny Krueger wrote:
"Rob" wrote in message

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


Yes, I agree. DBT is not a trivial thing though, and
surprisingly (to me) there doesn't seem to have been
many rigorous tests to underpin the 'little if any
difference' thesis.
What would constitute many?

I've done DBTs of several dozen hi fi power amps, and
found near-total support for the "little if any
difference" thesis.

Sure, of course - and it would be stunning if it weren't
for the fact that, in a domestic environment, most
people couldn't tell the difference between two pieces
of kit after a couple of goes back and forth - even if
*they* were making the switches fully sighted!!
Indeed - you've/I've caught me out on more than one
occasion :-)
There's no easy way to explain the whole thing

Speaks to the knowlege, intelligence, and expressive powers of the person
doing the explaining.


V. clever :-)

I just find listening to music a very different experience to listening
to
electrical equipment.

So how do you listen to electrical equipment without playing music through
it?


V. clever indeed! I don't know - innate gift?

how good are class D amplifiers?
 

"Dave Plowman (News)" wrote in message
...
In article ,
Arny Krueger wrote:
Sure, of course - and it would be stunning if it weren't
for the fact that, in a domestic environment, most
people couldn't tell the difference between two pieces
of kit after a couple of goes back and forth - even if
*they* were making the switches fully sighted!!

That's a remarkable change of tune from you?

Not at all - Keith is sneering down his nose at the quality and
sincerity of such the evaluations I was talking about. Since they don't
agree with his prejudices, they couldn't have been any good.

Still an about face. Everyone who hears *his* system - dustman to doctor -
immediately goes home and throws out their Krell, begging Keith for one of
his SET amps. Or have I read him wrong?

--
*Ambition is a poor excuse for not having enough sense to be lazy *

Dave Plowman London SW
To e-mail, change noise into sound.

I'm neither a dustman nor a doctor, and when I went to hear Keith's system,
I wouldn't have begged for one of his SET amps, except possibly had I been
in need of a boat anchor. His system *does* sound exciting (as in unbearably
coloured) and that's how he likes it.

Can't explain why Keith gets the reaction from visitors he tells us about
here. Maybe it's something in the air of St Neots.

S.
--
http://audiopages.googlepages.com

how good are class D amplifiers?
 

"Serge Auckland" wrote


I'm neither a dustman nor a doctor, and when I went to hear Keith's
system, I wouldn't have begged for one of his SET amps, except
possibly had I been in need of a boat anchor. His system *does* sound
exciting (as in unbearably coloured) and that's how he likes it.


Serge, I have mentioned before that my 'system' (one of what - 4
systems?) is greatly changed from what you heard and the Jericho
speakers never did 'come right' and have been consigned to the garage.
Right now, for example, I have a record playing through my
recently-acquired valve preamp/Dynaco Mk IIIs into the TLS80s - hardly
the 'triode & horns' that I usually use for vinyl, is it?

My preference for vinyl *is* triode amplification on the Lowthers (the
Holy Trinity) while movies, radio (FM and DAB), TV and CDs (mostly) go
through the SS/TLS80s system according to how I feel. Now that the
Dynies are up to the task (with the new preamp), it will be interesting
to see if they fully supplant the Technics SS pre/power combi that is
also new here and which I like a lot and which has a definite 'heat'
advantage, now that summer's coming. (And which almost certainly has far
better noise, distortion and S/N figures than the 'techno**** clown
bashers' can probably claim for their own kit??)

I suggest you look at my detractors when words like 'bigot' start get
flung around - I, at least, choose from the 'whole spectrum' when I
decide what to play on what.



Can't explain why Keith gets the reaction from visitors he tells us
about here. Maybe it's something in the air of St Neots.


The visitor who has *just left here* (having been here all afternoon)
has, after some 15 years of SS/digital audio, cloned my entire
valves/vinyl system apart from the the valve phono stage which he is
going to have to wait for from World Designs. (A reasonable person might
just stop to consider that he must have heard something significant
enough to prompt his actions - a moron would dismiss this out of hand as
it will not conform to his own narrow, prejudiced beliefs/preferences.)
Trust me that he is no fool and believe me that it has represented not
much more for me than another opportunity to spend my time for the
benefit of another 'enthusiast', collecting only a little out of pocket
expenditure along the way.

.....that said, I did get to buy the valve pre off him very reasonably
and he has just made me a gift of a set of motorcycle brake caliper
bolts (some 20 quid's worth at 'staff prices') to replace those on my
bike which have gone a bit manky:

http://www.apah69.dsl.pipex.com/show/LHBrake.JPG

http://www.apah69.dsl.pipex.com/show/RHBrake.JPG


Please don't consider yourself targetted when I throw my net to catch
the bigots and hypocrites in here - you, Don and one or two other
'intermittent posters' are examples of people whom I might regard as
*grossly misguided* and/or 'missing the point' at times, but I respect
your views/opinions/knowledge/experience and take your comments in the
spirit and manner which they are offered....

how good are class D amplifiers?
 

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

Sure, of course - and it would be stunning if it weren't for the fact
that, in a domestic environment, most people couldn't tell the
difference between two pieces of kit after a couple of goes back and
forth - even if *they* were making the switches fully sighted!!


Indeed - you've/I've caught me out on more than one occasion :-)

There's no easy way to explain the whole thing - I just find listening
to music a very different experience to listening to electrical
equipment.


Quite..

On one occasion I had Shiny Nigel (who has Golden Ears and claims to be
able to tell a CD from its CDR rip) here and had the same album (DS
'Brothers In Arms', IIRC) playing simultaneously on various players so
that he was listing to the LP, the original CD, a CDR rip and a disk
with the MP3s on it at various times. After switching between the
sources (which were not even exactly synched) a few times he has *no
idea* which was playing despite the fact that he and I were both in the
room in full sight when I was making the changes. The only one he could
could tell (and then not easily) was the LP if I left it on long enough
for a bit of crackle or a pop - it's a very quiet album!

Big difference (I imagine) making 'laboratory comparisons' than in the
domestic environment - too easy to fool the listener, as we both know!!

Otherwise, I think it goes like this - pros in a 'lab environment' will
choose the first sample most times, *ordinary people* in a domestic
environment will choose the last sample most times, especially if you
let it run a little longer! ;-)

No?

how good are class D amplifiers?
 

"Keith G" wrote in message
...

"Serge Auckland" wrote


I'm neither a dustman nor a doctor, and when I went to hear Keith's
system, I wouldn't have begged for one of his SET amps, except possibly
had I been in need of a boat anchor. His system *does* sound exciting (as
in unbearably coloured) and that's how he likes it.


Serge, I have mentioned before that my 'system' (one of what - 4 systems?)
is greatly changed from what you heard and the Jericho speakers never did
'come right' and have been consigned to the garage. Right now, for
example, I have a record playing through my recently-acquired valve
preamp/Dynaco Mk IIIs into the TLS80s - hardly the 'triode & horns' that I
usually use for vinyl, is it?

My preference for vinyl *is* triode amplification on the Lowthers (the
Holy Trinity) while movies, radio (FM and DAB), TV and CDs (mostly) go
through the SS/TLS80s system according to how I feel. Now that the Dynies
are up to the task (with the new preamp), it will be interesting to see if
they fully supplant the Technics SS pre/power combi that is also new here
and which I like a lot and which has a definite 'heat' advantage, now that
summer's coming. (And which almost certainly has far better noise,
distortion and S/N figures than the 'techno**** clown bashers' can
probably claim for their own kit??)

I will ask for an invitation to hear the TLS80s as soon as I've finished my
chores round the house here. As I've mentioned before, I used to have a
pair in IMFs myself (the smaller TLS50s ) and I've always regretted getting
rid of them, but they only work back-to-the-wall, so they would be of no use
to me now.



I suggest you look at my detractors when words like 'bigot' start get
flung around - I, at least, choose from the 'whole spectrum' when I decide
what to play on what.



Can't explain why Keith gets the reaction from visitors he tells us about
here. Maybe it's something in the air of St Neots.


The visitor who has *just left here* (having been here all afternoon) has,
after some 15 years of SS/digital audio, cloned my entire valves/vinyl
system apart from the the valve phono stage which he is going to have to
wait for from World Designs. (A reasonable person might just stop to
consider that he must have heard something significant enough to prompt
his actions - a moron would dismiss this out of hand as it will not
conform to his own narrow, prejudiced beliefs/preferences.) Trust me that
he is no fool and believe me that it has represented not much more for me
than another opportunity to spend my time for the benefit of another
'enthusiast', collecting only a little out of pocket expenditure along the
way.

....that said, I did get to buy the valve pre off him very reasonably and
he has just made me a gift of a set of motorcycle brake caliper bolts
(some 20 quid's worth at 'staff prices') to replace those on my bike which
have gone a bit manky:

http://www.apah69.dsl.pipex.com/show/LHBrake.JPG

http://www.apah69.dsl.pipex.com/show/RHBrake.JPG


Please don't consider yourself targetted when I throw my net to catch the
bigots and hypocrites in here - you, Don and one or two other
'intermittent posters' are examples of people whom I might regard as
*grossly misguided* and/or 'missing the point' at times, but I respect
your views/opinions/knowledge/experience and take your comments in the
spirit and manner which they are offered....

There are several ways to skin a cat, and you've found most of them........

S.

--
http://audiopages.googlepages.com

how good are class D amplifiers?
 

"Serge Auckland" wrote


snip


I will ask for an invitation to hear the TLS80s as soon as I've
finished my chores round the house here.


You are already invited, all we need to do is fix a date...


As I've mentioned before, I used to have a
pair in IMFs myself (the smaller TLS50s ) and I've always regretted
getting rid of them, but they only work back-to-the-wall, so they
would be of no use to me now.


Jammed right against the wall and hemmed, in in my room!! :-)

(I use them as equipment shelves also!!)



There are several ways to skin a cat, and you've found most of
them........


That there was a cat to skin is the whole reason for my 'explorations' -
any sane person would have stuck with the little Sony 'lifestyle' system
I mentioned recently and simply wicked it up a bit....

how good are class D amplifiers?
 

Jim Lesurf wrote:
In article , Rob
wrote:

snip


and surprisingly (to me) there doesn't seem to have been many rigorous
tests to underpin the 'little if any difference' thesis.

You would need to clarify what you mean as I am unsure of the point you are
making.

I'll try.

1. It is maintained that most amplifiers sound the same;
2. I haven't see many tests that support (1)

Rob

how good are class D amplifiers?
 

"Arny Krueger" wrote in message
. ..
"Rob" wrote in message


Yes, I agree. DBT is not a trivial thing though, and
surprisingly (to me) there doesn't seem to have been many
rigorous tests to underpin the 'little if any difference'
thesis.

What would constitute many?

I've done DBTs of several dozen hi fi power amps,


I actually doubt that....

how good are class D amplifiers?
 

"Arny Krueger" wrote in message
...
"Dave Plowman (News)" wrote in
message

In article ,
Keith G wrote:

Sure, of course - and it would be stunning if it weren't
for the fact that, in a domestic environment, most
people couldn't tell the difference between two pieces
of kit after a couple of goes back and forth - even if
*they* were making the switches fully sighted!!

That's a remarkable change of tune from you?

Not at all - Keith is sneering down his nose at the quality and
sincerity of such the evaluations I was talking about. Since they
don't agree with his prejudices, they couldn't have been any good.


To be accused of 'sneering' by Barmy Arny is like being accused of
having 'scant regard for human life' by Harold Shipman....

how good are class D amplifiers?
 

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

"Arny Krueger" wrote in message
. ..
"Rob" wrote in message


Yes, I agree. DBT is not a trivial thing though, and
surprisingly (to me) there doesn't seem to have been
many rigorous tests to underpin the 'little if any
difference' thesis.

What would constitute many?

I've done DBTs of several dozen hi fi power amps, and
found near-total support for the "little if any
difference" thesis.


Sure, of course - and it would be stunning if it weren't
for the fact that, in a domestic environment, most people
couldn't tell the difference between two pieces of kit
after a couple of goes back and forth - even if *they*
were making the switches fully sighted!!

Yet another irrelevant statement from a member of the "great
unwashed". The relevance problem here is that the evaluations I'm
talking about have been vastly more extensive than "a couple of goes
back and forth".


The relevance problem here is yours, squire - how many people here have
actually *witnessed* a DBT, let alone conducted one? Tbh, I see the free
and easy mention of DBTs by a small (but noisy) few here as a good
example of the Snake Oil Screamer's 'Snake Oil'....

Also define 'vastly more extensive' - having recently been accused of
'hyperbole' by the group's leading Distorter Of The Truth I am becoming
a little sensitive to exaggeration* myself. My point (elsewhere) is that
even sighted comparisons collapse only a few iterations of the switching
procedure and very quickly render an inabilty to clearly distinguish
different sources, IME....


*formerly known as 'bull****' in this group...

how good are class D amplifiers?
 

Jim Lesurf wrote:
In article , Rob
wrote:
Jim Lesurf wrote:
In article , Rob
wrote:

Another snag is that in the case of audio there may be many thousands
of different 'pictures' to 'view' and you might like some 'distorted'
by a specific 'glass', but other 'distorted' in other ways. So perhaps
this is simply another attempt at analogy that falls apart once you
try to use it at more that a trivial level. ;-


May well. My point was to emphasise that 'distortion' is a concept,

The word is actually used in audio in at least two ways.

One is referring to a property of a system which is rooted in a suitable
form of non-linerarily and thus causes a non-linear relationship between
the input and output of a system/unit.

The other is to the consequential alterations caused by the above property.

The results may be both measurable and audible, depending on the details.

Is that simply a 'concept'? I would have regarded it as a description of
something which arises in physical reality. 'Concept' seems to me to be a
term which sounds more like it was an abstract idea.


Yes, that's right - 'distortion' is a concept, and not a thing.


and not a single or pejorative (in the context of valves discussions
say) fact.

Pejorative would be 'in the ear of the belistener' I guess. :-)


Quite! If (and I say 'if'; I don't know) distortion is the cause of what
I consider to be the 'accurate' sound I get from a valve amplifier and
LPs then it's beneficial.

The reality, though, is that if the output has a nonlinear relation to the
input then it is a 'fact' that the result is being distorted according to
the relevant definitions. This can be measured, and may be audible,
depending on circumstances.

Whether someone likes or dislikes (or can even tell the difference) the
results is up to them. Of course, I'd like them to be able to make an
'informed' choice - hence my previous comments. But that isn't
compulsory... ;-


Yes. I think it may follow that you're led my measurement and I'm led by
the sound I hear. Of course, you have very good reasons for thinking
that measurements with which you're familiar matter. I simply don't
know. Now, is this wilful and ignorant ...

More generally...

The problem with wilful ignorance is that it gives you no guide if you
ever need to change anything. Similarly, it is no help to anyone else
who is interested in the results you got. Nor does it tell anyone if
what is claimed is for the reasons claimed, or is even real rather
than delusional.

I suppose I am old-fashioned. I prefer education and understanding to
ignorance, and I prefer views based on reliable evidence. Indeed, I
seem to get a lot of enjoyment and satisfaction out of learning,
understanding, etc. My experience thus far is that this has helped me
to design/choose/use equipment to allow me to enjoy recorded and
broadcast music. I have also repeatedly found that ideas presented in
claims by people have no foundations, so would probably have wasted my
time and impeded my being able to get to where I have in terms of
enjoying the results if I hadn't had the old-fashioned approach of
using measurements, understanding, etc, to try and find my way though
the claims. In my experience this has complimented listening very well.

So, no, I'm afraid I am not personally a great fan of wilful ignorance
as a policy of choice.


That's fine in the main, of course - it's your world and it suits you
(and probably many others). I'm not so happy, though, with lumping
enthusiastic commentary and enquiring minds in with 'wilful ignorance',
which I'm afraid is how I read the essence of what you seem to be saying.

Why are you assuing that enthusiam and enquiry mean wilifil ignorance? I'd
have said the exact opposite. I'm afraid that you are reading into what I
wrote something that I neither said not meant.


You skip from 'nonlinear' audio to 'informed choice' to 'unfounded
claims' to 'wilful ignorance'. I do the first three, but don't consider
myself wilfully ignorant. Delusional but happy maybe :-)

The bit where I would go along (in part at least) with your obviously
strong and informed opinions on this arise around the 'unfounded
claim', and the extent to which the adherent rams it down somebody
else's throat. But then I don't think an unfounded claim is incorrect,
or ignorant - wilful or otherwise.

An 'enquiring mind' would seek to *understand* what they experience - and
also seek to check if their impressions or ideas have any reliability or
are errors. Enthusiam is one of the things that can drive this.


OK, no doubt. 'Understanding' is, again, conceptual. And here I think
it's important to define your paradigm. I work in an applied social
science department, and an 'enthusiastic' row has erupted on the
teaching of research methods following the recent arrival of
environmental scientists. The economics of teaching means that it has to
be taught in one class. The detail's not particularly interesting in the
context of this discussion, but it does serve to highlight how
'understanding' means very different things to different people.

FWIW The main reason I've spent decades studying, building, testing, etc,
audio amplifiers and other kit is that I am largely driven by my enthusiasm
for the results - being able to enjoy the music. My point, therefore, was
that measurements, etc, are very valuable (if you understand them), and
allow you to make more progress.


And modesty no doubt forbids the qualification: 'measurement is not all' :-)

Being able to make measurements and analyse designs, etc, does not prevent
you from also listening to the results. There is no inherent dichotomy
here.

Of course.

If there is a problem it is in the area I referred to.

Which remains a tad fuzzy.

Rob

how good are class D amplifiers?
 

"Rob" wrote in message
...
Jim Lesurf wrote:
In article , Rob
wrote:

snip


and surprisingly (to me) there doesn't seem to have been many
rigorous
tests to underpin the 'little if any difference' thesis.

You would need to clarify what you mean as I am unsure of the point
you are
making.

I'll try.

1. It is maintained that most amplifiers sound the same;
2. I haven't see many tests that support (1)


The 'conventional wisdom' pooted in this group that that well-made SS
amplifiers have no *discernible* effect on the resultant sound from a
system in a domestic environment, as I understand it - quite the
opposite with valve gear where obvious differences in kit are used to
*create* a resultant sound, but let's not go there....

Anyway, I would tend to agree as I have no evidence otherwise and
couldn't care less as I think it is the amp/speaker pair in the given
room that counts, but what amuses me is that this does not seem to
survive far from this group - the 'magazines' do nothing but bang on
about the 'sound' of various amplifiers and write acres about the
differences and the effect on various aspects of different
performances!! Now, if *measurements* are what it is all about (and
there are those here who would have us think so) I would suggest the
numbers are very heavily in favour of the magazines and their combined
readerships which will (I do believe) greatly outnumber the those who
post/lurk/read here...??

We surely can be forgiven for thinking that the 'trade professionals'
(with their broad experience and the facilities at their disposal) might
just have that greater insight and that there may well be something in
what they say? My personal view is that 'listener fatigue' very quickly
renders 'quick comparisons' useles and that is why I like to audition
and compare kit over a period of months before I make any final
choices...

Just my toupee....

how good are class D amplifiers?
 

"Rob" wrote in message
...
Jim Lesurf wrote:
In article , Rob
wrote:
Jim Lesurf wrote:
In article , Rob
wrote:

Another snag is that in the case of audio there may be many
thousands
of different 'pictures' to 'view' and you might like some
'distorted'
by a specific 'glass', but other 'distorted' in other ways. So
perhaps
this is simply another attempt at analogy that falls apart once you
try to use it at more that a trivial level. ;-


May well. My point was to emphasise that 'distortion' is a concept,

The word is actually used in audio in at least two ways.

One is referring to a property of a system which is rooted in a
suitable
form of non-linerarily and thus causes a non-linear relationship
between
the input and output of a system/unit.

The other is to the consequential alterations caused by the above
property.

The results may be both measurable and audible, depending on the
details.

Is that simply a 'concept'? I would have regarded it as a description
of
something which arises in physical reality. 'Concept' seems to me to
be a
term which sounds more like it was an abstract idea.


Yes, that's right - 'distortion' is a concept, and not a thing.


Nope - it's measurable and 'viewable' with the right equipment.

(Apparently...)




and not a single or pejorative (in the context of valves discussions
say) fact.

Pejorative would be 'in the ear of the belistener' I guess. :-)


Quite! If (and I say 'if'; I don't know) distortion is the cause of
what I consider to be the 'accurate' sound I get from a valve
amplifier and LPs then it's beneficial.


Yep. 'Accurate' doesn't necessarily mean 'realistic' in my book, but I
guess it's the notion of 'realistic' that varies with the individual....

how good are class D amplifiers?
 

"Rob" wrote in message
...
Jim Lesurf wrote:
In article , Rob
wrote:
Jim Lesurf wrote:
In article , Rob
wrote:

Another snag is that in the case of audio there may be many thousands
of different 'pictures' to 'view' and you might like some 'distorted'
by a specific 'glass', but other 'distorted' in other ways. So perhaps
this is simply another attempt at analogy that falls apart once you
try to use it at more that a trivial level. ;-


May well. My point was to emphasise that 'distortion' is a concept,

The word is actually used in audio in at least two ways.

One is referring to a property of a system which is rooted in a suitable
form of non-linerarily and thus causes a non-linear relationship between
the input and output of a system/unit.

The other is to the consequential alterations caused by the above
property.

The results may be both measurable and audible, depending on the details.

Is that simply a 'concept'? I would have regarded it as a description of
something which arises in physical reality. 'Concept' seems to me to be a
term which sounds more like it was an abstract idea.


Yes, that's right - 'distortion' is a concept, and not a thing.

I disagree, distortion is very real, it can be measured and depending on the
severity, heard. I accept that the subjective effect of distortion will vary
with the individual, but that does not change the fact that distortion is
real.


and not a single or pejorative (in the context of valves discussions
say) fact.

Pejorative would be 'in the ear of the belistener' I guess. :-)


Quite! If (and I say 'if'; I don't know) distortion is the cause of what I
consider to be the 'accurate' sound I get from a valve amplifier and LPs
then it's beneficial.

The reality, though, is that if the output has a nonlinear relation to
the
input then it is a 'fact' that the result is being distorted according to
the relevant definitions. This can be measured, and may be audible,
depending on circumstances.

Correct:- If the output is not just a scaled version of the input, then
distortion has taken place. This distortion can be linear, as in a
distortion of frequency response, or non-linear, as in THD and IMD. The
addition of noise is also a distortion, but is generally viewed as an
addition rather than as a classic distortion.

Generally, distortion is considered a bad thing, but there are some who find
that the presence of distortion makes the sound "better" and so more
enjoyable.

S.

--
http://audiopages.googlepages.com
Whether someone likes or dislikes (or can even tell the difference) the
results is up to them. Of course, I'd like them to be able to make an
'informed' choice - hence my previous comments. But that isn't
compulsory... ;-


Yes. I think it may follow that you're led my measurement and I'm led by
the sound I hear. Of course, you have very good reasons for thinking that
measurements with which you're familiar matter. I simply don't know. Now,
is this wilful and ignorant ...

More generally...

The problem with wilful ignorance is that it gives you no guide if you
ever need to change anything. Similarly, it is no help to anyone else
who is interested in the results you got. Nor does it tell anyone if
what is claimed is for the reasons claimed, or is even real rather
than delusional.

I suppose I am old-fashioned. I prefer education and understanding to
ignorance, and I prefer views based on reliable evidence. Indeed, I
seem to get a lot of enjoyment and satisfaction out of learning,
understanding, etc. My experience thus far is that this has helped me
to design/choose/use equipment to allow me to enjoy recorded and
broadcast music. I have also repeatedly found that ideas presented in
claims by people have no foundations, so would probably have wasted my
time and impeded my being able to get to where I have in terms of
enjoying the results if I hadn't had the old-fashioned approach of
using measurements, understanding, etc, to try and find my way though
the claims. In my experience this has complimented listening very well.

So, no, I'm afraid I am not personally a great fan of wilful ignorance
as a policy of choice.


That's fine in the main, of course - it's your world and it suits you
(and probably many others). I'm not so happy, though, with lumping
enthusiastic commentary and enquiring minds in with 'wilful ignorance',
which I'm afraid is how I read the essence of what you seem to be
saying.

Why are you assuing that enthusiam and enquiry mean wilifil ignorance?
I'd
have said the exact opposite. I'm afraid that you are reading into what I
wrote something that I neither said not meant.


You skip from 'nonlinear' audio to 'informed choice' to 'unfounded claims'
to 'wilful ignorance'. I do the first three, but don't consider myself
wilfully ignorant. Delusional but happy maybe :-)

The bit where I would go along (in part at least) with your obviously
strong and informed opinions on this arise around the 'unfounded claim',
and the extent to which the adherent rams it down somebody else's throat.
But then I don't think an unfounded claim is incorrect, or ignorant -
wilful or otherwise.

An 'enquiring mind' would seek to *understand* what they experience -
and
also seek to check if their impressions or ideas have any reliability or
are errors. Enthusiam is one of the things that can drive this.


OK, no doubt. 'Understanding' is, again, conceptual. And here I think it's
important to define your paradigm. I work in an applied social science
department, and an 'enthusiastic' row has erupted on the teaching of
research methods following the recent arrival of environmental scientists.
The economics of teaching means that it has to be taught in one class. The
detail's not particularly interesting in the context of this discussion,
but it does serve to highlight how 'understanding' means very different
things to different people.

FWIW The main reason I've spent decades studying, building, testing, etc,
audio amplifiers and other kit is that I am largely driven by my
enthusiasm
for the results - being able to enjoy the music. My point, therefore, was
that measurements, etc, are very valuable (if you understand them), and
allow you to make more progress.

And modesty no doubt forbids the qualification: 'measurement is not all'
:-)

Being able to make measurements and analyse designs, etc, does not
prevent
you from also listening to the results. There is no inherent dichotomy
here.

Of course.

If there is a problem it is in the area I referred to.

Which remains a tad fuzzy.

Rob

how good are class D amplifiers?
 

In article ,
Keith G wrote:

"Arny Krueger" wrote in message
. ..
"Rob" wrote in message


[snip]

I've done DBTs of several dozen hi fi power amps,


I actually doubt that....

Why?

--
*Why is the man who invests all your money called a broker? *

Dave Plowman London SW
To e-mail, change noise into sound.

how good are class D amplifiers?
 

In article ,
Keith G wrote:
The relevance problem here is yours, squire - how many people here have
actually *witnessed* a DBT, let alone conducted one? Tbh, I see the free
and easy mention of DBTs by a small (but noisy) few here as a good
example of the Snake Oil Screamer's 'Snake Oil'....

I have - or at least been involved in several. A particularly interesting
one involved speakers concealed behind a acoustically transparent curtain,
live and recorded instruments and voices. Possibly not DBT to the exact
letter but as close as we could manage. The object was to select a new
monitoring loudspeaker and several domestic 'standards' were available as
well for reference purposes. Including a Lowther Acousta.

--
*Thank you. We're all refreshed and challenged by your unique point of view

Dave Plowman London SW
To e-mail, change noise into sound.

how good are class D amplifiers?
 

In article ,
Keith G wrote:
Yep. 'Accurate' doesn't necessarily mean 'realistic' in my book, but I
guess it's the notion of 'realistic' that varies with the individual....

Not too difficult for even yourself to try out. Record well with a good
mic a decent male voice of a friend - say alternate lines of a poem, etc.
Get him to stand alongside the speaker and say the other lines. Set levels
carefully of course. Repeat with speakers/amps of your choice. Which gets
closest to the live? Nothing you have will, but some will be better than
others.

--
*If at first you do succeed, try not to look too astonished.

Dave Plowman London SW
To e-mail, change noise into sound.

how good are class D amplifiers?
 

"Keith G" wrote in message

"Arny Krueger" wrote in message
...
"Dave Plowman (News)" wrote in
message

In article ,
Keith G wrote:

Sure, of course - and it would be stunning if it
weren't for the fact that, in a domestic environment,
most people couldn't tell the difference between two
pieces of kit after a couple of goes back and forth -
even if *they* were making the switches fully sighted!!

That's a remarkable change of tune from you?

Not at all - Keith is sneering down his nose at the
quality and sincerity of such the evaluations I was
talking about. Since they don't agree with his
prejudices, they couldn't have been any good.

To be accused of 'sneering' by Barmy Arny is like being
accused of having 'scant regard for human life' by Harold
Shipman....

On that scale Keith, you're someplace around Joseph Stalin. :-(

how good are class D amplifiers?
 

"Keith G" wrote in message

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

"Arny Krueger" wrote in message
. ..
"Rob" wrote in message


Yes, I agree. DBT is not a trivial thing though, and
surprisingly (to me) there doesn't seem to have been
many rigorous tests to underpin the 'little if any
difference' thesis.

What would constitute many?

I've done DBTs of several dozen hi fi power amps, and
found near-total support for the "little if any
difference" thesis.


Sure, of course - and it would be stunning if it weren't
for the fact that, in a domestic environment, most
people couldn't tell the difference between two pieces
of kit after a couple of goes back and forth - even if
*they* were making the switches fully sighted!!

Yet another irrelevant statement from a member of the
"great unwashed". The relevance problem here is that the
evaluations I'm talking about have been vastly more
extensive than "a couple of goes back and forth".


The relevance problem here is yours, squire - how many
people here have actually *witnessed* a DBT,

Thousands and thousands of audiophiles.

let alone conducted one?

Thousands and thousands of audiophiles, courtesty of www.pcabx.com and
numerous sites like it.

how good are class D amplifiers?
 

"Keith G" wrote in message

"Arny Krueger" wrote in message
. ..
"Rob" wrote in message


Yes, I agree. DBT is not a trivial thing though, and
surprisingly (to me) there doesn't seem to have been
many rigorous tests to underpin the 'little if any
difference' thesis.

What would constitute many?

I've done DBTs of several dozen hi fi power amps,


I actually doubt that....

Your track record for being wrong at just about every turn is unmolested,
Keith.

how good are class D amplifiers?
 

"Dave Plowman (News)" wrote in
message
In article ,
Keith G wrote:

"Arny Krueger" wrote in message
. ..
"Rob" wrote in message


[snip]

I've done DBTs of several dozen hi fi power amps,


I actually doubt that....

Why?

Personal bias.