Audio, hi-fi and car audio - how good are class D amplifiers?

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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.

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
. ..
"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.