http://www.next-power.net/next-tube/articles.php3?
article=articles/Cheever/abstract_en.inc&sub_menu_item=99

Sorry for the lapped over URL, folks. The PDF on this page is quite
interesting.

I'm not endorsing it at this time as the math is way beyond me. Anybody
here speak mathimatica?

-Bart

On Tue, 23 May 2006 01:16:29 -0400, bart wrote:

http://www.next-power.net/next-tube/articles.php3?
article=articles/Cheever/abstract_en.inc&sub_menu_item=99

Sorry for the lapped over URL, folks. The PDF on this page is quite
interesting.

I'm not endorsing it at this time as the math is way beyond me. Anybody
here speak mathimatica? snip

Sounds sort of like the kind of horse**** you get form Amar Bose or
Bob Carver.

It's bunk.

On Tue, 23 May 2006 01:16:29 -0400, bart wrote:

http://www.next-power.net/next-tube/articles.php3?
article=articles/Cheever/abstract_en.inc&sub_menu_item=99

Sorry for the lapped over URL, folks. The PDF on this page is quite
interesting.

I'm not endorsing it at this time as the math is way beyond me. Anybody
here speak mathimatica?

-Bart

I stopped at his opening paragraph. When one starts a paper with an
axiom that is total ******** (plus the obligatory spelling error -
accessed instead of assessed) there is really no point reading
further. HIs wife must be so proud to have that dedicated to her.

d

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

bart wrote:
http://www.next-power.net/next-tube/articles.php3?
article=articles/Cheever/abstract_en.inc&sub_menu_item=99

Sorry for the lapped over URL, folks. The PDF on this page is quite
interesting.

Try TinyURL to cut down the length of links, so they'll fit.
Now, see:
http://tinyurl.com/qu5pw


I'm not endorsing it at this time as the math is way beyond me. Anybody
here speak mathimatica?

-Bart

It's not a new idea. The Radiotron Designer's Handbook 4th ed
mentions weighting THD figures to get a better representation
of how listeners will judge the sound quality of an amplifier.
He's amplifying (if you'll pardon the expression) on the concept.

It's not a bad paper given the small sample size and the fact that
he did it himself. I wouldn't have cited Stereophile, it's not
a scholarly or scientific journal (to put it mildly).

The spelling errors were probably caused by the fellows
(native Russian speakers) who created the PDF file.
But I'd note that even a dyslexic can write a master's thesis,
so the mere prescence of spelling errors doesn't cancel
out in toto the validity of what's written.



--
Ned Carlson
SW side of Chicago, USA
www.tubezone.net

In article , says...
On Tue, 23 May 2006 01:16:29 -0400, bart wrote:

http://www.next-power.net/next-tube/articles.php3?
article=articles/Cheever/abstract_en.inc&sub_menu_item=99

Sorry for the lapped over URL, folks. The PDF on this page is quite
interesting.

I'm not endorsing it at this time as the math is way beyond me. Anybody
here speak mathimatica? snip

Sounds sort of like the kind of horse**** you get form Amar Bose or
Bob Carver.

It's bunk.

Did you read the PDF then? The author is described as having some very
good credentials. How does one check up on what is claimed on a web-
page?

-Bart

bart wrote

Sorry for the lapped over URL, folks. The PDF on this page is quite
interesting.

I'm not endorsing it at this time as the math is way beyond me. Anybody
here speak mathimatica?

It seems to be a reasonable introduction to some major issues. As Ned says, the
conclusion is not a new idea, but a competent survey seems to be good enough for
a masters. If you look at a few audio magazines, you will find various
expressions of similar ideas in the way they measure and report on their tests.
Perhaps they all add up to the same thing.

One problem with weighting is how to arrive at an agreed standard, particularly
when more than one number is the most that the majority of punters can cope with
simultaneously.

If you can't understand the maths, then how will it make any difference to you
whether it is true or not?

A problem of weighting that it is another step towards reducing the whole
measurement thing to absurdity. If the author had not set out to justify a
preconceived notion of weighted distortion, he may have drawn from all those
authors any number of other important aspects of amplifier performance, and may
have devised a whole heap of indicative measures. Analysis is, after all, a
process of disassembly, and more is often not better.

At the risk of upsetting the angry young technician, I suggest audio equipment
should be specified and assessed in the same way as musical instruments. That
has much more to do with the way real history has unfolded.

cheers, Ian

bart wrote:

In article , says...
On Tue, 23 May 2006 01:16:29 -0400, bart wrote:

http://www.next-power.net/next-tube/articles.php3?
article=articles/Cheever/abstract_en.inc&sub_menu_item=99

Sorry for the lapped over URL, folks. The PDF on this page is quite
interesting.

I'm not endorsing it at this time as the math is way beyond me. Anybody
here speak mathimatica? snip

Sounds sort of like the kind of horse**** you get form Amar Bose or
Bob Carver.

It's bunk.

Did you read the PDF then? The author is described as having some very
good credentials. How does one check up on what is claimed on a web-
page?

Sometimes one cannot know if the truth is being told at a website ( or in emails to a
news group.)
So where another website contradicts the first, and is convincing, then maybe either is
right.
The Internet was never designed so ONLY the truth could be ever posted since Truth
Filters have yet to be designed.
So one should always think that what one reads on the Net could be bull****e, ********,
rubbish,
garbage, idiocy, hot air, horse ****e, etc, etc, etc.

But where a list of reasons and mathematical proofs are offered, and you doubt it it
all, then you have to be able to unravel the proof mathematically by finding out where
they may have said the equivalent of 2+2 = 6 and 4x7= 31.8
and dismiss other reasons given for their stance
in a cold hard logical way to confirm your doubt.

One thing is certain, bull****e is everywhere, and we need gumboots to stride the world.

No matter how big a shovel and broom is that we take with us through life, there will
always be piles
of BS clear away, or avoid.
Truth is elusive, often evaded by people taking the Egyption Solution, ie, they are in
denial.

Patrick Turner.



-Bart

On Thu, 25 May 2006 03:14:18 GMT, Patrick Turner
wrote:


But where a list of reasons and mathematical proofs are offered, and you doubt it it
all, then you have to be able to unravel the proof mathematically by finding out where
they may have said the equivalent of 2+2 = 6 and 4x7= 31.8 snip

In that "theorem" (and I use the term mockingly) I digested enough of
the presented math to know that it is, indeed, "bull****e." Although
the equations work, they correlate to absolutely nothing known in the
field of acoustics.

Bob Carver and Amar Bose both made huge fortunes promoting such
bull****e.

Patrick Turner wrote:
Sometimes one cannot know if the truth is being told at a website ( or in emails to a
news group.)

One thing is certain, bull****e is everywhere, and we need gumboots to stride the world.

No matter how big a shovel and broom is that we take with us through life, there will
always be piles of BS clear away, or avoid.
Truth is elusive, often evaded by people taking the Egyption Solution, ie, they are in
denial.

Well said Patrick. You're a man with big gumboots.

bart wrote:

http://www.next-power.net/next-tube/articles.php3?
article=articles/Cheever/abstract_en.inc&sub_menu_item=99

Sorry for the lapped over URL, folks. The PDF on this page is quite
interesting.

I'm not endorsing it at this time as the math is way beyond me. Anybody
here speak mathimatica?

Does this basically just boil down to saying that the audibilty of distortion
depends on its order ? Which in turn is influenced by the choice of amplifying
device? If so it's hardly news !

Graham

On Fri, 26 May 2006 02:38:44 +0100, Pooh Bear
wrote:

Does this basically just boil down to saying that the audibilty of distortion
depends on its order ? Which in turn is influenced by the choice of amplifying
device? If so it's hardly news !

Sure 'nuf. There's been some perhaps interesting quantitative
work in the States, too, but I can't remember the authors'
names. Some of the AES guys in r.a.p like Scott D. or Arny K.
will know for sure.

The thrust seems to have been on generalizing a weighting
(for audibility) of terms from the harmonic sequence, hoping
to make a more meaningful "THD" single number. Can't hurt,
I'd guess.

All good fortune,

Chris Hornbeck

Chris Hornbeck wrote:

On Fri, 26 May 2006 02:38:44 +0100, Pooh Bear
wrote:

Does this basically just boil down to saying that the audibilty of distortion
depends on its order ? Which in turn is influenced by the choice of amplifying
device? If so it's hardly news !

Sure 'nuf. There's been some perhaps interesting quantitative
work in the States, too, but I can't remember the authors'
names. Some of the AES guys in r.a.p like Scott D. or Arny K.
will know for sure.

The thrust seems to have been on generalizing a weighting
(for audibility) of terms from the harmonic sequence, hoping
to make a more meaningful "THD" single number. Can't hurt,
I'd guess.

I can understand the desire to ennumerate this but I'm doubtful about it's
usefulness. It won't make amps with different distortion spectra sound the same !

Maybe quoting the level of a specific harmonic would be more useful ? Analogue
recording tape used 3rd harmonic to determine maximum output level and optimum
biasing IIRC as interesting historical note.

All good fortune,

And yourself.

Graham

Pooh Bear wrote

bart wrote:

http://www.next-power.net/next-tube/articles.php3?
article=articles/Cheever/abstract_en.inc&sub_menu_item=99

Sorry for the lapped over URL, folks. The PDF on this page is quite
interesting.

I'm not endorsing it at this time as the math is way beyond me. Anybody
here speak mathimatica?

Does this basically just boil down to saying that the audibilty of distortion
depends on its order ? Which in turn is influenced by the choice of amplifying
device? If so it's hardly news !

Not quite. I think it is saying (and it would be sensible to say) that
audibility in part depends on the level of each distortion product *relative to
the others*.

That seems to entail the idea that more can be less, in the sense that, perhaps,
adding a bit of 2H could reduce the audibility of 3H, etc. A fixed weighting
doesn't really reflect these organic relationships.

You should read it, anyway.

I suggest that this is all stock in trade for musical instrument makers. It's
about "natural" sound. Beauty and all that stuff is about proportion. Arguably
the best instruments were made before they started measuring them, BTW.

cheers, Ian

DeserTBoB wrote:
Although
the equations work, they correlate to absolutely nothing known in the
field of acoustics.

It doesn't have anything to do with acoustics, it's an amplifier,
not a speaker. The point of the article was to try to come up
(it may be a Sisyphean task) with a measurable electronic
merit figure for amplifiers that correlates with how listeners
usually judge them in listening tests. The monkey wrench in the
equation is speakers, of course. Switch speakers, and the
figure of merit might not correlate so well.

Bob Carver and Amar Bose both made huge fortunes promoting such
bull****e.

AFAIK, Mr Cheever, unlike Bose & Carver, isn't selling anything.
It's a master's thesis, not a piece of sales lierature.
He got his master's years ago, so complaining to his prof
is probably a waste of time.

--
Ned Carlson
SW side of Chicago, USA
www.tubezone.net