Jim Lesurf wrote:
Hi,

I've just put up a new web page at

http://www.audiomisc.co.uk/HFN/Squar...quareDeal.html

that looks at the use of squarewaves for assessing amplifiers, etc.

During a tidy up I found a 6 page article on "Square Wave Testing of Audio
Amplifiers" in the NZ publication - Radio & Electrical Review - of August
1955. In it, it goes on to describe the testing of amplifiers using square
waves as a relatively new process.

And just to show that that the more things change the more they stay the
same, the article also says - and I quote "Now when we have a number of
amplifiers whose specifications, as outlined , indicate such excellent
performance, one might legitimately expect, when listening tests are
conducted, using identical programme material, and the same pick-up and
speaker system, that all the amplifiers sound the same. It was with
considerable surprise that we found exactly the opposite. "

They did tests on 7 un-named amplifiers and included oscillograms of the
amplifiers at 30hz, 400hz & 10,000hz.

The conclusion reached was that square wave testing "can help sort the
sheep from the goats. With all its advantages, this type of test will still
not give an unambiguous answer to the 40 dollar question ...Will this
amplifier sound well on music?. It will give the experienced worker a
pretty good idea of where his designs could be improved, and it seems that
the very best amplifiers do give very similar square wave results. Where
faults are apparent, the test shows them up much more clearly than any
other method, and will also indicate fault conditions that cannot readily
be discovered at all in any other way."

So here we are, 55 years down the track and its deja vu all over again :0

Mike

On Sun, 10 Jan 2010 18:30:55 +1300, Mike Coatham
wrote:

Jim Lesurf wrote:
Hi,

I've just put up a new web page at

http://www.audiomisc.co.uk/HFN/Squar...quareDeal.html

that looks at the use of squarewaves for assessing amplifiers, etc.

During a tidy up I found a 6 page article on "Square Wave Testing of Audio
Amplifiers" in the NZ publication - Radio & Electrical Review - of August
1955. In it, it goes on to describe the testing of amplifiers using square
waves as a relatively new process.

And just to show that that the more things change the more they stay the
same, the article also says - and I quote "Now when we have a number of
amplifiers whose specifications, as outlined , indicate such excellent
performance, one might legitimately expect, when listening tests are
conducted, using identical programme material, and the same pick-up and
speaker system, that all the amplifiers sound the same. It was with
considerable surprise that we found exactly the opposite. "

They did tests on 7 un-named amplifiers and included oscillograms of the
amplifiers at 30hz, 400hz & 10,000hz.

The conclusion reached was that square wave testing "can help sort the
sheep from the goats. With all its advantages, this type of test will still
not give an unambiguous answer to the 40 dollar question ...Will this
amplifier sound well on music?. It will give the experienced worker a
pretty good idea of where his designs could be improved, and it seems that
the very best amplifiers do give very similar square wave results. Where
faults are apparent, the test shows them up much more clearly than any
other method, and will also indicate fault conditions that cannot readily
be discovered at all in any other way."

So here we are, 55 years down the track and its deja vu all over again :0

Mike


No chance of scanning it and making it available, is there? That would
be interesting.

d

Well, I suppose the misleading part of all this is actually calling them
square waves in th first place, as has been noted these do not exist.
There are other forms that can be used of course, the one sided square, with
a leading slope but a fast drop, and the inverse of this.
Then there are triangular waves of course, which sound almost as bad as
square waves.

I think the listening tests do prove some things though. Firstly, nobody is
really sure what 'right' actually is, so an amp may sound bad, but it might
be actually more accurate than one you like.

It is interesting sometimes to put a scope on the psu when an amp is running
too, often some frequencies exist at quite high levels, despite all the
decoupling in the world being there, indeed, decoupling itself can make an
amp sound leaden.

In the complexity of the audio and all the bits in the chain to how the
brain perceives the whole is still not well understood, I feel.

However, I do not think that most speaker wire tests are actually testing
the wire...

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Don Pearce" wrote in message
...
On Sun, 10 Jan 2010 18:30:55 +1300, Mike Coatham
wrote:

Jim Lesurf wrote:
Hi,

I've just put up a new web page at

http://www.audiomisc.co.uk/HFN/Squar...quareDeal.html

that looks at the use of squarewaves for assessing amplifiers, etc.

During a tidy up I found a 6 page article on "Square Wave Testing of Audio
Amplifiers" in the NZ publication - Radio & Electrical Review - of August
1955. In it, it goes on to describe the testing of amplifiers using square
waves as a relatively new process.

And just to show that that the more things change the more they stay the
same, the article also says - and I quote "Now when we have a number of
amplifiers whose specifications, as outlined , indicate such excellent
performance, one might legitimately expect, when listening tests are
conducted, using identical programme material, and the same pick-up and
speaker system, that all the amplifiers sound the same. It was with
considerable surprise that we found exactly the opposite. "

They did tests on 7 un-named amplifiers and included oscillograms of the
amplifiers at 30hz, 400hz & 10,000hz.

The conclusion reached was that square wave testing "can help sort the
sheep from the goats. With all its advantages, this type of test will
still
not give an unambiguous answer to the 40 dollar question ...Will this
amplifier sound well on music?. It will give the experienced worker a
pretty good idea of where his designs could be improved, and it seems that
the very best amplifiers do give very similar square wave results. Where
faults are apparent, the test shows them up much more clearly than any
other method, and will also indicate fault conditions that cannot readily
be discovered at all in any other way."

So here we are, 55 years down the track and its deja vu all over again :0

Mike


No chance of scanning it and making it available, is there? That would
be interesting.

d

On Sun, 10 Jan 2010 10:49:43 GMT, "Brian Gaff"
wrote:

Well, I suppose the misleading part of all this is actually calling them
square waves in th first place, as has been noted these do not exist.
There are other forms that can be used of course, the one sided square, with
a leading slope but a fast drop, and the inverse of this.
Then there are triangular waves of course, which sound almost as bad as
square waves.

If we limit the requirement to "within the meaning of the act", then
square waves are doable - to the same extent and for the same reasons
as triangular waves.

Of course the other big issue with square wave testing is
differentiation. It is quite easy to run out of voltage drive if the
peak to peak level has been doubled by a highpass filter.

I think the listening tests do prove some things though. Firstly, nobody is
really sure what 'right' actually is, so an amp may sound bad, but it might
be actually more accurate than one you like.

It is interesting sometimes to put a scope on the psu when an amp is running
too, often some frequencies exist at quite high levels, despite all the
decoupling in the world being there, indeed, decoupling itself can make an
amp sound leaden.


In a decent amp, it doesn't matter much what is going on at the supply
rails. A good PSRR will eliminate everything. I really don't know what
you mean by leaden though - care to elaborate?

In the complexity of the audio and all the bits in the chain to how the
brain perceives the whole is still not well understood, I feel.

However, I do not think that most speaker wire tests are actually testing
the wire...


They certainly weren't when Ben Duncan did them...

Brian

d

In article , Don Pearce
wrote:
On Sun, 10 Jan 2010 10:49:43 GMT, "Brian Gaff"
wrote:

Well, I suppose the misleading part of all this is actually calling
them square waves in th first place, as has been noted these do not
exist. There are other forms that can be used of course, the one sided
square, with a leading slope but a fast drop, and the inverse of this.
Then there are triangular waves of course, which sound almost as bad as
square waves.

If we limit the requirement to "within the meaning of the act", then
square waves are doable - to the same extent and for the same reasons as
triangular waves.

That is one of the things that I hope the webpage indicates. That the
'squarewave' needs to be in reality a practical form appropriate for a
given purpose. The snag being to assess what that means, and how to
interpet the results.

However, I do not think that most speaker wire tests are actually
testing the wire...


They certainly weren't when Ben Duncan did them...

Did you have

http://www.st-andrews.ac.uk/~www_pa/...eshift/cp.html

in mind there?... :-)

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

"Brian is one big long Gaffe"

Well, I suppose the misleading part of all this is actually calling them
square waves in th first place, as has been noted these do not exist.


** Only so noted by a criminally insane, mental retard.

**** of you DAMN TROLL !!!!!!!!!!



..... Phil

"Brian Gaff is a Know Nothing ******"



Tape, as I said in another response here had problems as it was obviously
impossible to record DC to a tape, so the flat tops were not flat.

** Huh ???????

Response down to DC is not a requirement for flat topped square waves !!!!

Square waves are NOT " little bits of DC " as fools like YOU think !!!!


You did not cover this aspect,


** Good thing he did not - since it would have been total ********.

For god's sake, learn some electronics - you damn fool.



..... Phil

In article , Brian Gaff
wrote:
Well, I suppose the misleading part of all this is actually calling them
square waves in th first place, as has been noted these do not exist.

Your objection is a tad too sweeping. Triangle waves, sinewaves, etc, also
"do not exist" if you require "exist" to mean that the real-world shape is
absolutely identical to the theoretical! :-)

I think the listening tests do prove some things though. Firstly, nobody
is really sure what 'right' actually is, so an amp may sound bad, but
it might be actually more accurate than one you like.

Alas the problem here is being expected to make sense of *someone else's*
'listening test' in a magazine when their ears, system, etc aren't yours.

The point of objective data - like ye olde fashioned squarewave test - was
to give data which could be interpreted or understood. For example showing
if there was a problem like a slew rate or max current limit that would be
too low for your own music listening in your specific situation. Thus - for
those who could interpret correctly - freeing you from having to guess what
the devil the reviewer was whittering on about when they claimed the amp
gave a 'nice chocolate sound' or whatever. :-)

The snag is that - as with many other types of measurement - they can
easily be done in an inappropriate manner, or their results totally
misinterpreted. Modern reviews generally 'solve' that problem by discarding
the idea of doing the test and trying to make sense of the results. :-)

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Don Pearce wrote:
On Sun, 10 Jan 2010 18:30:55 +1300, Mike Coatham
wrote:

Jim Lesurf wrote:
Hi,

I've just put up a new web page at

http://www.audiomisc.co.uk/HFN/Squar...quareDeal.html

that looks at the use of squarewaves for assessing amplifiers, etc.

During a tidy up I found a 6 page article on "Square Wave Testing of Audio
Amplifiers" in the NZ publication - Radio & Electrical Review - of August
1955. In it, it goes on to describe the testing of amplifiers using square
waves as a relatively new process.

And just to show that that the more things change the more they stay the
same, the article also says - and I quote "Now when we have a number of
amplifiers whose specifications, as outlined , indicate such excellent
performance, one might legitimately expect, when listening tests are
conducted, using identical programme material, and the same pick-up and
speaker system, that all the amplifiers sound the same. It was with
considerable surprise that we found exactly the opposite. "

They did tests on 7 un-named amplifiers and included oscillograms of the
amplifiers at 30hz, 400hz & 10,000hz.

The conclusion reached was that square wave testing "can help sort the
sheep from the goats. With all its advantages, this type of test will still
not give an unambiguous answer to the 40 dollar question ...Will this
amplifier sound well on music?. It will give the experienced worker a
pretty good idea of where his designs could be improved, and it seems that
the very best amplifiers do give very similar square wave results. Where
faults are apparent, the test shows them up much more clearly than any
other method, and will also indicate fault conditions that cannot readily
be discovered at all in any other way."

So here we are, 55 years down the track and its deja vu all over again :0

Mike


No chance of scanning it and making it available, is there? That would
be interesting.

d

No problem with that - I'll send you a copy later today. I'd also send Jim
a copy too before he gets on my case

Don Pearce wrote:
On Sun, 10 Jan 2010 18:30:55 +1300, Mike Coatham
wrote:

Jim Lesurf wrote:
Hi,

I've just put up a new web page at

http://www.audiomisc.co.uk/HFN/Squar...quareDeal.html

that looks at the use of squarewaves for assessing amplifiers, etc.

During a tidy up I found a 6 page article on "Square Wave Testing of Audio
Amplifiers" in the NZ publication - Radio & Electrical Review - of August
1955. In it, it goes on to describe the testing of amplifiers using square
waves as a relatively new process.

And just to show that that the more things change the more they stay the
same, the article also says - and I quote "Now when we have a number of
amplifiers whose specifications, as outlined , indicate such excellent
performance, one might legitimately expect, when listening tests are
conducted, using identical programme material, and the same pick-up and
speaker system, that all the amplifiers sound the same. It was with
considerable surprise that we found exactly the opposite. "

They did tests on 7 un-named amplifiers and included oscillograms of the
amplifiers at 30hz, 400hz & 10,000hz.

The conclusion reached was that square wave testing "can help sort the
sheep from the goats. With all its advantages, this type of test will still
not give an unambiguous answer to the 40 dollar question ...Will this
amplifier sound well on music?. It will give the experienced worker a
pretty good idea of where his designs could be improved, and it seems that
the very best amplifiers do give very similar square wave results. Where
faults are apparent, the test shows them up much more clearly than any
other method, and will also indicate fault conditions that cannot readily
be discovered at all in any other way."

So here we are, 55 years down the track and its deja vu all over again :0

Mike


No chance of scanning it and making it available, is there? That would
be interesting.

d
Don can you e-mail me direct and I'll send you the pdf My first attempt to
get it to you got bounced.

Mike