[Art Ludwig]

You can download three wav files that demonstrate one of the main points of
Cheever's thesis. One file is a pure 440 Hz tone - zero distortion.
Another file mimics a single ended tube amp (SE) at 5% total harmonic
distortion (THD). The last file mimics a solid state amp (SS) at 0.5% THD.
I can clearly hear the SS distortion, and I can't hear the SE distortion
even though it is 10 times higher.
The wav files are located at
http://members.cox.net/artludwig/
Details on the creation of the files is at
http://www.silcom.com/~aludwig/Amplifier_distortion.htm

[Peter Wieck]

On Mar 20, 6:16 pm, "Art Ludwig" wrote:
You can download three wav files that demonstrate one of the main points of
Cheever's thesis. One file is a pure 440 Hz tone - zero distortion.
Another file mimics a single ended tube amp (SE) at 5% total harmonic
distortion (THD). The last file mimics a solid state amp (SS) at 0.5% THD.
I can clearly hear the SS distortion, and I can't hear the SE distortion
even though it is 10 times higher.
The wav files are located athttp://members.cox.net/artludwig/
Details on the creation of the files is athttp://www.silcom.com/~aludwig/Amplifier_distortion.htm

OK... a simple question:

What would _any_ given SE amp show as THD? Pick your poison,
commercial or home-brew as long as it actually exists. Then use that
as a model. Define output voltage and level (i.e.: watts) at what %
modulation on the input, and the voltage level of the input. Define
the speakers as well, of course.

THEN:

Pick any given *production* SS amp from a list of 'reasonably well-
made SS amps with a reputation for reasonable fidelity. Pick either
vintage or current production. Pick anything from 1 watt to 1500 watt
(RMS) amps. Send exactly the same signal at the same level as above to
the same precise output level as from the SE amp. Into the same
speakers, of course.

Remember the definitions he

a) ANY SE amp of your choosing, as long as it actually exists.
b) ANY speakers of your choosing.
c) ANY well-reputed *production* SS amp as long as it is capable of
delivering the same power level as the SE amp.

What happens then?

Peter Wieck
Wyncote, PA

[Eeyore]

Art Ludwig wrote:

You can download three wav files that demonstrate one of the main points of
Cheever's thesis. One file is a pure 440 Hz tone - zero distortion.
Another file mimics a single ended tube amp (SE) at 5% total harmonic
distortion (THD). The last file mimics a solid state amp (SS) at 0.5% THD.
I can clearly hear the SS distortion, and I can't hear the SE distortion
even though it is 10 times higher.
The wav files are located at
http://members.cox.net/artludwig/
Details on the creation of the files is at
http://www.silcom.com/~aludwig/Amplifier_distortion.htm

Yes, in order to make the SS amp sound bad he created a model with clipping !

How wholly insincere ! It's simply not worth even bothering with. This has
absolutely nothing to do with listening at 'normal' levels at all.

In fact he's suggesting that a 130 wpc SS amp will clip before an SET !

Graham

[Eeyore]

Art Ludwig wrote:

Details on the creation of the files is at
http://www.silcom.com/~aludwig/Amplifier_distortion.htm

Oh I see.

YOU created them ! How about doing it so both peak at 10W (i.e. no clipping the
Rotel) ?

Graham

[Phil Allison]

"Eeysore"

Art Ludwig wrote:

Details on the creation of the files is at
http://www.silcom.com/~aludwig/Amplifier_distortion.htm

Oh I see.

YOU created them ! How about doing it so both peak at 10W (i.e. no
clipping the
Rotel) ?



** The cretin's trumped up test is UTTERLY dishonest.

No-one actually listens to such sine waves at carefully pre- set levels
!!!!


Far as SS amp clipping goes - with normal music or speech programme,
occasional peak clipping is simply NOT audible !!!

This is easily demonstrated with a power amp the includes a fast clipping
indicator - like the Crown IOC light.

Or, by means of an attached oscilloscope.

Soft clipping is greatly over-rated - except for instrument amplifiers.



....... Phil

[Peter Wieck]

On Mar 20, 7:14 pm, "Phil Allison" wrote:

** The cretin's trumped up test is UTTERLY dishonest.

No-one actually listens to such sine waves at carefully pre- set levels
!!!!

The first statement while true has nothing to do with the second
statement. What is more relevant is that even under the pre-supposed
test conditions, the test is utter crap as well as being crafted out
of whole cloth.

The honesty of the tester is not relevant either other than its rather
transparent agenda. I would attribute this to McCoy and its minions
other than for the simple fact that neither it nor its assorted sock-
puppets and miscellaneous creations is clever enough or capable of
even this level of psuedo-science.

Given a "SET" of desired results, I could "Art"-fully design a test to
show those results. No trick... but no connection to the real world as
really experienced either.

What is much more likely is that the cretin-in-question is a troll
seeking recognition and adulation.

Peter Wieck
Wyncote, PA

[Phil Allison]

"Peter Wieck Illiterate ASD ****ed MORON from Hell."



** The cretin's trumped up test is UTTERLY dishonest.

No-one actually listens to such sine waves at carefully pre- set levels
!!!!


The first statement while true has nothing to do with the second
statement.


** Oh, yes it does.

Only the Wieck autistic ****wit cannot grasp the obvious connection.

He DELIBERATELY snipped out the supplied reasoning.

Then has the GALL to say it does not exist !!

What a ****ING CRETINOUS ASSHOLE !!




........ Phil

[Patrick Turner]

Art Ludwig wrote:

You can download three wav files that demonstrate one of the main points of
Cheever's thesis. One file is a pure 440 Hz tone - zero distortion.
Another file mimics a single ended tube amp (SE) at 5% total harmonic
distortion (THD).

But why oh why have any mimic of anything here?

Why not just record the 440Hz after it passes
through an SE triode stage with 5% THD and be done with it????


The last file mimics a solid state amp (SS) at 0.5% THD.
I can clearly hear the SS distortion, and I can't hear the SE distortion
even though it is 10 times higher.

Again, you speak of mimicking something.

PLEASE give us REALITY, so find a BJT amp with 0.5% thd, and use that to
make your recording.

Then come back to us with your reported real world experiences, and we
shall
be VERY INTERESTED!

What is the result of having 20dB global NFB applied around the triode
amp,
and around the SS amp?
Please Specify carefully what sort of SS amp you are selecting; not all
have the same type of distortions.
Try having 40dB NFB around the SS amp.

If you have a BJT amp with 0.5% crossover Dn, then adjust its bias to
minimize the distortion.
Re-record the music tone with bias adjusted for lowest X-over Dn.

To give any real understanding you will need perhaps 10 wave files,
not just 3 which could be seen to have been purposefully set up to
discredit SS amps and favour SET amps,
but which in fact do not contribute to our pool of wisdom about
distortion in amplifiers,
and do not portray the everyday real world experience of amplifier
distortions,
and their significance.

My guess is that the original 440Hz tone without any distortion as you
claim
would not be audibly altered after passing through a low bias current PP
AB BJT amp
with bias correctly adjusted, and with 40dB of global NFB.

However, any test signal created by one Mr Motzart using many other
tones simultaneously
may reveal other sonic secrets.

I could be wrong of course.

Patrick Turner.

The wav files are located at
http://members.cox.net/artludwig/
Details on the creation of the files is at
http://www.silcom.com/~aludwig/Amplifier_distortion.htm

[Art Ludwig]

Interesting. Thank you all for your illuminating responses. The
intellectual level of this group is truly remarkable.
Sincerely, Art Ludwig

"Phil Allison" wrote in message
...

"Peter Wieck Illiterate ASD ****ed MORON from Hell."



** The cretin's trumped up test is UTTERLY dishonest.

No-one actually listens to such sine waves at carefully pre- set levels
!!!!


The first statement while true has nothing to do with the second
statement.


** Oh, yes it does.

Only the Wieck autistic ****wit cannot grasp the obvious connection.

He DELIBERATELY snipped out the supplied reasoning.

Then has the GALL to say it does not exist !!

What a ****ING CRETINOUS ASSHOLE !!




....... Phil

[Arny Krueger]

"Eeyore" wrote in
message
Art Ludwig wrote:

Details on the creation of the files is at
http://www.silcom.com/~aludwig/Amplifier_distortion.htm

Oh I see.

YOU created them ! How about doing it so both peak at 10W
(i.e. no clipping the Rotel) ?

Agreed.

The model of SS amp that Art is using is completely irrelevant to how
amplifiers are generally used for high fidelity purposes. Economical SS amps
have more than enough power to totally avoid clipping, and even avoid
approaching within 3 dB of clipping.

Art is showing something that has been shown many times before - that high
order distortion is far more audible with certain kinds of program material
than equal percentages of low order distortion.

Furthermore, it appears that he has hand-picked program material that tends
to avoid the common cases where even low order distortion is clearly
audible.

[Peter Wieck]

On Mar 21, 11:04 am, "Art Ludwig" wrote:
Interesting. Thank you all for your illuminating responses. The
intellectual level of this group is truly remarkable.

One doubts the 'sincerely'.

However, if you want an intellectual discussion, please bring in a
thesis that passes at least the very first "Smell Test". The tripe you
put in front of us was ripe, at least. For what appears to be your
first post since 2004, you aren't doing so well.

Peter Wieck
Wyncote, PA