John Byrns wrote:

In article , Patrick Turner
wrote:

John Stewart wrote:
(snip),

John- Go to
http://www.tvhandbook.com/support/pd...hapter13_3.pdf

where you will find an excellant paper certified free of Bull****. About 19
pages in pdf.

Thanks JH.

Its a pity one cannot save the document.

What do you mean "Its a pity one cannot save the document"? I had no
trouble saving the document, although I am not sure why one might want to
save it for any length of time, it really isn't a very inspiring document.

Its quite informative.

But no useful practical schematics for the test gear.

But the file menu showed no save-as option, no other way of saving it
here seemed to be possible...maybe they don't want you to save it.

Patrick Turner.



Regards,

John Byrns

Surf my web pages at, http://users.rcn.com/jbyrns/

wrote in message
oups.com...

Generally, I am not a fashion victim. I don't care what is new, I ask
first, 'What will it do for me?' I always operate several OS updates
and at least one hardware generation** behind Apple; I am nobody's
unpaid beta-tester!

Andre Jute


New OS issues from Apple seem to be pretty stable.
The Mac seems to be the platform of choice for graphic artists,
ad agencies, and audio post production people - a pretty
intelligent bunch in my experience.

Most digital audio workstations use a Mac front end.
The ubiquitous ProTools which flies on the Mac,
is also available on the PC platform but seems
decidedly "sticky"

I enjoy the Mac's multitasking capabilities.
One can back up a project to Exabite, copy the automation
data to diskette, make a digital clone to DAT and print the
invoice all at the same time:-)


Iain

Patrick Turner wrote:

Nah, when planes crash, lotsa silver coloured puddles of aluminium
laying around, a few charred bones and fried plastics.

Perhaps a few charred pieces of luggage as well?


"Dark" is a favourite trendy word used to describe anything
mysterious and new and unsettling.
So there is dark music, dark movie plots, dark art.


Ah, but Black is far darker than dark, or something like that... I wouldn't
consider Black Metal trendy, after all it started in the 80'ies. But perhaps
heavily over-accessorized, I think the number and size of the spikes, inverted
crosses etc have gotten out of hand.


Upon what to they suck prey tell?


A favorite object of suction seems to be alcohol containers


I'd rather read the news paper than listen to any modern idea of dark
music, unless its a top notch band. I like Louis Armstrong,
and Sammy Davis, and many dark artists.....


Hehe, we all have our little quirks

Regards,
Kimjand

"Kim Johan Andersson" wrote in message
...

I'd rather read the news paper than listen to any modern idea of dark
music, unless its a top notch band. I like Louis Armstrong,
and Sammy Davis, and many dark artists.....


Hehe, we all have our little quirks

Dark artists? I like that. A politically correct phrase if
ever there was one.

There is a famous quote by Cootie Williams
(himself an Afro American) lead trumpet with the
Duke Ellington Orchestra. The first time he heard the
Louis Armstrong band, he is said to have exclaimed:
"Man, dem ******s can sure play!"

Iain

"Patrick Turner" wrote

But the file menu showed no save-as option, no other way of saving
it
here seemed to be possible...maybe they don't want you to save it.

The little disk icon should be available for saving...tlh corner.

cheers, Ian

Ian Iveson wrote:

"Patrick Turner" wrote

But the file menu showed no save-as option, no other way of saving
it
here seemed to be possible...maybe they don't want you to save it.

The little disk icon should be available for saving...tlh corner.

Yep, I know about the little disk icon; it works most of the time but
not with that one.

Patrick Turner.



cheers, Ian

In article , Patrick Turner
wrote:

John Byrns wrote:

In article , Patrick Turner
wrote:

John Stewart wrote:
(snip),

John- Go to
http://www.tvhandbook.com/support/pd...hapter13_3.pdf

where you will find an excellant paper certified free of Bull****.
About 19
pages in pdf.

Thanks JH.

Its a pity one cannot save the document.

What do you mean "Its a pity one cannot save the document"? I had no
trouble saving the document, although I am not sure why one might want to
save it for any length of time, it really isn't a very inspiring document.

Its quite informative.

It seemed like a rehash of known information to me.

But no useful practical schematics for the test gear.

I wasn't expecting that.

But the file menu showed no save-as option, no other way of saving it
here seemed to be possible...maybe they don't want you to save it.

Your "file menu" must be defective, I just told it to save and it did.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/

The different distortion behavior of triodes & pentodes is widely known.
The reason for it comes from the different shape of the I/V curve: a simple
power law for triodes where I is proportional to the 3/2 power of V, and a
log function for pentodes. The Fourier analysis of these different
functions shows in the first case the presence of even-order harmonics only,
rapidly fading, while in the second case both even and odd-order harmonics
are present and slowly fading. This is better explained in Morgan Jones'
"Valve Amplifier" book: if You're a math guru, be patient if I wrote some
bull, I got my Chemical Engineering degree in 1990 and I never messed with
high-level math ever since.
This different harmonic content is particularly important for audio 'cause
2nd H. is just the same tone, one octave higher, and is not perceived as
disturbing. High-order odd harmonics are NOT harmonically correlated with
the original tone and sound awful. There's even a physiological reason: the
acoustic nerve gets overloaded when many harmonically unrelated frequencies
need to be transmitted, this is why Ella's voice sounds better than a
splittering glass. There was an interesting article on "Scientific
American" on this subject, about 1 year ago I think.
Without resorting to Fourier analysis, triode distortion nulling due to PP
operation can be easily understood from anode curves. It is apparent that
the curves are more "crowded" in the high voltage zone (in the right part of
the graph), therefore the same grid voltage swing produces a higher anode
voltage swing during the positive half cycle (when grid V moves "to the
left").
In SE operation, therefore, one half of an incoming sine wave becomes "more
amplificated" than the other one, and this corresponds essentially to 2nd H.
When using PP, the negative half is phase inverted and fed to the other tube
in the PP couple; then, the two halves are "tied" again in the output
transformer. This way, the output is always "symmetric" 'cause only the
"positive" part of eac valve's cycle is used.

Hope it helped, otherwise I'll need to wipe the dust off my old math book
and I'm scared to face the evidence of my intellectual decadence...

Ciao

Fabio



"J.Koning" ha scritto nel messaggio
...

"Stewart Pinkerton" wrote in message
...

[...]
Triodes distortion is mainly 2nd harmonic,
[...]
Why?

Because it is. The full answer is highly technical. Does it matter?
I'm not afraid to do some reading, so, throw-up.


[...]
Pentodes produce most odd-order distortion,
[...]
Why?

Because they do. The full answer is highly technical. Does it matter?
I'm not afraid to do some reading, so, throw-up.

Rgds,
Jan.

Fabio Berutti wrote:

The different distortion behavior of triodes & pentodes is widely known.
The reason for it comes from the different shape of the I/V curve: a simple
power law for triodes where I is proportional to the 3/2 power of V, and a
log function for pentodes. The Fourier analysis of these different
functions shows in the first case the presence of even-order harmonics only,
rapidly fading, while in the second case both even and odd-order harmonics
are present and slowly fading.

Indeed. I have been wondering about all this for days.
The pentode curves vary rather a lot between each other, and there does
not seem to be a general rule for the *rate* of 3H increase for a given output
power and declining RL.


This is better explained in Morgan Jones'
"Valve Amplifier" book: if You're a math guru, be patient if I wrote some
bull, I got my Chemical Engineering degree in 1990 and I never messed with
high-level math ever since.

RDH4 does some math, and does some graphical analysis,
but notice how there is no ruler which can be laid along the curves
to estimate the 3H.

By far the best method to understand it all is to build and measure.

Sorry, but there really is nothing like an injection of reality
to aid the mind to understand.


This different harmonic content is particularly important for audio 'cause
2nd H. is just the same tone, one octave higher, and is not perceived as
disturbing. High-order odd harmonics are NOT harmonically correlated with
the original tone and sound awful.

Not necessarily Fabio.
Music contains myriads of tones, and a pluck of a single
fresh guitar string near the bridge yeilds many harmonics,
2,3,4,5,6,7,8,9,1011,12,13,14,14,15, etc.
Not all of these sound pleasant if they were individually boosted
to an unatural level, certainly not the 7th H.
It don't relate to a musical tone.

2,3,4,5 are related, and many others, but hey, there is a lot on all this in
RDH4
and musical tone frequencies are given, so understanding is possible.
What makes an ancient Italian cello or violin sound magnificent?
Its the mix of harmonics, many are present.
What make Pavarotti a darling of the opera? his forment, or harmonics in his
voice.
Most of us have horrid harmonics in our voices, and we'd sound awful
if we went before the limelight.
Nature just gives the harmonics it wants to give us, and we either like it or
suffer it. Some cannot stand a saxophone; some can only
like Stratocaster.

Electronics subjects a signal to some increased harmonic content,
and if it was only harmonic distortion we got things would be OK,
but the intermodulation products make what is noise like mush in the
signal, not pretty at all, so we should minimise their quantity rationally
but no need to be obsessive.
Even in a guitar, a bass string tugging on a bridge will affect treble
strings.....




There's even a physiological reason: the
acoustic nerve gets overloaded when many harmonically unrelated frequencies
need to be transmitted, this is why Ella's voice sounds better than a
splittering glass.

Especially when Ms Fitzgerald is singing with Satchmo.

There was an interesting article on "Scientific
American" on this subject, about 1 year ago I think.
Without resorting to Fourier analysis, triode distortion nulling due to PP
operation can be easily understood from anode curves. It is apparent that
the curves are more "crowded" in the high voltage zone (in the right part of
the graph), therefore the same grid voltage swing produces a higher anode
voltage swing during the positive half cycle (when grid V moves "to the
left").

That's a function of higher gm as Ia increases.
This increase makes up for the lower gm when both tubes are working
in class A, and then you have the more gradual cut off nature of triodes, which
makes
class AB triode amps rather forgivable amplifiers than any other.




In SE operation, therefore, one half of an incoming sine wave becomes "more
amplificated" than the other one, and this corresponds essentially to 2nd H.
When using PP, the negative half is phase inverted and fed to the other tube
in the PP couple; then, the two halves are "tied" again in the output
transformer. This way, the output is always "symmetric" 'cause only the
"positive" part of eac valve's cycle is used.

Usually most PP amps exhibit mild compression of their wave forms
to both +ve and -ve peaks of the waves due to the symetrical
"pull down" of voltage at each anode as load current increases.
There is reluctance of the tubes to keep producing current linearly
as voltage excursion approaches extremes.
We need to differentiate the increase in 3H so often seen with reduction of
RL value for a given output power with a reduction of extreme "on"
resistance and resulting 3H from the mis-biasing of cathode bias with AB amps,
or the result of gain change after going past class A conditions.





Hope it helped, otherwise I'll need to wipe the dust off my old math book
and I'm scared to face the evidence of my intellectual decadence...

Just measure an amp. That will tell what is valid for that amp.
Then measure another, and that will tell you about itself,
and so on.
Don't expect the same story.

Patrick Turner.




Ciao

Fabio

"J.Koning" ha scritto nel messaggio
...

"Stewart Pinkerton" wrote in message
...

[...]
Triodes distortion is mainly 2nd harmonic,
[...]
Why?

Because it is. The full answer is highly technical. Does it matter?
I'm not afraid to do some reading, so, throw-up.


[...]
Pentodes produce most odd-order distortion,
[...]
Why?

Because they do. The full answer is highly technical. Does it matter?
I'm not afraid to do some reading, so, throw-up.

Rgds,
Jan.