snip


So what exactly are you saying here ? That it's right to use the word
"digital" in it's modern context, which all service engineers world-wide
would understand, or not ? Each time I read thru' what you've said, I
arrive at an opposite conclusion ! :-)

When talking to others, it is 'better' to use the meaning of the word, as
THEY define it.

OK. I see what you are saying. What I am saying is that it seems to now be
accepted, pretty much world-wide, that the meaning of the word "digital", in
the context of modern electronics, and specifically to this debate,
amplification, has changed (expanded ?) to encompass topologies and design
schemes, that do not fit into the older, narrower definition, as embraced
and strictly adhered to by William. As I am using the word in its majority
context, as is evidenced by the huge number of references on the web, then I
consider that I *am* using the word as the majority on here *would* define
it, and it is William who is not. Do you think that is a fair and reasonable
assessment of what we have been dancing around ? If you think I am wrong,
please feel free to say so. I will not be offended, and will consider your
reasoning, to see if it reverses, or modifies my position.

I don't believe, however, in this particular case, that it serves any useful
purpose to the general understanding of the class D topology, to ignore the
vast weight of manufacturers data where it *is* defined as being digital, in
favour of William's contention that it is actually analogue.



There is nothing to prevent you from saying [often to yourself]
'"normally",
I use that word to mean xxxxx [but in this case I will use your definition
so
we can communicate].'

I am just trying to point out the fact that it is "pointless" to 'argue'
over
the meaning of a word. Either you choose to agree upon a meaning so you
can
communicate, or you misunderstand or are "mistook".

I ENJOY playing with words and will often go a mile out of my way to make
a
pun.


I *try* to be a careful communicator always, allowing for the fact that
people who are not native English speakers, may well be reading, and
also that many Americans will be reading, who tend to use the language
in a much more 'literal' way than those of us in the UK. That
difference, and the difference in sense of humour, can easily lead to
conflict, so I try to take both of those factors into account when I do
post.

I think that you usually do well.


Thank you for that.



Maybe I don't get it right all the time, but at least I do try ..

Arfa (dah-di-dah)

As I said, the conversation has been intersting and educational.

di-di-di-dah-di-dah



tu su dit dit



CW was never my preferred mode. Is that a 'final' final ? If so, back at ya,
OM d;~}

Arfa




--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap

In some ways, it is the way that you pick on tiny facets, and labour
them to the point of being excruciating, to defend a position that is
often contentious, or even potentially untenable, that gives me the
most problem with trying to have a discussion with you. You berate
people for not being able to take on an alternative view of something
that you consider them to be wrong on, but then flatly refuse to even
consider modifying your own position.

Why should I, when I'm right? We don't take a vote on whether the Earth is
flat, or similar issues. Some things are objectively true, others are a
matter of opinion, and not debatable. This is one of the latter.

I don't care much for RegeR's music (which might be poor music in some
"objective" fashion), but I listen to it occasionally to see if my taste has
changed. But if some tells me that he has proof Special Relativity is wrong,
I'm not like to consider modifying my opinion that it's right.

(Amost) whenever someone tells me I'm wrong about something, I give it
careful consideration. And you know what? I'm often wrong.


Just as a matter of interest, do you consider a circuit constructed
simple logic gates, to be 'digital', even though no numeric values
are being handled by it ?

That's not an unreasonable question.

The answer is "yes", because the output of the circuit is presumably one of
two logic states -- 0 or 1, true or false. Digital is about quantization --
not numbers, per se.

This is what gets so many people torqued up. When I point out that
quantizing a signal level converts it to digital, they start yelling "Where
are the numbers!". You don't need numbers. All you need is to reduce the
data to a finite number of states or values. And then the data are digital.

"William Sommerwerck" wrote in message
...
"Class D amplifiers can be controlled by either analog or digital
circuits.
The digital control introduces additional distortion called quantization
error caused by its conversion of the input signal to a digital value."

I'm sorry, but I consider that to be an ill-informed gobbledy-gook
statement.

It's overly terse, but quite correct (though I would have said "signals"
rather than "circuits").



It is not. We've already agreed that the signal in a class D topology
amplifier, is not converted to any kind of digital value at any point. This
is the fundamental tenet upon which you have based your entire argument that
it is not a digital mode. Since the signal has not been 'quantized' into a
step value, no such distortion that would normally be associated with
quantization error, has been introduced.

I think that you are mis-understanding what the author is trying to convey
in his statement. When he said "controlled by ...... circuits ", that's
probably exactly what he meant, and was referring to control of volume,
balance etc by use of either a fully analogue pot, or a digitally-controlled
pot IC.

However, even if a pot IC is employed, no quantization of the signal takes
place within it, and if for no other reason, he is wrong to suggest
otherwise. A digitally-controlled pot IC is merely a step attenuator, based
on FET-switched resistors. Thus, for all practical purposes, it is no more
than a conventional resistive pot, and introduces no more or less distortion
into the signal path, than a conventional resistive pot would.

Therefore, no matter which way you take his intended meaning, it is still
actually meaning-LESS and ill-informed gobbledy-gook.

Arfa

"Arfa Daily" wrote in message
...

"William Sommerwerck" wrote in message
...
"Class D amplifiers can be controlled by either analog or digital
circuits.
The digital control introduces additional distortion called
quantization
error caused by its conversion of the input signal to a digital
value."

I'm sorry, but I consider that to be an ill-informed gobbledy-gook
statement.

It's overly terse, but quite correct (though I would have said "signals"
rather than "circuits").

It is not. We've already agreed that the signal in a class D topology
amplifier, is not converted to any kind of digital value at any point.


No, we didn't. I said that most (if not all) PWM amplifiers are analog. But
you can have a digital PWM amplifier.



I think that you are mis-understanding what the author is trying to convey
in his statement. When he said "controlled by ...... circuits ",
that's
probably exactly what he meant, and was referring to control of volume,
balance etc by use of either a fully analogue pot, or a
digitally-controlled
pot IC.

It's possible, and I agree it's ambiguous, but given the way he states it,
ADC is implied.


However, even if a pot IC is employed, no quantization of the signal takes
place within it, and if for no other reason, he is wrong to suggest
otherwise. A digitally-controlled pot IC is merely a step attenuator,
based
on FET-switched resistors. Thus, for all practical purposes, it is no more
than a conventional resistive pot, and introduces no more or less
distortion
into the signal path, than a conventional resistive pot would.

You're right in principle, but the way this piece is written, ADC is
implied.

"Arfa Daily" wrote in
:

"Class D amplifiers can be controlled by either analog or digital
circuits.
The digital control introduces additional distortion called
quantization error caused by its conversion of the input signal to a
digital value."

I'm sorry, but I consider that to be an ill-informed gobbledy-gook


Sorry to interject again but the quoted person is saying that the width of
the pulses can be controlled by either an analogue means or by a digital
means.

For example, the frequency of an oscillator could be controlled by
directly varying the voltage across a vari-cap (diode) with the audio
signal. This would be an analogue method of modulating the frequency of an
oscillator, and thus the width of pulses when the oscillator's output is
converted to a square wave at the same fundamental frequency.

Or the frequency could be controlled by taking the audio signal, doing A
to D conversion and using a computer controlled PLL to generate a signal
which varies in frequency.

He goes on to say that in the case where digital control is used, an
additional distortion called 'quantization error' is introduced.

There is nothing ill informed or gobbledy gook about what what was said.
It is similar to saying that the frequency of an FM transmitter can be
controlled by analog or digital circuits, and if controlled by digital
circuits, there is an additional distortion introduced....

There is nothing there that has anything to do with a 'Pot' [unless you
mean potential, rather than potentiometer].



--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap

Arfa Daily wrote:

"William Sommerwerck" wrote in message

"The letter D used to designate this amplifier class is simply the next
letter after C, and does not stand for digital. Class D and Class E
amplifiers are sometimes mistakenly described as "digital" because the
output waveform superficially resembles a pulse-train of digital symbols,
but a Class D amplifier merely converts an input waveform into a
continuously pulse-width modulated (square wave) analog signal. (A digital
waveform would be pulse-code modulated.)"

Except for the last sentence, this is a correct statement.

Only "mistakenly described" if you ignore the views of the vast majority of
IC and hardware manufacturers, and apply the narrow out of date definition
of "digital", which you do ...

Hey you can get 'digital' cables and headphones now for around $3 ! It's the
most abused term in the world apart maybe from 'an honest politician'.

Graham

Eeyore wrote:


Arfa Daily wrote:


"William Sommerwerck" wrote in message

"The letter D used to designate this amplifier class is simply the next
letter after C, and does not stand for digital. Class D and Class E
amplifiers are sometimes mistakenly described as "digital" because the
output waveform superficially resembles a pulse-train of digital symbols,
but a Class D amplifier merely converts an input waveform into a
continuously pulse-width modulated (square wave) analog signal. (A digital
waveform would be pulse-code modulated.)"

Except for the last sentence, this is a correct statement.

Only "mistakenly described" if you ignore the views of the vast majority of
IC and hardware manufacturers, and apply the narrow out of date definition
of "digital", which you do ...


Hey you can get 'digital' cables and headphones now for around $3 ! It's the
most abused term in the world apart maybe from 'an honest politician'.

Graham


Oh goody goody, how about a digital antenna!

http://webpages.charter.net/jamie_5"