On Thu, 05 Aug 2004 22:02:05 GMT, "Trevor Wilson"
wrote:

Provided an amplifier is competently designed and reasonably biassed (into
the linear operating region of the active deive/s) more bias current (Class
A) is simply overkill and unnecessary. Moreover, the Class A operating point
of an amplifier is completley dependent upon the load connected to that
amplifier. For instance: Stewart's Krell is rated for 50 Watts Class A
operation into an 8 Ohm load. Thus, it's Class A operating point is 25 Watts
@ 4 Ohms and 12.5 Watts @ 2 Ohms, etc.

Quite so - a basic point often overlooked by those who claim that
Class A amps somehow sound better than others. While my Krell will
happily pump out 195 watts/channel into 4 ohms all day long, it's
certainly not operating in Class A while doing this!

As for the statement that an amplifier is Class A, most are not. Here's a
few I've measured:

Musical Fidelity A370 - Rated at 185 Watts Class A. Actual Class A power -
15 Watts.
Musical Fidelity A1 - Rated at 20 Watts Class A - Actual Class A power - 2
Watts.
Krell KSA150 - Inferred Class A power 150 Watts - Actual Class A power - 35
Watts.
Krell KSA200 - Inferred Class A power 200 Watts - Actual Class A power - 40
Watts.
Marantz PM80-II (Class A switched on) - Claimed Class A power 30 Watts -
Actual Class A power - 3 Watts.

And my Audiolab 8000P, rated at 100 watts Class AB, actual Class A
power less than 1 watt - and it sounds exactly like my Krell.........
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Fri, 6 Aug 2004 03:19:19 +0100, "Keith G"
wrote:

"Trevor Wilson" wrote

**And my question was: Who cares?

I do.

Well, you shouldn't, because it doesn't matter.


Full Class A operation of any amplifier
(save SE products, of course) is simply not necessary. I will say this,
however: Opertaing a crappily designed amplifier into Class A, will likely
make it sound better than it otherwise would. Operating a properly designed
amplifier into Class A, will not make it any better.

Sez who?

Anyone who knows anything about amplifier design. Read Doug Self's
excellent book on the matter, where he clearly shows (among lots of
other very good stuff) that the most accurate possible amplifier is in
fact a Class AB design.

All Class A does, is reduce the expected lifetime of the amp by making
it run a lot hotter than it would otherwise have to!

Both my valve are *fully* Class A and'experts' have assured me it makes a
Difference....!!!

I'm glad you put quote marks around 'experts', because they clearly
lack expertise..................

**What is the load impedance? Does it vary? Your unamed "experts" are
entitled to their opinions. Their opinions will be givne the weighting they
deserve (ie: none).

A thousand references on the Net, a million references in hifi comix and two
people running their own 'Audio' companies that I have personally conversed
with beats your opinions (sorry), in my book....

Keith, you are quite simply talking out of your arse here. You will
not find *any* authoritative article *anywhere*, that shows class A
operation as providing any real-world advantage - except of course for
single-ended operation, where you don't have much choice.

There are occasions where, as Trevor already said, Class A operation
will make the best of a poor design. This does not however make a good
design any better, and please note that all of the *really* good valve
amps, such as the ARC VT100 already mentioned, are Class AB designs.

Remember, you're talking here to someone who both owns one of the
classic 'Class A' amps, and has designed and built several dozen amps,
both Class A and Class AB.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Thu, 05 Aug 2004 22:05:54 GMT, "Trevor Wilson"
wrote:

**I dated a Scotswoman for awhile. Yep, I even ate Haggis. She never told me
what was in it. It tasted fine.

Best not to ask, really........... :-)
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Fri, 6 Aug 2004 06:13:10 +0000 (UTC), Stewart Pinkerton
wrote:

On Thu, 05 Aug 2004 22:05:54 GMT, "Trevor Wilson"
wrote:

**I dated a Scotswoman for awhile. Yep, I even ate Haggis. She never told me
what was in it. It tasted fine.

Best not to ask, really........... :-)

Must admit, I fell straight into major euphemism mode there too for a
moment.

d

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

In article , Stewart Pinkerton
wrote:
On Fri, 6 Aug 2004 03:19:19 +0100, "Keith G"
wrote:

"Trevor Wilson" wrote


Both my valve are *fully* Class A and'experts' have assured me it
makes a Difference....!!!

I'm glad you put quote marks around 'experts', because they clearly lack
expertise..................

**What is the load impedance? Does it vary? Your unamed "experts" are
entitled to their opinions. Their opinions will be givne the
weighting they deserve (ie: none).

A thousand references on the Net, a million references in hifi comix
and two people running their own 'Audio' companies that I have
personally conversed with beats your opinions (sorry), in my book....

Keith, you are quite simply talking out of your arse here. You will not
find *any* authoritative article *anywhere*, that shows class A
operation as providing any real-world advantage - except of course for
single-ended operation, where you don't have much choice.

Alas, many articles that are presented as if 'authoritative' say all kinds
of muddled and unreliable things about amplifiers. Witness, for example,
the series that has been running in 'Electronics World' recently... :-/

I had hoped that things like these had died out, but alas not...

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

In article , Stewart
Pinkerton
wrote:
On Thu, 05 Aug 2004 22:05:54 GMT, "Trevor Wilson"
wrote:

**I dated a Scotswoman for awhile. Yep, I even ate Haggis. She never
told me what was in it. It tasted fine.

Best not to ask, really........... :-)

A few years ago - during the time when the USA had banned our beef as a
result of BSE - we had a NATO deligation visit us. We served a choice of
Haggis or Roast Beef at at the celegration dinner. :-

... the vistors all chose Haggis.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

And my Audiolab 8000P, rated at 100 watts Class AB, actual Class A
power less than 1 watt - and it sounds exactly like my Krell.........

So why do you have the Krell then?.....

--
Tony Sayer

In article , Tat Chan
writes
Trevor Wilson wrote:

"Tat Chan" wrote in message
...

**I know what you mean. My masseusse is a (female) Polish wrestler of
olympic quality (she wrestles men, here in Oz, due to the lack of female
competition. She usually beats the men, too. It really ****es them off.
Sidenote: She looks more like a model than a wrestler.

so is she going to Athens? More importantly, did she appear in the Black
+ White athlete photo shoot?




**A reasonable desire. I visited some newly arrived Vietnamese guys once.
none could speak any English. The only word we had in common was: "Beer". We
got on just fine, after that. :-)

And you would have picked up the words "Ba Ba Ba" ...



**You'll fit in just fine ion most areas of Sydney. I'm in Hurstville and I
am in the minority ethnic group (Anglo).

Haven't been down that way in a while, but I take it that Hurstville has
lots of Chinese people (from Hong Kong?)

Ashfield == mainland Chinese
Chatswood == Taiwanese and Hongkies


**Dream on. There are 1.3 Billion Chinese who desire a better standard of
living. That will take quite a few years. India is likely to be the next low
cost manufacturing nation.

I don't know why India isn't a manufacturing nation. They are a services
nation, since lots of IT and call centre work gets outsourced there!
Could be due to them being able to read/write English, unlike the Chinese.


Get a mobile phone on the 3 network and you can have the "pleasure"
of speaking to them all too often
--
Tony Sayer

As I thought this thread has degenerated into the usual mindless mud slinging.
Reminds me of a friend who went to Japan. He came back the first time
depressed that he couldn't communicate with anybody since nobody spoke English.
The second time he came back he announced "I've made a breakthrough - I just go
up to people and say "Do you speak Japanese"'

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

"Stewart Pinkerton" wrote


Keith, you are quite simply talking out of your arse here.


Stop complaining - you got to let others take a turn occasionally! ;-)


You will
not find *any* authoritative article *anywhere*, that shows class A
operation as providing any real-world advantage - except of course for
single-ended operation, where you don't have much choice.


If you Google "Class A" and "Amplifier" you will get 62,500 results. If you
Google "Class A Amplifier" you get 3,990.....


There are occasions where, as Trevor already said, Class A operation
will make the best of a poor design. This does not however make a good
design any better, and please note that all of the *really* good valve
amps, such as the ARC VT100 already mentioned, are Class AB designs.

Remember, you're talking here to someone who both owns one of the
classic 'Class A' amps, and has designed and built several dozen amps,
both Class A and Class AB.


........which, added to say even the last 'expert' I have had discussions
with - a 'professional amp builder and designer' (who incidentally attended
the same school as your wife and my partner....) kinda beats your own not
inconsiderable record of amp-building. (Details off-list, if you are
curious...)

Further refine the search with "Fidelity" and you will reduce the number to
only 641.....

Now, to clarify my position - I have only a crude idea of the way 'Class A'
works but with only 2 out of 6 of my amps being 'Fully Class A' take it that
I have not got a 'serious weed up my arse' about it, other than for 'special
amps'. I do wonder and suspect that FCA is the very thing that gives the amp
those special 'tactile' qualites that I supect you (as a numerologist) have
never considered and the the comix (as bollocologists) can't stop going on
about.

I have different requirements from an amplifier to you - the next amp I
throw together *will* be FCA and it *will* be a SET because, guess what? - I
like them and have heard or seen no argument here (or anwhere else) to put
me off.