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Andre Jute Andre Jute is offline
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Default Velleman K40x0, the very model of an all-round amp

On Oct 19, 12:11 am, "Iain Churches" wrote:
"Andre Jute" wrote

Real tubies build real valve amp kits, like
my Velleman K4000, three EL34 per side for 18W in Class A and 101W in
Class B (measured, they claim only 16/96W). Now that is an amp that
leaves hairy footprints.


Interesting you should mention the Velleman. It is indeed a good sounding
amp. It is a long time since I have seen a K4000, but I seem to recollect
it had four EL34's in push pull parallel per side.


PPP.

It seems as though the K4000 is discontinued.


Mine is ancient. Early to mid-1990s, at a guess, without looking up
the reviews I wrote of it.

I listened to a 4040 not too long ago, with a pair of splendid Tannoy
Canterbury
SE speakers. Very pleasing indeed. The amp was running far below its full
power potential.


Quite a bizarre thing to say, I suppose, but the Velleman is probably
overmatched to the Tannoys. It has around 16 to 18W in Class A alone.
I sometimes used mine for driving a bass bin, where its 100W in Class
A/B could sometimes come into play, at least theoretically (I'm not a
headbanger).

The noise floor was exceptionally low. Later, a quick
look on the bench revealed the noise floor to be 100µV, so a
SNR of 105dB and at 96W, the THD was only 0.1%


It depends on your outlook whether you view the Velleman K40x0 as that
rare thing, a perfect all-round amp -- or as a perfectly schizophrenic
amp: on the one hand superbly well designed and good-sounding,
escpecially in that very hefty Class A segment, a delicate match to
ESL-63, on the other hand a brutish bass thumper on demand. As an all-
round amp of excellent quality and durability it is of course a very
great bargain at the price.

The Belgians know how to make more than just chocolates:-)


We used to make a round trip of 50 miles to buy Belgian chocolates in
Cork...

Regards
Iain


Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

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Default Velleman K40x0, the very model of an all-round amp


overmatched to the Tannoys. It has around 16 to 18W in Class A alone.
I sometimes used mine for driving a bass bin, where its 100W in Class
A/B could sometimes come into play, at least theoretically (I'm not a
headbanger).




hey-Hey!!!,
An amp with maximum output happening with one phase of its PP set cut
off is *NOT* class A. A real class A amp has both phases conducting at
maximum power, and not from some variable pitch grid winding, remote
cut-off stuff either.

That Vellman amp is an AB, and barely so at that.
cheers,
Douglas

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John Byrns John Byrns is offline
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Default Velleman K40x0, the very model of an all-round amp

In article . com,
Multi-grid wrote:

hey-Hey!!!,
An amp with maximum output happening with one phase of its PP set cut
off is *NOT* class A. A real class A amp has both phases conducting at
maximum power, and not from some variable pitch grid winding, remote
cut-off stuff either.


Is there actually a power tube with a variable pitch grid winding
designed to do this? I never heard about it before, inquiring minds
want to know more.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
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Andre Jute Andre Jute is offline
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Default Velleman K40x0, the very model of an all-round amp

On Oct 19, 3:50 pm, Multi-grid wrote:
overmatched to the Tannoys. It has around 16 to 18W in Class A alone.
I sometimes used mine for driving a bass bin, where its 100W in Class
A/B could sometimes come into play, at least theoretically (I'm not a
headbanger).


hey-Hey!!!,
An amp with maximum output happening with one phase of its PP set cut
off is *NOT* class A. A real class A amp has both phases conducting at
maximum power, and not from some variable pitch grid winding, remote
cut-off stuff either.

That Vellman amp is an AB, and barely so at that.
cheers,
Douglas


What are you on about, Dougles? I just told you, it is a class AB amp.
Class AB amps by definition have some class A output and the rest in
Class B. If you want an unadulterated Class A amp with a 100W output,
you're going to be paying real money, and if you're a snob who wants
it in SE, you're going to be paying Range Rover Vogue money. I know; I
built an 80W SE amp, which of course by definition ran only in Class
A. The Velleman is relatively inexpensive, very sturdy, very good
value amplifier kit from the most famous makers of all kinds of
electronic kits in the world. But its price will look a tip to a
doorman by the time you finish paying for a 100W Class A amp.

And what's that rubbish about "maximum output" anyway? By definition a
class AB amp's Class A output is at some lower power than maximum,
otherwise it would be a Class A amp, period. The whole point about a
Class AB amp is that most music is played where such an amp makes its
sweetest sounds, but that it has headroom for any contingency, though
you sacrifice a little something in quality when that headroom is
taken up.

If your taste is so refined that you must have nothing but Class A,
there are a bunch of designs for Class A amps on my netsite. And, for
the sake of completeness, my own favourite everyday amp is my own T113
"Triple Threat" design, which runs PP EL34s in triode and strictly in
Class A. But you'd need about 8 of those to get 100W...

You know an audiophool snob when he starts talking about "pure" Class
A...

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

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Multi-grid Multi-grid is offline
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Default Velleman K40x0, the very model of an all-round amp

On Oct 20, 3:34 am, Andre Jute wrote:
On Oct 19, 3:50 pm, Multi-grid wrote:

overmatched to the Tannoys. It has around 16 to 18W in Class A alone.
I sometimes used mine for driving a bass bin, where its 100W in Class
A/B could sometimes come into play, at least theoretically (I'm not a
headbanger).


hey-Hey!!!,
An amp with maximum output happening with one phase of its PP set cut
off is *NOT* class A. A real class A amp has both phases conducting at
maximum power, and not from some variable pitch grid winding, remote
cut-off stuff either.


That Vellman amp is an AB, and barely so at that.
cheers,
Douglas


What are you on about, Dougles? I just told you, it is a class AB amp.
Class AB amps by definition have some class A output and the rest in
Class B.


No it doesn't, it has no power in Class A. That's why it is called an
AB amp. It is really simple.


If you want an unadulterated Class A amp with a 100W output,
you're going to be paying real money, and if you're a snob who wants
it in SE, you're going to be paying Range Rover Vogue money. I know; I
built an 80W SE amp, which of course by definition ran only in Class
A. The Velleman is relatively inexpensive, very sturdy, very good
value amplifier kit from the most famous makers of all kinds of
electronic kits in the world. But its price will look a tip to a
doorman by the time you finish paying for a 100W Class A amp.


I don't recall ever telling you what I wanted, or owned, or for that
matter what I've built. None of that has any bearing on your marketing-
based dafynishion of what you'd like an AB amp to be.


And what's that rubbish about "maximum output" anyway? By definition a
class AB amp's Class A output is at some lower power than maximum,
otherwise it would be a Class A amp, period.


Just because both of the finals are conducting does not mean it is
Class A. That is reserved for amps that keep both conducting *AT FULL
POWER*. Why *******ize the definition just because some marketing fool
likes says it's OK? A Class AB amp doesn't have any Class A output.
Both phases conducting does not make Class A....or is that too hard to
grasp?



The whole point about a
Class AB amp is that most music is played where such an amp makes its
sweetest sounds, but that it has headroom for any contingency, though
you sacrifice a little something in quality when that headroom is
taken up.

If your taste is so refined that you must have nothing but Class A,
there are a bunch of designs for Class A amps on my netsite.


I don't think I'll be considering any of those amps. Kinda off-the-
rack and boring.


And, for
the sake of completeness, my own favourite everyday amp is my own T113
"Triple Threat" design, which runs PP EL34s in triode and strictly in
Class A. But you'd need about 8 of those to get 100W...


You know an audiophool snob when he starts talking about "pure" Class
A...

Probably just somebody who knows how to use the language properly. You
can join the club anytime you wish to conduct yourself properly....and
leave it just as quickly.
cheers,
Douglas




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Default Velleman K40x0, the very model of an all-round amp

On Oct 20, 2:18 am, John Byrns wrote:
In article . com,

Multi-grid wrote:
hey-Hey!!!,
An amp with maximum output happening with one phase of its PP set cut
off is *NOT* class A. A real class A amp has both phases conducting at
maximum power, and not from some variable pitch grid winding, remote
cut-off stuff either.


Is there actually a power tube with a variable pitch grid winding
designed to do this? I never heard about it before, inquiring minds
want to know more.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/


Hi John,
I don't know of any either, but given the definition of Class A, I
thought it wise to rule out the remote cut-off behaviour that *COULD*
provide a loophole to somebody fixed on disagreement, yes?
cheers,
Douglas


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Default Velleman K40x0, the very model of an all-round amp

On Oct 19, 7:27 am, Andre Jute wrote:
On Oct 19, 12:11 am, "Iain Churches" wrote:

"Andre Jute" wrote


Real tubies build real valve amp kits, like
my Velleman K4000, three EL34 per side for 18W in Class A and 101W in
Class B (measured, they claim only 16/96W). Now that is an amp that
leaves hairy footprints.


Interesting you should mention the Velleman. It is indeed a good sounding
amp. It is a long time since I have seen a K4000, but I seem to recollect
it had four EL34's in push pull parallel per side.


PPP.

It seems as though the K4000 is discontinued.


Mine is ancient. Early to mid-1990s, at a guess, without looking up
the reviews I wrote of it.

I listened to a 4040 not too long ago, with a pair of splendid Tannoy
Canterbury
SE speakers. Very pleasing indeed. The amp was running far below its full
power potential.


Quite a bizarre thing to say, I suppose, but the Velleman is probably
overmatched to the Tannoys. It has around 16 to 18W in Class A alone.
I sometimes used mine for driving a bass bin, where its 100W in Class
A/B could sometimes come into play, at least theoretically (I'm not a
headbanger).

The noise floor was exceptionally low. Later, a quick
look on the bench revealed the noise floor to be 100µV, so a
SNR of 105dB and at 96W, the THD was only 0.1%


It depends on your outlook whether you view the Velleman K40x0 as that
rare thing, a perfect all-round amp -- or as a perfectly schizophrenic
amp: on the one hand superbly well designed and good-sounding,
escpecially in that very hefty Class A segment, a delicate match to
ESL-63, on the other hand a brutish bass thumper on demand. As an all-
round amp of excellent quality and durability it is of course a very
great bargain at the price.

The Belgians know how to make more than just chocolates:-)


We used to make a round trip of 50 miles to buy Belgian chocolates in
Cork...

Regards
Iain


Andre Jute
Visit Jute on Amps athttp://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review


Of all the decent amps out there why would you pick something like
This?

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Default Velleman K40x0, the very model of an all-round amp

On Oct 19, 6:37 pm, Multi-grid wrote:
On Oct 20, 3:34 am, Andre Jute wrote:



On Oct 19, 3:50 pm, Multi-grid wrote:


overmatched to the Tannoys. It has around 16 to 18W in Class A alone.
I sometimes used mine for driving a bass bin, where its 100W in Class
A/B could sometimes come into play, at least theoretically (I'm not a
headbanger).


hey-Hey!!!,
An amp with maximum output happening with one phase of its PP set cut
off is *NOT* class A. A real class A amp has both phases conducting at
maximum power, and not from some variable pitch grid winding, remote
cut-off stuff either.


That Vellman amp is an AB, and barely so at that.
cheers,
Douglas


What are you on about, Dougles? I just told you, it is a class AB amp.
Class AB amps by definition have some class A output and the rest in
Class B.


No it doesn't, it has no power in Class A. That's why it is called an
AB amp. It is really simple.

If you want an unadulterated Class A amp with a 100W output,

you're going to be paying real money, and if you're a snob who wants
it in SE, you're going to be paying Range Rover Vogue money. I know; I
built an 80W SE amp, which of course by definition ran only in Class
A. The Velleman is relatively inexpensive, very sturdy, very good
value amplifier kit from the most famous makers of all kinds of
electronic kits in the world. But its price will look a tip to a
doorman by the time you finish paying for a 100W Class A amp.


I don't recall ever telling you what I wanted, or owned, or for that
matter what I've built. None of that has any bearing on your marketing-
based dafynishion of what you'd like an AB amp to be.



And what's that rubbish about "maximum output" anyway? By definition a
class AB amp's Class A output is at some lower power than maximum,
otherwise it would be a Class A amp, period.


Just because both of the finals are conducting does not mean it is
Class A. That is reserved for amps that keep both conducting *AT FULL
POWER*. Why *******ize the definition just because some marketing fool
likes says it's OK? A Class AB amp doesn't have any Class A output.
Both phases conducting does not make Class A....or is that too hard to
grasp?

The whole point about a

Class AB amp is that most music is played where such an amp makes its
sweetest sounds, but that it has headroom for any contingency, though
you sacrifice a little something in quality when that headroom is
taken up.


If your taste is so refined that you must have nothing but Class A,
there are a bunch of designs for Class A amps on my netsite.


I don't think I'll be considering any of those amps. Kinda off-the-
rack and boring.

And, for

the sake of completeness, my own favourite everyday amp is my own T113
"Triple Threat" design, which runs PP EL34s in triode and strictly in
Class A. But you'd need about 8 of those to get 100W...


You know an audiophool snob when he starts talking about "pure" Class A...

Probably just somebody who knows how to use the language properly. You
can join the club anytime you wish to conduct yourself properly....and
leave it just as quickly.


Yes, I see what this is about: another clown storming into RAT with a
mission to see me off. Thanks for coming, Dougles, but I don't think I
would care to belong to any club that lets you in.

cheers,
Douglas



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Default Velleman K40x0, the very model of an all-round amp

On Oct 20, 6:42 am, Andre Jute wrote:
On Oct 19, 6:37 pm, Multi-grid wrote:





On Oct 20, 3:34 am, Andre Jute wrote:


On Oct 19, 3:50 pm, Multi-grid wrote:


overmatched to the Tannoys. It has around 16 to 18W in Class A alone.
I sometimes used mine for driving a bass bin, where its 100W in Class
A/B could sometimes come into play, at least theoretically (I'm not a
headbanger).


hey-Hey!!!,
An amp with maximum output happening with one phase of its PP set cut
off is *NOT* class A. A real class A amp has both phases conducting at
maximum power, and not from some variable pitch grid winding, remote
cut-off stuff either.


That Vellman amp is an AB, and barely so at that.
cheers,
Douglas


What are you on about, Dougles? I just told you, it is a class AB amp.
Class AB amps by definition have some class A output and the rest in
Class B.


No it doesn't, it has no power in Class A. That's why it is called an
AB amp. It is really simple.


If you want an unadulterated Class A amp with a 100W output,


you're going to be paying real money, and if you're a snob who wants
it in SE, you're going to be paying Range Rover Vogue money. I know; I
built an 80W SE amp, which of course by definition ran only in Class
A. The Velleman is relatively inexpensive, very sturdy, very good
value amplifier kit from the most famous makers of all kinds of
electronic kits in the world. But its price will look a tip to a
doorman by the time you finish paying for a 100W Class A amp.


I don't recall ever telling you what I wanted, or owned, or for that
matter what I've built. None of that has any bearing on your marketing-
based dafynishion of what you'd like an AB amp to be.


And what's that rubbish about "maximum output" anyway? By definition a
class AB amp's Class A output is at some lower power than maximum,
otherwise it would be a Class A amp, period.


Just because both of the finals are conducting does not mean it is
Class A. That is reserved for amps that keep both conducting *AT FULL
POWER*. Why *******ize the definition just because some marketing fool
likes says it's OK? A Class AB amp doesn't have any Class A output.
Both phases conducting does not make Class A....or is that too hard to
grasp?


The whole point about a


Class AB amp is that most music is played where such an amp makes its
sweetest sounds, but that it has headroom for any contingency, though
you sacrifice a little something in quality when that headroom is
taken up.


If your taste is so refined that you must have nothing but Class A,
there are a bunch of designs for Class A amps on my netsite.


I don't think I'll be considering any of those amps. Kinda off-the-
rack and boring.


And, for


the sake of completeness, my own favourite everyday amp is my own T113
"Triple Threat" design, which runs PP EL34s in triode and strictly in
Class A. But you'd need about 8 of those to get 100W...


You know an audiophool snob when he starts talking about "pure" Class A...


Probably just somebody who knows how to use the language properly. You
can join the club anytime you wish to conduct yourself properly....and
leave it just as quickly.


Yes, I see what this is about: another clown storming into RAT with a
mission to see me off. Thanks for coming, Dougles, but I don't think I
would care to belong to any club that lets you in.



cheers,
Douglas- Hide quoted text -


- Show quoted text -- Hide quoted text -

- Show quoted text -


hey-Hey!!!,
Well Andre, you can imagine my mission to be what ever it you want.
Again, that has no bearing what so ever on your mis-use of the
definition. Please stay on topic if you'd be so kind. Quit clouding
the issue please.

Do people go 'storming into RAT with a mission to see me off' alot
lately? Are you paranoid or something? Where would you get such an
idea?

I'll type slowly so you can understand it, this club I referred to
only requires its members to use accepted audio definitions and terms
properly. Of course it doesn't really exist, save for in
metaphore...but an accomplished writer like you would know all this,
right?

While you're at it, a schematic of your 80W SE amp would be nice to
look at.
cheers,
Douglas

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Default Velleman K40x0, the very model of an all-round amp


"Andre Jute" wrote in message
oups.com...
On Oct 19, 12:11 am, "Iain Churches" wrote:

The noise floor was exceptionally low. Later, a quick
look on the bench revealed the noise floor to be 100µV, so a
SNR of 105dB and at 96W, the THD was only 0.1%


It depends on your outlook whether you view the Velleman K40x0 as that
rare thing, a perfect all-round amp --

(snip)

Oh,. I don't think it is anywhere near that!
I regard it as a good-sounding DIY project, no more.
The fact that the tube sockets are mounted on the PCB
really put me off.

I have a Radford STA 100. So no contest.

Iain








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Default Velleman K40x0, the very model of an all-round amp



(snip)

Oh,. I don't think it is anywhere near that!
I regard it as a good-sounding DIY project, no more.
The fact that the tube sockets are mounted on the PCB
really put me off.

I have a Radford STA 100. So no contest.

Iain



I owned one that another fellow put together. I remember replacing some of
the 10 ohm resistors because of excessive cathode current draw.

It was a nice looking amp, with plenty of power. The PCBs were a turn-off,
but not a killer for me (Hey, if you want to have some REAL fun, do
component-level work on an Audio Research D-70. What a nightmare to repair!)

In my continuing search for the holy grail of sound, that amp went to a new
owner. To my ears, the sound was kind of harsh for a tube amp, and lacking
excitement.

I agree that it is "a good-sounding DIY project."

Jon

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Default Velleman K40x0, the very model of an all-round amp


"Jon Yaeger" wrote in message
...

I owned one that another fellow put together. I remember replacing some
of
the 10 ohm resistors because of excessive cathode current draw.

It was a nice looking amp, with plenty of power. The PCBs were a turn-off,
but not a killer for me (Hey, if you want to have some REAL fun, do
component-level work on an Audio Research D-70. What a nightmare to
repair!)

In my continuing search for the holy grail of sound, that amp went to a
new
owner. To my ears, the sound was kind of harsh for a tube amp, and
lacking
excitement.

I agree that it is "a good-sounding DIY project."

And, in that respect, if it does something to light the spark
of interest in tube audio, then it has served a very useful purpose.

Iain



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Default Velleman K40x0, the very model of an all-round amp

On Oct 21, 7:48 am, "Iain Churches" wrote:
"Andre Jute" wrote in message

oups.com...
On Oct 19, 12:11 am, "Iain Churches" wrote:

The noise floor was exceptionally low. Later, a quick
look on the bench revealed the noise floor to be 100µV, so a
SNR of 105dB and at 96W, the THD was only 0.1%


It depends on your outlook whether you view the Velleman K40x0 as that
rare thing, a perfect all-round amp --


It's all opinion. Some opinions are informed by relevant experience
and therefore more valuable. Some opinions are informed by nothing but
street corner gossip or personal animosity and are therefore
worthless.

Oh,. I don't think it is anywhere near that!
I regard it as a good-sounding DIY project, no more.
The fact that the tube sockets are mounted on the PCB
really put me off.

I have a Radford STA 100. So no contest.


And I have a Quad II. No contest, to my mind at least; it depends what
you want to measure and hear. Except that the Quad II doesn't put out
100W. Let's compare apples with apples, not with gilded plums, mmm?

I could compare the Velleman K4000 100W with a bunch of other kits I
have built and used extensively: Arion Adonis PP 5581 20W, Audio
Innovations Classic Stereo 25 PP EL34 25W, Triode Supply Japan Miyabe
300B SEPP 16W, etc, etc, and in no instance would it be comparing
apples with apples, for the good and simple reason that none of them
have 100W. In that the Velleman K40*0 stands alone, and gives the
beginner versatility to use the most grossly insensitive bookshelf
speakers to get real oomph on any music whatsoever. I could have
chosen any of the amps listed, or any of the other kits I have built,
including some I don't list because they have less than 10W, and said
they're fine on some aspect (or even the best) but, while all of them
have served me very well indeed, none of them can be put up against
the Velleman without admitting some handicap in some perfectly common
everyday use for an identifiable group of users.

I might add that my favourite among that lot is the AI, which is a
gentleman's amp, never intrusive; an amp you can play 14 hours every
day and never find fault with. I find the Velleman far too analytical
for my taste but that is because it is so accurate, a characteristic
many value. But, to illustrate once more that all this is relative to
usage and opinion, I play mainly chamber music at low volume;
symphonic or other "big" music played on insensitive speakers
*requires* a big amp. If I were into heavy metal or whatever the
current fave of the loud set is called, I wouldn't touch any of my
favourite amps for chamber music -- they'd all be less than convincing
-- I'd go straight to the Velleman and acoustic overload heaven.

By the way, the Velleman K40*0 is eminently tweakable. On my old
netsite I had an entire big section devoted to altering the factory
spec to make it sound like anything you wanted it to sound like. The
"harshness" Jon Yaeger objects to, for instance, was just a matter of
swapping out a ceramic (! now that's an excess of engineering...) cap
for a film cap; you would of course sacrifice a little of the
excellent noise spec (which was why the designer put it in there) but
might consider the loss worthwhile to gain precisely the sound you
want. I'm amazed that Yaeger doesn't know that.

As for the snobbery of demanding point to point wiring on kits, go
right ahead: you'll be helping to kill the hobby off faster than is
necessary. In my experience eliminating the PCB, or insisting on
sockets mounted to the chassis, just about triples the price of the
kit, and ensures that the successful assembly rate is halved.
(Suppliers who give a completion guarantee, or who provide a
handholding service, keep very good records of these matters! Or you
can read between the lines in the instructions and on the sites of
those who sell PTP kits how fed up they are with seeing time and
profits dribble away in support to eejits who cannot follow simple
instructions.)

If you insist on hardwiring, nothing stops you buying a Velleman K40*0
kit, or any other kit with a chassis, to get the design and all the
parts, and simply drilling the cover to hold sockets for the tubes and
then fitting the components to tag strips you supply. Nor is there any
secret to designing a PCB construction properly for heat management:
either ascertain that the kit has ceramic standoffs for power tubes
and resistors as standard, or add them yourself. I'm really amazed at
discovering DIYers who brag about their craftsmanship, then complain
about an amp because it is designed to be built on a PCB: if you don't
like it, change it!

Iain


For those who need or want a 100W and prefer tubes, the Velleman K40x0
is unique, zero competition that I know about.

I don't see much point in nitpicking commercial amps against
irrelevant self-proclaimed "standards"; the test is whether the thing
works in the hands of owners, and the K40*0 worked fine for a decade
and more in my hands. We've already had a bunch of clowns in this
thread condemning one of the most succesful commercial amps in the
world *without ever seeing one or hearing it*. That sort of street
corner gossip repeated as gospel is what trashes the reputation of
RAT, not putting down the thieves of intellectual rights or netbullies
and netstalkers -- on the contrary, it is toleration and protection of
such people that trashes our reputation.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

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Default Velleman K40x0, the very model of an all-round amp


"Andre Jute" wrote in message oups.com...
On Oct 21, 7:48 am, "Iain Churches" wrote:
"Andre Jute" wrote in message

oups.com...
On Oct 19, 12:11 am, "Iain Churches" wrote:

The noise floor was exceptionally low. Later, a quick
look on the bench revealed the noise floor to be 100µV, so a
SNR of 105dB and at 96W, the THD was only 0.1%


It depends on your outlook whether you view the Velleman K40x0 as that
rare thing, a perfect all-round amp --


It's all opinion. Some opinions are informed by relevant experience
and therefore more valuable. Some opinions are informed by nothing but
street corner gossip or personal animosity and are therefore
worthless.

Oh,. I don't think it is anywhere near that!
I regard it as a good-sounding DIY project, no more.
The fact that the tube sockets are mounted on the PCB
really put me off.

I have a Radford STA 100. So no contest.


And I have a Quad II. No contest, to my mind at least; it depends what
you want to measure and hear. Except that the Quad II doesn't put out
100W. Let's compare apples with apples, not with gilded plums, mmm?

I could compare the Velleman K4000 100W with a bunch of other kits I
have built and used extensively: Arion Adonis PP 5581 20W, Audio
Innovations Classic Stereo 25 PP EL34 25W, Triode Supply Japan Miyabe
300B SEPP 16W, etc, etc, and in no instance would it be comparing
apples with apples, for the good and simple reason that none of them
have 100W. In that the Velleman K40*0 stands alone, and gives the
beginner versatility to use the most grossly insensitive bookshelf
speakers to get real oomph on any music whatsoever. I could have
chosen any of the amps listed, or any of the other kits I have built,
including some I don't list because they have less than 10W, and said
they're fine on some aspect (or even the best) but, while all of them
have served me very well indeed, none of them can be put up against
the Velleman without admitting some handicap in some perfectly common
everyday use for an identifiable group of users.

I might add that my favourite among that lot is the AI, which is a
gentleman's amp, never intrusive; an amp you can play 14 hours every
day and never find fault with. I find the Velleman far too analytical
for my taste but that is because it is so accurate, a characteristic
many value. But, to illustrate once more that all this is relative to
usage and opinion, I play mainly chamber music at low volume;
symphonic or other "big" music played on insensitive speakers
*requires* a big amp. If I were into heavy metal or whatever the
current fave of the loud set is called, I wouldn't touch any of my
favourite amps for chamber music -- they'd all be less than convincing
-- I'd go straight to the Velleman and acoustic overload heaven.

By the way, the Velleman K40*0 is eminently tweakable. On my old
netsite I had an entire big section devoted to altering the factory
spec to make it sound like anything you wanted it to sound like. The
"harshness" Jon Yaeger objects to, for instance, was just a matter of
swapping out a ceramic (! now that's an excess of engineering...) cap
for a film cap; you would of course sacrifice a little of the
excellent noise spec (which was why the designer put it in there) but
might consider the loss worthwhile to gain precisely the sound you
want. I'm amazed that Yaeger doesn't know that.

As for the snobbery of demanding point to point wiring on kits, go
right ahead: you'll be helping to kill the hobby off faster than is
necessary. In my experience eliminating the PCB, or insisting on
sockets mounted to the chassis, just about triples the price of the
kit, and ensures that the successful assembly rate is halved.
(Suppliers who give a completion guarantee, or who provide a
handholding service, keep very good records of these matters! Or you
can read between the lines in the instructions and on the sites of
those who sell PTP kits how fed up they are with seeing time and
profits dribble away in support to eejits who cannot follow simple
instructions.)

If you insist on hardwiring, nothing stops you buying a Velleman K40*0
kit, or any other kit with a chassis, to get the design and all the
parts, and simply drilling the cover to hold sockets for the tubes and
then fitting the components to tag strips you supply. Nor is there any
secret to designing a PCB construction properly for heat management:
either ascertain that the kit has ceramic standoffs for power tubes
and resistors as standard, or add them yourself. I'm really amazed at
discovering DIYers who brag about their craftsmanship, then complain
about an amp because it is designed to be built on a PCB: if you don't
like it, change it!

Iain


For those who need or want a 100W and prefer tubes, the Velleman K40x0
is unique, zero competition that I know about.

I don't see much point in nitpicking commercial amps against
irrelevant self-proclaimed "standards"; the test is whether the thing
works in the hands of owners, and the K40*0 worked fine for a decade
and more in my hands. We've already had a bunch of clowns in this
thread condemning one of the most succesful commercial amps in the
world *without ever seeing one or hearing it*. That sort of street
corner gossip repeated as gospel is what trashes the reputation of
RAT, not putting down the thieves of intellectual rights or netbullies
and netstalkers -- on the contrary, it is toleration and protection of
such people that trashes our reputation.


Horse****, Andre. It isn't the reputation of RAT that's trashed, it's the
atmosphere that people have been fleeing. That atmosphere has been
trashed by your relentless personal attacks on everyone you can find
even the slightest reason to go after.

But it's OK; pretty soon you and your sock puppets will have this place
all to yourselves. You'll be able to launch devastating attacks on your
sock puppets every day and no one will complain unless you do it for
them.

He he, Andre, what a horse's ass you are.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review



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Default Velleman K40x0, the very model of an all-round amp



I don't see much point in nitpicking commercial amps against
irrelevant self-proclaimed "standards"; the test is whether the thing
works in the hands of owners, and the K40*0 worked fine for a decade
and more in my hands. We've already had a bunch of clowns in this
thread condemning one of the most succesful commercial amps in the
world *without ever seeing one or hearing it*. That sort of street
corner gossip repeated as gospel is what trashes the reputation of
RAT, not putting down the thieves of intellectual rights or netbullies
and netstalkers -- on the contrary, it is toleration and protection of
such people that trashes our reputation.

Andre Jute


I'll second Phread, it is the personal attacking that makes this place
less-than. If you'd examine the history, RAT was a reasonable going
concern until the Jute v. Magnetquest war. Seems Andre was unable to
make a legitimate criticism of Mikey stick.

So then Andre, you mention an AB amp having A power, you reference an
80W SE amp, claim an off the rack Vellman kit is brilliant, and then
attack anybody who'd have the guts to say you've over reached. Even
with poor S/N ratio there is still signal. Let's see some from you.
cheers,
Douglas



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Default Velleman K40x0, the very model of an all-round amp

On Mon, 22 Oct 2007 13:50:47 -0700, Multi-grid wrote:


snip

So then Andre, you mention an AB amp having A power, you reference an
80W SE amp, claim an off the rack Vellman kit is brilliant, and then
attack anybody who'd have the guts to say you've over reached. Even with
poor S/N ratio there is still signal. Let's see some from you. cheers,



Surely though, a class AB amp such as the Vellman *is* running in class A
up to the point where one output device starts to turn off isn't it? The
changeover to class B happens at that point and is dependent on the
quiescent current in the outputs.

A true class A amp is only a special case of the normal AB class. It's
just that it clips symmetrically instead of moving smoothly into class
B. ;-)

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info http://mixpix.batcave.net

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Default Velleman K40x0, the very model of an all-round amp


Surely though, a class AB amp such as the Vellman *is* running in class A
up to the point where one output device starts to turn off isn't it?
--
Mick (Working in a M$-free zone!)
Web:http://www.nascom.info http://mixpix.batcave.net


Nope, not a chance. That both tubes are conducting does not mean it is
A. Have some respect... AB amps don't have any A power, that is why
there is a seperate classification.
cheers,
Douglas

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Andre Jute Andre Jute is offline
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Default Output classes A and AB

On Oct 22, 2:33 pm, mick wrote:
On Mon, 22 Oct 2007 13:50:47 -0700, Multi-grid wrote:

snip

So then Andre, you mention an AB amp having A power, you reference an
80W SE amp, claim an off the rack Vellman kit is brilliant, and then
attack anybody who'd have the guts to say you've over reached. Even with
poor S/N ratio there is still signal. Let's see some from you. cheers,


Who is this fellow "Multi-grid", and why is he addressing me?

Surely though, a class AB amp such as the Vellman *is* running in class A
up to the point where one output device starts to turn off isn't it? The
changeover to class B happens at that point and is dependent on the
quiescent current in the outputs.


I would have thought anyone with a handle like "Multi-grid" would have
taken that sort of basic tube knowledge from the teat. Mind you, I
remember when Ron Bales wanted us here on RAT to give everyone who
claimed a "tubie-handle" a test of tube knowledge to ensure they don't
give a respectable hobby a bad name by wielding their ignorance like
clubs. That was about 1998. Looks like this "Multi-grid" fellow is a
prime candidate for the Bales Test.

A true class A amp is only a special case of the normal AB class. It's
just that it clips symmetrically instead of moving smoothly into class
B. ;-)


It is beneath my dignity to rise to such provocation -- sniff. A Class
AB amp is a compromised Class A amp, and it probably requires negative
feedback too to work even acceptably. A properly designed Class A amp
never clips because the operating parameters were so chosen that it
runs out of signal from the intended source before it can clip (that
is one reason why the design instructions on my netsite feature the
*design center* process so heavily). It is only "engineers" who
"design" amps to hog the maximum power from each tube who even need a
concept like clipping; for sane tubies it is obsolete terminology.

--
Mick (Working in a M$-free zone!)
Web:http://www.nascom.infohttp://mixpix.batcave.net


Andre Jute
Our legislators managed to criminalize fox-hunting and smoking; when
will they get off their collective fat backside and criminalize
negative feedback? It is clearly consumed only by thickoes.

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Default Output classes A and AB

A properly designed Class A amp
never clips because the operating parameters were so chosen that it
runs out of signal from the intended source before it can clip (that
is one reason why the design instructions on my netsite feature the
*design center* process so heavily).


Stay on topic please.

While you're at it, please refrain from making personal attacks, it is
beneath you( I hope ).

Class A has nothing to do with its input signal. The finals clip
symetrically. Or perhaps unsymetrically if it is power limited A, so
to say overbiased given the load and B+. If you have plate dissipation
to spare, it is certainly possible. Matter of fact I am listening to
one such amp now...
cheers,
Douglas

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Default Output classes A and AB



Multi-grid wrote:

A properly designed Class A amp
never clips because the operating parameters were so chosen that it
runs out of signal from the intended source before it can clip (that
is one reason why the design instructions on my netsite feature the
*design center* process so heavily).


Stay on topic please.

While you're at it, please refrain from making personal attacks, it is
beneath you( I hope ).

Class A has nothing to do with its input signal. The finals clip
symetrically. Or perhaps unsymetrically if it is power limited A, so
to say overbiased given the load and B+. If you have plate dissipation
to spare, it is certainly possible. Matter of fact I am listening to
one such amp now...
cheers,
Douglas


I believe the point it changes from 'class A' to 'class AB' is commonly
accepted to be the point where the output stage begins to draw more
current from the power supply. By commonly accepted, I mean I've read a
ton of magazine reviews of tube amps where they use this logic, stated
almost exactly as Andre has used it.

In other words, the amp is biased a bit hotter than class B, and this
lowers low level distortion a bit at the expense of peak power output.

Stating that "the amplifier is Class A until XXX watts", really, is
telling you how hot the tubes are biased relative to the two extremes of
pure class A (full dissapation), and pure class (cut off).




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John Byrns John Byrns is offline
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Default Output classes A and AB

In article . com,
Andre Jute wrote:

On Oct 22, 2:33 pm, mick wrote:
On Mon, 22 Oct 2007 13:50:47 -0700, Multi-grid wrote:

snip

So then Andre, you mention an AB amp having A power, you reference an
80W SE amp, claim an off the rack Vellman kit is brilliant, and then
attack anybody who'd have the guts to say you've over reached. Even with
poor S/N ratio there is still signal. Let's see some from you. cheers,


Who is this fellow "Multi-grid", and why is he addressing me?


Hi Andre,

This fellow "Multi-grid" is either a Troll, ignorant, or most likely
both, his goal appears to be trying to stir up trouble so he is best
ignored.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
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Multi-grid Multi-grid is offline
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Default Output classes A and AB

On Oct 23, 6:01 am, maxhifi wrote:
Multi-grid wrote:
A properly designed Class A amp
never clips because the operating parameters were so chosen that it
runs out of signal from the intended source before it can clip (that
is one reason why the design instructions on my netsite feature the
*design center* process so heavily).


Stay on topic please.


While you're at it, please refrain from making personal attacks, it is
beneath you( I hope ).


Class A has nothing to do with its input signal. The finals clip
symetrically. Or perhaps unsymetrically if it is power limited A, so
to say overbiased given the load and B+. If you have plate dissipation
to spare, it is certainly possible. Matter of fact I am listening to
one such amp now...
cheers,
Douglas


I believe the point it changes from 'class A' to 'class AB' is commonly
accepted to be the point where the output stage begins to draw more
current from the power supply. By commonly accepted, I mean I've read a
ton of magazine reviews of tube amps where they use this logic, stated
almost exactly as Andre has used it.

In other words, the amp is biased a bit hotter than class B, and this
lowers low level distortion a bit at the expense of peak power output.

Stating that "the amplifier is Class A until XXX watts", really, is
telling you how hot the tubes are biased relative to the two extremes of
pure class A (full dissapation), and pure class (cut off).- Hide quoted text -

- Show quoted text -


Class A has nothing to do with dissipation either. Just because some
marketing group noticed that class A means something good, does not
make it right either. Just because it seems to make sense is no reason
to *******ize the definition. Find some other way to describe it.
cheers,
Douglas

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Default Output classes A and AB

On Oct 23, 6:33 am, John Byrns wrote:
In article . com,
Andre Jute wrote:

On Oct 22, 2:33 pm, mick wrote:
On Mon, 22 Oct 2007 13:50:47 -0700, Multi-grid wrote:


snip


So then Andre, you mention an AB amp having A power, you reference an
80W SE amp, claim an off the rack Vellman kit is brilliant, and then
attack anybody who'd have the guts to say you've over reached. Even with
poor S/N ratio there is still signal. Let's see some from you. cheers,


Who is this fellow "Multi-grid", and why is he addressing me?


Hi Andre,

This fellow "Multi-grid" is either a Troll, ignorant, or most likely
both, his goal appears to be trying to stir up trouble so he is best
ignored.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/


It appears you folks are living up to your reputation for making
personal attacks. It isn't this:
That sort of street
corner gossip repeated as gospel is what trashes the reputation of
RAT, not putting down the thieves of intellectual rights or
netbullies
and netstalkers -- on the contrary, it is toleration and protection
of
such people that trashes our reputation.

that's doing RAT harm. Getting nasty on the other hand...
cheers,
Douglas

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Peter Wieck Peter Wieck is offline
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Default Output classes A and AB

On Oct 22, 11:33 pm, John Byrns wrote:

This fellow "Multi-grid" is either a Troll, ignorant, or most likely
both, his goal appears to be trying to stir up trouble so he is best
ignored.


Ever ready with the diaper, John?

Peter Wieck
Wyncote, PA

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Default Output classes A and AB



Multi-grid wrote:

maxhifi wrote:

Stating that "the amplifier is Class A until XXX watts", really, is
telling you how hot the tubes are biased relative to the two extremes of
pure class A (full dissapation), and pure class (cut off).- Hide quoted text -



Class A has nothing to do with dissipation either. Just because some
marketing group noticed that class A means something good, does not
make it right either. Just because it seems to make sense is no reason
to *******ize the definition. Find some other way to describe it.


The definition of Class A is very simple. It requires that the output device(s)
never cease conducting under any signal condition.

Graham



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Default Output classes A and AB

On Tue, 23 Oct 2007 14:34:31 +0100, Eeyore wrote:

Multi-grid wrote:

maxhifi wrote:

Stating that "the amplifier is Class A until XXX watts", really, is
telling you how hot the tubes are biased relative to the two extremes
of pure class A (full dissapation), and pure class (cut off).- Hide
quoted text -



Class A has nothing to do with dissipation either. Just because some
marketing group noticed that class A means something good, does not
make it right either. Just because it seems to make sense is no reason
to *******ize the definition. Find some other way to describe it.


The definition of Class A is very simple. It requires that the output
device(s) never cease conducting under any signal condition.



Correct. A class AB amp fulfills this up to the point where one side
starts to turn off.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info http://mixpix.batcave.net

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Default Output classes A and AB


Multi-grid wrote:
Class A has nothing to do with dissipation either.


Then Poopie wrote:
The definition of Class A is very simple. It requires that the output
device(s) never cease conducting under any signal condition.


Then Mick http://www.nascom.info and http://mixpix.batcave.net wrote:
Correct. A class AB amp fulfills this up to the point where one side
starts to turn off.


I can see what you're getting at, Poopie, and so can Mick apparently,
but I don't think I want to wear your definition where it says "under
any signal condition". That's most misleading, especially with a
newbie on the board who stubbornly keeps claiming signal has nothing
to do with Class A. Any power stage that is hitherto Class A can
driven to cutoff by simply increasing the signal until the output cuts
out at either zero current or zero voltage.

In any and all cases, Class A is defined, though usually implicitly
rather than explcitly, as at a particular, *limited* signal voltage. I
therefore prefer the definition of Class A which says simply:
***Class A operating conditions do not permit the output device to
cease conducting.***
If you insist on describing the signal condition, you could add the
words *at the design or intended or specified signal*.

As for Dougles Multi-grid's silly insistence that signal and
dissipation have nothing to do with Class A operation, thanks for the
giggle, sonny, but you'd better hit the books lots more before you
seek entry to this club. In particular, you should pay attention to
this, which often comes as a bolt from the blue to repair hacks like
you, who tend to assume that the parameters are godgiven and fixed:
the *designer* chooses the plate voltage and negative bias, that sets
the current at quiescence, through which the designer then runs the
loadline at a particular angle when he chooses a primary impedance for
his output transformer, the slope of the loadline determining how far
the quiescent point is from current cutoff (or voltage cutoff...), and
that in turn defines the signal voltage that can be put in for Class A
operation, which in turn defines the output power. Thus the signal
level has everything to do with Class A operation, and in turn defines
maximum possible dissipation from Class A operation. Cruise my
netsite; all this is explained in both words and pictures.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

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Default Output classes A and AB

On Oct 23, 3:37 pm, Andre Jute wrote:
Multi-grid wrote:
Class A has nothing to do with dissipation either.

Then Poopie wrote:
The definition of Class A is very simple. It requires that the output
device(s) never cease conducting under any signal condition.


Then Mickhttp://www.nascom.infoandhttp://mixpix.batcave.netwrote:

Correct. A class AB amp fulfills this up to the point where one side
starts to turn off.


I can see what you're getting at, Poopie, and so can Mick apparently,
but I don't think I want to wear your definition where it says "under
any signal condition". That's most misleading, especially with a
newbie on the board who stubbornly keeps claiming signal has nothing
to do with Class A. Any power stage that is hitherto Class A can
driven to cutoff by simply increasing the signal until the output cuts
out at either zero current or zero voltage.

In any and all cases, Class A is defined, though usually implicitly
rather than explcitly, as at a particular, *limited* signal voltage. I
therefore prefer the definition of Class A which says simply:
***Class A operating conditions do not permit the output device to
cease conducting.***
If you insist on describing the signal condition, you could add the
words *at the design or intended or specified signal*.

As for Dougles Multi-grid's silly insistence that signal and
dissipation have nothing to do with Class A operation, thanks for the
giggle, sonny, but you'd better hit the books lots more before you
seek entry to this club. In particular, you should pay attention to
this, which often comes as a bolt from the blue to repair hacks like
you, who tend to assume that the parameters are godgiven and fixed:
the *designer* chooses the plate voltage and negative bias, that sets
the current at quiescence, through which the designer then runs the
loadline at a particular angle when he chooses a primary impedance for
his output transformer, the slope of the loadline determining how far
the quiescent point is from current cutoff (or voltage cutoff...), and
that in turn defines the signal voltage that can be put in for Class A
operation, which in turn defines the output power. Thus the signal
level has everything to do with Class A operation, and in turn defines
maximum possible dissipation from Class A operation. Cruise my
netsite; all this is explained in both words and pictures.


Mmm. It occurs to me that when dealing with a newbie, even if it is
all explained on my netsite, and Patrick's, and all the textbooks, and
in Crowhurst, which Multi-grid could read with profit, I should
explain what signal voltage has to do with power output. Power is the
product of voltage and current. The bigger the voltage and current
swing, the greater the power output (for a given load). The plate
voltage and current swing is proportional to the size of the signal
working through mu, the amplification factor of the tube. Thus the
greater the signal that can be put in under a particular class of
operation, in this case Class A, the greater the voltage swing and the
more the current change between the peaks of the signal, the bigger
the product of voltage and current, and the greater the power. So, you
see, sonny, in Class A operation, which is in any event very
inefficient, the amount of space the designer allows for signal to
swing without breaching Class A conditions determines the entire
outcome. The same applies to Class AB, where the signal-travel the
designer has arranged (by his choice of plate voltage and negative
grid bias and primary impedance) during which current is not cut off
determines how much of the output can be in Class A, with the rest by
definition in Class B.

Andre Jute
Visit Jute on Amps athttp://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review



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Default Output classes A and AB

On Oct 24, 2:56 am, Andre Jute wrote:
On Oct 23, 3:37 pm, Andre Jute wrote:





Multi-grid wrote:
Class A has nothing to do with dissipation either.

Then Poopie wrote:
The definition of Class A is very simple. It requires that the output
device(s) never cease conducting under any signal condition.


Then Mickhttp://www.nascom.infoandhttp://mixpix.batcave.netwrote:


Correct. A class AB amp fulfills this up to the point where one side
starts to turn off.


I can see what you're getting at, Poopie, and so can Mick apparently,
but I don't think I want to wear your definition where it says "under
any signal condition". That's most misleading, especially with a
newbie on the board who stubbornly keeps claiming signal has nothing
to do with Class A. Any power stage that is hitherto Class A can
driven to cutoff by simply increasing the signal until the output cuts
out at either zero current or zero voltage.


In any and all cases, Class A is defined, though usually implicitly
rather than explcitly, as at a particular, *limited* signal voltage. I
therefore prefer the definition of Class A which says simply:
***Class A operating conditions do not permit the output device to
cease conducting.***
If you insist on describing the signal condition, you could add the
words *at the design or intended or specified signal*.


As for Dougles Multi-grid's silly insistence that signal and
dissipation have nothing to do with Class A operation, thanks for the
giggle, sonny, but you'd better hit the books lots more before you
seek entry to this club. In particular, you should pay attention to
this, which often comes as a bolt from the blue to repair hacks like
you, who tend to assume that the parameters are godgiven and fixed:
the *designer* chooses the plate voltage and negative bias, that sets
the current at quiescence, through which the designer then runs the
loadline at a particular angle when he chooses a primary impedance for
his output transformer, the slope of the loadline determining how far
the quiescent point is from current cutoff (or voltage cutoff...), and
that in turn defines the signal voltage that can be put in for Class A
operation, which in turn defines the output power. Thus the signal
level has everything to do with Class A operation, and in turn defines
maximum possible dissipation from Class A operation. Cruise my
netsite; all this is explained in both words and pictures.


Mmm. It occurs to me that when dealing with a newbie, even if it is
all explained on my netsite, and Patrick's, and all the textbooks, and
in Crowhurst, which Multi-grid could read with profit, I should
explain what signal voltage has to do with power output. Power is the
product of voltage and current. The bigger the voltage and current
swing, the greater the power output (for a given load). The plate
voltage and current swing is proportional to the size of the signal
working through mu, the amplification factor of the tube. Thus the
greater the signal that can be put in under a particular class of
operation, in this case Class A, the greater the voltage swing and the
more the current change between the peaks of the signal, the bigger
the product of voltage and current, and the greater the power. So, you
see, sonny, in Class A operation, which is in any event very
inefficient, the amount of space the designer allows for signal to
swing without breaching Class A conditions determines the entire
outcome. The same applies to Class AB, where the signal-travel the
designer has arranged (by his choice of plate voltage and negative
grid bias and primary impedance) during which current is not cut off
determines how much of the output can be in Class A, with the rest by
definition in Class B.



Andre Jute
Visit Jute on Amps athttp://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review- Hide quoted text -


- Show quoted text -- Hide quoted text -

- Show quoted text -


keep repeating yourself, it may come true sometime.

In the meantime, some additional proof besides the circular stuff you
keep digging up might show you the holes in your arguement. As to
Crowhurst, his creativity outstripped his ability to write
unequivocally.

While you're digging, why not produce some documentation of the 80W SE
amp you mentioned earlier.
cheers,
Douglas

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Default Output classes A and AB

On Oct 24, 1:37 am, Andre Jute wrote:
Multi-grid wrote:
Class A has nothing to do with dissipation either.

Then Poopie wrote:
The definition of Class A is very simple. It requires that the output
device(s) never cease conducting under any signal condition.


Then Mickhttp://www.nascom.infoandhttp://mixpix.batcave.netwrote:

Correct. A class AB amp fulfills this up to the point where one side
starts to turn off.


I can see what you're getting at, Poopie, and so can Mick apparently,
but I don't think I want to wear your definition where it says "under
any signal condition". That's most misleading, especially with a
newbie on the board who stubbornly keeps claiming signal has nothing
to do with Class A. Any power stage that is hitherto Class A can
driven to cutoff by simply increasing the signal until the output cuts
out at either zero current or zero voltage.

In any and all cases, Class A is defined, though usually implicitly
rather than explcitly, as at a particular, *limited* signal voltage. I
therefore prefer the definition of Class A which says simply:
***Class A operating conditions do not permit the output device to
cease conducting.***
If you insist on describing the signal condition, you could add the
words *at the design or intended or specified signal*.

As for Dougles Multi-grid's silly insistence that signal and
dissipation have nothing to do with Class A operation, thanks for the
giggle, sonny, but you'd better hit the books lots more before you
seek entry to this club.


They don't Andre, no matter how much you claim they do. Class A, is as
simple as you first stated it:

***Class A operating conditions do not permit the output device to
cease conducting.***


It should get the addition that remote cut off behaviour is not
included.

In particular, you should pay attention to
this, which often comes as a bolt from the blue to repair hacks like
you, who tend to assume that the parameters are godgiven and fixed:
the *designer* chooses the plate voltage and negative bias, that sets
the current at quiescence, through which the designer then runs the
loadline at a particular angle when he chooses a primary impedance for
his output transformer, the slope of the loadline determining how far
the quiescent point is from current cutoff (or voltage cutoff...), and
that in turn defines the signal voltage that can be put in for Class A
operation, which in turn defines the output power. Thus the signal
level has everything to do with Class A operation, and in turn defines
maximum possible dissipation from Class A operation. Cruise my
netsite; all this is explained in both words and pictures.



I make no such assumptions. That you'd think I would only shows your
limitations. Stay off this group-killing personal attacking if you
please. Isn't one war named after you enough?
cheers,
Douglas



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John Byrns John Byrns is offline
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Default Output classes A and AB

In article . com,
Multi-grid wrote:

On Oct 24, 1:37 am, Andre Jute wrote:

As for Dougles Multi-grid's silly insistence that signal and
dissipation have nothing to do with Class A operation, thanks for the
giggle, sonny, but you'd better hit the books lots more before you
seek entry to this club.


They don't Andre, no matter how much you claim they do. Class A, is as
simple as you first stated it:

***Class A operating conditions do not permit the output device to
cease conducting.***


Precisely, that is why when the operating conditions of a class AB
amplifier are restricted by limiting the applied input voltage the
amplifier is able to put out class A power at a level that is lower than
the maximum available class AB power.

It should get the addition that remote cut off behaviour is not
included.


Most real world tubes display remote cut off behaviour as the plate
curves become distinctly compressed in the high voltage low current
quadrant. I guess that rules out the possibility of any tube amplifier
operating class A.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
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Peter Wieck Peter Wieck is offline
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Default Output classes A and AB

On Oct 23, 8:51 pm, John Byrns wrote:
In article . com,

Multi-grid wrote:
On Oct 24, 1:37 am, Andre Jute wrote:


As for Dougles Multi-grid's silly insistence that signal and
dissipation have nothing to do with Class A operation, thanks for the
giggle, sonny, but you'd better hit the books lots more before you
seek entry to this club.


They don't Andre, no matter how much you claim they do. Class A, is as
simple as you first stated it:


***Class A operating conditions do not permit the output device to
cease conducting.***


Precisely, that is why when the operating conditions of a class AB
amplifier are restricted by limiting the applied input voltage the
amplifier is able to put out class A power at a level that is lower than
the maximum available class AB power.

It should get the addition that remote cut off behaviour is not
included.


Most real world tubes display remote cut off behaviour as the plate
curves become distinctly compressed in the high voltage low current
quadrant. I guess that rules out the possibility of any tube amplifier
operating class A.


John, with respect:

Andre is out of his depth on this one. And his typical response to
being out of his depth is to repeat, attack, repeat, attack, and then
repeat again. But none of that makes what he states true or correct.

And as your life's work is somewhere between cleaning up after him,
powdering him and changing his diapers and seeking exceptions and
outliers, I am not surprised that you are joining this discussion as
per usual.

There have actually been some reasonable discussions on tube lore
lately - those from which Andre has stayed away. And, were he to
refrain from delivering (typically incorrect) absolutes he might even
be capable of intiating and even participating in such discussions.

But, it is very hard for a pretender to stick to what he knows and for
a poseur to pronounce with less than "papal" infallibility. Which
makes Andre little more than a charlatan and never-was with delusions
of adequacy. All-and-at-the-same-time, he is a big boy of some 60+
summers and well able to manage his own affairs and discussions... or
it would be so were he mature enough to understand. Infants usually
and eventually become potty-trained. And that is the essential
difference between Andre and an infant, and why your efforts at clean
up after him are futile. He will never change however heroic your
efforts.

If you want an analogy, GM, some time back had a V8 engine that
*could* fire on 4, 6, or 8 cylinders depending on load conditions. But
it was never "other than" a V8, nor could any amount of wishful
thinking or closely held beliefs make it "other than" a V8.

Peter Wieck
Wyncote, PA

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Patrick Turner Patrick Turner is offline
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Default Output classes A and AB



Multi-grid wrote:

On Oct 23, 6:01 am, maxhifi wrote:
Multi-grid wrote:
A properly designed Class A amp
never clips because the operating parameters were so chosen that it
runs out of signal from the intended source before it can clip (that
is one reason why the design instructions on my netsite feature the
*design center* process so heavily).


Stay on topic please.


While you're at it, please refrain from making personal attacks, it is
beneath you( I hope ).


Class A has nothing to do with its input signal. The finals clip
symetrically. Or perhaps unsymetrically if it is power limited A, so
to say overbiased given the load and B+. If you have plate dissipation
to spare, it is certainly possible. Matter of fact I am listening to
one such amp now...
cheers,
Douglas


I believe the point it changes from 'class A' to 'class AB' is commonly
accepted to be the point where the output stage begins to draw more
current from the power supply. By commonly accepted, I mean I've read a
ton of magazine reviews of tube amps where they use this logic, stated
almost exactly as Andre has used it.

In other words, the amp is biased a bit hotter than class B, and this
lowers low level distortion a bit at the expense of peak power output.

Stating that "the amplifier is Class A until XXX watts", really, is
telling you how hot the tubes are biased relative to the two extremes of
pure class A (full dissapation), and pure class (cut off).- Hide quoted text -

- Show quoted text -


Class A has nothing to do with dissipation either.


Class A has everything to do with dissipation!!!!

But lets begin with class B.
In class B, there is ZERO anode dissipation because the tubes ( or SS
devices )
are biased at cut off. The amplifier only has device dissipation when
signal flows.
But distortion is notoriously high, and to avoid the worst of it, class
AB is used
where the tubes/devices are biased with idle dissipation well below the
maximum allowable fpr the tube or device.
This allows a small amount of pure class A working power until cut off
begins to occur in tubes/devices
on each alternate wave peak.
Hence a pair of KT88 might be set up with Ea = 600V, and Ia at idle of
30mA, for a Pda at idle
of 18 watts. Maximum allowable for a single KT88 is 42 watts.
The AB power avaliable with 600V is around 100Watts class AB but the
pure class A might be less than 10 watts
for the load where 100Watts AB is possible, which will be a load a lot
less than the load required for
pure class A operation up to clipping.
Its possible to have two KT88 dissipating a total of 36 watts, Ea =
600V, and have a load which ensures all the power
is class A. It is a high ohm load, but achievable if you connect a 16
ohm speaker to an AB amp with an outlet
for 4 ohms; the reflected anode load of say 5k becomes 20k.
And the beam terode class A efficiency will be up to about 45% and so
you'll get a maximum
of 16.2 watts of pure class A power from a pair of KT88 with a total of
36 watts Pda.
If the Pda is raised to 72 watts for the pair by doubling the Ia, then
max class A
also doubles if efficiency is constant, so 36 watts is possible.

The load can be a lot lower as well.

I suggest you learn much more about basic output tube behaviour before
you shoot your mouth off
by saying that " Class A has nothing to do with dissipation either. "



Just because some
marketing group noticed that class A means something good, does not
make it right either. Just because it seems to make sense is no reason
to *******ize the definition. Find some other way to describe it.
cheers,
Douglas


You are looking like the one *******izing something imho.

Please clarify your reasons for whatever your stance really is.

Patrick Turner.
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Default Output classes A and AB



Eeyore wrote:

Multi-grid wrote:

maxhifi wrote:

Stating that "the amplifier is Class A until XXX watts", really, is
telling you how hot the tubes are biased relative to the two extremes of
pure class A (full dissapation), and pure class (cut off).- Hide quoted text -



Class A has nothing to do with dissipation either. Just because some
marketing group noticed that class A means something good, does not
make it right either. Just because it seems to make sense is no reason
to *******ize the definition. Find some other way to describe it.


The definition of Class A is very simple. It requires that the output device(s)
never cease conducting under any signal condition.


It means slightly more than this because tubes don't cut off as sharply
as other devices.

So class A means where PP power tubes do not have Ia on either side of
the PP circuit ever
having Ia fall below 10% of the idle value.
Below about 10% of the idle value, the cut off behaviour becomes
substantially non linear, as opposed to substantially linear prior to
cut off.

Gradual cut off in triodes makes them particularly nice to use in AB
amps.
Minimal switching artifacts are generated. And the gm rises with Ia, so
the
load change reduction happening after cut off of one tube means the
triode compensates for the sudden drop in gain you see in pentodes and
beam tubes.
Its the internal triode NFB at work to give the low Ra.

And if the first 1/2 of output power maximum is class A by my
definition, then is its deemed A,
and the remaining 1/2 is B, and the total action is AB.

Most ppl will not hear any difference if the bias is increased to ensure
all power
up to clipping is pure class A.

The load experienced by one of the tubes in an AB PP pair is NOT a
straight line load
as one would draw across the anode curves of a given tube.
While in class A, each tube sees an almost straight line load, but
always of slightly
different ohm value because the gm of each tube isn't the same.
But the RL for each tube while in class A is approximately 1/2 of
RLa-a.1
Once cut off has begun in earnest during each wave cycle, the load each
tube sees
become its "class B load" = 1/4 RLa-a, and one has to draw a CURVED LOAD
LINE to describe the loading
of each PP output tube to describe what each is really doing.
The load of one tube is affected by the load on the other until cut off
happens,
and then each tube is on its own to deal with the load of 1/4 RLa-a.


Patrick Turner.



Graham

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Default Output classes A and AB




Class A, is as simple as you first stated it:

***Class A operating conditions do not permit the output device to

cease conducting.***


It should get the addition that remote cut off behaviour is not
included.



. Isn't one war named after you enough?
- Show quoted text -


sorry about that, forgot one thing...That is *AT FULL POWER*, if one
gets cut off before that, it is AB, which is neither A nor B.
cheers,
Douglas



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Default Output classes A and AB



I suggest you learn much more about basic output tube behaviour before
you shoot your mouth off
by saying that " Class A has nothing to do with dissipation either. "



- Show quoted text -


The dissipation is only related to the output power. A Class A amp
does not need a particular fraction of plate dissipation to be used in
order to classify as A. Examples are not needed, symbolic notation
will be fine.

The amp is defined by its behaviour. The bias that goes from 360-
degree conduction to something closer to 180 gets labled AB. Iff it
can maintain 360 degree conduction it gets the A.

Since it's usually quality over max power choices that run to class A
designs, the marketers decide to appropriate it for their own in AB
designs. You remember the advertisements general content( reference
Andre's comments on the Vellman ).

B is supposedly 180 degree, but given cut-off bunching, none are that
small. Why not have this discussion about the differences between AB
and B?
cheers,
Douglas

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Default Output classes A and AB



Patrick Turner wrote:

Eeyore wrote:
Multi-grid wrote:
maxhifi wrote:

Stating that "the amplifier is Class A until XXX watts", really, is
telling you how hot the tubes are biased relative to the two extremes of
pure class A (full dissapation), and pure class (cut off).- Hide quoted text -


Class A has nothing to do with dissipation either. Just because some
marketing group noticed that class A means something good, does not
make it right either. Just because it seems to make sense is no reason
to *******ize the definition. Find some other way to describe it.


The definition of Class A is very simple. It requires that the output device(s)
never cease conducting under any signal condition.


It means slightly more than this because tubes don't cut off as sharply
as other devices.


I see what you're saying but I do believe that the definition is unchanged. Obviously
avoiding any region of significant non-linearity is preferable but that in its own right
doesn't change the definition.

Graham

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Default Output classes A and AB

In article .com,
Peter Wieck wrote:

On Oct 23, 8:51 pm, John Byrns wrote:
In article . com,

Multi-grid wrote:

***Class A operating conditions do not permit the output device to
cease conducting.***


Precisely, that is why when the operating conditions of a class AB
amplifier are restricted by limiting the applied input voltage the
amplifier is able to put out class A power at a level that is lower than
the maximum available class AB power.


John, with respect:

Andre is out of his depth on this one.


Peter, I know you are obsessed with Andre, but this is not about Andre,
it is about Multi-grid's silly statement that a class AB amplifier can't
put out a limited amount of "class A power". Multi-grid is confusing
the definition of a PP amplifier's class with it's ability to deliver
some amount of power, less than rated output, without either output tube
cutting off. It has been common usage for as long as I can remember to
call this "class A power" because at this power level both output tubes
are conducting over the full 360 degree cycle, as in a class A
amplifier. An amplifiers class is determined by the operation of the
tubes at the rated power output, however in the case of a class AB
amplifier, a lesser amount of "class A power" is available.

To illustrate how silly Multigrid's claim is, consider a class AB
amplifier with a rated output of 50 Watts in class AB. Further suppose
this amplifier is capable of putting out 15 Watts without either output
tube cutting off, 15 Watts of what Andre, and many other famous
amplifier designers, call "class A power". Now we all agree that this
is a class AB amplifier, but suppose we connect a suitable network of
Zener and ordinary diodes across the primary of the output transformer
which clamp the maximum output voltage at the level necessary to produce
an output of 15 Watts. Has this amplifier now become a class A
amplifier simply because we have placed this clamp circuit across the
primary of the output transformer? If we test it with our sine wave
generator and oscilloscope we are going to conclude that it is a class A
amplifier because both tubes are still conducting over the full 360
degree cycle at the point of clipping. I leave the implications of this
experiment for the student to consider.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
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Default Output classes A and AB

On Oct 24, 6:57 am, flipper wrote:
On Wed, 24 Oct 2007 13:44:13 +0100, Eeyore



wrote:

Patrick Turner wrote:


Eeyore wrote:
Multi-grid wrote:
maxhifi wrote:


Stating that "the amplifier is Class A until XXX watts", really, is
telling you how hot the tubes are biased relative to the two extremes of
pure class A (full dissapation), and pure class (cut off).- Hide quoted text -


Class A has nothing to do with dissipation either. Just because some
marketing group noticed that class A means something good, does not
make it right either. Just because it seems to make sense is no reason
to *******ize the definition. Find some other way to describe it.


The definition of Class A is very simple. It requires that the output device(s)
never cease conducting under any signal condition.


It means slightly more than this because tubes don't cut off as sharply
as other devices.


I see what you're saying but I do believe that the definition is unchanged. Obviously
avoiding any region of significant non-linearity is preferable but that in its own right
doesn't change the definition.


People are talking semantically past each other with some speaking of
the definition of the 'amplifier' class while others are speaking of
it's behavior under a restricted set of operating conditions; and it
is useful to observe that under an appropriately restricted set of
conditions the output tubes conduct 360 degrees as in 'Class A'
operation.


"Useful", indeed, Flipper. Thanks. But I would go further and say that
the signal and dissipation restriction is part of the definition, as
you go on to imply:

For example, if maximum power, or efficiency, were the primary concern
then one might bias more to the 'B' side of the equation while if
fidelity were the primary concern one might bias more to the 'A'.


Precisely. Both Class A operation and Class B operation are inherent
in the nomenclature and definition and their relative importance is
clearly intended to be in the designer's discretion.

Historically, the original purpose of Class AB was to annihilate the
second harmonic which before made up such a very large part of the
THD, while still allowing beam tubes and pentodes to give much larger
power than available before. The "invention" of Class AB as a hi-
fidelity amp is what spurred part of a Olsen's work on perception;
before it wasn't known that odd harmonics are proportionately much
more disturbing than even harmonics. It seems to me that AB amps with
largish parts of their output in Class A is a relatively modern trend,
possibly related to ever less-sensitive speakers.

One might also observe that's likely why it's called Class AB and not
Class insert unique letter.


There is in fact a class between Class A and Class AB with a unique
description: "Limiting Class A1", which is set up so that the
crossover happens when one valve just reaches current cutoff and the
other simultaneously reaches zero bias. It makes for an amazingly
smooth sound but it is a bitch to set up and keep tuned if you want to
keep your circuits simple. I was therefore rather interested in what
Patrick said elsewhere in this thread (in more general sense rather
than specifically about LImitiing Class A1) about within 10 per cent
of conduction angle being imperceptible...

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

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Default Output classes A and AB

On Oct 24, 5:44 am, Eeyore
wrote:
Patrick Turner wrote:
Eeyore wrote:
The definition of Class A is very simple. It requires that the output device(s)
never cease conducting under any signal condition.


It means slightly more than this because tubes don't cut off as sharply
as other devices.


I see what you're saying but I do believe that the definition is unchanged. Obviously
avoiding any region of significant non-linearity is preferable but that in its own right
doesn't change the definition.

Graham


Let's look at your definition again:

Poopie Stevenson wrote:
The definition of Class A is very simple. It requires that the output device(s)
never cease conducting under any signal condition.


Why don't you explain to us how a Class A amp can operate within the
class "under any signal condition", which presumably includes *much*
larger signals than the negative bias?

Your definition ipso facto makes Class A an impossible operating
condition because an increasing level of signal, permitted "under any
signal condition", will sooner or later drive the amp into cutoff. Of
course, long before then it will cease to be a high fidelity
amplifier, though, on the evidence of your posts, we don't expect that
to matter to you.

I repeat, a Class A amp, including that part of a Class AB amp
operating in Class A, are always and under any circumstances subject
to the designer's input signal limit or, if instead stated,
dissipation limit. To demand that a Class A amplifier work "under any
signal condition" is stupid for even a newbie, never mind someone like
you, Graham Stevenson, who claims to design electronic gear for sound
professional to use.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

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