[Patrick Turner]

Phil Allison has tried to say how awful OPTs are in audio amps
because they limit the amount of NFB that can be applied.

He has failed to move any of us who like well made tube amps.

Phil likes the Quad range of ESL rather a lot, and guess what,
they have audio transformers and NO NFB around them and they sound
superb, do they
not Phil?

And the skills of Mr Walker included exploiting the phase shift in the
ESL transformers
where it was appropriate.

I have to say that Walker's expertise in his Quad II OPT could have been

greater, but the bean counters prevented much of what was produced being
any better.

McIntosh found that an OPT didn't present much of an obstacle to a high
amount of NFB,
and they continued using OPTs even with SS devices in the output.

Many OPTs are crap and do prevent much NFB being applied, but not
in the better made amplifiers.

Patrick Turner

[Andre Jute]

Patrick Turner wrote:
Phil Allison has tried to say how awful OPTs are in audio amps
because they limit the amount of NFB that can be applied.

He has failed to move any of us who like well made tube amps.

Phil likes the Quad range of ESL rather a lot, and guess what,
they have audio transformers and NO NFB around them and they sound
superb, do they
not Phil?

And the skills of Mr Walker included exploiting the phase shift in the
ESL transformers
where it was appropriate.

I have to say that Walker's expertise in his Quad II OPT could have been

greater, but the bean counters prevented much of what was produced being
any better.

McIntosh found that an OPT didn't present much of an obstacle to a high
amount of NFB,
and they continued using OPTs even with SS devices in the output.

Many OPTs are crap and do prevent much NFB being applied, but not
in the better made amplifiers.

Patrick Turner

Sheesh, Patrick.

Phil set a trap for you and, without pausing for thought, you jumped
into it, shouting "Hallelujah!"

This is a tube conference. We already know that a good output
transformer permits all the NFB that is necessary or desirable and
quite a big safety margin too.

It is none of our business to prove that output transformers permit
unreasonable, diseased or unlimited amounts of NFB.

Overuse of NFB is an obsession of the silicon slime. Leave them to it.
Don't be tempted to conduct the argument in their terms or by their
rules. They are the supplicants on our conference. We make the terms of
reference and the rules. (1)

Andre Jute
No negotiation, no retreat, attack constantly on an expanding 360
degree perimeter

(1) The terms of reference is what is good for the best tubes, and the
rules I'll tell them after they've broken them and been punished for
it. That's rule number one. Rule number two is that you don't get told
rule number three until you're already receiving a whipping for
breaking it. That's clear enough, I think.

[Arny Krueger]

"Patrick Turner" wrote in message

Phil Allison has tried to say how awful OPTs are in audio
amps
because they limit the amount of NFB that can be applied.

He has failed to move any of us who like well made tube
amps.

Just goes to show that tube bigots are refractory to logic and reason. Hey,
it is a hobby, why does it need to make sense?

Phil likes the Quad range of ESL rather a lot, and guess
what, they have audio transformers and NO NFB around them and
they sound superb, do they not Phil?

Actually, they create some of the problems that Phil hopes his power amps
don't exacerbate with high output source impedances.

And the skills of Mr Walker included exploiting the phase
shift in the ESL transformers where it was appropriate.

There you go.

I have to say that Walker's expertise in his Quad II OPT
could have been
greater, but the bean counters prevented much of what was
produced being any better.

Typical European amp of the day - kind of spare with materials.

McIntosh found that an OPT didn't present much of an
obstacle to a high amount of NFB,

A lot of their feedback is taken from unique windings on the OPT.

and they continued using OPTs even with SS devices in the
output.

Well, they had this transformer shop to keep busy.

Many OPTs are crap and do prevent much NFB being applied,
but not in the better made amplifiers.

Show me a amp with an OPT that has DF 100 from 20 to 2 KHz. I'm willing to
be educated. ;-)

[Arny Krueger]

"Andre Jute" wrote in message
ups.com


Overuse of NFB is an obsession of the silicon slime.


Overuse of personal attacks where the use of factual arguments would be in
order seems to be an obsession of "Mr. Jute".

[Patrick Turner]

Andre Jute wrote:

Patrick Turner wrote:
Phil Allison has tried to say how awful OPTs are in audio amps
because they limit the amount of NFB that can be applied.

He has failed to move any of us who like well made tube amps.

Phil likes the Quad range of ESL rather a lot, and guess what,
they have audio transformers and NO NFB around them and they sound
superb, do they
not Phil?

And the skills of Mr Walker included exploiting the phase shift in the
ESL transformers
where it was appropriate.

I have to say that Walker's expertise in his Quad II OPT could have been

greater, but the bean counters prevented much of what was produced being
any better.

McIntosh found that an OPT didn't present much of an obstacle to a high
amount of NFB,
and they continued using OPTs even with SS devices in the output.

Many OPTs are crap and do prevent much NFB being applied, but not
in the better made amplifiers.

Patrick Turner

Sheesh, Patrick.

Phil set a trap for you and, without pausing for thought, you jumped
into it, shouting "Hallelujah!"

This is a tube conference. We already know that a good output
transformer permits all the NFB that is necessary or desirable and
quite a big safety margin too.

It is none of our business to prove that output transformers permit
unreasonable, diseased or unlimited amounts of NFB.

Overuse of NFB is an obsession of the silicon slime. Leave them to it.
Don't be tempted to conduct the argument in their terms or by their
rules. They are the supplicants on our conference. We make the terms of
reference and the rules. (1)

Andre Jute
No negotiation, no retreat, attack constantly on an expanding 360
degree perimeter

(1) The terms of reference is what is good for the best tubes, and the
rules I'll tell them after they've broken them and been punished for
it. That's rule number one. Rule number two is that you don't get told
rule number three until you're already receiving a whipping for
breaking it. That's clear enough, I think.

I take all your points with due consideration and I practice due restraint
in promoting my audio philosophy any more than I have to.

All I really need to say is at my website.

Sometimes I do need to add to what i say at the website and
remind the doubters and the knockers of tube technology
that tubes and their transformer using habits are NOT the evil second class
audio citizens that the SS brigade would have us believe.

I don't have time for all 360 degree defense stratergies 24/7 365 days per
year.

I don't need to because of the constant stream of customers who have a listen
to
SS and then tubes and let their ears decide.

Patrick Turner.

[Patrick Turner]

Arny Krueger wrote:

"Patrick Turner" wrote in message

Phil Allison has tried to say how awful OPTs are in audio
amps
because they limit the amount of NFB that can be applied.

He has failed to move any of us who like well made tube
amps.

Just goes to show that tube bigots are refractory to logic and reason. Hey,
it is a hobby, why does it need to make sense?

Phil likes the Quad range of ESL rather a lot, and guess
what, they have audio transformers and NO NFB around them and
they sound superb, do they not Phil?

Actually, they create some of the problems that Phil hopes his power amps
don't exacerbate with high output source impedances.

And the skills of Mr Walker included exploiting the phase
shift in the ESL transformers where it was appropriate.

There you go.

I have to say that Walker's expertise in his Quad II OPT
could have been
greater, but the bean counters prevented much of what was
produced being any better.

Typical European amp of the day - kind of spare with materials.

McIntosh found that an OPT didn't present much of an
obstacle to a high amount of NFB,

A lot of their feedback is taken from unique windings on the OPT.

and they continued using OPTs even with SS devices in the
output.

Well, they had this transformer shop to keep busy.

Many OPTs are crap and do prevent much NFB being applied,
but not in the better made amplifiers.

Show me a amp with an OPT that has DF 100 from 20 to 2 KHz. I'm willing to
be educated. ;-)

One doesn't need a DF 10.

Having a DF = 100 means the amplifier Rout = 0.08 ohms.

Quite unecessary.

Typical Rout of a class A triode amp without any loop NFB using KT90 in triode
( but a pair of 300B would do just as well ) with OPT ratio
of 10,000 ohms to 5 ohms ( 2,000:1 ) is about 1.2 ohms.
After application of only 12 dB of global NFB this is reduced to
0.3 ohms, giving a more than adequate DF of 20 with a 6 ohm speaker.

Patrick Turner.

[Patrick Turner]

Arny Krueger wrote:

"Andre Jute" wrote in message
ups.com

Overuse of NFB is an obsession of the silicon slime.

Overuse of personal attacks where the use of factual arguments would be in
order seems to be an obsession of "Mr. Jute".

But in a reply to me you said,

" Just goes to show that tube bigots are refractory to logic and reason. Hey,
it is a hobby, why does it need to make sense?"

This implies tube users are dopey arsoles, but of course we ain't,
so when we refer to silicon slime, its a justifiable response to the way YOU
insultingly regard tube users.

Patrick Turner.

[Arny Krueger]

"Patrick Turner" wrote in message
...


Arny Krueger wrote:

"Andre Jute" wrote in message
ups.com

Overuse of NFB is an obsession of the silicon slime.

Overuse of personal attacks where the use of factual arguments would be
in
order seems to be an obsession of "Mr. Jute".

But in a reply to me you said,

" Just goes to show that tube bigots are refractory to logic and reason.
Hey,
it is a hobby, why does it need to make sense?"

Not the same thing at all.

This implies tube users are dopey arsoles,

That's a creation of your mind, Patrick.

but of course we ain't,

Now you are deifying yourself, Patrick. Some tube bigots are dopey
whatevers, some aren't. Being a tube bigot does not confer instant immunity
to being dopey.

As I said above, if fooling with tubes is just a hobby, there's no public
harm that's done. I'd rather see Jute solder parts and fantasize about
foriegn agents than be an online predator. It seems like he spends a lot of
time thinking about the latter.

If one lives in a delusional world where obsolete technology is superior to
highly effective modern technology, then someone should step in and provide
an occasional reality check.

so when we refer to silicon slime, its a justifiable response to the way
YOU
insultingly regard tube users.

Jute threw the first through five-hundreth stones many years ago, with nary
a response from me. Then he threw some more and I still cut him slack. One
day I read in the bible, which says that Jute used up his allotment of
gratuitous insults "Seven times seventy", so that made him fair game.
(Joke - I'm playing fast and loose with the true Biblical meaning).

Let's be frank Pat - Jute is playing a game. He wants to get a rise out of
people he chooses to disagree with, and I help him with his little game.

Bottom line Pat, I've got no problem with people who want to fool around
with obsolete electronic parts in their garages and have what they think is
fun. It's the continual agressive acts, and lies and deceptions that gets a
rise out of me.

[Arny Krueger]

"Bret Ludwig" wrote in message
ups.com...

Arny Krueger wrote:
snip



McIntosh found that an OPT didn't present much of an
obstacle to a high amount of NFB,

A lot of their feedback is taken from unique windings on the OPT.

Since the patents ran out decades ago maybe the rest of the tube amp
builders will pull their head out and smell the coffee someday.

I favor simply doing away with the OPTs. The Futterman patents if there were
any, should be "mature".

and they continued using OPTs even with SS devices in the
output.

Well, they had this transformer shop to keep busy.

They are also majorly cheap. The Mcintosh autoformer is a GOOD THING
in many applications.

Such as, aside from the obvious?

I would turn it around and say there are TOO FEW
solid state amps with transformers.

Don't know about that. Educate me.

Many OPTs are crap and do prevent much NFB being applied,
but not in the better made amplifiers.

Show me a amp with an OPT that has DF 100 from 20 to 2 KHz. I'm willing
to
be educated. ;-)

Why, when 20 is as high a DF a normal audio amp needs?

Simply not true. That allows the amp to, for example put a 3-octave-wide
almost 0.5 dB dip right around a midrange crossover frequency. Careful
listeners will hear it.

[Arny Krueger]

"Patrick Turner" wrote in message
...


Arny Krueger wrote:

Many OPTs are crap and do prevent much NFB being applied,
but not in the better made amplifiers.

Show me a amp with an OPT that has DF 100 from 20 to 2 KHz. I'm willing
to
be educated. ;-)

One doesn't need a DF 10.

Sure you do. A DF of 10 gives the power amp a license to add 1 dB dip or
rise wherever it wants to.

Having a DF = 100 means the amplifier Rout = 0.08 ohms.

Or 0.04 ohms if one admits that there are such things as 4 ohm speakers.

Quite unecessary.

It's all about avoiding unecessary frequency response variations.

Typical Rout of a class A triode amp without any loop NFB using KT90 in
triode
( but a pair of 300B would do just as well ) with OPT ratio
of 10,000 ohms to 5 ohms ( 2,000:1 ) is about 1.2 ohms.

Yikes!

After application of only 12 dB of global NFB this is reduced to
0.3 ohms, giving a more than adequate DF of 20 with a 6 ohm speaker.

Sorry Pat but I just debunked the DF = 20 argument for Bret.

[Andre Jute]

Thanks for your gracious reply, Patrick. On reflection, mine is one of
those letters better sent privately or, best of all, not at all. --
Andre Jute

Patrick Turner wrote:
Andre Jute wrote:

Patrick Turner wrote:
Phil Allison has tried to say how awful OPTs are in audio amps
because they limit the amount of NFB that can be applied.

He has failed to move any of us who like well made tube amps.

Phil likes the Quad range of ESL rather a lot, and guess what,
they have audio transformers and NO NFB around them and they sound
superb, do they
not Phil?

And the skills of Mr Walker included exploiting the phase shift in the
ESL transformers
where it was appropriate.

I have to say that Walker's expertise in his Quad II OPT could have been

greater, but the bean counters prevented much of what was produced being
any better.

McIntosh found that an OPT didn't present much of an obstacle to a high
amount of NFB,
and they continued using OPTs even with SS devices in the output.

Many OPTs are crap and do prevent much NFB being applied, but not
in the better made amplifiers.

Patrick Turner

Sheesh, Patrick.

Phil set a trap for you and, without pausing for thought, you jumped
into it, shouting "Hallelujah!"

This is a tube conference. We already know that a good output
transformer permits all the NFB that is necessary or desirable and
quite a big safety margin too.

It is none of our business to prove that output transformers permit
unreasonable, diseased or unlimited amounts of NFB.

Overuse of NFB is an obsession of the silicon slime. Leave them to it.
Don't be tempted to conduct the argument in their terms or by their
rules. They are the supplicants on our conference. We make the terms of
reference and the rules. (1)

Andre Jute
No negotiation, no retreat, attack constantly on an expanding 360
degree perimeter

(1) The terms of reference is what is good for the best tubes, and the
rules I'll tell them after they've broken them and been punished for
it. That's rule number one. Rule number two is that you don't get told
rule number three until you're already receiving a whipping for
breaking it. That's clear enough, I think.

I take all your points with due consideration and I practice due restraint
in promoting my audio philosophy any more than I have to.

All I really need to say is at my website.

Sometimes I do need to add to what i say at the website and
remind the doubters and the knockers of tube technology
that tubes and their transformer using habits are NOT the evil second class
audio citizens that the SS brigade would have us believe.

I don't have time for all 360 degree defense stratergies 24/7 365 days per
year.

I don't need to because of the constant stream of customers who have a listen
to
SS and then tubes and let their ears decide.

Patrick Turner.

[Andre Jute]

Have you guys seen the latest issue of "Debating Trade Tricks"? In a
thread (below) which until now was distributed only on rec.audio.tubes,
home of the tubies, Arny "I spoke in error" Krueger tries to claim that
his attacks on tubes, in a tube conference, are provoked by me at home
on a tube conference! So in Arnyland, if a scumball burgles your house,
you provoked him by owning nice things?

Sit down before you read this: Arny claims his assaults on me (sample
below) are inspired by his reading of his Bible! Makes one wonder
precisely how much odder than the Koran Arny "Just call me Mullah"
Krueger's Bible must be. Hell, the bibilous little mouthfoamer keeps
this up and soon "Debating Trade Tricks" will have to be renamed
"Revisionist History for Illiterates who cannot use Google".

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


Arny "I spoke in error" Krueger wrote:
"Patrick Turner" wrote in message
...


Arny Krueger wrote:

"Andre Jute" wrote in message
ups.com

Overuse of NFB is an obsession of the silicon slime.

Overuse of personal attacks where the use of factual arguments would be
in
order seems to be an obsession of "Mr. Jute".

But in a reply to me you said,

" Just goes to show that tube bigots are refractory to logic and reason.
Hey,
it is a hobby, why does it need to make sense?"

Not the same thing at all.

This implies tube users are dopey arsoles,

That's a creation of your mind, Patrick.

but of course we ain't,

Now you are deifying yourself, Patrick. Some tube bigots are dopey
whatevers, some aren't. Being a tube bigot does not confer instant immunity
to being dopey.

As I said above, if fooling with tubes is just a hobby, there's no public
harm that's done. I'd rather see Jute solder parts and fantasize about
foriegn agents than be an online predator. It seems like he spends a lot of
time thinking about the latter.

If one lives in a delusional world where obsolete technology is superior to
highly effective modern technology, then someone should step in and provide
an occasional reality check.

so when we refer to silicon slime, its a justifiable response to the way
YOU
insultingly regard tube users.

Jute threw the first through five-hundreth stones many years ago, with nary
a response from me. Then he threw some more and I still cut him slack. One
day I read in the bible, which says that Jute used up his allotment of
gratuitous insults "Seven times seventy", so that made him fair game.
(Joke - I'm playing fast and loose with the true Biblical meaning).

Let's be frank Pat - Jute is playing a game. He wants to get a rise out of
people he chooses to disagree with, and I help him with his little game.

Bottom line Pat, I've got no problem with people who want to fool around
with obsolete electronic parts in their garages and have what they think is
fun. It's the continual agressive acts, and lies and deceptions that gets a
rise out of me.

[Arny Krueger]

"Andre Jute" wrote in message
oups.com...

Sit down before you read this: Arny claims his assaults on me (sample
below) are inspired by his reading of his Bible!

Arny Krueger wrote:

Jute threw the first through five-hundreth stones many years ago, with
nary
a response from me. Then he threw some more and I still cut him slack.
One
day I read in the Bible, which says that Jute used up his allotment of
gratuitous insults "Seven times seventy", so that made him fair game.
(Joke - I'm playing fast and loose with the true Biblical meaning).


So there you have it. I can tell a joke, clearly label it as a joke, and
Jute misrepresents as a "claim".

[Ian Iveson]

Arny Krueger wrote:

After application of only 12 dB of global NFB this is reduced to
0.3 ohms, giving a more than adequate DF of 20 with a 6 ohm
speaker.

Sorry Pat but I just debunked the DF = 20 argument for Bret.

Hardly.

20 is OK for some speakers in some circumstances. 10 appears to be a
commonly accepted minimum for stage-to-stage coupling.

But haven't you missed an opportunity here? What about your 20Hz to
20kHz? I wonder if Patrick's hypothetical amp maintains its claimed 20
across that frequency range.

cheers, Ian

[Arny Krueger]

"Ian Iveson" wrote in message
...
Arny Krueger wrote:

After application of only 12 dB of global NFB this is reduced to
0.3 ohms, giving a more than adequate DF of 20 with a 6 ohm speaker.

Sorry Pat but I just debunked the DF = 20 argument for Bret.

Hardly.

Certainly.

20 is OK for some speakers in some circumstances.

Bread and water is a good meal in some circumstances. I just don't want to
be there! ;-)

10 appears to be a commonly accepted minimum for stage-to-stage coupling.

Huh?

But haven't you missed an opportunity here? What about your 20Hz to 20kHz?
I wonder if Patrick's hypothetical amp maintains its claimed 20 across
that frequency range.

Good question. It is well known that otherwise good transformers can go on
potty break below 50 Hz.

[Andre Jute]

Arny Krueger wrote:
"Andre Jute" wrote in message
oups.com...

Sit down before you read this: Arny claims his assaults on me (sample
below) are inspired by his reading of his Bible!

Arny Krueger wrote:

Jute threw the first through five-hundreth stones many years ago, with
nary
a response from me. Then he threw some more and I still cut him slack.
One
day I read in the Bible, which says that Jute used up his allotment of
gratuitous insults "Seven times seventy", so that made him fair game.
(Joke - I'm playing fast and loose with the true Biblical meaning).


So there you have it. I can tell a joke, clearly label it as a joke, and
Jute misrepresents as a "claim".

Krueger's "joke" -- haw-haw, excuse me while I groan -- is that he
was "playing fast and loose with the *true* Biblical meaning".

We are agreed that Krueger *read* his Bible. He does not deny it. He
does not tell us that Bible-reading is another "joke". He does not tell
us that Biblical *condemnation* is a "joke". We are meant to take
reading and condemnation as true, but leave the interpretation of what
he read to Krueger's "joke". In other words, he's setting himself up as
an old fashioned prophet to point the finger. The little man's hubris
never ceases to amaze me.

I did not say Krueger's Bible *instructed* him to to assault me. I said
that his reading *inspired* his assualt on me, via Krueger's dull
"joke" on "the true Biblical meaning" and his intepretation "so that
made him [Jute} fair game." This is a distinction perhaps too subtle
for an illiterate like Krueger; it is nonetheless real and significant.

You want to live by debating trade tricks, Krueger, you can also die by
them.

It is significant that the worst bullies in the magistrate's court
always claim, "We were only having a little fun stomping the old
pensioner to death." And the number of spurious reasons a mullah or a
Himmler can invent to give a veneer of dishonest "morality" to a deadly
"joke" is matched only by those Arny Krueger can invent. In this
instance, the Bible he drags in is supposed to justify his invasion of
rec.audio.tubes and his attempts here to spoil our pleasure in our
hobby for his own sick satisfaction.

You're scum, Krueger. Worse, you're hypocritical scum.

Andre Jute

[Patrick Turner]

Arny Krueger wrote:

"Patrick Turner" wrote in message
...


Arny Krueger wrote:

"Andre Jute" wrote in message
ups.com

Overuse of NFB is an obsession of the silicon slime.

Overuse of personal attacks where the use of factual arguments would be
in
order seems to be an obsession of "Mr. Jute".

But in a reply to me you said,

" Just goes to show that tube bigots are refractory to logic and reason.
Hey,
it is a hobby, why does it need to make sense?"

Not the same thing at all.

This implies tube users are dopey arsoles,

That's a creation of your mind, Patrick.

but of course we ain't,

Now you are deifying yourself, Patrick. Some tube bigots are dopey
whatevers, some aren't. Being a tube bigot does not confer instant immunity
to being dopey.

As I said above, if fooling with tubes is just a hobby, there's no public
harm that's done. I'd rather see Jute solder parts and fantasize about
foriegn agents than be an online predator. It seems like he spends a lot of
time thinking about the latter.

If one lives in a delusional world where obsolete technology is superior to
highly effective modern technology, then someone should step in and provide
an occasional reality check.

so when we refer to silicon slime, its a justifiable response to the way
YOU
insultingly regard tube users.

Jute threw the first through five-hundreth stones many years ago, with nary
a response from me. Then he threw some more and I still cut him slack. One
day I read in the bible, which says that Jute used up his allotment of
gratuitous insults "Seven times seventy", so that made him fair game.
(Joke - I'm playing fast and loose with the true Biblical meaning).

Let's be frank Pat - Jute is playing a game. He wants to get a rise out of
people he chooses to disagree with, and I help him with his little game.

Bottom line Pat, I've got no problem with people who want to fool around
with obsolete electronic parts in their garages and have what they think is
fun. It's the continual agressive acts, and lies and deceptions that gets a
rise out of me.

There is no useful information on audio transformers in your above post so no
reply is required from me.

Patrick Turner

[Patrick Turner]

Arny Krueger wrote:

"Bret Ludwig" wrote in message
ups.com...

Arny Krueger wrote:
snip



McIntosh found that an OPT didn't present much of an
obstacle to a high amount of NFB,

A lot of their feedback is taken from unique windings on the OPT.

Since the patents ran out decades ago maybe the rest of the tube amp
builders will pull their head out and smell the coffee someday.

I favor simply doing away with the OPTs. The Futterman patents if there were
any, should be "mature".

and they continued using OPTs even with SS devices in the
output.

Well, they had this transformer shop to keep busy.

They are also majorly cheap. The Mcintosh autoformer is a GOOD THING
in many applications.

Such as, aside from the obvious?

I would turn it around and say there are TOO FEW
solid state amps with transformers.

Don't know about that. Educate me.

Many OPTs are crap and do prevent much NFB being applied,
but not in the better made amplifiers.

Show me a amp with an OPT that has DF 100 from 20 to 2 KHz. I'm willing
to
be educated. ;-)

Why, when 20 is as high a DF a normal audio amp needs?

Simply not true. That allows the amp to, for example put a 3-octave-wide
almost 0.5 dB dip right around a midrange crossover frequency. Careful
listeners will hear it.

More BS.

Patrick Turner.

[Patrick Turner]

Arny Krueger wrote:

"Patrick Turner" wrote in message
...


Arny Krueger wrote:

Many OPTs are crap and do prevent much NFB being applied,
but not in the better made amplifiers.

Show me a amp with an OPT that has DF 100 from 20 to 2 KHz. I'm willing
to
be educated. ;-)

One doesn't need a DF 10.

Sure you do. A DF of 10 gives the power amp a license to add 1 dB dip or
rise wherever it wants to.

Having a DF = 100 means the amplifier Rout = 0.08 ohms.

Or 0.04 ohms if one admits that there are such things as 4 ohm speakers.

Quite unecessary.

It's all about avoiding unecessary frequency response variations.

Typical Rout of a class A triode amp without any loop NFB using KT90 in
triode
( but a pair of 300B would do just as well ) with OPT ratio
of 10,000 ohms to 5 ohms ( 2,000:1 ) is about 1.2 ohms.

Yikes!

After application of only 12 dB of global NFB this is reduced to
0.3 ohms, giving a more than adequate DF of 20 with a 6 ohm speaker.

Sorry Pat but I just debunked the DF = 20 argument for Bret.

You are succeeding to dump your credibility.

Patrick Turner.

[Patrick Turner]

Ian Iveson wrote:

Arny Krueger wrote:

After application of only 12 dB of global NFB this is reduced to
0.3 ohms, giving a more than adequate DF of 20 with a 6 ohm
speaker.

Sorry Pat but I just debunked the DF = 20 argument for Bret.

Hardly.

20 is OK for some speakers in some circumstances. 10 appears to be a
commonly accepted minimum for stage-to-stage coupling.

But haven't you missed an opportunity here? What about your 20Hz to
20kHz? I wonder if Patrick's hypothetical amp maintains its claimed 20
across that frequency range.

cheers, Ian

All well made tube amps with wide open loop bandwidth have the same Rout
between
20Hz and 20kHz. The applied NFB is reduced with reducing gain outside
these
frequencies.
In many of my amps the open loop bw is the same as the closed loop bw, ie,
about
14Hz to 65kHz.

Many amps of the past such as the Mullard 520 had less open loop bw with
HF gain/phase shift tweaking networks in place.
So in such an amp the applied FB at 20khz was maybe 4dB less at 20kHz,
with a resulting slight
and negligible rise in Rout.


Patrick Turner.

[Ian Iveson]

Patrick Turner said

In many of my amps the open loop bw is the same as the closed loop
bw, ie,
about
14Hz to 65kHz.

I don't believe you.

Has anyone ever confirmed this claim? Can you back up any of your
boasts?

Ian

[Patrick Turner]

Ian Iveson wrote:

Patrick Turner said

In many of my amps the open loop bw is the same as the closed loop
bw, ie,
about
14Hz to 65kHz.

I don't believe you.

Has anyone ever confirmed this claim? Can you back up any of your
boasts?

Ian

The world doesn't bother one iota about what you believe or not.

I have had enough info on OPT design and construction for anyone to make
superb OPTs for
the last 5 years.

Not once has anyone refuted my methodology.

If you follow all the advice about building OPT at my website you will
discover that
it is VERY EASY to make any OPT be able to produce full power between
14Hz and at least 65 kHz.

The OPT in my mosfet amps with 5P and 6S sections has 10Hz to 200kHz+
capability
at 50 watts, and the much larger 300 watt tube amp OPTs also have
similar bw
with the 5P x 6S interleaving arrangement.

In 1947 D.T.N. Williamson gave the world a recipe for 10Hz to 100kHz
from an OPT.
The rest of the amp using 6SN7 and KT66 in triode meant the open loop
BW was as wide as the closed loop.

However, to ensure HF stability with NFB and capacitor loads the open
loop BW was reduced with zobel RC across the V1
anode load above 20kHz.
This still meant the closed loop bw was as wide as the open loop
un-tweaked bw.

But the TL12 Leaks and the Mullard 520 with pentode input tubes subject
to
the Miller C of V2 etc rolled off early.

Many folks including Leak used attrocious OPT quality which prevented
wide open loop bw.
Leak TL12 has leakage L at around 50mH wheras in my designs it allways
less than 5mH for the same tubes and power.

I use plenty of interleaving, yet I keep the interleaved sections well
apart with about 0.5mm of low dielectric constant insulation therfore
minimizing shunt capacitances and ensuring wide bw.

The reason why so many crummy OPTs have given audio transformers a bad
name is greed and sloth
in the human performance.

BTW, the method for calculating the shunt C of a given OPT is being
prepared following
recent careful measurements with OPTs for an 845 SET project.
My measurements closely co-relate with calculations I have made
and the method will be incorporated to the material at my website in the
next day or two.

Its not a real big deal to add this info because if ppl just follow the
method for interleaving
and use the recommended thicknesses of insulation which is at least
0.4mm,
then the capacitance won't be a problem, especially when the Ra of the
tube in parallel with its load
is a low resistance value which is not much affected by capacitance as
is the case with
having a dozen 6550 in the output stage in a 300 watt amp.

Capacitance in IST coupling trannies and other types of trannies such as
step up trannies for ESL
needs careful thought however.

Patrick Turner.

[Ian Iveson]

Buried in extraneous self-aggrandisement, Patrick Turner sullenly
admitted:

In many of my amps the open loop bw is the same as the closed
loop
bw, ie,
about
14Hz to 65kHz.

I don't believe you.

Has anyone ever confirmed this claim? Can you back up any of your
boasts?

This still meant the closed loop bw was as wide as the open loop
***un-tweaked*** bw.

My emphasis.

Squirming again.

cheers, Ian

[Patrick Turner]

Ian Iveson wrote:

Buried in extraneous self-aggrandisement, Patrick Turner sullenly
admitted:

In many of my amps the open loop bw is the same as the closed
loop
bw, ie,
about
14Hz to 65kHz.

I don't believe you.

Has anyone ever confirmed this claim? Can you back up any of your
boasts?

This still meant the closed loop bw was as wide as the open loop
***un-tweaked*** bw.

My emphasis.

Squirming again.

cheers, Ian

You really are a snotty nosed pomme.


Your understanding and level of expertise in tube amp and OPT design and
use
is abysmal.

The closed loop bw in many of my amps is LESS than the open loop bw.

Usually, its the other way around in many commercial designs such as
thew Mullard 520
where the NFB is used to extend the open loop BW because its so darn
poor, like many SS amps.

But in my case I have ZERO wish to have an amp with 1Mhz of BW after
applying NFB because its asking for trouble
and serves ZERO purpose in sonic betterment.

So hence the open loop BW is trimmed down to make it easier to
limit the closed loop bw.

But all you can do in your grossly ignorant manner is accuse me of
"extraneous self-aggrandisement" .

I see that you cannot refute ONE SINGLE SENTENCE of the advice I give at
my website
with regard to output transformers.

If you want to impress anyone favourably, create your own website with
your own message.

Patrick Turner.

[Ian Iveson]

Patrick Turner continued squirming [extraneous self-aggrandisement
deleted]:

...The closed loop bw in many of my amps is LESS than the open loop
bw.

...So hence the open loop BW is trimmed down to make it easier to
limit the closed loop bw.

You've done it again.

The reason I don't read your stuff generally is that, except for the
mistakes, lies and irksome banter, it just comes from RDH4, which I
have already. Hence I have visited your web pages only once, briefly.

You said the open loop bandwidth was the same as the closed loop. You
said that here. When I pointed out your error you squirmed as usual.
You still haven't said what the open loop bandwidth is. I guess that's
because you don't know what open loop means.

Instead of learning, you lie, as usual.

If you want to impress anyone favourably, create your own website
with
your own message.

Just about sums you up your intentions. Tell me about this impressing
people thing...can I start at the bottom and work up somehow?

Ian

[Patrick Turner]

Ian Iveson wrote:

Patrick Turner continued squirming [extraneous self-aggrandisement
deleted]:

...The closed loop bw in many of my amps is LESS than the open loop
bw.

...So hence the open loop BW is trimmed down to make it easier to
limit the closed loop bw.

You've done it again.

The reason I don't read your stuff generally is that, except for the
mistakes, lies and irksome banter, it just comes from RDH4, which I
have already. Hence I have visited your web pages only once, briefly.

It took me a year to convince you to buy a copy of RDH4 after you'd spent
a year
advising ppl with BS as a knwo nothing busy body.
Oh how you hated my corrections. Too bad.

You remain pig ignorant.



You said the open loop bandwidth was the same as the closed loop. You
said that here. When I pointed out your error you squirmed as usual.
You still haven't said what the open loop bandwidth is. I guess that's
because you don't know what open loop means.

Let me explain further dunce head.

In my amps the open loop bandwidth WITHOUT any phase tweaking
networks and with at least 16 dB of global NFB applied is the same at
least as the closed loop BW, ie, from
20Hz to 65 kHz, WITH THE RATED RESISTANCE LOAD.
Often I achieve MORE bw with NFB applied becauuse the open loop bw is
excessive, ie, 100kHz, and the NFB
simply extends it further.

If I left the closed loop bw at 200kHz there is a danger that with a
capacitance load or no load at all the
amp would become unstable and perhaps oscillate at some F above 50kHz.

So steps are taken to compensate the NFB path network AND REDUCE THE OPEN
LOOP GAIN
WHICH IS EXCESSIVE.

HAD YOU READ ANYTHING AT MY WEBSITE, OR LEARNT ANYTHING from reading my
website pages
which you refuse to because your mind id locked into staying ignorant,
then the art of
getting adequate open loop bw equal to the close loop bw with an R load
would have become apparent.






Instead of learning, you lie, as usual.

If you want to impress anyone favourably, create your own website
with
your own message.

Just about sums you up your intentions. Tell me about this impressing
people thing...can I start at the bottom and work up somehow?

All ppl are seeing from you is BS and more BS and very little about tube
craft.

If you want to call me a liar, then you should have adequate evidence, but
youse ****in have none.

Patrick Turner.





Ian

[Ian Iveson]

More babble. Where I have pointed out your error, you are in error.

Another demonstration of why you are not worth talking to. You are a
lying cheat.

Ian

"Patrick Turner" wrote in message
...


Ian Iveson wrote:

Patrick Turner continued squirming [extraneous self-aggrandisement
deleted]:

...The closed loop bw in many of my amps is LESS than the open
loop
bw.

...So hence the open loop BW is trimmed down to make it easier to
limit the closed loop bw.

You've done it again.

The reason I don't read your stuff generally is that, except for
the
mistakes, lies and irksome banter, it just comes from RDH4, which I
have already. Hence I have visited your web pages only once,
briefly.

It took me a year to convince you to buy a copy of RDH4 after you'd
spent
a year
advising ppl with BS as a knwo nothing busy body.
Oh how you hated my corrections. Too bad.

You remain pig ignorant.



You said the open loop bandwidth was the same as the closed loop.
You
said that here. When I pointed out your error you squirmed as
usual.
You still haven't said what the open loop bandwidth is. I guess
that's
because you don't know what open loop means.

Let me explain further dunce head.

In my amps the open loop bandwidth WITHOUT any phase tweaking
networks and with at least 16 dB of global NFB applied is the same
at
least as the closed loop BW, ie, from
20Hz to 65 kHz, WITH THE RATED RESISTANCE LOAD.
Often I achieve MORE bw with NFB applied becauuse the open loop bw
is
excessive, ie, 100kHz, and the NFB
simply extends it further.

If I left the closed loop bw at 200kHz there is a danger that with a
capacitance load or no load at all the
amp would become unstable and perhaps oscillate at some F above
50kHz.

So steps are taken to compensate the NFB path network AND REDUCE THE
OPEN
LOOP GAIN
WHICH IS EXCESSIVE.

HAD YOU READ ANYTHING AT MY WEBSITE, OR LEARNT ANYTHING from reading
my
website pages
which you refuse to because your mind id locked into staying
ignorant,
then the art of
getting adequate open loop bw equal to the close loop bw with an R
load
would have become apparent.






Instead of learning, you lie, as usual.

If you want to impress anyone favourably, create your own website
with
your own message.

Just about sums you up your intentions. Tell me about this
impressing
people thing...can I start at the bottom and work up somehow?

All ppl are seeing from you is BS and more BS and very little about
tube
craft.

If you want to call me a liar, then you should have adequate
evidence, but
youse ****in have none.

Patrick Turner.





Ian

[Andre Jute]

Ian Iveson wrote:
More babble. Where I have pointed out your error, you are in error.

Holy geschittnik, you really do fancy yourself, Iveson. For a clown who
is repeatedly caught out not knowing the simplest electronics, you are
pretty loud. Have you, for instance, learned yet how slew rate works?
Or how the operating current in a tube is set?

Another demonstration of why you are not worth talking to. You are a
lying cheat.

No, Patrick simply knows vastly more theory than you do, and has vastly
more experience. Hmm. "Vastly" is superflous. Any theory and any
experience would be a huge amount more than your demonstrable near-zero
store.

This is another demonstration of your immaturity, Iveson, and your
wilful inability to understand that physics doesn't answer to the
"laws" (hee! hee!) of Marxist dialectics. Patrick, a far better
socialist than you, has a far better grasp of the material world
exactly because he is a better socialist.

Ian

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


"Patrick Turner" wrote in message
...


Ian Iveson wrote:

Patrick Turner continued squirming [extraneous self-aggrandisement
deleted]:

...The closed loop bw in many of my amps is LESS than the open
loop
bw.

...So hence the open loop BW is trimmed down to make it easier to
limit the closed loop bw.

You've done it again.

The reason I don't read your stuff generally is that, except for
the
mistakes, lies and irksome banter, it just comes from RDH4, which I
have already. Hence I have visited your web pages only once,
briefly.

It took me a year to convince you to buy a copy of RDH4 after you'd
spent
a year
advising ppl with BS as a knwo nothing busy body.
Oh how you hated my corrections. Too bad.

You remain pig ignorant.



You said the open loop bandwidth was the same as the closed loop.
You
said that here. When I pointed out your error you squirmed as
usual.
You still haven't said what the open loop bandwidth is. I guess
that's
because you don't know what open loop means.

Let me explain further dunce head.

In my amps the open loop bandwidth WITHOUT any phase tweaking
networks and with at least 16 dB of global NFB applied is the same
at
least as the closed loop BW, ie, from
20Hz to 65 kHz, WITH THE RATED RESISTANCE LOAD.
Often I achieve MORE bw with NFB applied becauuse the open loop bw
is
excessive, ie, 100kHz, and the NFB
simply extends it further.

If I left the closed loop bw at 200kHz there is a danger that with a
capacitance load or no load at all the
amp would become unstable and perhaps oscillate at some F above
50kHz.

So steps are taken to compensate the NFB path network AND REDUCE THE
OPEN
LOOP GAIN
WHICH IS EXCESSIVE.

HAD YOU READ ANYTHING AT MY WEBSITE, OR LEARNT ANYTHING from reading
my
website pages
which you refuse to because your mind id locked into staying
ignorant,
then the art of
getting adequate open loop bw equal to the close loop bw with an R
load
would have become apparent.






Instead of learning, you lie, as usual.

If you want to impress anyone favourably, create your own website
with
your own message.

Just about sums you up your intentions. Tell me about this
impressing
people thing...can I start at the bottom and work up somehow?

All ppl are seeing from you is BS and more BS and very little about
tube
craft.

If you want to call me a liar, then you should have adequate
evidence, but
youse ****in have none.

Patrick Turner.





Ian

[Patrick Turner]

Ian Iveson wrote:

More babble. Where I have pointed out your error, you are in error.

Another demonstration of why you are not worth talking to. You are a
lying cheat.

My detailed address to the group on this subject and your response prooves
you had nothinmg to offer anyone.

Patrick Turner.



Ian

"Patrick Turner" wrote in message
...


Ian Iveson wrote:

Patrick Turner continued squirming [extraneous self-aggrandisement
deleted]:

...The closed loop bw in many of my amps is LESS than the open
loop
bw.

...So hence the open loop BW is trimmed down to make it easier to
limit the closed loop bw.

You've done it again.

The reason I don't read your stuff generally is that, except for
the
mistakes, lies and irksome banter, it just comes from RDH4, which I
have already. Hence I have visited your web pages only once,
briefly.

It took me a year to convince you to buy a copy of RDH4 after you'd
spent
a year
advising ppl with BS as a knwo nothing busy body.
Oh how you hated my corrections. Too bad.

You remain pig ignorant.



You said the open loop bandwidth was the same as the closed loop.
You
said that here. When I pointed out your error you squirmed as
usual.
You still haven't said what the open loop bandwidth is. I guess
that's
because you don't know what open loop means.

Let me explain further dunce head.

In my amps the open loop bandwidth WITHOUT any phase tweaking
networks and with at least 16 dB of global NFB applied is the same
at
least as the closed loop BW, ie, from
20Hz to 65 kHz, WITH THE RATED RESISTANCE LOAD.
Often I achieve MORE bw with NFB applied becauuse the open loop bw
is
excessive, ie, 100kHz, and the NFB
simply extends it further.

If I left the closed loop bw at 200kHz there is a danger that with a
capacitance load or no load at all the
amp would become unstable and perhaps oscillate at some F above
50kHz.

So steps are taken to compensate the NFB path network AND REDUCE THE
OPEN
LOOP GAIN
WHICH IS EXCESSIVE.

HAD YOU READ ANYTHING AT MY WEBSITE, OR LEARNT ANYTHING from reading
my
website pages
which you refuse to because your mind id locked into staying
ignorant,
then the art of
getting adequate open loop bw equal to the close loop bw with an R
load
would have become apparent.






Instead of learning, you lie, as usual.

If you want to impress anyone favourably, create your own website
with
your own message.

Just about sums you up your intentions. Tell me about this
impressing
people thing...can I start at the bottom and work up somehow?

All ppl are seeing from you is BS and more BS and very little about
tube
craft.

If you want to call me a liar, then you should have adequate
evidence, but
youse ****in have none.

Patrick Turner.





Ian

[Patrick Turner]

Andre Jute wrote:

Ian Iveson wrote:
More babble. Where I have pointed out your error, you are in error.

Holy geschittnik, you really do fancy yourself, Iveson. For a clown who
is repeatedly caught out not knowing the simplest electronics, you are
pretty loud. Have you, for instance, learned yet how slew rate works?
Or how the operating current in a tube is set?

Another demonstration of why you are not worth talking to. You are a
lying cheat.

No, Patrick simply knows vastly more theory than you do, and has vastly
more experience. Hmm. "Vastly" is superflous. Any theory and any
experience would be a huge amount more than your demonstrable near-zero
store.

This is another demonstration of your immaturity, Iveson, and your
wilful inability to understand that physics doesn't answer to the
"laws" (hee! hee!) of Marxist dialectics. Patrick, a far better
socialist than you, has a far better grasp of the material world
exactly because he is a better socialist.

I don't mind what people are even if they are socialists.

I just try to be social, and if a few folks here get their wires crossed
about
open loop gain and closed loop gain then i can only explain so far and then
if they still don't get it then its a lost cause and I won't loose sleep
over them.

Fact:- Some but not all designers of tube amps since D.T.N.Williamson have
presented the world
with amps that had as much open loop bandwidth without any global FB as
there was bandwidth when the loop
FB was added.

The Williamson was a very fast amplifier compared to all the rest without
any loop NFB.

When loop NFB is connected to a Williamson the amp the bw is not just
retained, but is slightly extended.
This makes it a candidate for instability at frequencies either side of the
af band but never within the band.
This is due to the inevitable effects of LF and HF time constants causing
enough phase shift to cause oscillations
should the OPT deviate from Williamson's original design, which was dumbed
down by nearly all
who pretended to build a "Williamson" to benefit from association with a
famous name.

The Williamson amp is fine with a resistance load but unloaded or with a
0.1uF cap
it will oscillate if the OPT is slightly poor, and most are.

In order to ensure that people could build a Williamson without problems of
instability
Williamson presented a means to reduce the open loop gain, but not
bw, just slightly with a zobel network across the V1 triode load.

Other makers used an R and C in parallel ahead of the CR coupling between V1
and V2,
so that where you have a 0.47 uF and 220k coupling V1 and V2,
a 1M and 0.033 is placed as a parallel network between the 0.47 and 220k,
so that below about 20Hz the open loop LF response is stepped down about
12dB before
the ultimate response which is a pole caused by 0.47uF and 1.22M.
The 90 degree phase shift at very low F thus occurs where open loop gain is
low so oscillations don't occur.
The overall open loop bw of the amp isn't much affected when we consider the
total open loop
bw which may go to 100kHz. This LF "gain stepper" much improves the bass
because the
typical hump in the response of a tube NFB amp below 15hz is abolished.
The LF gain stepper compensates well for an OPT without enough Lp, and in SE
amps where
the OPT is gapped, there is rarely enough Lp for best LF stability with NFB.

Having 100kHz of open loop bw is a royal PITA unless you know the amp
will always be loaded with the correct size R load, and the OPT is a work of
art.
So to make things stable at HF regardless of whether a load is connected or
if any value of capacitance is used as a load the open loop bw can be
reduced
by stepping the response by loading an input stage with a series RC network
across the main load for an input tube.
The Williamson used a 47k as a load for V1 1/2 6SN7, and
Williamson recommended 4.7k and 470pF as the gain reducer network.
At 72kHz the load on V1 anode is approx 6.6k, and this reduces the gain of
V1 from
approx 16 to approx 8, a halving of gain.
The open loop bandwidth is actually extended because the phase shift is
reduced, but there is a pole
produced below 72kHz where the open loop gain is reduced 3dB, at about
35kHz.
If a Williamson has its NFB compensation cap trimmed to produce 35kHz of
closed loop
bw then the closed loop bw equals the open loop bw.
Such an amp would be VERY stable.
Its not exactly always what i do however, and I like to have closed loop bw
out to 65kHz,
so I allow the open loop bw to be out more than 35kHz on many of my amps.
The adjustment of the NFB compensation network is then adjusted for 65kHz of
closed loop
bw and although there is some overshoot on square waves the amp is stable
and won't
oscillate on any value of cap load or without a load at all.

One must differentiate between GAIN and PHASE SHIFT. In an amp which
has an RC series "CRITICAL DAMPING NETWORK" such as I have described,
then the open loop phase shift is reduced at say 85kHz and the ultimate tube
input stage/driver stage
phase shift is reduced, and although the gain has been stepped down the
amp will amplify at 200kHz with less phase shift than without the critical
damping network.

Such networks cannot ever be guessed and they cannot ever be accurately
simulated;
they are critical because 20% changes to values chosen could make the amp
less stable or too stabe at a cost of bw into a resistive load.

Some idiots just place a cap across v1 anode load without the right value of
series R.
This places a pole in the response which always worsens stability unless the
C is huge and
brutal HF restriction is endured. Such clumsy attempts to stop a troublesome
amp
oscillating at HF really do reduce the open loop response severely, ie, open
gain
begins to roll off way too early, say at 7kHz, and open phases shift is
90degrees by 10kHz.
Usually a 0.1uF load will make such an amp oscillate badly.
many amps I have re-engineered are like this; they have real troubles with
producing
a decent HF response without nearly saturating their input stages with a
huge error signal
every time someone bashes a pair of cymbals.

So the trick is to use just the right value of RC to prevent oscillations
so there is negligible rise in amplitude of the error signal within the
audio band.
What happens outside the audio band isn't of great concern because there are
almost
no signals in audio above 20kHz. Noise occurs though, and the amp must still

be stabilised against noise starting HF oscillations.

Nearly all my amps use loop NFB and quite a few have blameless open loop
bw equal to 70kHz before the loop NFB is applied.
Zobel RC netorks are used across the output or across each 1/2 primary
of the OPT sometimes when needed to give the output tubes
a resistive load at above 50kHz which helps if not prevents oscillations
when no load is connected.

Now there are those who are allergic to NFB but I am not one such afflicted
because I gain too much sonic betterment to justify abandoning NFB.
I just don't like using too much, and were I to use more global NFB than I
do
in such amplifiers with NFB between the OPT and output cathodes then i would
probably
have to use a more restricted open loop bw created in the driver stages.

In my integrated PP amp, the 8585,
http://www.turneraudio.com.au/8585integrated.html
and the 35W SECFB monoblocs,
http://www.turneraudio.com.au/se35cfbmonobloc.html
there IS NO HF STEPPING networks used in the open loop gain structure
because there is no need to fiddle
with the already high open loop gain and low phase shift and because the
amount of
global NFB applied is less than 10dB.

So Ian Iveson should learn to read my website schematics before calling me a
liar about all this stuff.

In the case of SS amps where the open loop bw may be very many times more
than
that in a tube amp, the open loop gain is often reduced after a peak in the
response at say 500Hz,
and therafter it rolls off at 6dB /octave.

if Ian had gone to the 300W amp schematic at
http://www.turneraudio.com.au/solids...s1mosfets.html
then he'd have spotted R23 and C12 which comprise a NFB network between the
high impedance
collector outputs of the Q7 and Q8 driver stage and their input bases.
When the global NFB is disconnected, the amp displays about 5kHz of open
loop
bw, somewhat better than many amps with onlt 500Hz.

Such high open loop gain in SS amps and open loop low HF poles are not
necessarity evil.
The open loop gain has 90 degrees of phase lag well within the audio band,
but this is all pushed back to nearly no phase lag because of the amount of
NFB applied,
which is perhaps about 53dB in the case of my SS amp, and up to about 3 kHz.

Above 3 kHz because the open gain rolls off at 6dB, gain at 30kHz is 20 dB
less than it is at
below 3 kHz and the amount of NFB is reduced 20 dB to only about 33dB, or
approaching
the amount of NFB as in a tube amp.
By 300kHz the open loop, gain is reduced another 20 dB and there is open
loop
roll off elsewhere so the applied FB does not actually reduce the gain at
such an F.
The SS amp like mine has a zobel LR and CR network on its output to prevent
the
phase shift caused by capacitor loading to ever cause an EXTRA phase shift
at the source connections
where the NFB is sampled for return back to the FB input port of the input
differential amp.
I have seen attempts to use LR zobel networks in tube amps to increase
stability
by DECOUPLING THE LOAD from the amp at HF, where the amp is really
considered
only really what is directly enclosed by the global NFB loop.
Neville Thiel applied this idea in TV set sound amps way back in about 1958
with a pair of 6BM8 set up very much like Quad II.
Such tricks with zobel networks allowed OPTs to have less quality, and were
thus cheaper
to manufacture.

With developments in SS amplifier design over the last 10 years in such
brands as
Halcro such ordinary gain management methods I have been using
along with guys like Douglas Self and others of note may seem antiquated.
I am not sure how Halcro manage to get such extraordinarily low THD
measurements
at such high power and high frequencies.
I don't care much because these latest attempts at measured hyper-fidelity
don't make the music any better because human ears have serious limitations
and don't notice 1,000 times the THD in a Halcro. ( 0.1% is 1,000 times
worse than 0.0001% )
In fact its likely that even golden eared youngsters at their peak
create 100 times the thd in their ears compared to what is generated in a
Halcro amp.

Any audiologists in the audience like to comment?????

Some folks like to think that phase lag cannot ever really be cured by NFB
because its like saying that the phase error is like a delay, and you can't
fix a signal delay beacuse you would have to make a correction before the
electricty
set out on its journey through the amp, and for that you'd need a time
machine,
and HG Wells stopped selling those years ago.
They don't understand phase shift.

Amazing as it may seem the SS 300 watt amp of mine has a remarkably CLEAN
looking correction signal even when any value of C is connected as a load.
There is extremely little ring with square waves at any electrode.
This also should be the case with the error correction signal in a tube
power amp,
but because the leakage inductance is included in the global NFB loop and
there is other shunt C here and there
then there will be some ring in the correction signal, but the ampint of
ring
shouldn't saturate any stage.
Some tube amps with NFB have a lot of ring in the error signal on square
waves, especially
at the output tube anodes but little shows up on the output. Its struggling
to get its transients right...

A decent OPT with adequate and carefully applied critical damping will
minimize the
technical problems in tube amps with regard to stability.

In the 1950s Mullard came out with the 520 with EF86 driving a 12AX7
LTP gain/driver/pahse splitter stage.
This amp with crook OPTs was particularly unstable at HF and needed fairly
severe
critcal damping since 20dB of applied global NFB was recommended.
Not everyone built the Mullard with Partridge of Savage OPTs of highest
category.
Smoke from DIYers' sheds was a common feature of the home built hi-fi
experience.
The high Ra of the EF86 meant its Rout was determined by the anode RL
and then the following 12AX7 Miller C meant it was nowhere near as fast as a
Williamson
which had a 1/26SN7 coupled to a concertina phase splitter with extremely
low Miller C.
So where the Williamson input /driver stages had 300kHz of bw, the Mullard
only managed about
20kHz, and that needed to be stepped down with a gain/phase shift tweaker.
Mullard relied more heavily on NFB to make their design have good
characteristics.
Leak did much the same in a very similar apprach.

And if ppl were not told, hardly anyone would immediately think they were
listening to music via a slow old Mullard....

Just my 2c worth.

Patrick Turner.




Ian

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


"Patrick Turner" wrote in message
...


Ian Iveson wrote:

Patrick Turner continued squirming [extraneous self-aggrandisement
deleted]:

...The closed loop bw in many of my amps is LESS than the open
loop
bw.

...So hence the open loop BW is trimmed down to make it easier to
limit the closed loop bw.

You've done it again.

The reason I don't read your stuff generally is that, except for
the
mistakes, lies and irksome banter, it just comes from RDH4, which I
have already. Hence I have visited your web pages only once,
briefly.

It took me a year to convince you to buy a copy of RDH4 after you'd
spent
a year
advising ppl with BS as a knwo nothing busy body.
Oh how you hated my corrections. Too bad.

You remain pig ignorant.



You said the open loop bandwidth was the same as the closed loop.
You
said that here. When I pointed out your error you squirmed as
usual.
You still haven't said what the open loop bandwidth is. I guess
that's
because you don't know what open loop means.

Let me explain further dunce head.

In my amps the open loop bandwidth WITHOUT any phase tweaking
networks and with at least 16 dB of global NFB applied is the same
at
least as the closed loop BW, ie, from
20Hz to 65 kHz, WITH THE RATED RESISTANCE LOAD.
Often I achieve MORE bw with NFB applied becauuse the open loop bw
is
excessive, ie, 100kHz, and the NFB
simply extends it further.

If I left the closed loop bw at 200kHz there is a danger that with a
capacitance load or no load at all the
amp would become unstable and perhaps oscillate at some F above
50kHz.

So steps are taken to compensate the NFB path network AND REDUCE THE
OPEN
LOOP GAIN
WHICH IS EXCESSIVE.

HAD YOU READ ANYTHING AT MY WEBSITE, OR LEARNT ANYTHING from reading
my
website pages
which you refuse to because your mind id locked into staying
ignorant,
then the art of
getting adequate open loop bw equal to the close loop bw with an R
load
would have become apparent.






Instead of learning, you lie, as usual.

If you want to impress anyone favourably, create your own website
with
your own message.

Just about sums you up your intentions. Tell me about this
impressing
people thing...can I start at the bottom and work up somehow?

All ppl are seeing from you is BS and more BS and very little about
tube
craft.

If you want to call me a liar, then you should have adequate
evidence, but
youse ****in have none.

Patrick Turner.





Ian

[Margaret von B]

"Arny Krueger" wrote in message
. ..

So there you have it. I can tell a joke, clearly label it as a joke,

That is certainly one of the things that labels you such an utter moron.