Arny Krueger wrote:

"Patrick Turner" wrote in message


They are only as linear as a triode with regard to
voltage gain when external loops of NFB have been applied,
as in the case of the emitter follower connection or
having a few BJTs with a loop of NFB around the
lot of them to correct all their mistakes.

BJTs are inherently non linear for voltage gain and MUST
rely on large amounts of externally connected loops of
NFB.

Simply not true. Local feedback works well with BJTs.

Local loops are externally applied loops of NFB.

Bjts are so damned non linear with regard to voltage gain that large amount of
NFB, local or otherwises must be applied
to linearize the outcome, as well as raise input impedance.



This applies regardless of whether you build a preamp
with an opamp, a discrete transistor preamp,
or any power amp.

Triodes don't, they have a small amount of NFB built into
them.

Compared to BJTs, triodes have massive amounts of local NFB built into them,
and they are often used with addtiional local and/or loop NFB.

You don't know how much NFB is within any given triode now do you?

Please provide some calculations and details to prove to the group that you have
the slightest idea about what you are talking about.

Keep your answer to less than 5,000 words.



I would ask Trevor to set up a simple 1 transistor preamp
with a BC109, and without any
NFB applied, not even an emitter current feedback
resistor, and as a common emitter voltage amplifier with
a supply of 20V.

An apples-to-apples comparison would involve comparing circuits with gain
and impedances, both input and output, that are as typical and similar as
possible. However, this comparison is totally ludicrous, because nobody in
their right mind uses a stand-alone BC109 as a high grade audio amplifier
any more. They'll use some kind of an op amp, perhaps a NE 5532 or its
equivalent.

It isn't ludicous to drag people screaming back to the basics.
The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied anywhere
have hopelessly poor
voltage gain linearity.
Statements have been made on the group that what i am saying is untrue.

All opamps also must be used with NFB, and they contain many interconnected bjts
like many
discrete component amplifier, so the non linearity of all these adds together
and must be linearized with NFB.
opamps usually have way too much gain without NFB; and usually poor open loop
bandwidth,
something also flattened out by NFB.


To understand his own utter stupidity, I ask Trevor to
also set up a 6SN7 with a 250V supply to act as a preamp
and without any loop NFB, and he can then tell us all
about the results which will prove what a
jackarse he is.

Illogical comparison. Everybody knows that 6SN7s have a ton of internal
feedback, and that BJTs compare most closely to pentodes, not triodes.

A "ton" of NFB is an extremely uninformative unit applied to NFB.

Please try be specific and factual lest we consider you to be utterly stupid
like Trevor.

Exactly how much NFB is within a 6SN7?

I will also say that a 6AU6 pentode would be more linear at a volt of output
than a BC109 at a volt of output,
with both devices tested without NFB of any kind.

Unless you have done the experiments and comparisons, you remain uneducated
about the basics.

When people talk about the linearity of devices, what is being stated is the
linearity of the devices without
any external loops of NFB applied. That is what engineers understand when
somebody talks of device linearity.

bjts offer fair current linearity between base current and collector current but
offer hopeless
voltage linearity.
Amplifiers are built to provide voltage linearity regardless of current
variations due to load variations.

External loops in circuit applications of NFB are never included in discussions
defining device linearity.

You cannot say a bjt is linear if you are using an emitter follower as an
example of the device use.
The term "emitter follower" is a description of a circuit where a large amount
of series voltage NFB is
employed so that the voltage gain of the bjt is reduced from a disgustingly non
linear large number, say
100 times to say 0.99, and the open loop THD is reduced 100 times.

I will say to that where you have a 12AX7 set up as a cathode follower then
there is a gain reduction
of say 75 to just less than 1.0, so the linearity of the device cannot be known
without more provisos.

if you have an EF bjt circuit and THD = 0.01% at 1Vrms and if open loop gain was
100,
then the THD without the follower connection with the load used will be 100 x
0.01 = 1%.

The 1/2 12AX7 in a CF will typically produce only 0.0005% THD at 1V out.
If the same tube was working without the CF connection but in common cathode
the THD = 75 x 0.0005 = 0.0375%, and a small fraction of what is produced by the
BC109 without any NFB.




Patrick Turner.

Iain Churches wrote:

"Stewart Pinkerton" wrote in message
...
On 26 Mar 2006 17:16:29 -0800, "Andre Jute" wrote:

Wilson, you're getting nuttier and nuttier. First you claim my opinions
and some really basic, totally uncontroversial science are lies because
I haven't dotted thousands of tees you claim make your contrary point.
Now you want me to defend tubes against BJTs, which as far as I can
tell are Blow Jobs by Transvestites.

I notice you fail to address the fact that the modern BJT can be more
linear *without feedback* than your beloved DHTs. Surely a *true*
'ultrafidelista' would see this as the Holy Grail of the 'silent'
amplifier? Better linearity and no humming heaters?

Erm. Stewart. DHTs don't have "heaters" :-((

But the DHT's cathode is self heating and unless adequate steps are taken to
have
good hum nulling if the cathode has a mains F applied end to end then indeed
hum could be a bother.

Using IHT overcomes the problem.

But don't worry, I have to repair many BJT based amps with hum problems....

Patrick Turner.



Iain

Arny Krueger wrote:

"Patrick Turner" wrote in message

Stewpid Oinkerton squealed....

I notice you fail to address the fact that the modern
BJT can be more linear *without feedback* than your
beloved DHTs. Surely a *true* 'ultrafidelista' would see
this as the Holy Grail of the 'silent' amplifier? Better
linearity and no humming heaters?

The fact is that the modern transistor must rely on NFB
for it to be acceptable in any way.

As do the vaccum-state devices that compare best to BJTs - pentodes.

Turner wants us to think that using BJTs with emitter resistors is a crime
of some kind.

I do not want this. Stop being an arsole by incorrectly stating what i want
readers to think.

I have designed built a considerable number of BJT based amplifiers. All rely
on NFB loops
to counter the terrible non-linearity of the BJTs with no NFB.

Patrick Turner

Unfortunately, Trevor has been spewing this drivel about BJTs being more
linear
than triodes for years.

**Look at the spec sheets, Patrick. It's a fact. Ignore if you wish, but the
facts speak for themselves.

You continue to spew drivel.

Patrick Turner.

"Patrick Turner" wrote in message

Arny Krueger wrote:

"Patrick Turner" wrote in
message

They are only as linear as a triode with regard to
voltage gain when external loops of NFB have been
applied, as in the case of the emitter follower
connection or having a few BJTs with a loop of NFB
around the
lot of them to correct all their mistakes.

BJTs are inherently non linear for voltage gain and MUST
rely on large amounts of externally connected loops of
NFB.

Simply not true. Local feedback works well with BJTs.

Local loops are externally applied loops of NFB.

External to the device, but not external to the stage of amplification.

Bjts are so damned non linear with regard to voltage gain
that large amount of NFB, local or otherwises must be
applied to linearize the outcome, as well as raise input
impedance.

So what? In the end BJTs can be, with a trivial amount of effort, be used to
make the most linear amplifiers known to man.

This applies regardless of whether you build a preamp
with an opamp, a discrete transistor preamp,
or any power amp.

Triodes don't, they have a small amount of NFB built
into them.

Compared to BJTs, triodes have massive amounts of local
NFB built into them, and they are often used with
addtiional local and/or loop NFB.

You don't know how much NFB is within any given triode
now do you?

In the case of triode-connected pentodes, the amount of NFB is exactly
knowable. Just reconnect as a pentode.

But it doesn't matter because nobody in their right mind who is out to
design the lowest distortion amp around is going to use tubes.

Please provide some calculations and details to prove to
the group that you have the slightest idea about what you
are talking about.

Asked and answered.

Keep your answer to less than 5,000 words.

Been there, done that.

I would ask Trevor to set up a simple 1 transistor
preamp with a BC109, and without any
NFB applied, not even an emitter current feedback
resistor, and as a common emitter voltage amplifier with
a supply of 20V.

An apples-to-apples comparison would involve comparing
circuits with gain and impedances, both input and
output, that are as typical and similar as possible.
However, this comparison is totally ludicrous, because
nobody in their right mind uses a stand-alone BC109 as a
high grade audio amplifier any more. They'll use some
kind of an op amp, perhaps a NE 5532 or its equivalent.

It isn't ludicous to drag people screaming back to the
basics.
The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR
OTHERWISE applied anywhere have hopelessly poor
voltage gain linearity.

It doesn't seem to matter, does it. In fact the lowest distortion amps
around are SS, not tubes. In fact every modern recording console of
substance is based on SS. Every modern music player is based on SS.

Statements have been made on the group that what i am
saying is untrue.

I've mostly said the truth about your statements, Patrick: They are
irrelevant.

All opamps also must be used with NFB, and they contain
many interconnected bjts like many
discrete component amplifier, so the non linearity of all
these adds together and must be linearized with NFB.
opamps usually have way too much gain without NFB; and
usually poor open loop bandwidth,
something also flattened out by NFB.

So what? There is no such thing as a tubed amplifier that is even 1/10 as
linear as a $0.25 op amp, as said op amp is typically used.

To understand his own utter stupidity, I ask Trevor to
also set up a 6SN7 with a 250V supply to act as a preamp
and without any loop NFB, and he can then tell us all
about the results which will prove what a
jackarse he is.

Illogical comparison. Everybody knows that 6SN7s have a
ton of internal feedback, and that BJTs compare most
closely to pentodes, not triodes.

A "ton" of NFB is an extremely uninformative unit applied
to NFB.

OK, its more like 1,000 KG. ;-)

Please try be specific and factual lest we consider you
to be utterly stupid like Trevor.

Exactly how much NFB is within a 6SN7?

It's not practically knowable, and its irrelevant on the best day of its
life.

I will also say that a 6AU6 pentode would be more linear
at a volt of output than a BC109 at a volt of output,
with both devices tested without NFB of any kind.

Say what you will Patrick. Your challenge is finding anybody with a brain
who cares.

Unless you have done the experiments and comparisons, you
remain uneducated about the basics.

The facts are before us. Nobody in their right mind who wants the most
linear amplifier uses tubes. Tubed amplifiers are mostly used in the 21st
century as EFX boxes.

When people talk about the linearity of devices, what is
being stated is the linearity of the devices without
any external loops of NFB applied. That is what engineers
understand when somebody talks of device linearity.

It doesn't matter. Consumers don't care what the parts inside a box do, they
care about what the box does.

bjts offer fair current linearity between base current
and collector current but offer hopeless
voltage linearity.

So, use feedback to linearize them. Where's the beef?

Amplifiers are built to provide voltage linearity
regardless of current variations due to load variations.

Thanks for agreeing with my claim that consumers don't care what the parts
inside a box do, they care about what the box does.


External loops in circuit applications of NFB are never
included in discussions defining device linearity.

So what?

You cannot say a bjt is linear if you are using an
emitter follower as an example of the device use.
The term "emitter follower" is a description of a circuit
where a large amount of series voltage NFB is
employed so that the voltage gain of the bjt is reduced
from a disgustingly non linear large number, say
100 times to say 0.99, and the open loop THD is reduced
100 times.

I see a dead horse being flogged very energetically. One word: Why?

On Tue, 28 Mar 2006 09:09:02 GMT, Patrick Turner
wrote:



Arny Krueger wrote:

"Patrick Turner" wrote in message

Stewpid Oinkerton squealed....

I notice you fail to address the fact that the modern
BJT can be more linear *without feedback* than your
beloved DHTs. Surely a *true* 'ultrafidelista' would see
this as the Holy Grail of the 'silent' amplifier? Better
linearity and no humming heaters?

The fact is that the modern transistor must rely on NFB
for it to be acceptable in any way.

As do the vaccum-state devices that compare best to BJTs - pentodes.

Turner wants us to think that using BJTs with emitter resistors is a crime
of some kind.

I do not want this. Stop being an arsole by incorrectly stating what i want
readers to think.

I have designed built a considerable number of BJT based amplifiers. All rely
on NFB loops
to counter the terrible non-linearity of the BJTs with no NFB.

Try building KISASS - it uses a BJT which is *inherently* more linear
than a 3090B, the 2SC2922. No feedback required.....
--

Stewart Pinkerton | Music is Art - Audio is Engineering

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On Tue, 28 Mar 2006 09:14:50 GMT, Patrick Turner
wrote:


Unfortunately, Trevor has been spewing this drivel about BJTs being more
linear
than triodes for years.

**Look at the spec sheets, Patrick. It's a fact. Ignore if you wish, but the
facts speak for themselves.

You continue to spew drivel.

You continue to ignore the evidence of the spec sheet. Why? Is it
against your tube religion that triodes are in fact *not* the most
linear active devices available? See if you can find any triode which
is more linear than a 2SA1216.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

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On Tue, 28 Mar 2006 08:59:43 GMT, Patrick Turner
wrote:



Arny Krueger wrote:

"Patrick Turner" wrote in message


They are only as linear as a triode with regard to
voltage gain when external loops of NFB have been applied,
as in the case of the emitter follower connection or
having a few BJTs with a loop of NFB around the
lot of them to correct all their mistakes.

BJTs are inherently non linear for voltage gain and MUST
rely on large amounts of externally connected loops of
NFB.

Simply not true. Local feedback works well with BJTs.

Local loops are externally applied loops of NFB.

Bjts are so damned non linear with regard to voltage gain that large amount of
NFB, local or otherwises must be applied
to linearize the outcome, as well as raise input impedance.

Some BJTs are more linear than say a 300B. Why do you keep ignoring
this *fact*. Heresy?

It isn't ludicous to drag people screaming back to the basics.
The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied anywhere
have hopelessly poor
voltage gain linearity.

Utter bunk, check the spec sheet for the 2SA1216. Gain linearity is
flat as a pancake at elevated junction temperatures, as would be
experienced in a Class A amplifier.

Statements have been made on the group that what i am saying is untrue.

That's because it is - see above.

All opamps also must be used with NFB, and they contain many interconnected bjts
like many
discrete component amplifier, so the non linearity of all these adds together
and must be linearized with NFB.
opamps usually have way too much gain without NFB; and usually poor open loop
bandwidth,
something also flattened out by NFB.

Opamps are *designed* to be used with large amounts of NFB, and a
decent audio opamp such as the B-B OPA2604 is much more linear than
any tube (or combination of tubes) at the same stage gain. How you get
to there doesn't matter, it's the 'black box' performance that counts.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

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"Stewart Pinkerton" wrote in message
...
: On Tue, 28 Mar 2006 08:59:43 GMT, Patrick Turner
: wrote:
:
:
:
: Arny Krueger wrote:
:
: "Patrick Turner" wrote in message
:
:
: They are only as linear as a triode with regard to
: voltage gain when external loops of NFB have been applied,
: as in the case of the emitter follower connection or
: having a few BJTs with a loop of NFB around the
: lot of them to correct all their mistakes.
:
: BJTs are inherently non linear for voltage gain and MUST
: rely on large amounts of externally connected loops of
: NFB.
:
: Simply not true. Local feedback works well with BJTs.
:
: Local loops are externally applied loops of NFB.
:
: Bjts are so damned non linear with regard to voltage gain that large amount of
: NFB, local or otherwises must be applied
: to linearize the outcome, as well as raise input impedance.
:
: Some BJTs are more linear than say a 300B. Why do you keep ignoring
: this *fact*. Heresy?
:
: It isn't ludicous to drag people screaming back to the basics.
: The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied
anywhere
: have hopelessly poor
: voltage gain linearity.
:
: Utter bunk, check the spec sheet for the 2SA1216. Gain linearity is
: flat as a pancake at elevated junction temperatures, as would be
: experienced in a Class A amplifier.


yep, checking, i found it he
http://users.otenet.gr/~athsam/database.htm

the third graph shows Vbe - Ic, the _run hot_ curve
does 0.8 V Vbe @ 6 A, 400 mVtt giving 6 Att with 1.6 % distortion
certainly impressive. but, now realize the curves are taken at a
constant Vce=4V - not very realistic, is it ?

now, Hfe about 100, at this 24W class A idle point,
60 mA of base current is required. oops, at 10 A, Hfe has
gone south to only 60, creating an additional few dozens
of THD %.

2nd take:
0.6Vbe, 2.2 A idle now Hfe stays flat with 200 mVtt in, 4Att out,
distortion is 7 % or so that's indeed quite an achievement

but considering it's taken at constant Vce
reality will be worse

: Statements have been made on the group that what i am saying is untrue.
:
: That's because it is - see above.

hm, about 12 W / 8 Ohm available, 7 % THD, 8.8 W idle with the 2SA1216
you're saying there are no tubes that can beat that ?
hmmm

the truth,
Rudy
: --
:
: Stewart Pinkerton | Music is Art - Audio is Engineering

: http://www.usenet.com

"Stewart Pinkerton" wrote in message
...
:
: Try building KISASS - it uses a BJT which is *inherently* more linear
: than a 3090B, the 2SC2922. No feedback required.....
: --
:
: Stewart Pinkerton | Music is Art - Audio is Engineering

the 3090B ?
you mean, the 300 kW pulse TPS3 radar tube ??
~ http://www.r-type.org/exhib/aac0090.htm ~
You've tried *that* for comparison ???

yah, right :-)

Rudy