I had the chance to evaluate some solid state current amplifiers
(observations only). I had quite high expectations towards these
amplifiers. However, they could only match part of my expectations.

The interesting part is that the bass area worked extremely well, best I
have heard from any amplifier so far. Very musical and detailed, unlike any
other SS design I have heard.

Unfortunately the tonal balance and general dynamics was not too good, I do
however doubt that it is the basic concept of current amplification, that is
to blame.

I spoke to a couple of speaker designers, and they both confirmed that
"speakers are current based devices" and they also said that the basic idea
of current amplification is good, providing it is implemented the right way.

The reason for my high expectations was, that my beloved OTL tube amplifiers
works like current amplifiers (however not entirely linear) and these has an
excellent tonality and the way they handle the bass area, feels just right.
Actually, the way the OTLs handles the bass area, is quite similar to the SS
current amplifiers, the OTLs are just not quite as detailed in the lowest
end.

Karsten

All Ears wrote:

I had the chance to evaluate some solid state current amplifiers
(observations only). I had quite high expectations towards these
amplifiers. However, they could only match part of my expectations.

The interesting part is that the bass area worked extremely well, best I
have heard from any amplifier so far. Very musical and detailed, unlike any
other SS design I have heard.

Unfortunately the tonal balance and general dynamics was not too good, I do
however doubt that it is the basic concept of current amplification, that is
to blame.

I spoke to a couple of speaker designers, and they both confirmed that
"speakers are current based devices" and they also said that the basic idea
of current amplification is good, providing it is implemented the right way.

The reason for my high expectations was, that my beloved OTL tube amplifiers
works like current amplifiers (however not entirely linear) and these has an
excellent tonality and the way they handle the bass area, feels just right.
Actually, the way the OTLs handles the bass area, is quite similar to the SS
current amplifiers, the OTLs are just not quite as detailed in the lowest
end.

Karsten

All output devices must produce both current changes
and voltage changes at the load, in order to get power.

Transistors, like mosfets and pentodes and tetrodes, and triodes used in
OTL amps, are mere current generators because their
output resistances relative to the load is much higher, so we regard them as
current sources.

In triodes used with loads of much higher value than their plate resistance,
we get a greater range of voltage change than there is current change,
and we call them voltage devices.
This is certainly true of the tube amp input stages, and
to an extent, transformer coupled triode output stages.

In transistor driver stages though, there is very little voltage change
in the early stages, and voltage change is only allowed at the voltage amp
stage,
just before the output stage, which is changed from a high impedance
current source to a low impedance voltage source with negative feedback.

Theoretically, transistor amps should sound well, but alas, so many don't.
Some do though.

One either like tubes, or you don't.

Patrick Turner.

snip
Most of my customers tell me the bass response is more delicious with a
tube
amp,
than when produced by SS amps. I don't think SS amps have a monopoly
on great bass production.

To my opinion SS scores in the "slam" department (which some likes). I do
however feel that the bass from a good tube amp is more realistic to my
ears.

In a comparison here between a Valve Mark amp, with chinese 300B for each
channel,
and a 100 watt/ch locally made SS amp of good reputation,
the tube amp created higher bass levels.

I'm not talking so much about general level, more how the bottom octaves
fits into the music.

This was probably due to the higher output impedance of the tube amp,
and that the speakers had a peak in their impedance at bass F.
There was otherwise little difference.
But we then place a tube preamp before both these power amps,
it improved both further, with the all tube combo sounding marginally
better
overall.

To those who like really loud sound, the tubes would be useless.

Depends on the power.....

But it sure is possible to make excellent bass with tubes, just
use the rigtht OPT, and allow a -3dB point at 10 Hz.

It is possible to make low distortion high output impedance amps,
ie, current amps, devoid of any VOLTAGE nfb, and having instead,
only CURRENT nfb. These have very high output impedance,
so the damping factor is said to be poor.

Most realistic sound, in my set-up, is running the two way 8 ohm speakers at
2-3 ohm output impedance, and the bigger three way 4 ohm speakers at 1.5 - 2
ohms. (There is a variable feed-back on the OTLs) The power is 100W in 8 ohm
and 70W in 4 ohm. Distortion is not a problem.

But speakers are designed mainly to have a low output impedance drive.
If not, they have to be designed to have equal acoustic output
across the band and an equal impedance, so that with a constant current,
there is a constant power, and constant spl.

Nobody has achieved this, afaik.

Speakers have reactive components, and spl varies with cone size for a
given
power input, which all works against using a current source, not
to mention that crossovers that work from a current source are hard to
design
with
desired slopes of attenuation.

The OTLs are doing a good (read breathtaking) job, the SS "variant" only
scores in the bass department.

Karsten


Mainstream practice may seem boring, or somehow invalid, and perhaps the
enemy.
Know thy enemy, at least, before attacking him.
Creativity may follow soon, if your'e lucky.

Patrick Turner.

All Ears wrote:

snip
Most of my customers tell me the bass response is more delicious with a
tube
amp,
than when produced by SS amps. I don't think SS amps have a monopoly
on great bass production.

To my opinion SS scores in the "slam" department (which some likes). I do
however feel that the bass from a good tube amp is more realistic to my
ears.

ppl tell me they like the fast dynamics of tubes, slam included....



In a comparison here between a Valve Mark amp, with chinese 300B for each
channel,
and a 100 watt/ch locally made SS amp of good reputation,
the tube amp created higher bass levels.

I'm not talking so much about general level, more how the bottom octaves
fits into the music.

The 300B made sure the low bass was well fitted to the rest of the music



This was probably due to the higher output impedance of the tube amp,
and that the speakers had a peak in their impedance at bass F.
There was otherwise little difference.
But we then place a tube preamp before both these power amps,
it improved both further, with the all tube combo sounding marginally
better
overall.

To those who like really loud sound, the tubes would be useless.

Depends on the power.....

Indeed, but most ppl get 25 watt tube amps, and connect them to
modern speakers, maybe only 89 dB sensitivity, 1W@1M.



But it sure is possible to make excellent bass with tubes, just
use the rigtht OPT, and allow a -3dB point at 10 Hz.

It is possible to make low distortion high output impedance amps,
ie, current amps, devoid of any VOLTAGE nfb, and having instead,
only CURRENT nfb. These have very high output impedance,
so the damping factor is said to be poor.

Most realistic sound, in my set-up, is running the two way 8 ohm speakers at
2-3 ohm output impedance, and the bigger three way 4 ohm speakers at 1.5 - 2
ohms. (There is a variable feed-back on the OTLs) The power is 100W in 8 ohm
and 70W in 4 ohm. Distortion is not a problem.

But speakers are designed mainly to have a low output impedance drive.
If not, they have to be designed to have equal acoustic output
across the band and an equal impedance, so that with a constant current,
there is a constant power, and constant spl.

Nobody has achieved this, afaik.

Speakers have reactive components, and spl varies with cone size for a
given
power input, which all works against using a current source, not
to mention that crossovers that work from a current source are hard to
design
with
desired slopes of attenuation.

The OTLs are doing a good (read breathtaking) job, the SS "variant" only
scores in the bass department.

OTLs should be OK right across the band.

Patrick Turner.



Karsten


Mainstream practice may seem boring, or somehow invalid, and perhaps the
enemy.
Know thy enemy, at least, before attacking him.
Creativity may follow soon, if your'e lucky.

Patrick Turner.

"Patrick Turner" wrote in message
...


All Ears wrote:

snip
Most of my customers tell me the bass response is more delicious with
a
tube
amp,
than when produced by SS amps. I don't think SS amps have a monopoly
on great bass production.

To my opinion SS scores in the "slam" department (which some likes). I
do
however feel that the bass from a good tube amp is more realistic to my
ears.

ppl tell me they like the fast dynamics of tubes, slam included....

Of course, the difference to me is that the SS produces the "kick in the
chest" and the tubes does the slam of a snare drum etc.




In a comparison here between a Valve Mark amp, with chinese 300B for
each
channel,
and a 100 watt/ch locally made SS amp of good reputation,
the tube amp created higher bass levels.

I'm not talking so much about general level, more how the bottom octaves
fits into the music.

The 300B made sure the low bass was well fitted to the rest of the music

Ahhhh...



This was probably due to the higher output impedance of the tube amp,
and that the speakers had a peak in their impedance at bass F.
There was otherwise little difference.
But we then place a tube preamp before both these power amps,
it improved both further, with the all tube combo sounding marginally
better
overall.

To those who like really loud sound, the tubes would be useless.

Depends on the power.....

Indeed, but most ppl get 25 watt tube amps, and connect them to
modern speakers, maybe only 89 dB sensitivity, 1W@1M.

Which of course is more than adequite for normal listening levels.....




But it sure is possible to make excellent bass with tubes, just
use the rigtht OPT, and allow a -3dB point at 10 Hz.

It is possible to make low distortion high output impedance amps,
ie, current amps, devoid of any VOLTAGE nfb, and having instead,
only CURRENT nfb. These have very high output impedance,
so the damping factor is said to be poor.

Most realistic sound, in my set-up, is running the two way 8 ohm
speakers at
2-3 ohm output impedance, and the bigger three way 4 ohm speakers at
1.5 - 2
ohms. (There is a variable feed-back on the OTLs) The power is 100W in 8
ohm
and 70W in 4 ohm. Distortion is not a problem.

But speakers are designed mainly to have a low output impedance drive.
If not, they have to be designed to have equal acoustic output
across the band and an equal impedance, so that with a constant
current,
there is a constant power, and constant spl.

Nobody has achieved this, afaik.

Speakers have reactive components, and spl varies with cone size for a
given
power input, which all works against using a current source, not
to mention that crossovers that work from a current source are hard to
design
with
desired slopes of attenuation.

The OTLs are doing a good (read breathtaking) job, the SS "variant" only
scores in the bass department.

OTLs should be OK right across the band.

Really has mooved some limits, for what I thought was possible, in the field
of music reproduction.

Karsten


Patrick Turner.



Karsten


Mainstream practice may seem boring, or somehow invalid, and perhaps
the
enemy.
Know thy enemy, at least, before attacking him.
Creativity may follow soon, if your'e lucky.

Patrick Turner.

Clearly power requires both current and voltage, so we must be
careful we know what is meant by "current based".

Either it is hocus pocus, or it means that the speaker is linear
with respect to current, rather than voltage.

It is probably a blend of the two. Perhaps depending on many things
like frequency and amplitude. Perhaps it's best to bi-amp?

I suppose one remarkable thing about current output is that the
source output is coded as a voltage, which is why we talk of
amplifier front ends as voltage amplifiers. If you check currents
around the circuit you find that they can be a very long way from a
facsimile of the signal. The amp supplies whatever current is
necessary to support the correct voltage.

So how do you get from voltage to current encoding? With a
voltage-controlled current source. But the output impedance of a
current source is infinite, because it will always supply whatever
voltage is necessary to support the correct current. So what about
damping? That's the other remarkable thing.

Perhaps I'm barking up the wrong tree...

In practice, the last thing my speakers want is a current source.
They are tuned to give a flat response to voltage. A current source
would fall away much more sharply in the bass, for example. That's
another remarkable thing.

And do they have current-derived feedback in those amps?

cheers, Ian

"All Ears" wrote in message
k...
I had the chance to evaluate some solid state current amplifiers
(observations only). I had quite high expectations towards these
amplifiers. However, they could only match part of my
expectations.

The interesting part is that the bass area worked extremely well,
best I
have heard from any amplifier so far. Very musical and detailed,
unlike any
other SS design I have heard.

Unfortunately the tonal balance and general dynamics was not too
good, I do
however doubt that it is the basic concept of current
amplification, that is
to blame.

I spoke to a couple of speaker designers, and they both confirmed
that
"speakers are current based devices" and they also said that the
basic idea
of current amplification is good, providing it is implemented the
right way.

The reason for my high expectations was, that my beloved OTL tube
amplifiers
works like current amplifiers (however not entirely linear) and
these has an
excellent tonality and the way they handle the bass area, feels
just right.
Actually, the way the OTLs handles the bass area, is quite similar
to the SS
current amplifiers, the OTLs are just not quite as detailed in the
lowest
end.

Karsten

snip

I did once try an amp which had a total of 20 dB of CFB, and VFB,
but it sounded dull and lifeless.

A bit like what I am experiencing...

So far, I like amps with VFB only, and which are voltage sources,
especially triode amps.


Do you think this idea is too "crazy" to work in a real world?

It needs some work.

But perhaps you should have a triode voltage source amp as a reference,
and if you get a current amp to sound better, then
you have achieved something.

Thanks for your wise words.

I am comparing this amp to a 100W triode OTL amp, but there is a loooong way
for the SS "current" amp to even come close to the sonic pleasures of the
OTL. Somehow I doubt that it will ever be possible, but it is interesting to
try

Well, maybe I should just buy some shares in the local power plant, and
enjoy the OTLs

Karsten

So far, I like amps with VFB only, and which are voltage sources,
especially triode amps.

The guys who did this SS "current" amp, did it in an attempt to simulate the
way a tube amp. optimally handles a dynamic speaker. It could look like they
misunderstood something in the process?
I know they are quite skilled in DSP stuff, and does some great things in
the digital domain (that really sounds analog

Do you think it would be possible to simulate how a good triode voltage amp
handles a dynamic speaker, by monitoring the impedance of the speaker
terminals and adjusting feedback from this information?

Hope these questions are not too blasphemic

Karsten

All Ears wrote:

snip

I did once try an amp which had a total of 20 dB of CFB, and VFB,
but it sounded dull and lifeless.

A bit like what I am experiencing...

So far, I like amps with VFB only, and which are voltage sources,
especially triode amps.


Do you think this idea is too "crazy" to work in a real world?

It needs some work.

But perhaps you should have a triode voltage source amp as a reference,
and if you get a current amp to sound better, then
you have achieved something.

Thanks for your wise words.

I am comparing this amp to a 100W triode OTL amp, but there is a loooong way
for the SS "current" amp to even come close to the sonic pleasures of the
OTL. Somehow I doubt that it will ever be possible, but it is interesting to
try

Well, maybe I should just buy some shares in the local power plant, and
enjoy the OTLs

Karsten

I suggest try a class A triode tranny coupled amp, with say 12 dB of FB.
with 2 x EL34, 807, whatever, at 2 watts, they are pretty blameless,
if the load is say 10ka-a, ie, on the high side. Go for fidelity, not power.

Then see how your OTL compares.

And regards to the boys at the power station, I hope they
never tire of shovelling coal for your efforts with transistor current power
sources.

I'd think mosfets, maybe a quad of Exicon 16 amp types, each ok for
25 reliable watts of dissipation.
Input c is high, so one must learn to use low impedance drive circuits.



Patrick Turner.

All Ears wrote:


So far, I like amps with VFB only, and which are voltage sources,
especially triode amps.

The guys who did this SS "current" amp, did it in an attempt to simulate the
way a tube amp. optimally handles a dynamic speaker. It could look like they
misunderstood something in the process?

All bjt output SS devices are like penotdes after feeding them 2 tonnes of
steroids.
Their working currents and voltages are well matched to speaker loads
between 1 ohm and 30 ohms.

BUT, like pentodes, or beam tubes, the collector dynamic impedance,
which is the source resistance, or generator resistance of the signal driving a
load
is VERY high in comparison to the speaker loads.
Same with mosfets.

The use of about at least 20 dB of voltage series or shunt NFB
is required to convert what is a current source, ie, high Ro amp,
to a low Ro amp, to be able to cope with speakers which ahve been designed
to give the specified acoustic output levels IF they are driven ONLY
from a voltage source which doesn't vary, regardless of
the instananeous load value.

If a current source is used, ie, high Ro from the amp is used, then the LOAD
mustn't vary.

You get a poor result if BOTH load value, and voltage applied are
variable. The response will be anything but flat, like a graphic eq device
set to some crazy random boost and cut profile.

Its damned hard to make a constant impedance speaker, regardless of
frequency. Its terribly easy to make a stiff voltage source,
simply use any devices, triodes, pentodes, tetrodes, mosfets, bjts, whatever,
and all of them, even triodes, will have Ro which is, or could be too high for
good sound.
Applying NFB is SO EASY, compared to building a flat impedance speaker.

So we have the conventions established, and to usurp those conventions,
its a difficult way over the mountain.




I know they are quite skilled in DSP stuff, and does some great things in
the digital domain (that really sounds analog

Do you think it would be possible to simulate how a good triode voltage amp
handles a dynamic speaker, by monitoring the impedance of the speaker
terminals and adjusting feedback from this information?

Hmm, sounds like you'd need a powerful PC to tell the amp what to do with the
applied current,
in real time.

So when the speaker voltage goes high at some peak in the impedance,
and you get huge increase in sound level at that peak, the hardware
has to conduct a survey, analyse results, and legislate to have the
current source attenuated to compensate against the rotten peak we didn't like.

To me this is exactly what voltage NFB achieves, and it makes the amp
an equivalent of a signal generator with much lower output resistance
than it has without any FB.



Hope these questions are not too blasphemic

If DSP is to be used in amps, then exactly to what aims would it be put?

Patrick Turner.



Karsten

snip

If DSP is to be used in amps, then exactly to what aims would it be put?

The DSP would be used to control the feedback as a function of the impedance
at the speaker terminals, in real time.

Thanks a lot for taking the time to reply to these postings, you have been a
great help in making me understand all these things.

Karsten


Patrick Turner.



Karsten

All Ears wrote:

snip

If DSP is to be used in amps, then exactly to what aims would it be put?

The DSP would be used to control the feedback as a function of the impedance
at the speaker terminals, in real time.

Thanks a lot for taking the time to reply to these postings, you have been a
great help in making me understand all these things.

I am having trouble understanding exactly how you might "control the feedback"
as a function of the instaneous speaker impedance.

Presumably, a tiny 0.1 ohm R would sense the speaker current,
and a voltage divider from the active output terminal gives you a voltage
sample,
so you have the voltage and current in the circuit, and this could be fed to a
computer
with a program to tell a digital circuit what the speaker impedance is.

What would be done with this info?

Would it be used to control voltage output?
if output voltage tried to climb, due to rising speaker impedance,
this would be expressed as an increase in speaker impedance.
Ie, would the info be used to maintain the applied speaker voltages
as an exact replica of the amp input wave?
There has to be a reference point from which to start.
Voltage NFB already does this, but never perfectly, because
an infinite amount of FB cannot be applied.
Digital methods may allow it. Its because digital circuits don't have phase
shift.
Would the current waveform be maintained as an exact replica
of the voltage wave input?
Just to be awkward, it all has to be done using 24 bit 96 kHz digital.

Oh, and what of distortion? it wouldn't be much use making the world's
lowest Ro amp, and letting all the thd through.
Or the world's most perfect constant current amp,
and let the thd through.

Somehow, I think there are problems with such digital techniques
for correction or alteration to the signal going to the speaker,
or coming from it back to the amp.

If only we could define what the heck you had in mind
in terms of impedances.

Patrick Turner.





Karsten


Patrick Turner.



Karsten

All Ears wrote:

I had the chance to evaluate some solid state current amplifiers
(observations only). I had quite high expectations towards these
amplifiers. However, they could only match part of my expectations.

You need to be specific.

There are no "current amplifier" power amps that I am aware of.

There are some "current ampifier" chips however. You can take a look
at them and see that they produce no voltage without a specific load, and
that the load sets the gain in most cases.

There are some power amps that use a current stage or two as gain stages.
Even the venerable old Phase Linear 400 had a current gain stage. No signal
can be found at the output of this stage, since there is only current gain present.
Makes for tougher troubleshooting for sure.

Some of the Strickland/Hafler designs use a bunch of current amp stages.



The interesting part is that the bass area worked extremely well, best I
have heard from any amplifier so far. Very musical and detailed, unlike any
other SS design I have heard.

A side effect of other factors, almost certainly. Mosfet outputs??



snip




I spoke to a couple of speaker designers, and they both confirmed that
"speakers are current based devices" and they also said that the basic idea
of current amplification is good, providing it is implemented the right way.

Rather a nonsensical way to look at things. Speakers represent a load whose
impedance changes with frequency. So, if you provided pure current amplification
the POWER presented to the speaker would change with frequency as the impedance
changed - and depending upon the source impedance of the current "amp"
it would either be higher or lower than the power at the nominal impedance.

But all amps do this sort of thing... note below:



The reason for my high expectations was, that my beloved OTL tube amplifiers
works like current amplifiers (however not entirely linear) and these has an
excellent tonality and the way they handle the bass area, feels just right.

Au Contraire, OTLs are voltage amps, ones that usually have a higher output
impedance than the load that they drive. Therefore when there is a peak in
the impedance curve, the output POWER goes up. Whereas with a solid state,
or other low impedance source amp, for the same impedance *peak* the output
power goes DOWN, not up. The one thing that OTLs do well is to *swing voltage*,
not current.


Actually, the way the OTLs handles the bass area, is quite similar to the SS
current amplifiers, the OTLs are just not quite as detailed in the lowest
end.

In otherwords, the OTLs that you are used to run out of *current* as the impedance
drops, and the demand for current = power goes up at low frequencies.

What you are likely hearing with the amps you've described so far ('current amps')
is a solid state design with anemic power supply, and reduced damping factor, thus
exhibiting effects similar to a ZFB tube amp, or an OTL at bass frequencies (where this
sort of thing is audible).



Karsten

_-_-bear

Bear,

Thanks for your feedback. The things you tell, corresponds very well with
what I have heard others say.

At this point I have been evaluating this amplifier and giving some feedback
to the manufacturer.

The tonal balance is messed up, acustic instruments, especially strings,
seems to get most of the harmonic structure shaven off.

I had some doubts about the general idea behind this development, and it
looks like my suspicions has been confirmed.

Have you had the chance to listen to some of the current amplifiers you
mention? Were they any good?

Karsten


"BEAR" wrote in message
...


All Ears wrote:

I had the chance to evaluate some solid state current amplifiers
(observations only). I had quite high expectations towards these
amplifiers. However, they could only match part of my expectations.

You need to be specific.

There are no "current amplifier" power amps that I am aware of.

There are some "current ampifier" chips however. You can take a look
at them and see that they produce no voltage without a specific load, and
that the load sets the gain in most cases.

There are some power amps that use a current stage or two as gain stages.
Even the venerable old Phase Linear 400 had a current gain stage. No
signal
can be found at the output of this stage, since there is only current gain
present.
Makes for tougher troubleshooting for sure.

Some of the Strickland/Hafler designs use a bunch of current amp stages.



The interesting part is that the bass area worked extremely well, best I
have heard from any amplifier so far. Very musical and detailed, unlike
any
other SS design I have heard.

A side effect of other factors, almost certainly. Mosfet outputs??



snip




I spoke to a couple of speaker designers, and they both confirmed that
"speakers are current based devices" and they also said that the basic
idea
of current amplification is good, providing it is implemented the right
way.

Rather a nonsensical way to look at things. Speakers represent a load
whose
impedance changes with frequency. So, if you provided pure current
amplification
the POWER presented to the speaker would change with frequency as the
impedance
changed - and depending upon the source impedance of the current "amp"
it would either be higher or lower than the power at the nominal
impedance.

But all amps do this sort of thing... note below:



The reason for my high expectations was, that my beloved OTL tube
amplifiers
works like current amplifiers (however not entirely linear) and these
has an
excellent tonality and the way they handle the bass area, feels just
right.

Au Contraire, OTLs are voltage amps, ones that usually have a higher
output
impedance than the load that they drive. Therefore when there is a peak in
the impedance curve, the output POWER goes up. Whereas with a solid state,
or other low impedance source amp, for the same impedance *peak* the
output
power goes DOWN, not up. The one thing that OTLs do well is to *swing
voltage*,
not current.


Actually, the way the OTLs handles the bass area, is quite similar to
the SS
current amplifiers, the OTLs are just not quite as detailed in the
lowest
end.

In otherwords, the OTLs that you are used to run out of *current* as the
impedance
drops, and the demand for current = power goes up at low frequencies.

What you are likely hearing with the amps you've described so far
('current amps')
is a solid state design with anemic power supply, and reduced damping
factor, thus
exhibiting effects similar to a ZFB tube amp, or an OTL at bass
frequencies (where this
sort of thing is audible).



Karsten

_-_-bear

Ur getting blasted on rahe... so, keep in mind that what they are
saying
to you is pretty much on target. I tend to be calmer than that group
you've
stirred up. :-)

It has been quite interesting to compare the very different kind of replys I
got from raising this discussion here and in RAHE.

Here I got very accurate, constructive and informative answers, dispite my
questions was based partly on a misunderstanding.

It took me 10 % the efford to get 300% better and 400% more friendly answers
here.

Some people seems to enjoy telling others how stupid they are, so they will
seem relatively smarter themselves


The amps I spoke of; Strickland designs; the Acoustat TNT and the
newer
Hafler brand amps ARE NOT "current amps" the way you are speaking of.
They are amps that use CURRENT AMPLIFIER STAGES *internally*.
The output stage is STILL a standard high current complementary push
pull solid state (mosfet in this case) output stage.

Okay.

It is important to get your terminology correct and clear, since
otherwise
you will have disputes just over that, before you get to the ideas that
you
want to find out about.

Sure, of course.....But it also seems to depend on who you are asking

Karsten

_-_-bear

All Ears wrote:

Bear,

Thanks for your feedback. The things you tell, corresponds very well
with
what I have heard others say.

At this point I have been evaluating this amplifier and giving some
feedback
to the manufacturer.

The tonal balance is messed up, acustic instruments, especially strings,
seems to get most of the harmonic structure shaven off.

I had some doubts about the general idea behind this development, and it
looks like my suspicions has been confirmed.

Have you had the chance to listen to some of the current amplifiers you
mention? Were they any good?

Karsten

"BEAR" wrote in message
...


All Ears wrote:

I had the chance to evaluate some solid state current amplifiers
(observations only). I had quite high expectations towards these
amplifiers. However, they could only match part of my expectations.

You need to be specific.

There are no "current amplifier" power amps that I am aware of.

There are some "current ampifier" chips however. You can take a look
at them and see that they produce no voltage without a specific load,
and
that the load sets the gain in most cases.

There are some power amps that use a current stage or two as gain
stages.
Even the venerable old Phase Linear 400 had a current gain stage. No
signal
can be found at the output of this stage, since there is only current
gain
present.
Makes for tougher troubleshooting for sure.

Some of the Strickland/Hafler designs use a bunch of current amp
stages.



The interesting part is that the bass area worked extremely well,
best I
have heard from any amplifier so far. Very musical and detailed,
unlike
any
other SS design I have heard.

A side effect of other factors, almost certainly. Mosfet outputs??



snip




I spoke to a couple of speaker designers, and they both confirmed
that
"speakers are current based devices" and they also said that the
basic
idea
of current amplification is good, providing it is implemented the
right
way.

Rather a nonsensical way to look at things. Speakers represent a load
whose
impedance changes with frequency. So, if you provided pure current
amplification
the POWER presented to the speaker would change with frequency as the
impedance
changed - and depending upon the source impedance of the current "amp"
it would either be higher or lower than the power at the nominal
impedance.

But all amps do this sort of thing... note below:



The reason for my high expectations was, that my beloved OTL tube
amplifiers
works like current amplifiers (however not entirely linear) and
these
has an
excellent tonality and the way they handle the bass area, feels just
right.

Au Contraire, OTLs are voltage amps, ones that usually have a higher
output
impedance than the load that they drive. Therefore when there is a
peak in
the impedance curve, the output POWER goes up. Whereas with a solid
state,
or other low impedance source amp, for the same impedance *peak* the
output
power goes DOWN, not up. The one thing that OTLs do well is to *swing
voltage*,
not current.


Actually, the way the OTLs handles the bass area, is quite similar
to
the SS
current amplifiers, the OTLs are just not quite as detailed in the
lowest
end.

In otherwords, the OTLs that you are used to run out of *current* as
the
impedance
drops, and the demand for current = power goes up at low frequencies.

What you are likely hearing with the amps you've described so far
('current amps')
is a solid state design with anemic power supply, and reduced damping
factor, thus
exhibiting effects similar to a ZFB tube amp, or an OTL at bass
frequencies (where this
sort of thing is audible).



Karsten

_-_-bear

Well, the only place that it would make sense to put a DSP to use
is to get a sound pressure reading of an accurate nearfield
microphone and use that for adjusting gain, adjusted for microphone
inaccuracy. But then again
most of what you'd want to accomplish, say within' 1 dB flat
response from 20 to 35 kHz or so could come from using
a well-calibrated microphone to start with and using analog
voltage feedback from the measured acoustic lsp output.

my 2c.
Rudy
"All Ears" wrote in message
k...
:
: "Patrick Turner" wrote in message
: ...
:
:
: All Ears wrote:
:
: snip
:
: If DSP is to be used in amps, then exactly to what aims would it be
: put?
:
: The DSP would be used to control the feedback as a function of the
: impedance
: at the speaker terminals, in real time.
:
: Thanks a lot for taking the time to reply to these postings, you have
: been a
: great help in making me understand all these things.
:
: I am having trouble understanding exactly how you might "control the
: feedback"
: as a function of the instaneous speaker impedance.
:
: Presumably, a tiny 0.1 ohm R would sense the speaker current,
: and a voltage divider from the active output terminal gives you a
voltage
: sample,
: so you have the voltage and current in the circuit, and this could be
fed
: to a
: computer
: with a program to tell a digital circuit what the speaker impedance is.
:
: What would be done with this info?
:
: Would it be used to control voltage output?
: if output voltage tried to climb, due to rising speaker impedance,
: this would be expressed as an increase in speaker impedance.
: Ie, would the info be used to maintain the applied speaker voltages
: as an exact replica of the amp input wave?
: There has to be a reference point from which to start.
: Voltage NFB already does this, but never perfectly, because
: an infinite amount of FB cannot be applied.
: Digital methods may allow it. Its because digital circuits don't have
: phase
: shift.
: Would the current waveform be maintained as an exact replica
: of the voltage wave input?
: Just to be awkward, it all has to be done using 24 bit 96 kHz digital.
:
: Oh, and what of distortion? it wouldn't be much use making the world's
: lowest Ro amp, and letting all the thd through.
: Or the world's most perfect constant current amp,
: and let the thd through.
:
: Somehow, I think there are problems with such digital techniques
: for correction or alteration to the signal going to the speaker,
: or coming from it back to the amp.
:
: If only we could define what the heck you had in mind
: in terms of impedances.
:
: Patrick Turner.
:
: Patrick,
:
: Very qualified questions you are asking. Unfortunately I do not have the
: answers (might be able to get them though)
:
: I am not designing this amplifier, only evaluating. I see clearly now,
that
: there are lots of potential problems by doing what they are attempting to
: do.
:
: Again, thanks for your reply.
:
: Karsten
:
:

All Ears wrote:


Ur getting blasted on rahe... so, keep in mind that what they are
saying
to you is pretty much on target. I tend to be calmer than that group
you've
stirred up. :-)

It has been quite interesting to compare the very different kind of replys I
got from raising this discussion here and in RAHE.

Here I got very accurate, constructive and informative answers, dispite my
questions was based partly on a misunderstanding.

It took me 10 % the efford to get 300% better and 400% more friendly answers
here.

Some people seems to enjoy telling others how stupid they are, so they will
seem relatively smarter themselves

Here, some of us have already come to terms that we are AUDIO OUTLAWS,
because we use those silly old bottles that glow.
We have have given up the delusions of grandure, and we rest serenly and
securely
with the knowledge that it ain't a waste of time to use tubes for audio,
which is something our ears tell us.

Here we learn that patience and tolerance are virtuous,
and if the bull**** ego talk is left out, then a greater experience of wisdom
and learning is possible. Here is is rare that our discussions are
punctuated by polluting obscenities, unless for humour's sake.

Patrick Turner.






The amps I spoke of; Strickland designs; the Acoustat TNT and the
newer
Hafler brand amps ARE NOT "current amps" the way you are speaking of.
They are amps that use CURRENT AMPLIFIER STAGES *internally*.
The output stage is STILL a standard high current complementary push
pull solid state (mosfet in this case) output stage.

Okay.

It is important to get your terminology correct and clear, since
otherwise
you will have disputes just over that, before you get to the ideas that
you
want to find out about.

Sure, of course.....But it also seems to depend on who you are asking

Karsten

_-_-bear

All Ears wrote:

Bear,

Thanks for your feedback. The things you tell, corresponds very well
with
what I have heard others say.

At this point I have been evaluating this amplifier and giving some
feedback
to the manufacturer.

The tonal balance is messed up, acustic instruments, especially strings,
seems to get most of the harmonic structure shaven off.

I had some doubts about the general idea behind this development, and it
looks like my suspicions has been confirmed.

Have you had the chance to listen to some of the current amplifiers you
mention? Were they any good?

Karsten

"BEAR" wrote in message
...


All Ears wrote:

I had the chance to evaluate some solid state current amplifiers
(observations only). I had quite high expectations towards these
amplifiers. However, they could only match part of my expectations.

You need to be specific.

There are no "current amplifier" power amps that I am aware of.

There are some "current ampifier" chips however. You can take a look
at them and see that they produce no voltage without a specific load,
and
that the load sets the gain in most cases.

There are some power amps that use a current stage or two as gain
stages.
Even the venerable old Phase Linear 400 had a current gain stage. No
signal
can be found at the output of this stage, since there is only current
gain
present.
Makes for tougher troubleshooting for sure.

Some of the Strickland/Hafler designs use a bunch of current amp
stages.



The interesting part is that the bass area worked extremely well,
best I
have heard from any amplifier so far. Very musical and detailed,
unlike
any
other SS design I have heard.

A side effect of other factors, almost certainly. Mosfet outputs??



snip




I spoke to a couple of speaker designers, and they both confirmed
that
"speakers are current based devices" and they also said that the
basic
idea
of current amplification is good, providing it is implemented the
right
way.

Rather a nonsensical way to look at things. Speakers represent a load
whose
impedance changes with frequency. So, if you provided pure current
amplification
the POWER presented to the speaker would change with frequency as the
impedance
changed - and depending upon the source impedance of the current "amp"
it would either be higher or lower than the power at the nominal
impedance.

But all amps do this sort of thing... note below:



The reason for my high expectations was, that my beloved OTL tube
amplifiers
works like current amplifiers (however not entirely linear) and
these
has an
excellent tonality and the way they handle the bass area, feels just
right.

Au Contraire, OTLs are voltage amps, ones that usually have a higher
output
impedance than the load that they drive. Therefore when there is a
peak in
the impedance curve, the output POWER goes up. Whereas with a solid
state,
or other low impedance source amp, for the same impedance *peak* the
output
power goes DOWN, not up. The one thing that OTLs do well is to *swing
voltage*,
not current.


Actually, the way the OTLs handles the bass area, is quite similar
to
the SS
current amplifiers, the OTLs are just not quite as detailed in the
lowest
end.

In otherwords, the OTLs that you are used to run out of *current* as
the
impedance
drops, and the demand for current = power goes up at low frequencies.

What you are likely hearing with the amps you've described so far
('current amps')
is a solid state design with anemic power supply, and reduced damping
factor, thus
exhibiting effects similar to a ZFB tube amp, or an OTL at bass
frequencies (where this
sort of thing is audible).



Karsten

_-_-bear

Here, for the most part, we're all just hobbyists, enthusiasts, and
students of life, the universe, and everything.

Seems like the way go

Interesting projects you are doing, thanks for sharing.

Karsten


Cheers,
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects, Vacuum Tubes & other stuff: |
| http://www.dogstar.dantimax.dk |
+--------------------------------------------+

snip
Here, some of us have already come to terms that we are AUDIO OUTLAWS,
because we use those silly old bottles that glow.
We have have given up the delusions of grandure, and we rest serenly and
securely
with the knowledge that it ain't a waste of time to use tubes for audio,
which is something our ears tell us.

Here we learn that patience and tolerance are virtuous,
and if the bull**** ego talk is left out, then a greater experience of
wisdom
and learning is possible. Here is is rare that our discussions are
punctuated by polluting obscenities, unless for humour's sake.

Patrick Turner.

Sounds soo right to me

I forwarded your questions to the manufacturer of this amp, I'll send you a
copy of the answers.

BTW, it you want to see a "high-tech" approach in using these "silly old
glowing bottles" take a look at www.davidberning.com Pretty interesting
stuff he is doing.

Karsten







The amps I spoke of; Strickland designs; the Acoustat TNT and the
newer
Hafler brand amps ARE NOT "current amps" the way you are speaking of.
They are amps that use CURRENT AMPLIFIER STAGES *internally*.
The output stage is STILL a standard high current complementary push
pull solid state (mosfet in this case) output stage.

Okay.

It is important to get your terminology correct and clear, since
otherwise
you will have disputes just over that, before you get to the ideas
that
you
want to find out about.

Sure, of course.....But it also seems to depend on who you are asking

Karsten

_-_-bear

All Ears wrote:

Bear,

Thanks for your feedback. The things you tell, corresponds very well
with
what I have heard others say.

At this point I have been evaluating this amplifier and giving some
feedback
to the manufacturer.

The tonal balance is messed up, acustic instruments, especially
strings,
seems to get most of the harmonic structure shaven off.

I had some doubts about the general idea behind this development,
and it
looks like my suspicions has been confirmed.

Have you had the chance to listen to some of the current amplifiers
you
mention? Were they any good?

Karsten

"BEAR" wrote in message
...


All Ears wrote:

I had the chance to evaluate some solid state current amplifiers
(observations only). I had quite high expectations towards these
amplifiers. However, they could only match part of my
expectations.

You need to be specific.

There are no "current amplifier" power amps that I am aware of.

There are some "current ampifier" chips however. You can take a
look
at them and see that they produce no voltage without a specific
load,
and
that the load sets the gain in most cases.

There are some power amps that use a current stage or two as gain
stages.
Even the venerable old Phase Linear 400 had a current gain stage.
No
signal
can be found at the output of this stage, since there is only
current
gain
present.
Makes for tougher troubleshooting for sure.

Some of the Strickland/Hafler designs use a bunch of current amp
stages.



The interesting part is that the bass area worked extremely
well,
best I
have heard from any amplifier so far. Very musical and detailed,
unlike
any
other SS design I have heard.

A side effect of other factors, almost certainly. Mosfet outputs??



snip




I spoke to a couple of speaker designers, and they both
confirmed
that
"speakers are current based devices" and they also said that the
basic
idea
of current amplification is good, providing it is implemented
the
right
way.

Rather a nonsensical way to look at things. Speakers represent a
load
whose
impedance changes with frequency. So, if you provided pure current
amplification
the POWER presented to the speaker would change with frequency as
the
impedance
changed - and depending upon the source impedance of the current
"amp"
it would either be higher or lower than the power at the nominal
impedance.

But all amps do this sort of thing... note below:



The reason for my high expectations was, that my beloved OTL
tube
amplifiers
works like current amplifiers (however not entirely linear) and
these
has an
excellent tonality and the way they handle the bass area, feels
just
right.

Au Contraire, OTLs are voltage amps, ones that usually have a
higher
output
impedance than the load that they drive. Therefore when there is a
peak in
the impedance curve, the output POWER goes up. Whereas with a
solid
state,
or other low impedance source amp, for the same impedance *peak*
the
output
power goes DOWN, not up. The one thing that OTLs do well is to
*swing
voltage*,
not current.


Actually, the way the OTLs handles the bass area, is quite
similar
to
the SS
current amplifiers, the OTLs are just not quite as detailed in
the
lowest
end.

In otherwords, the OTLs that you are used to run out of *current*
as
the
impedance
drops, and the demand for current = power goes up at low
frequencies.

What you are likely hearing with the amps you've described so far
('current amps')
is a solid state design with anemic power supply, and reduced
damping
factor, thus
exhibiting effects similar to a ZFB tube amp, or an OTL at bass
frequencies (where this
sort of thing is audible).



Karsten

_-_-bear

All Ears wrote:

snip
Here, some of us have already come to terms that we are AUDIO OUTLAWS,
because we use those silly old bottles that glow.
We have have given up the delusions of grandure, and we rest serenly and
securely
with the knowledge that it ain't a waste of time to use tubes for audio,
which is something our ears tell us.

Here we learn that patience and tolerance are virtuous,
and if the bull**** ego talk is left out, then a greater experience of
wisdom
and learning is possible. Here is is rare that our discussions are
punctuated by polluting obscenities, unless for humour's sake.

Patrick Turner.

Sounds soo right to me

I forwarded your questions to the manufacturer of this amp, I'll send you a
copy of the answers.

BTW, it you want to see a "high-tech" approach in using these "silly old
glowing bottles" take a look at www.davidberning.com Pretty interesting
stuff he is doing.

Karsten

The wonderful Mr Berning breaks two rules about tube audio,
one, he rubbishes the tried and tested ideas on normal output transformers,
and two, he uses complex circuitry, negating the simplicity so desirable.
Not much point to point circuitry, and lotsa pcbs.

May as well build a digital amplifier using all solid state parts.

And I don't like the boring black box approach.

I wish him well, since humanity respects diversity.....

Patrick Turner.

All Ears wrote:

"Patrick Turner" wrote in message
...


All Ears wrote:

snip
Here, some of us have already come to terms that we are AUDIO OUTLAWS,
because we use those silly old bottles that glow.
We have have given up the delusions of grandure, and we rest serenly
and
securely
with the knowledge that it ain't a waste of time to use tubes for
audio,
which is something our ears tell us.

Here we learn that patience and tolerance are virtuous,
and if the bull**** ego talk is left out, then a greater experience of
wisdom
and learning is possible. Here is is rare that our discussions are
punctuated by polluting obscenities, unless for humour's sake.

Patrick Turner.

Sounds soo right to me

I forwarded your questions to the manufacturer of this amp, I'll send
you a
copy of the answers.

BTW, it you want to see a "high-tech" approach in using these "silly old
glowing bottles" take a look at www.davidberning.com Pretty interesting
stuff he is doing.

Karsten

The wonderful Mr Berning breaks two rules about tube audio,
one, he rubbishes the tried and tested ideas on normal output
transformers,
and two, he uses complex circuitry, negating the simplicity so desirable.
Not much point to point circuitry, and lotsa pcbs.

May as well build a digital amplifier using all solid state parts.

And I don't like the boring black box approach.

I wish him well, since humanity respects diversity.....

Patrick Turner.


Mr. Berning is probably one of the biggest "outlaws" in the audio industry,
because what he is doing is so different from anything else.
You are of course right, it is very complex circuits, not really for the
hobbyist. However he is point to point wiring the signal path.

I do not agree that he might as well build a digital amp, because what he is
doing is basically just using a different type of impedance transformation.
Because he can get a ratio of 64:1 with this transformation, the tubes can
run high voltage and low current, which makes sence to me.

But the tubes operating conditions cannot be much different to
any standard AF amp.
To me its seems the man is transforming RF,
instead of AF, so the transorming is done at RF, like in a SMPS.
the problems of LF AF distortions are avoided.
But well made OPT avoid such problems.

A 64:1 "impedance transformation ratio" isn't very high,
but since he has a lot of tubes in there, maybe its OK.
My 300 watters have 1.1k RL to 5 ohms, which is 220:1 OPT ratio.
And I use 12 x 6550.
I don't think quoting the 64:1 ratio without seeing a schematic really explains
anything about these Berning amps.



The black boxes are not to my taste either, the Siegfried he did, looks nice
though.

I am fascinated by the amps Mr Berning makes.
I am allowed not to like the appearance, and I do
see a lot of support circuitry, which probably is solid state,
and better off done using pcbs, rather than point to point.
There are quite a lot of wires running all over, so sure,
there is point to point.

There is no schematic, no way I could form any real opinion on
exactly how the thing works.
Looks like RF is involved, maybe it has the information of the audio
signal carried on an RF carrier,
amplified, and detected, I really can't say.
But don't ask me if the delicacy and detail of good analog is conveyed
by such complexities.

There is another amp maker, Halcro, of Sth Australia,
and they make 200 watt mono amps with 0.0001% thd,
which isn't much, and I raise me hat to those guys.
The HK audio club was reported as saying of the Halcro,
"Like 300B, but go louder".
I hope the maker took that as a compliment.
And obviously, our grandfathers knew about good sound in 1928,
when a few got together to start making the 300B.
The Halcro cost about US $25,000 per pair.
Are two extra zeros after the decimal point worth $20,000???
Some folks think so.

As the world turns slowly on its orbit round the sun,
ideas come and go, and some stay, and become desirable
to buyers, and others perish on the vine, and yet others
become cherished by a minority of minorities,
and all of these may, or may not take away what is percieved to be
the creativity of the maker.
When you do become a maker of something, and you do go public with it,
you'll get the admirers and the knockers, and maybe a few
will make great suggestions, or ask awkward questions.
It makes life interesting.

Patrick Turner.


Karsten

snip

I am fascinated by the amps Mr Berning makes.
I am allowed not to like the appearance, and I do
see a lot of support circuitry, which probably is solid state,
and better off done using pcbs, rather than point to point.
There are quite a lot of wires running all over, so sure,
there is point to point.

There is no schematic, no way I could form any real opinion on
exactly how the thing works.

Look in the patents section of his web page, there is a good description.

Looks like RF is involved, maybe it has the information of the audio
signal carried on an RF carrier,
amplified, and detected, I really can't say.

Yes, he is using a 250 khz carrier..

But don't ask me if the delicacy and detail of good analog is conveyed
by such complexities.

I would describe the amplifiers as fast with very good dynamics and
tonallity.
The really interesting aspect, is that it is possible to listen to tubes,
that really are not suitable as output tubes. His microZOTL uses a 6SN7 as
output tube in a class A push-pull configuration within the same triode
tube! Also, since he is running the tubes with a very modest load and
voltage, the expected life time is 15 - 20 years.


There is another amp maker, Halcro, of Sth Australia,
and they make 200 watt mono amps with 0.0001% thd,
which isn't much, and I raise me hat to those guys.
The HK audio club was reported as saying of the Halcro,
"Like 300B, but go louder".
I hope the maker took that as a compliment.
And obviously, our grandfathers knew about good sound in 1928,
when a few got together to start making the 300B.
The Halcro cost about US $25,000 per pair.
Are two extra zeros after the decimal point worth $20,000???
Some folks think so.

How silly when you could get a really good set of speaker cables at the same
cost... :-)


As the world turns slowly on its orbit round the sun,
ideas come and go, and some stay, and become desirable
to buyers, and others perish on the vine, and yet others
become cherished by a minority of minorities,
and all of these may, or may not take away what is percieved to be
the creativity of the maker.
When you do become a maker of something, and you do go public with it,
you'll get the admirers and the knockers, and maybe a few
will make great suggestions, or ask awkward questions.
It makes life interesting.

It is really interesting to see new ideas being born, and how it seems like
some ideas develop independantant and simultainously around the globe, like
they come when it is their time.
I have always felt the most sorry for those who are too much ahead of their
time, and try to promote ideas and innovations before the world is ready for
them....

Karsten


Patrick Turner.


Karsten

All Ears wrote:

snip

I am fascinated by the amps Mr Berning makes.
I am allowed not to like the appearance, and I do
see a lot of support circuitry, which probably is solid state,
and better off done using pcbs, rather than point to point.
There are quite a lot of wires running all over, so sure,
there is point to point.

There is no schematic, no way I could form any real opinion on
exactly how the thing works.

Look in the patents section of his web page, there is a good description.

Not enough info to diy one for myself, or for the chinese to be able to copy, I
bet...



Looks like RF is involved, maybe it has the information of the audio
signal carried on an RF carrier,
amplified, and detected, I really can't say.

Yes, he is using a 250 khz carrier..

But don't ask me if the delicacy and detail of good analog is conveyed
by such complexities.

I would describe the amplifiers as fast with very good dynamics and
tonallity.
The really interesting aspect, is that it is possible to listen to tubes,
that really are not suitable as output tubes. His microZOTL uses a 6SN7 as
output tube in a class A push-pull configuration within the same triode
tube! Also, since he is running the tubes with a very modest load and
voltage, the expected life time is 15 - 20 years.


There is another amp maker, Halcro, of Sth Australia,
and they make 200 watt mono amps with 0.0001% thd,
which isn't much, and I raise me hat to those guys.
The HK audio club was reported as saying of the Halcro,
"Like 300B, but go louder".
I hope the maker took that as a compliment.
And obviously, our grandfathers knew about good sound in 1928,
when a few got together to start making the 300B.
The Halcro cost about US $25,000 per pair.
Are two extra zeros after the decimal point worth $20,000???
Some folks think so.

How silly when you could get a really good set of speaker cables at the same
cost... :-)


As the world turns slowly on its orbit round the sun,
ideas come and go, and some stay, and become desirable
to buyers, and others perish on the vine, and yet others
become cherished by a minority of minorities,
and all of these may, or may not take away what is percieved to be
the creativity of the maker.
When you do become a maker of something, and you do go public with it,
you'll get the admirers and the knockers, and maybe a few
will make great suggestions, or ask awkward questions.
It makes life interesting.

It is really interesting to see new ideas being born, and how it seems like
some ideas develop independantant and simultainously around the globe, like
they come when it is their time.
I have always felt the most sorry for those who are too much ahead of their
time, and try to promote ideas and innovations before the world is ready for
them....

Just imagine if the transistor had been invented in 1903, instead of the triode!

Maybe Hitler would have developed better guided weapons.
Maybe the Internet of 1933 would have raised awareness to Stalin,
and Hitler's menaces, and war could have been avoided,
or more peaceful ways found to promote prosperity for the people,
beyond conning them with propaganda about great leaps forward,
and 5 year plans that were all BS.

Alas, millions died in agony, and before their time, because we were
not technologically advanced, and then a whole lot more died
because we were advanced, especially in japan, 1945.

There are no answers to the riddles of our existance.

Patrick Turner.



Karsten


Patrick Turner.


Karsten

It's just a tube type switching supply hooked around funny...

Nice idea - for an industrial application. :- )

_-_-bear

All Ears wrote:

"Patrick Turner" wrote in message
...


All Ears wrote:

snip
Here, some of us have already come to terms that we are AUDIO OUTLAWS,
because we use those silly old bottles that glow.
We have have given up the delusions of grandure, and we rest serenly
and
securely
with the knowledge that it ain't a waste of time to use tubes for
audio,
which is something our ears tell us.

Here we learn that patience and tolerance are virtuous,
and if the bull**** ego talk is left out, then a greater experience of
wisdom
and learning is possible. Here is is rare that our discussions are
punctuated by polluting obscenities, unless for humour's sake.

Patrick Turner.

Sounds soo right to me

I forwarded your questions to the manufacturer of this amp, I'll send
you a
copy of the answers.

BTW, it you want to see a "high-tech" approach in using these "silly old
glowing bottles" take a look at www.davidberning.com Pretty interesting
stuff he is doing.

Karsten

The wonderful Mr Berning breaks two rules about tube audio,
one, he rubbishes the tried and tested ideas on normal output
transformers,
and two, he uses complex circuitry, negating the simplicity so desirable.
Not much point to point circuitry, and lotsa pcbs.

May as well build a digital amplifier using all solid state parts.

And I don't like the boring black box approach.

I wish him well, since humanity respects diversity.....

Patrick Turner.


Mr. Berning is probably one of the biggest "outlaws" in the audio industry,
because what he is doing is so different from anything else.
You are of course right, it is very complex circuits, not really for the
hobbyist. However he is point to point wiring the signal path.

I do not agree that he might as well build a digital amp, because what he is
doing is basically just using a different type of impedance transformation.
Because he can get a ratio of 64:1 with this transformation, the tubes can
run high voltage and low current, which makes sence to me.

The black boxes are not to my taste either, the Siegfried he did, looks nice
though.

Karsten

Patrick Turner wrote:



snip



There is no schematic, no way I could form any real opinion on
exactly how the thing works.
Looks like RF is involved, maybe it has the information of the audio
signal carried on an RF carrier,
amplified, and detected, I really can't say.
But don't ask me if the delicacy and detail of good analog is conveyed
by such complexities.

Look up the patent. No RF "carrier" , much BS in the site description.
Turned me off. Don't like BS like that.

Think this way: draw current? drive load. :- )



There is another amp maker, Halcro, of Sth Australia,
and they make 200 watt mono amps with 0.0001% thd,
which isn't much, and I raise me hat to those guys.
The HK audio club was reported as saying of the Halcro,
"Like 300B, but go louder".
I hope the maker took that as a compliment.
And obviously, our grandfathers knew about good sound in 1928,
when a few got together to start making the 300B.
The Halcro cost about US $25,000 per pair.
Are two extra zeros after the decimal point worth $20,000???
Some folks think so.

It's quiet, and measures well, for certain.

It uses some well known design ideas, that are reasonably recent in
concept...

It is nothing like a 300B.

It has problems at 4 ohms. Which is an oddity to me. Something off
in the design? Implementation? Dunno.

Similar amps have been done before the Halcro, just not commercially.

'- )

_-_-bear



As the world turns slowly on its orbit round the sun,
ideas come and go, and some stay, and become desirable
to buyers, and others perish on the vine, and yet others
become cherished by a minority of minorities,
and all of these may, or may not take away what is percieved to be
the creativity of the maker.
When you do become a maker of something, and you do go public with it,
you'll get the admirers and the knockers, and maybe a few
will make great suggestions, or ask awkward questions.
It makes life interesting.

Patrick Turner.


Karsten

Not sure Berning's theories can actually apply to improving audio
quality in a meaningful way...Berning is more or less self taught,
apparently, with limited understanding of his theories at a
fundamental level - my son the Physicist says his notions regarding
hysteresis in transistors are lacking in correct understanding of
Quantum Theory - apparently the quantum spin state of electrons are
affected by hysteresis by orders of magnitude so small that there's no
way it could influence any parameters that could possibly affect
audiblitiy in any way...I'll have to pass that on w/o comment myself,
as I'm not the Nuclear Physicist....anyhow, for what it's worth.....
Roger in NY


BEAR wrote in message ...
It's just a tube type switching supply hooked around funny...

Nice idea - for an industrial application. :- )

_-_-bear

All Ears wrote:

"Patrick Turner" wrote in message
...


All Ears wrote:

snip
Here, some of us have already come to terms that we are AUDIO OUTLAWS,
because we use those silly old bottles that glow.
We have have given up the delusions of grandure, and we rest serenly
and
securely
with the knowledge that it ain't a waste of time to use tubes for
audio,
which is something our ears tell us.

Here we learn that patience and tolerance are virtuous,
and if the bull**** ego talk is left out, then a greater experience of
wisdom
and learning is possible. Here is is rare that our discussions are
punctuated by polluting obscenities, unless for humour's sake.

Patrick Turner.

Sounds soo right to me

I forwarded your questions to the manufacturer of this amp, I'll send
you a
copy of the answers.

BTW, it you want to see a "high-tech" approach in using these "silly old
glowing bottles" take a look at www.davidberning.com Pretty interesting
stuff he is doing.

Karsten

The wonderful Mr Berning breaks two rules about tube audio,
one, he rubbishes the tried and tested ideas on normal output
transformers,
and two, he uses complex circuitry, negating the simplicity so desirable.
Not much point to point circuitry, and lotsa pcbs.

May as well build a digital amplifier using all solid state parts.

And I don't like the boring black box approach.

I wish him well, since humanity respects diversity.....

Patrick Turner.


Mr. Berning is probably one of the biggest "outlaws" in the audio industry,
because what he is doing is so different from anything else.
You are of course right, it is very complex circuits, not really for the
hobbyist. However he is point to point wiring the signal path.

I do not agree that he might as well build a digital amp, because what he is
doing is basically just using a different type of impedance transformation.
Because he can get a ratio of 64:1 with this transformation, the tubes can
run high voltage and low current, which makes sence to me.

The black boxes are not to my taste either, the Siegfried he did, looks nice
though.

Karsten

According some, audio quality is already at a level exceeding the human
hearing many times. The only meaningful way to go, is to go by what sounds
realistic or pleasing depending on personal taste.

What I find interesting about the Berning approach, is that it is possible
to use a 6SN7 tube as output tube, giving 1W in 4 ohm, without any feedback.
This means that it gives possibilities that are not available in other
designs. There are many tubes that could be interesting to listen to
directly, that are not suited as output tubes, with conventional technology.

Karsten




"firedome" wrote in message
om...
Not sure Berning's theories can actually apply to improving audio
quality in a meaningful way...Berning is more or less self taught,
apparently, with limited understanding of his theories at a
fundamental level - my son the Physicist says his notions regarding
hysteresis in transistors are lacking in correct understanding of
Quantum Theory - apparently the quantum spin state of electrons are
affected by hysteresis by orders of magnitude so small that there's no
way it could influence any parameters that could possibly affect
audiblitiy in any way...I'll have to pass that on w/o comment myself,
as I'm not the Nuclear Physicist....anyhow, for what it's worth.....
Roger in NY


BEAR wrote in message
...
It's just a tube type switching supply hooked around funny...

Nice idea - for an industrial application. :- )

_-_-bear

All Ears wrote:

"Patrick Turner" wrote in message
...


All Ears wrote:

snip
Here, some of us have already come to terms that we are AUDIO
OUTLAWS,
because we use those silly old bottles that glow.
We have have given up the delusions of grandure, and we rest
serenly
and
securely
with the knowledge that it ain't a waste of time to use tubes
for
audio,
which is something our ears tell us.

Here we learn that patience and tolerance are virtuous,
and if the bull**** ego talk is left out, then a greater
experience of
wisdom
and learning is possible. Here is is rare that our discussions
are
punctuated by polluting obscenities, unless for humour's sake.

Patrick Turner.

Sounds soo right to me

I forwarded your questions to the manufacturer of this amp, I'll
send
you a
copy of the answers.

BTW, it you want to see a "high-tech" approach in using these
"silly old
glowing bottles" take a look at www.davidberning.com Pretty
interesting
stuff he is doing.

Karsten

The wonderful Mr Berning breaks two rules about tube audio,
one, he rubbishes the tried and tested ideas on normal output
transformers,
and two, he uses complex circuitry, negating the simplicity so
desirable.
Not much point to point circuitry, and lotsa pcbs.

May as well build a digital amplifier using all solid state parts.

And I don't like the boring black box approach.

I wish him well, since humanity respects diversity.....

Patrick Turner.


Mr. Berning is probably one of the biggest "outlaws" in the audio
industry,
because what he is doing is so different from anything else.
You are of course right, it is very complex circuits, not really for
the
hobbyist. However he is point to point wiring the signal path.

I do not agree that he might as well build a digital amp, because what
he is
doing is basically just using a different type of impedance
transformation.
Because he can get a ratio of 64:1 with this transformation, the tubes
can
run high voltage and low current, which makes sence to me.

The black boxes are not to my taste either, the Siegfried he did,
looks nice
though.

Karsten

I think the Berning output stage is quite an elegant solution. It
replaces the output xfmr and the HV xfmr with just a small ferrite
xfmr and some mosfet switches. These are the two heaviest and most
expensive parts in an amplifier. It also is quite amenable to DIYers
after some changes (see below), most importantly the number of turns
on the xfmrs is small, no more 3000 turn primaries to wind. On the
other hand, it has some issues with switching noise which are of
concern. Concerning elimination of hysteresis, it does this in much
the same way as the HF bias does for tape recording. The switching
signal provides the threshold signal to overcome coercive friction in
the core material. The material still has hysteresis (ferrite has low
hysteresis loss anyway), but the HF signal deals with it, not the
audio signal.
Here is what I would change in the design to make it a DIYer
friendly technique. As currently implemented it uses square wave
switching and a low pass filter on the output to get rid of
fundamental switching frequency harmonics and switching glitches. The
switching frequency has to be really high so that the filter can roll
off enough at the top end of the audio band. Square waves with fast
rise and fall times are required to maintain near continuity of the
audio signal. No DIYer wants to deal with such an EMI monster. What to
do?
Unfortunately for the simple is best group, it takes twice as many
parts to tame the EMI problem. Use TWO ferrite xfmrs and associated
switches and diodes and operate one of them at 90 degrees phase with
respect to the other. This way, the audio always has a direct path
thru while one phase is switching. Next, slow the rise and fall times
down using RC filters on the drive signals to the switches, the switch
connected duty cycle only has to cover 50% time now with two phases
operating, so they can be trapezoids instead of square waves. Next,
select the schottky diodes for matched voltage drop and similarly the
mosfets (can just use huge mosfets to swamp out on-resistance
variation and use schottkys from the same batch). Now we can lower the
fundamental switching frequency down to just above the top of the
audio band, no output filter needed. (well, maybe a glitch filter
still) EMI problems solved, unless you can hear 30KHz residuals!
Just as a side note, the Cuk (shuck) converter topology also
provides a nice switching impedance converter foundation since it has
no output ripple. Maybe I will get around to a design with this
sometime, more complex than the Berning stage however.
Another impedance converter topology which does not use switching
is the composite amplifier technique, the Sandman class S design and
Technics class AA were somewhat compromised versions of this. Can be
done much better. (These of course would use a solid state current
output amplifier for one of the amplifiers, and an small OTL type tube
amplifier for the other.)

All Ears wrote:
According some, audio quality is already at a level exceeding the human
hearing many times. The only meaningful way to go, is to go by what sounds
realistic or pleasing depending on personal taste.

What I find interesting about the Berning approach, is that it is possible
to use a 6SN7 tube as output tube, giving 1W in 4 ohm, without any feedback.
This means that it gives possibilities that are not available in other
designs. There are many tubes that could be interesting to listen to
directly, that are not suited as output tubes, with conventional technology.

Karsten

Actually, the use of 6SN7's as moderate output-power tubes is nothing
new. Amateur radio operators have, I'm sure, squeezed a lot more than a
mere 1 watt out of them from the day they were introduced. In class AB1
it should be possible to get about five watts out of one 6SN7 in
push-pull, while staying within the 7.5w maximum plate dissipation. (No,
it probably won't sound the greatest, but that's beside the point.)

Yes, it's conventionally used as a driver, and yes, it's pleasing to see
them used in other applications. Just as it's pleasing (to me, anyway)
to see seven 12AU7's used as a PPP output device (Hi Tim), horizontal
sweep tubes used in guitar amplifiers, tubes designed as pass regulators
used for hi-fi OTL designs, and [shameless plug department] vertical
circuit dissimilar triodes used for low-power SE or PP triode amplifiers.

The possible permutations are still vast, even within the framework of
"conventional" technology. While I'm certainly still young enough in
spirit to be open to new approaches (almost to the point of obsession at
times) I'm also old enough to know that "different" is not necessarily
"better," and that there are very good reasons why the common toplogies
are common.

If all the accepted "audio" tubes (300B, KTxx, ECC83, 6L6 family, EL34,
etc.) disappeared overnight, and all we had at our disposal were the
much-maligned "TV" tubes, there would still be innovative designers and
experimenters building very well-performing tube amplifiers around
6JT8's, 33JV6's, and 6GF7's. It's much less the qualities of individual
parts (tubes in this case) than it is the qualities of the overall
design, as thought out by an ingenious and interested human being.

Cheers,
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects, Vacuum Tubes & other stuff: |
| http://www.dogstar.dantimax.dk |
+--------------------------------------------+

All Ears wrote:

According some, audio quality is already at a level exceeding the human
hearing many times. The only meaningful way to go, is to go by what sounds
realistic or pleasing depending on personal taste.

What I find interesting about the Berning approach, is that it is possible
to use a 6SN7 tube as output tube, giving 1W in 4 ohm, without any feedback.
This means that it gives possibilities that are not available in other
designs. There are many tubes that could be interesting to listen to
directly, that are not suited as output tubes, with conventional technology.

Look again.

That's not how his "amp" works exactly...

_-_-bear



Karsten

"firedome" wrote in message
om...
Not sure Berning's theories can actually apply to improving audio
quality in a meaningful way...Berning is more or less self taught,
apparently, with limited understanding of his theories at a
fundamental level - my son the Physicist says his notions regarding
hysteresis in transistors are lacking in correct understanding of
Quantum Theory - apparently the quantum spin state of electrons are
affected by hysteresis by orders of magnitude so small that there's no
way it could influence any parameters that could possibly affect
audiblitiy in any way...I'll have to pass that on w/o comment myself,
as I'm not the Nuclear Physicist....anyhow, for what it's worth.....
Roger in NY


BEAR wrote in message
...
It's just a tube type switching supply hooked around funny...

Nice idea - for an industrial application. :- )

_-_-bear

All Ears wrote:

"Patrick Turner" wrote in message
...


All Ears wrote:

snip
Here, some of us have already come to terms that we are AUDIO
OUTLAWS,
because we use those silly old bottles that glow.
We have have given up the delusions of grandure, and we rest
serenly
and
securely
with the knowledge that it ain't a waste of time to use tubes
for
audio,
which is something our ears tell us.

Here we learn that patience and tolerance are virtuous,
and if the bull**** ego talk is left out, then a greater
experience of
wisdom
and learning is possible. Here is is rare that our discussions
are
punctuated by polluting obscenities, unless for humour's sake.

Patrick Turner.

Sounds soo right to me

I forwarded your questions to the manufacturer of this amp, I'll
send
you a
copy of the answers.

BTW, it you want to see a "high-tech" approach in using these
"silly old
glowing bottles" take a look at www.davidberning.com Pretty
interesting
stuff he is doing.

Karsten

The wonderful Mr Berning breaks two rules about tube audio,
one, he rubbishes the tried and tested ideas on normal output
transformers,
and two, he uses complex circuitry, negating the simplicity so
desirable.
Not much point to point circuitry, and lotsa pcbs.

May as well build a digital amplifier using all solid state parts.

And I don't like the boring black box approach.

I wish him well, since humanity respects diversity.....

Patrick Turner.


Mr. Berning is probably one of the biggest "outlaws" in the audio
industry,
because what he is doing is so different from anything else.
You are of course right, it is very complex circuits, not really for
the
hobbyist. However he is point to point wiring the signal path.

I do not agree that he might as well build a digital amp, because what
he is
doing is basically just using a different type of impedance
transformation.
Because he can get a ratio of 64:1 with this transformation, the tubes
can
run high voltage and low current, which makes sence to me.

The black boxes are not to my taste either, the Siegfried he did,
looks nice
though.

Karsten

My initial reaction is that if you slow down the leading
edges on the square wave you wack the efficiency big time.
The thing depends upon small core size and fast transitions
to get the results... but maybe with a bigger core and slightly
less efficiency it would be alright... probably not.

The "carrier" never gets seen at the load, with Berning's
method, so why worry... he's just creating a way to modulate
current to drive a load... it's indirect.

The filtering is trivial.

_-_-bear

smoking-amp wrote:

I think the Berning output stage is quite an elegant solution. It
replaces the output xfmr and the HV xfmr with just a small ferrite
xfmr and some mosfet switches. These are the two heaviest and most
expensive parts in an amplifier. It also is quite amenable to DIYers
after some changes (see below), most importantly the number of turns
on the xfmrs is small, no more 3000 turn primaries to wind. On the
other hand, it has some issues with switching noise which are of
concern. Concerning elimination of hysteresis, it does this in much
the same way as the HF bias does for tape recording. The switching
signal provides the threshold signal to overcome coercive friction in
the core material. The material still has hysteresis (ferrite has low
hysteresis loss anyway), but the HF signal deals with it, not the
audio signal.
Here is what I would change in the design to make it a DIYer
friendly technique. As currently implemented it uses square wave
switching and a low pass filter on the output to get rid of
fundamental switching frequency harmonics and switching glitches. The
switching frequency has to be really high so that the filter can roll
off enough at the top end of the audio band. Square waves with fast
rise and fall times are required to maintain near continuity of the
audio signal. No DIYer wants to deal with such an EMI monster. What to
do?
Unfortunately for the simple is best group, it takes twice as many
parts to tame the EMI problem. Use TWO ferrite xfmrs and associated
switches and diodes and operate one of them at 90 degrees phase with
respect to the other. This way, the audio always has a direct path
thru while one phase is switching. Next, slow the rise and fall times
down using RC filters on the drive signals to the switches, the switch
connected duty cycle only has to cover 50% time now with two phases
operating, so they can be trapezoids instead of square waves. Next,
select the schottky diodes for matched voltage drop and similarly the
mosfets (can just use huge mosfets to swamp out on-resistance
variation and use schottkys from the same batch). Now we can lower the
fundamental switching frequency down to just above the top of the
audio band, no output filter needed. (well, maybe a glitch filter
still) EMI problems solved, unless you can hear 30KHz residuals!
Just as a side note, the Cuk (shuck) converter topology also
provides a nice switching impedance converter foundation since it has
no output ripple. Maybe I will get around to a design with this
sometime, more complex than the Berning stage however.
Another impedance converter topology which does not use switching
is the composite amplifier technique, the Sandman class S design and
Technics class AA were somewhat compromised versions of this. Can be
done much better. (These of course would use a solid state current
output amplifier for one of the amplifiers, and an small OTL type tube
amplifier for the other.)

BEAR wrote in message ...
My initial reaction is that if you slow down the leading
edges on the square wave you wack the efficiency big time.
The thing depends upon small core size and fast transitions
to get the results... but maybe with a bigger core and slightly
less efficiency it would be alright... probably not.

This is true if using single phase switching as presently
implemented, slow transitions would cause losses and create a lot more
switching hash to filter out too.
But, with a two phase setup, both phase switches (90 degrees out of
phase for switching polarity thru their related xfmr.) are in parallel
between tube and load. This is like connecting up a circuit with two
clip leads. We can remove one to change it without any effect as long
as the other is providing a low resistance connection. Each phase
"covers" the other while reversing connection thru the related ferrite
xfmr. This is possible to do because each phase has its own set of
comutating rectifiers going to the tube, the tube doesn't care which
way it is connecting thru an xfmr. core or which xfmr. core is
providing the connection, as long as it gets its HV DC of the right
polarity from the diodes.

The "carrier" never gets seen at the load, with Berning's
method, so why worry... he's just creating a way to modulate
current to drive a load... it's indirect.

The filtering is trivial.

_-_-bear

This is true for a perfect square wave with instantaneous rise and
fall times. In reality, these finite transitions chop the audio with
glitches at the switching frequency and the filter is necessary to
remove them. Non perfect Rds matching between the mosfets (and
commutating diodes too) also injects some residual noise into the
audio at the switching frequency.
With two phase switching the audio does not get chopped at all due
to the redundant "covering" effect between phases. This is sort of
like a synchromesh in an auto transmission, each phase comes up to
identical speed and passes off control to the other thru the
commutating diodes. In fact, if the components were perfectly matched
for voltage drops we could drop the switching frequency down into the
audio range with no audible effect on the output. It would require
bigger xfmrs. as you mentioned however. The main advantage of two
phase switching is that each phase only has to "cover" 50% of the
time so that leaves us with the other 50% of the time to do slow
transitions so as not to generate EMI. Some PWM switching supplies
designed for critical noise environments use this exact scheme, so
nothing new here. Since the components will never be perfectly
matched, 30KHz would keep this residual noise out of the hearing
range. Consideration of the hysteresis nulling phenonena due to HF in
the xfmr. cores might lead us to use a little higher frequency, have
to experiment there.

Don

All Ears wrote:

According some, audio quality is already at a level exceeding the human
hearing many times. The only meaningful way to go, is to go by what sounds
realistic or pleasing depending on personal taste.

What I find interesting about the Berning approach, is that it is possible
to use a 6SN7 tube as output tube, giving 1W in 4 ohm, without any feedback.
This means that it gives possibilities that are not available in other
designs. There are many tubes that could be interesting to listen to
directly, that are not suited as output tubes, with conventional technology.

1.0 watt into 4 ohms means 2 vrms at 0.5 amps rms,
and correct me if I am wrong, but where does one find a variety
of 6SN7 to sustain a linearly changing current up to a peak 707 mA?

Without a simple clear schematic to cast light, I am sure there is more to
Berning's amps
than any simple one liner explanation here offers.

Patrick Turner.

Patrick Turner wrote in message ...

Without a simple clear schematic to cast light, I am sure there is more to
Berning's amps
than any simple one liner explanation here offers.

Patrick Turner.

A pretty good review with rough schematic is given in Glass Audio
Volume 12 No. 1 year 2000 page 22-30, also some follow up in the next
issue.
An actual schematic is online at: http://www.triodeel.com/schindex.htm
Look under: Berning - Siegfried
Also the last issue of VTV has something on it, haven't seen it yet.

Don

smoking-amp wrote:

Patrick Turner wrote in message ...

Without a simple clear schematic to cast light, I am sure there is more to
Berning's amps
than any simple one liner explanation here offers.

Patrick Turner.

A pretty good review with rough schematic is given in Glass Audio
Volume 12 No. 1 year 2000 page 22-30, also some follow up in the next
issue.
An actual schematic is online at: http://www.triodeel.com/schindex.htm


Look under: Berning - Siegfried

Yep, its full of mosfets and transformers working off the mosfets.
1 step forward, 2 steps backward?

Patrick Turner.


Also the last issue of VTV has something on it, haven't seen it yet.

Don

"Patrick Turner" wrote in message
...


smoking-amp wrote:

Patrick Turner wrote in message
...

Without a simple clear schematic to cast light, I am sure there is
more to
Berning's amps
than any simple one liner explanation here offers.

Patrick Turner.

A pretty good review with rough schematic is given in Glass Audio
Volume 12 No. 1 year 2000 page 22-30, also some follow up in the next
issue.
An actual schematic is online at: http://www.triodeel.com/schindex.htm


Look under: Berning - Siegfried

Yep, its full of mosfets and transformers working off the mosfets.
1 step forward, 2 steps backward?

The mosfets and transformers should only conduct the impedance
transformation, and should not give any, or only little, audible effect. I
would say that this circuit most likely affects the signal from the tubes
less than a conventional transformer. If this is desired or not, will of
course be a matter of personal taste.

Karsten


Patrick Turner.


Also the last issue of VTV has something on it, haven't seen it yet.

Don