[Patrick Turner]

Andre Jute wrote:

On Nov 8, 6:32 am, Patrick Turner wrote:
Andre Jute wrote:
,,,but decided
not to complicate what I wrote with qualifications (no doubt Trevor
Wilson will next accuse me of *lying*!).

Shock, Horror, will someone tell you if you lied? how awful....

I don't mind if I'm wrong on some statement I made being corrected,
preferably politely of course. But Wilson accuses people of lying if
they don't include his fave Blow Jobs for Transvestites when they talk
about tubes; I just don't see how such an omission is a lie. If I want
to talk about BJTs, I can go to the alt.perverts.ss.gruppenfuhrer
newsgroup. But jokes aside, if we once open the door to a single mad
obsessive like Trevor Wilson, soon we'll have one-string ramkiekie
players around here demanding to know why they aren't mentioned every
time we mention a favourite recording of say, a Bach Cantata. The
Wilson Road runs from madness to madness.

But its become very well known amoung those of us who live nearer to TW
to keep
blood off the wattle by simply not taking what he says about tube amps
too seriously.

He does tolerate the better measuring large output power ARCs and the
like, when they are
properly biased and working well, which seems to be a rare event for
many american amps
I find due to their generally very poor biasing arrangements.
((I now have a McIntosh re-issue MC275 in for damage appraisal which is
spitting out KT88 and blowing fuses,
and it was only purchased 4 months ago.
Can't the yanks get ANYTHING right?))

TW has no time for SE amps with a lone 300B.

He's not alone, and a whole army of knockers loathe any 8 watt wanabe
amps....

But the 8 watts is fine for any speakers with high enough sensitivity to
allow the corresponding
wanted output levels.

One has to fumble through life accompanied or surrounded by ppl who are
addicted to some view or other which to
us is a complete nonsense; perhaps their religious belief, political
belief, financial habits,
historical views, sexual habits et all.
Even amplifier habits as well.
Hence sex, politics and religion are forbidden to be discussed at polite
dinner parties,
and if amps are mentioned, hardly anyone will understand what is said
just like nobody can decipher the gobbledegook political speaches being
made right now
by Labour and Liberal leaders in the last 3 weeks before our Federal
Election.

Put simply, our Liberal Johnny Bloward is saying "I've raised prices and
lowered wages, and you'll get more of that
if you vote for me like youse did last time", and the wannabe Prime
Minister contestant from Labour, Kevin Dudd
is saying, "yeah, that's maybe roughly about what i say too." Labour
Midnight Oil singer Peter Guardrat, wanabe environment minister
say "we'll change it all when we get voted in..." Dudd was quite miffed.

Well, we all know they ALL goner do that anyway, but the truth wasn't
appreciated....

Look at what's been said here about pearl Harbour, and behaviour of the
German ppl
with regard to jews in WW2.

Sure is plenty to disagree with.

But my world won't disintegrate if I simply don't bother to join in
these OT
discussions very much.

So whatever is said about tubes or all this OT politico/socio crap won't
change my faith in using tubes.

I am secure in my beliefs, welcoming any challenge to them but they do
need to be
VERY convincing challenges if I am to change seriously.

And I have limited time. I'd rather spend 4 hours doing a 100k bike ride
or concentrating more fully
on the numerous tube projects required by my clients and friends.
Its better than spending 4 hours so easily arguing and typing counter BS
with ppl on OT subjects where the resulting net
effect is a negative outcome; ie, a completely wasted effort, and a
clutter of the archives which no ******* ever reads,
and nothing done to further enhance anyone's existance.

I would rather leave a tangible legacy appreciated right now than watch
TV all night or type BS.


And Cantata 199 to every cyclist: "My heart pumps a whole lotta
blood", freely translated (very) from the Cherman "Mein Herze swimt im
Blut."

Hubert Opperman once said at maybe my age that older cyclists are like
old tyres.
They may have been designed to take high pressure, but sometimes they
blow up.

I regard myself as extremely fortunate to be able to ride 108k in 4.5
hours
on truly difficult and hilly country roads in the hills and valleys at
the back of Canberra at my age.

I don't plan to heed the advice of others who'd say i should buy a
motorcycle.

I am criticized for taking so long to do things.
But I am very good at doing things that take a long time to get right.

During the little 108km ride organised by Pedal Power here,
it seems I did no damage to my knees despite the condition of pain I had
3 years ago
and despite doctors having diagnosed that a pair of titanium knee joints
was what i really needed.

Doctors, like many experts, can be incorrect.

Those of us like TW, and myself, and Andre and all of us here can also
be wrong.
Its something worth remembering all the time.

For those who do tolerate cyclist matters being discussed, the Pedal
Power event called Fitz's Challenge
attracted about 450 riders spread over 4 distances, 210km with
3,500metres of steep climbing,
160km with 2,200m of climbing, 108km with 1,200m of climbing, and 50km
with maybe 500m of climbing.

20 years ago I did the inaugural 147km ride, a slightly different route,
but very hard, and rode from home to the course start/finish and then
home which made 177km for the day.
I do not want to be able to finish this distance at 60. Enough is
enough.
I like the speed of a good ride, but not to spend too long in agony,
and its impossible for me to just amble along slowly.
In 20 years i have slowed considerably and was just wize enough to
select a lower range of gears appropriate to my age.
My lowest was 39 chain ring, 27 cog at the rear wheel. At 40 I managed
the same hills on 42 x 23,
and some elite lightweight young riders would use 42 x 17 or even higher
lowest gear.


Last fortnight one fellow of 29 covered the 210km course in about 7.3
hours, and he's done this october ride
about 9 times. Many others DNF.
Unlike last year, nobody died on the course during a rapid dangerous
descent this year.

Nobody has ever suffered heart failure. I'm sure many have worse hearts
than I have.

Such "randoneur" events are not bad to ride in because its not a race,
but you are out on roads
with many cyclists about, and the occasional car drivers on the sunday
morning get reminded to take care.
I treated my distance like a race as many others of all ages did, and I
started 1/2 an hour before the official
start time for my distance group at 8.30. I was passed by only 2 young
fellows under 35 who eventually caught me.
I wondered what took them so darn long, I had only taken for myself a
1/2 hour start ahead of them while giving
them a 25 year start on me.....

There were quite a few ppl who appeared to be my age who did the 160km
course. I didn't
see the group who attempted the 210km, because they started at about
6.30am.

Tonight my resting heart rate is 48 beats per minute.
3 years ago I was 20Kg heavier, and HR was 65bpm.

I am at peace, and I don't give a **** if I die in 5 minutes time.

Patrick Turner.









Andre Jute
No real corpses were harmed in the assembly of my golem Worthless
Wieckless. I made him by stuffing a cow's bladder with pig offal. --
Creepy Mike LaFevre, Magnequest Transformers, Philadelphia

[Iain Churches[_2_]]

"Andre Jute" wrote in message
ups.com...
On Nov 2, 5:22 pm, John Byrns wrote:
In article ,
"Arny Krueger" wrote:

"Dave" wrote in message
news:CfGWi.1359$8S5.242@edtnps82...

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

I know for a fact that people cannot
hear as much as 3/4 per cent second harmonic but can hear that much
odd harmonic very clearly, and many people can hear or are made
uncomfortable by 0.3 per cent odd harmonics.

This order of harmonics issue is way overblown. Doesn't matter whether
it is
odd or even order nonlinearity, it all makes IM. IM is generally
aharmonic
and it all sounds bad.

But even order IM is much more obvious and annoying in listening tests,
although I suppose others may find odd order IM more annoying, its
probably partly a matter of personal preference.

Arny is trolling. It is widely known that second harmonic is
euphonious whereas third and higher harmonics are disturbing.

2H is an exact octave of the fundamental, and so in reasonable
amounts, may be considered benign. 3H is an octave and a fifth
above the findamental. That might seem OK on the face of it.
But consider a chord that has no fifth (the thirteenth is a good
example)

Here is another aural perception experiment which
most students find of interest:

Ask a section of five saxophones to play that chord. If the
amplifier is adding a fifth to each of the five instruments, then
you have another 13th chord set one and a half octaves above
what they are actually playing. That's horrific!

Iain

[Andre Jute]

On Nov 8, 4:38 pm, "Iain Churches" wrote:
"Andre Jute" wrote in message

ups.com...



On Nov 2, 5:22 pm, John Byrns wrote:
In article ,
"Arny Krueger" wrote:

"Dave" wrote in message
news:CfGWi.1359$8S5.242@edtnps82...

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

I know for a fact that people cannot
hear as much as 3/4 per cent second harmonic but can hear that much
odd harmonic very clearly, and many people can hear or are made
uncomfortable by 0.3 per cent odd harmonics.

This order of harmonics issue is way overblown. Doesn't matter whether
it is
odd or even order nonlinearity, it all makes IM. IM is generally
aharmonic
and it all sounds bad.

But even order IM is much more obvious and annoying in listening tests,
although I suppose others may find odd order IM more annoying, its
probably partly a matter of personal preference.

Arny is trolling. It is widely known that second harmonic is
euphonious whereas third and higher harmonics are disturbing.

2H is an exact octave of the fundamental, and so in reasonable
amounts, may be considered benign. 3H is an octave and a fifth
above the findamental. That might seem OK on the face of it.
But consider a chord that has no fifth (the thirteenth is a good
example)

Here is another aural perception experiment which
most students find of interest:

Ask a section of five saxophones to play that chord. If the
amplifier is adding a fifth to each of the five instruments, then
you have another 13th chord set one and a half octaves above
what they are actually playing. That's horrific!

Oh, I doubt Krueger will even hear there is something wrong...

Iain

Andre Jute
Perception is a skill that requires study and careful development over
along period of time. Few have it as a natural gift. -- Iain Churches

[Andre Jute]

On Nov 8, 11:22 am, RdM wrote:
Patrick Turner writes, inter alia, in
. au:

How many recordings of Vivaldi's Four Seasons does the world really
need?

Oh, well over 400, I should think ...http://svalander.se/vivaldi.htm

His wife is probably glad it keeps him out of the pub, judging by the
romantic photo she took of him.

In June 2002 I sent him details of one I had that he hadn't; not even on his
wanted list, so probably not known to him; Quattro Stagioni by the
Kammerensemble Cologne, on the Swiss Kutlu label; the lead violinist played a
1724 Stradivarius;

Never heard of the label, but I too have heard the KEC. I looked into
my catalogue and I have, in a collection of 6000 discs, three versions
of the Four Seasons, all the of them listed by your chum.

I bought the CD after the concert at the church they played
in here; I miss it very much, it having been left at a friends place which was
like a railway station with regular weekly music nights, and vanished ...

A close friend is one who can "borrow" your books and CDs permanently
without being struck off your Christmas card list.

I'd very much like a copy again, if anybody ever sees one:http://i17.tinypic.com/6ypj5zm.jpg

And perhaps some of the recording quality had to do with the equipment used:http://i11.tinypic.com/8evj28x.jpg(trimmed, much reduced quality of scan!)
(I had thought I might see if I could sneak a 40kb jpg into a text attachment
to the end of this message, re recent discussions, but nah, can't be bothered)

AJ may NB the Stax SR-Lambda Pro used for monitoring.

My ad agency owned a recording studio, which we bought in an (idle)
quest to give me more control over the quality of our advertisements.
There a set of Stax headphones was kept for me in a locked wooden box,
to which my boxers'n'sox dolly (the assistant who carried clean
panties for the girl and me so that we didn't smell too bad after four
days on my little plane), carried the key. I can't remember now what
model it was but, given the time, the late 1960s, it was probably
electret. I'm not into Stax history, which is pretty convoluted. But I
can say that a modern fixed bias Stax sounds just like the real deal
of ESL-63, whereas the electret of all those years ago didn't come to
within a mile of ESL-57. My Stax are absolutely amazing loudspeakers
compared to, for instance, the Senheisers I also have, but then they
should be, considering the price difference. But the Stax also leave
my old Bang & Olufsen dynamic headphones in the shade, and B&O don't
have the excuse that their product is cheaper.

Not sure if the comment on "transformerless" will win PT's heart, though!

One wonders if they mean "windingless" or if this is a mistranslation
for "not processed in any way".

An absolute proscription on transformers would be a new audiophool
obsession you have discovered, if true.

[No "tubes", either!]
--
Ross Matheson
(in nz, not zz...)

Andre Jute
"I was at a board meeting for the LA Chapter of the Audio Engineering
Society last night on XM Satellite radio audio and data transmission.
Sadly, we missed you there, and at the SMPTE and Acoustical Society
recent meetings as well. Everyone was asking, 'Where is that wonderful
Andre Jute? The world just doesn't rotate without him...'" -- John
Mayberry, Emmaco

[Phil Allison]

"Iain Churches"
"Arny Krueger"
John wrote:
And then there is ordinary real music from instruments.
Presumably a fair amount of IMD is included.

Wrong, because in a live performance there is very little that mixes the
whole acoustic output of the musicians into a single signal and then puts
that single signal through a strongly nonlinear process.


Arny, Try this experiment. Sit amongst an orchestra during rehearsals or
recording. Place your chair at the back and to the right of the French
horn
section, where the microphone would be on a multi-mic setup. Four horns
are good, five horns are better. Sibelius 5, Op 82 Eb is a perfect
example.

Then tell me there is no acoustic IMD.


** That is not "acoustic" ie the science of sound.

That is a defect in human hearing that varies from one individual tt
another.

The fact effect it goes away when listeners are at a greater distance ( ie
listening to a lower SPL version of the same sound ) proves the point.




........ Phil

[Patrick Turner]

John Byrns wrote:

In article ,
"Arny Krueger" wrote:

"Patrick Turner" wrote in message


And then there is ordinary real music from instruments.
Presumably a fair amount of IMD is included.

Wrong, because in a live performance there is very little that mixes the
whole acoustic output of the musicians into a single signal and then puts
that single signal through a strongly nonlinear process.

What about the ear of the listener, isn't IMD produced there that mixes
the whole acoustic output of the musicians?

Indeed ears create artifacts, and as we age the dynamic range of ears to
cope with wide dynamic range is seriously reduced.
Everything one does at 25 becomes restricted or down graded as we age,
except
perhaps becomeing wize, which requires accumulated experience.

But in a simple guitar, bass string tension at the bridge pulls the
bridge and other string tensions are
altered slightly, and some IMD must result.
I don't know how linear the stop start air flow in organ pipes or
trumpets might be,
or in bows on violins, but surely they ain't perfectly linear,
and some IMD products are produced.

Arny suggests there are no non-linearities in musical instruments, and
none in the air,
or caused by the room, so its only the microphone of other electronics
that can create it.

I'm not talking about huge amounts as Arny think I am either.

No use talking to Arny, one gets Kroogerated.

Patrick Turner.

Regards,

John Byrns

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

[Patrick Turner]

Andre Jute wrote:

On Nov 8, 3:23 pm, "Arny Krueger" wrote:
"Iain Churches" wrote in message

i.fi

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

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

The explanation is simple. Loop NFB causes artifacts
of ever lower magnitude but higher order.

Good example of majoring in the minors. Loop NFB drops nonlinearity by 20
dB or more. The equipment in question was not entirely free of higher order
nonliner distortion, and the secondary effect being obsessed over here
typically adds far less distortion than was already there.OTOH, the loop
feedback drops all nonlinear distortion by 20 dB. The net higher order
distortion is thus dramatically reduced.

We're not talking about the net number, Krueger. We're talking about
the effect of the composition of the residual distortion.

Well yes, but with music this is an extremely complex mix
of dynamically changing frequencies, and listened to alone
separated from the undistorted signal, sounds like noise and range of
harmonically and unharmonically related tones; bloody awful sounding,
worse than pink noise or any real music.

Its the aim of every tube amp maker to reduce this to below audible
levels
without applying too many tricks.



These high
order distortions, even at 60dB below conscious
perception are very, very disturbing,

If they are so disturbing, why aren't the SET owners
running out of the room
screaming every time they turn their MI amps on? Repeat, its not like SET
amps are free of higher order distoriton.They are based on tubes and tubes
are exponentially-based devices. The expansion of their theoretical
amplitude transfer function includes signficant higher-order terms, loop
feedback or not!

A conservatively designed and well-developed 300B amp can easily get
the third and higher harmonics down to 0.03 per cent without any loop
or stage feedback. I don't see how that is "significant" at all.

Hmm, most SET amps with 300B need to be powering horns so THD/IMD
is less than 0.2 watts and then you might get down to 0.03%.

But with ordinary speakers of 88dB/W/M, the SE amp with one little 300B
will have at least 3% at 5 watts with a highish RL, and at 0.5W average
power for such insentive speakers
the output voltage is about 1/3 that for 5 watts, and THD is 0.75%,
mainly all 2H, but
way above 0.03%, which is only realizable if you have lots more 300B in
parallel
or you have a PP pair, and powered by a balanced PP input stage to avoid
the 2H made in so many half baked designs
for PP where the 2H of the single lousy driver is way above the mainly
3H of the PP output stage THD.

If the output SE stage's 2H is cancelled by the driver stage's 2H then
its possible to very
much reduce 2H down to less than the 0.03% at up to a few watts, but
then that's only
for one value of load, as the amount of 2H changes with load on the
output tube.
Natural cancelling of 2H by *VOLTAGE* cancelation in SE amps instead of
*CURRENT* cancelations
in PP stages actually makes tube sound better, so my clients tell me.

In a generic SET amp with 300B, it is thus possible to make a triode
driver stage
which makes 0.75% of 2H at the 0.75W output level, but its also not
wise,
since at that low output level most well designed driver stages won't
make that much 2H to cancel anything much. A driver stage naking such a
lot of 2H will struggle
at higher levels, and maybe clip earlier than the output stage.
IMD produced in the driver get passed on and muddy the output spectra.

Hence my solution is to use local CFB from the OPT around
tetrodes/pentodes, and reduce max
output stage THD to say 2% at 20 watts, abd then the driver stage when
loaded with an RL 10Ra
will never struggle or muddy up the sound, and what little 2H it makes
willo
nicely cancel the output stage 2H....and presumably most other even
order products.
The result is beautiful un-muddied SE sound, and because the amps I make
have
over 20 watt capability, there is enough headroom for most ppl
and perhaps 1/10 of the THD/IMD as one may hear with a lone 300B with
average power at 1W.

The odd order junk isn't thus cancelled, but will be a vile residue.
But its at such a low level below what would otherwise be a large 2H
amount, it matter not,
even if you weighted the audibility acording to the Nsquared/4 rule.

So in fact in my amps I *actually do achieve* your quoted 0.03%, but
nobody else seems to.
Most SET amps I have to rewire or teach how to sing and how to behave
are travesties of engineering
because the makers fail so dismally with basic loadings on tubes, and
thd and noise is way above what is
possible.

Because all amps I make have wide bad OPTs giving over 50khz of
bandwidth WITHOUT dependance on global NFB,
when I do apply a bit of NFB, say 9dB, to ensure Rout of the amp is at
least 1/5 of RL,
and preferably 1/10 RL, then the THD and IMD is further reduced and the
net residual artifacts no matter what they
are would be much lower level and far less unpleasant if sent to the
speakers without the music signal present
compared to the rubbish and junk which exists in an average low power
SET amp signal if played a little too loud
and without distortion cancelling schemes either bt way of clever driver
or PP design, and
without loop NFB.

Audio is a gentle low level energy in the air and excites our fabulously
sensitive ears
which have evolved over millions of years.

But folks seem hell bent on owning insensitive speakers, and sometimes
will aquire low power SET amps. If they listen up close to the speakers
at low level, fine,
and I know guys who do this, but filling a large hall sized lounge with
high level is impossible and silly.

Its not easy to accurately reproduce the sound of a loud trombone player
right in front of you
without clipping anything. Ditto someone pounding away on a grand piano,
lid up,
facing towards you. Horns come to mind. And lotsa watts.

whereas second
harmonic up to three-quarter per cent cannot even be
distinguished by professional musicians. It is a
subliminal effect, and of course in pentode mode it is
exaggerated. People look at the total harmonic
distortion but in fact the higher harmonics must be
weighted much more heavily than the second harmonic to
account for its extraordinary subliminal effect, often
described as "edgineess" by professional musicians.

This was the explanation I was looking for. thank you.

Yes. That seems to be a good description of what is going
on, and explains why two similar tubes/valves of the same
type but by different makers may sound different. They
usually have the same or very similar THD but the
distortion spectra are sometimes surprisingly different. 2H is exactly an
octave of the fundamental, and so, in
"trace" amounts may be regarded as benign. 3H, 5H, 7H
and 9H, even at much lower levels are considerably more disturbing.

Same mythical thinking, repeated.

All right, Krueger, so you don't like psycho-acoustic truths
observable in repeatable tests disturbing your fauz certainties. So,
slumber on.

Repeat again, its not like SET amps are free of higher order distortion.They
are based on tubes and tubes are exponentially-based devices. The expansion
of their theoretical amplitude transfer function of a tubed amp includes
signficant higher-order terms, loop feedback or not!

So you keep saying, Krueger, but so far you have provided no proof of
your contention, which those of who bulld SETs know is untrue.

I have heard many excellent sounding systems with 8W SET amps with a
lone 300B.
The best had either professional horn speakers made by JBL or Altec,
or large sensitive Tannoys in huge bins for great bass.
Average power was miniscule, and issues of audible THD/IMD are not worth
discussion, because the levels are so low.

It so happens that at a watt, 2H from a 300B or other tride such as
trioded KT88, 6550, or KT90
etc is often 20 times the level of any other H.

Pentodes and beam tubes are not so benign, and produce varying amounts
of many harmonics
and 2H will be high like in a triode with too low a load when it is
loaded low,
then fall to zero at some critical medium load value, and then rise
again as RL is increased,
but the phase of the 2H is opposite below and above the critical RL.
The odd numbered H are many and varied with pentodes and beam tubes and
the
best way of dealing with them is NFB, and this is achieved in every
triode because of the
electrtostatic NFB acting between anode and space charge summing point
between cathode and grid.
The triode NFB does a pretty good job at odd order H reduction.
But if a similar amount of local CFB from an OPT is applied then the H
reduction
is similar to triode.
So to shoehorn a beam or pentode tube into low THD production,
the open loop gain must be well reduced to about the same as low µ
triodes.

So in my latest work with 13E1, the open loop gain is 16, but reduced to
2.5 only
with the local NFB from OPT CFB and THD becomes benign.

The tube sound IS THERE, but not muddied by anything very much.

The baby is retained, only the bath water is thrown out.

With BJTs, the effort to make them tolerable to listen to always
requires lotsa NFB as with pentodes or beam tubes.

Arny doesn't take in the variety and differences in tubes; triodes are
infinitely more tolerable sonically than pentodes or beam tubes or BJTs
or mosfets
when used *WITHOUT* any NFB.
That mantle radio set with a lone 6V6 is a HORRID little audio crapper
if ever there
was one, but generally has no GNFB or local NFB.
Any single BJT used similarly would even be worse..




Some years ago, the technical director of Svetlana sent
me the findings of a listening group with whom he had been working. Their
task was to evaluate 6CG7 tubes by different
makers, and put them in order of preference, so that they
could be measured and analysed. Although I was not able to obtain all
twelve makes on the list, with
some colleagues, I repeated the experiment.The differences
were most interesting. The interpretation of which is
"better" must be left to individual taste, but in general
terms, we ranked the tubes in roughly the same order as the Svetlana
listeners. In case you are wondering, the
RCA cleartop was the best sounding. It also had the lowest odd order
harmonics when measured in a mu follower circuit.

Yet another anecdote with questionable relevance.

Well here I have to agree that sonic differences in preamp tubes can be
heard.
Even when THD and IMD measures below 0.01%, a typical value where
you have a line stage preamp with volume pot before a generic gain stage
using a 6CG7.

I have, with 4 other guys spent an afternoon tube rolling with 6CG7
samples.
We agreed the NOS Seimans were best, then made in Oz Miniwatts, then
Mullard, and
then very much last were recent Sovtek versions.

SNIP,,,

Right now I'm running a solid
state amp which is rated at 50W RMS with THD of 0.08%. I guess this
isn't a
reasonable target for a tube amp unless I run multiple
parallel UL PP pairs
per channel...
A while ago, I built a push pull parallel EL34 amp, with
two parallel pairs per channel. It can achieve 0.08% THD
at full power.
http://www.kolumbus.fi/iain.churches...em/C50_002.jpg

I don't know whether to laugh or cry.

Ah well, decisions, decisions.

But the SS amp that makes 0.08% at a dB below 50W clip
could make 0.08% at 1/2 a Watt if not carefully designed because of
crossover thd.

The tube amp which makes 0.08% at 50W will have
smoothly decreasing THD as output voltage is reduced, so
that at 5W, THD will be perhaps 0.03%, and at 0.5W its 0.01%,
and utterly inaudible no matter what the harmonics are.

If the amp moves from class AB to class A at the low PO level
there is ZERO crossover H generated at low levels,
because all is handled by devices in their linear regions.

Patrick Turner.

Snip more...

[Iain Churches[_2_]]

"Patrick Turner" wrote in message
...


John Byrns wrote:

In article ,
"Arny Krueger" wrote:

"Patrick Turner" wrote in message


And then there is ordinary real music from instruments.
Presumably a fair amount of IMD is included.

Wrong, because in a live performance there is very little that mixes
the
whole acoustic output of the musicians into a single signal and then
puts
that single signal through a strongly nonlinear process.

What about the ear of the listener, isn't IMD produced there that mixes
the whole acoustic output of the musicians?

But in a simple guitar, bass string tension at the bridge pulls the
bridge and other string tensions are
altered slightly, and some IMD must result.

And when one uses two or more strings, IMD is
also created.

My example of a French horn section is the best example which
one can demonstrate to students, and be heard by all.

Arny suggests there are no non-linearities in musical instruments, and
none in the air,
or caused by the room, so its only the microphone of other electronics
that can create it.

Arny should listen carefully, from a well-chosen position
from within the orchestra.

I'm not talking about huge amounts as Arny think I am either.

The amounts do not have to be large to be easily heard. Horns
seem to be the worst offenders (and so make a good example)

No use talking to Arny, one gets Kroogerated.

;:-)

Iain

[Iain Churches[_2_]]

"Andre Jute" wrote in message
ups.com...
On Nov 7, 7:34 am, "Iain Churches" wrote:

Take a look at the signal envelope of a typical pop-chart CD. In many
cases you will find severe compression and clipping. I know from
my close connections with record labels that CD returns for
technical reasons are very low indeed. I have asked the children
of friends who buy this kind of music whether or not they find this
clipping
disturbing. Usually the reply is, "it sounds good and loud in the car"

Uh-huh. I wondered if I should mention what you describe:
" levels of expectation have fallen considerably, (and with it the
standard reference by which we all make our evalöuations)" but decided
not to complicate what I wrote with qualifications (no doubt Trevor
Wilson will next accuse me of *lying*!).

Quite possibly:-))


It seems to me that somewhere
around or perhaps after 1990 there was a turning point at which
quantity replaced quality (in a strictly technical sense: the quality
of the content of of the best classical recordings, which is what I
know about, in the 80s and 90s was extraordinary). It coincided with
MP3, miniaturized personal players and so on. But there were still
audiophiles among the higheer socioeconomic groups.

Fortunately this is a problem that is extremely rare in both classical
and jazz recordings, where the brief for the mastering engineer is
now, just as it was back in the vinyl days; "Make a 1:1 of this please!

I have a number of pop CDs that were mastered in the mid 80's
and then re-mastered (awful term!) some ten years later. It is
interesting to compare them. Evaluation on a digital audio workstation
provides some tell-tale statistics. Identical peak level on both early
and later CDs - no surprise there, but the signal reached 0 FS
about 12 times more often on the later remaster.
The average level is increased by some 5dB. (!!)
The original CD has no instances of clipping, the second CD
had many hundreds per track. The dynamic of the music
hafd suffered considerably, but yes, "It sounded good and loud
in the car" This is a clear case of giving the public what they think
they want.

The killer --
where I think futureaudio-historians will point the finger -- was the
rise home cinema, which took the attention and disposable income
previously spent on music-audio and on music, and took it in precisely
the key market niche. That also accounts for why the hi-fi industry so
easily sashayed itself into the home video industry: they were dealing
with the same customers.

Yes this may well be the case, although I do know plenty of people who
still have a dedicated music room separate from the living room in
which they watch HT.

You know that joke Patrick tells against Halcro, about the time the
Hong Kong Audio Club tested one? To a lateral thinker it is instant
proof of not only this contention of mine but another more
controversial matter on which you and I also agree, that the mix of
artifacts in THD is as important as its level.

My good friend Peter Lewis, put me on to this, many years ago.
It is only fairly recently that I have access to the equipment to confirm
what he told me. When I mentioned it to the former technical
director Svetlana, he replied "I thought you would have known
about that"

Iain

[John Byrns]

In article ,
Patrick Turner wrote:


Hmm, most SET amps with 300B need to be powering horns so THD/IMD
is less than 0.2 watts and then you might get down to 0.03%.

But with ordinary speakers of 88dB/W/M, the SE amp with one little 300B
will have at least 3% at 5 watts with a highish RL, and at 0.5W average
power for such insentive speakers
the output voltage is about 1/3 that for 5 watts, and THD is 0.75%,
mainly all 2H, but
way above 0.03%, which is only realizable if you have lots more 300B in
parallel
or you have a PP pair, and powered by a balanced PP input stage to avoid
the 2H made in so many half baked designs
for PP where the 2H of the single lousy driver is way above the mainly
3H of the PP output stage THD.

If the output SE stage's 2H is cancelled by the driver stage's 2H then
its possible to very
much reduce 2H down to less than the 0.03% at up to a few watts, but
then that's only
for one value of load, as the amount of 2H changes with load on the
output tube.
Natural cancelling of 2H by *VOLTAGE* cancelation in SE amps instead of
*CURRENT* cancelations
in PP stages actually makes tube sound better, so my clients tell me.

In a generic SET amp with 300B, it is thus possible to make a triode
driver stage
which makes 0.75% of 2H at the 0.75W output level, but its also not
wise,
since at that low output level most well designed driver stages won't
make that much 2H to cancel anything much. A driver stage naking such a
lot of 2H will struggle
at higher levels, and maybe clip earlier than the output stage.
IMD produced in the driver get passed on and muddy the output spectra.

Why not build a blameless driver stage, and then create the desired 2H
to cancel the output stage 2H by using a pre-distorter network? A
single vacuum diode like half of a 6AL5 and a couple of resistors could
be used to create a pre-distorter that would cancel all the 2H at full
output, as well as at one lower level, without greatly increasing 2H at
the lowest levels. I haven't done the math, but I assume the downside
of this scheme is that it probably increases the amount of odd harmonics
present at higher levels. A simple pre-distorter that wouldn't create
additional odd harmonics could be built, but it would only cancel 2H at
one output level and would increase the 2H at lower levels, although
maybe that would be a feature, creating a euphonious sound. I suppose
the ultimate would be a more complex pre-distorter, probably silicon
based, that would exactly complement the transfer function of the output
stage, eliminating all distortion below clipping, at least into a fixed
resistive load.

Hence my solution is to use local CFB from the OPT around
tetrodes/pentodes, and reduce max
output stage THD to say 2% at 20 watts, abd then the driver stage when
loaded with an RL 10Ra
will never struggle or muddy up the sound, and what little 2H it makes
willo
nicely cancel the output stage 2H....and presumably most other even
order products.
The result is beautiful un-muddied SE sound, and because the amps I make
have
over 20 watt capability, there is enough headroom for most ppl
and perhaps 1/10 of the THD/IMD as one may hear with a lone 300B with
average power at 1W.

The odd order junk isn't thus cancelled, but will be a vile residue.
But its at such a low level below what would otherwise be a large 2H
amount, it matter not,
even if you weighted the audibility acording to the Nsquared/4 rule.

So in fact in my amps I *actually do achieve* your quoted 0.03%, but
nobody else seems to.
Most SET amps I have to rewire or teach how to sing and how to behave
are travesties of engineering
because the makers fail so dismally with basic loadings on tubes, and
thd and noise is way above what is
possible.

Because all amps I make have wide bad OPTs giving over 50khz of
bandwidth WITHOUT dependance on global NFB,
when I do apply a bit of NFB, say 9dB, to ensure Rout of the amp is at
least 1/5 of RL,
and preferably 1/10 RL, then the THD and IMD is further reduced and the
net residual artifacts no matter what they
are would be much lower level and far less unpleasant if sent to the
speakers without the music signal present
compared to the rubbish and junk which exists in an average low power
SET amp signal if played a little too loud
and without distortion cancelling schemes either bt way of clever driver
or PP design, and
without loop NFB.

Couldn't you easily meet your 1/5 of RL goal for Rout with only CFB and
a moderately efficient OPT, without resorting to global NFB? I would
think you might even be able to meet 1/10 of RL with an aggressive OPT
design and perhaps a touch more CFB.


Regards,


John Byrns

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

[Iain Churches[_2_]]

"Patrick Turner" wrote in message
...

Well here I have to agree that sonic differences in preamp tubes can be
heard.
Even when THD and IMD measures below 0.01%, a typical value where
you have a line stage preamp with volume pot before a generic gain stage
using a 6CG7.

I have, with 4 other guys spent an afternoon tube rolling with 6CG7
samples.
We agreed the NOS Seimans were best, then made in Oz Miniwatts, then
Mullard, and
then very much last were recent Sovtek versions.

Nice to find that (unlike Arny) others also take
the trouble to listen, and evaluate. RCA cleartop came
at the top of our list then Siemens and Westnghouse
close behind.

A while ago, I built a push pull parallel EL34 amp, with
two parallel pairs per channel. It can achieve 0.08% THD
at full power.

I don't know whether to laugh or cry.

Ah well, decisions, decisions.

To build something better in tubes would be a good project
for Arny. It would also keep him away from RAT for a
*very* long time :-))

The tube amp which makes 0.08% at 50W will have
smoothly decreasing THD as output voltage is reduced, so
that at 5W, THD will be perhaps 0.03%, and at 0.5W its 0.01%,
and utterly inaudible no matter what the harmonics are.

Indeed.

Iain

[Iain Churches[_2_]]

"Arny Krueger" wrote in message
. ..

Iain wrote:
Some years ago, the technical director of Svetlana sent
me the findings of a listening group with whom he had been working. Their
task was to evaluate 6CG7 tubes by different
makers, and put them in order of preference, so that they
could be measured and analysed. Although I was not able to obtain all
twelve makes on the list, with
some colleagues, I repeated the experiment.The differences
were most interesting. The interpretation of which is
"better" must be left to individual taste, but in general
terms, we ranked the tubes in roughly the same order as the Svetlana
listeners. In case you are wondering, the
RCA cleartop was the best sounding. It also had the lowest odd order
harmonics when measured in a mu follower circuit.

Yet another anecdote with questionable relevance.

Have you made the comparison, Arny?



I have been involved in experiments on which panels of
listeners have been asked to differentiate between two identical
amplifiers, one set up to have 0.05% and the other 0.5%
THD. This is a difference of 20dB. No one, even the professionals on the
panel, could tell
which was which.

Probably not a well-run test.

Orhanised by a broadcast studio (EBU)
Participants were recording professionals and musicians.
A better-run test is hard to imagine.


Tests like this are strongly depenendent on the choice of program
material. Most audiophile self-select program material that sounds good on
their home systems.

There were no "audiophiles" present.

If the person doing the selecting has a system at home with relatively
high nonlinear distortion, he's going to pick recordings that are tolerant
of relatively high nonlinear distortion. So, they unconsciously
desensitize the experiment because of their preferences.

A shortlist of material was drawn up several weeks before the listening
sessions. There were some ten titles in all, ranging from Baroque to
voice and piano. All were chosen as clean sources. No rock'n'roll:-)

It is a long time since I have read the book, but IIRC
Olson states that listeners could not detect distortion
levels up to 1% on a music signal.

Again, that depends on context. How many CDs had Olson listened to by the
time he made that claim?

Do you have evidence that Olson's statement is incorrect?


A while ago, I built a push pull parallel EL34 amp, with
two parallel pairs per channel. It can achieve 0.08% THD
at full power.

http://www.kolumbus.fi/iain.churches...em/C50_002.jpg

I don't know whether to laugh or cry.

Don't do either. Just post a pic of your tube amplifiers.

Iain

[Patrick Turner]

John Byrns wrote:

In article ,
Patrick Turner wrote:


Hmm, most SET amps with 300B need to be powering horns so THD/IMD
is less than 0.2 watts and then you might get down to 0.03%.

But with ordinary speakers of 88dB/W/M, the SE amp with one little 300B
will have at least 3% at 5 watts with a highish RL, and at 0.5W average
power for such insentive speakers
the output voltage is about 1/3 that for 5 watts, and THD is 0.75%,
mainly all 2H, but
way above 0.03%, which is only realizable if you have lots more 300B in
parallel
or you have a PP pair, and powered by a balanced PP input stage to avoid
the 2H made in so many half baked designs
for PP where the 2H of the single lousy driver is way above the mainly
3H of the PP output stage THD.

If the output SE stage's 2H is cancelled by the driver stage's 2H then
its possible to very
much reduce 2H down to less than the 0.03% at up to a few watts, but
then that's only
for one value of load, as the amount of 2H changes with load on the
output tube.
Natural cancelling of 2H by *VOLTAGE* cancelation in SE amps instead of
*CURRENT* cancelations
in PP stages actually makes tube sound better, so my clients tell me.

In a generic SET amp with 300B, it is thus possible to make a triode
driver stage
which makes 0.75% of 2H at the 0.75W output level, but its also not
wise,
since at that low output level most well designed driver stages won't
make that much 2H to cancel anything much. A driver stage naking such a
lot of 2H will struggle
at higher levels, and maybe clip earlier than the output stage.
IMD produced in the driver get passed on and muddy the output spectra.

Why not build a blameless driver stage, and then create the desired 2H
to cancel the output stage 2H by using a pre-distorter network? A
single vacuum diode like half of a 6AL5 and a couple of resistors could
be used to create a pre-distorter that would cancel all the 2H at full
output, as well as at one lower level, without greatly increasing 2H at
the lowest levels. I haven't done the math, but I assume the downside
of this scheme is that it probably increases the amount of odd harmonics
present at higher levels. A simple pre-distorter that wouldn't create
additional odd harmonics could be built, but it would only cancel 2H at
one output level and would increase the 2H at lower levels, although
maybe that would be a feature, creating a euphonious sound. I suppose
the ultimate would be a more complex pre-distorter, probably silicon
based, that would exactly complement the transfer function of the output
stage, eliminating all distortion below clipping, at least into a fixed
resistive load.

Any deliberate attempt to create distortion with diodes is doomed to
failure IMHO.
and perhaps if you tried what you said you'd see what a dismal rewsult
you'd get.

My idea is to linearize the output pentode or tetrode with local CFB
from the OPT
so that its THD at the wanted nominal load for max power, ie, 0.9 x
Ea/Ia reduces to about between 1% to 2%.
The Ra will also fall to less than the Ra if the tube were triode
connected.

Final gain is thus usually less than triode.

THEN one concentrates on a driver triode with resistance load which is
say 10 x Ra
and arranged so it is as linear as can be naturally expected with RL =
10Ra.
So with EL34, and with 125Vrms output with 22k RL due to dc carrying RL
and ac coupled
bias R, the driver THD will cancel the output tube THD because both
produce around say 1.5%
and hence the cancelation of even order products.
At ALL levels of output, the THD cancells well if this regime is
followed.

At low levels, order is very low, and typically the the THD at 5 watts
in an SE pentode amp made for 35 watts at clip
is similar to low levels found in PP amps. And we have not applied any
global NFB.



Hence my solution is to use local CFB from the OPT around
tetrodes/pentodes, and reduce max
output stage THD to say 2% at 20 watts, abd then the driver stage when
loaded with an RL 10Ra
will never struggle or muddy up the sound, and what little 2H it makes
willo
nicely cancel the output stage 2H....and presumably most other even
order products.
The result is beautiful un-muddied SE sound, and because the amps I make
have
over 20 watt capability, there is enough headroom for most ppl
and perhaps 1/10 of the THD/IMD as one may hear with a lone 300B with
average power at 1W.

The odd order junk isn't thus cancelled, but will be a vile residue.
But its at such a low level below what would otherwise be a large 2H
amount, it matter not,
even if you weighted the audibility acording to the Nsquared/4 rule.

So in fact in my amps I *actually do achieve* your quoted 0.03%, but
nobody else seems to.
Most SET amps I have to rewire or teach how to sing and how to behave
are travesties of engineering
because the makers fail so dismally with basic loadings on tubes, and
thd and noise is way above what is
possible.

Because all amps I make have wide bad OPTs giving over 50khz of
bandwidth WITHOUT dependance on global NFB,
when I do apply a bit of NFB, say 9dB, to ensure Rout of the amp is at
least 1/5 of RL,
and preferably 1/10 RL, then the THD and IMD is further reduced and the
net residual artifacts no matter what they
are would be much lower level and far less unpleasant if sent to the
speakers without the music signal present
compared to the rubbish and junk which exists in an average low power
SET amp signal if played a little too loud
and without distortion cancelling schemes either bt way of clever driver
or PP design, and
without loop NFB.

Couldn't you easily meet your 1/5 of RL goal for Rout with only CFB and
a moderately efficient OPT, without resorting to global NFB? I would
think you might even be able to meet 1/10 of RL with an aggressive OPT
design and perhaps a touch more CFB.

The 13E1 with 33% of its primary devoted to a cathode winding
with an OPT for 2.7k:5 ohms has Rout = 0.7 ohms without GNFB.
The 9dB of the GNF reduces all THD and further flattens response and
reduces
Rout to 0.26ohms, which is a DF = 19 approx.

There was no choice for the amount of CFB in the case of my 13E1 amps.
1/3 or one entire P section between two of the four S sections is
devoted to CFB so that
all the winding is at 0V potential. The other 2 anode sections are at
+510V.

But in the SE35cfb amps seen at my website the amount of CFB is much
less
and the result witha quad of 6CA7 is very nice if you read the page.
http://www.turneraudio.com.au/se35cfbmonobloc.html

In my PP 8585 amps, CFB = 12.5% of P windings, and now in my 300W amps
its 20%.

I am designing a 13E1 PP amp for a colleage to build for a client with
Quad 2805 ESL.

Power will be 100W class AB1 into 5k, about 16.6% CFB, Ea = 550V, Eg2 =
200V approx, Ia per tube = 100mA,
and class A content = 25 watts.

OPT is a 62mm stack 51 tongue GOSS, and losses less than 5%, BW 100k
without NFB, ,Fsat at 16Hz, full power.

We think this will be a masterpiece amplifier.

My colleague isn't so hot with calculations, but does a great job on
chassis, finish,
and general construction, and I design all his OPT, and I get to know
how they all work.

Its possible to get maybe 200W class AB from a pair of 13E1.
But these will be limited to making about 150W with 4 ohms connected to
the
8 ohm outlet match. But class A content is low, and distortions are
higher.

With the right load of 8 ohms, there is 100W AB with 25W of class A,
and if the 8 ohms is connected to the 3.6 ohm OPT config, you get 50W+
of pure class A,
because Pda total at idle with two tubes is 110W. With each at 55W Pda,
they should last very well
and never thermal out, because the anodes won't glow red until Pda = a
continuous 85W.

The performance is similar to a six pack of EL34, or a quad of KT90.

Its not wise to run such tubes in ordinary UL because the screen voltage
should be well below the
anode supply voltage for the 13E1.

One could have Ea = 800V, Eg2 at +150V only, and RL about 6ka-a, and get
some serious PO,
like when one uses 800V for KT88, and get 140W. TT21 is better in this
role
because then the top cap anode connection allows the HV, and the screen
voltage for such
tubes is happy being only 300V to 400V, OK in an octal socket.
13E1 has a socket unlikely to arc with HV.

Such amps usually sound very well.

Using 6 x EL84 in parallel PP like Baird amps will give 60W AB, and a
nice 30W in pure class A.
Because the anode to cathode voltage isn't much more than 210Vrms,
one may simply use a circlotron design or McIntosh, so 105Vrms is at
anode and cathode,
and grid drive is maybe 115Vrms, and and as long as the drive voltage is
not distorted,
Rout is very low.
6 x EL84 in SE parallel pentode will give 30 watts in pure class A.
Pda = 72 watts, like a single 13E1, and gm = 60mA/V total which is more
than twice 13E1.

The first amp I made which sounded really well with some sensitive
speakers was EL84
in SE pentode mode with about 10% CFB, because the gm and µ of this tube
is so high, you don't need much CFB to perform wonders with distortion,
and it sings. Grand piano sounded fabulous.

Patrick Turner.











Regards,

John Byrns

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

[John Byrns]

In article ,
Patrick Turner wrote:

John Byrns wrote:

In article ,
Patrick Turner wrote:

[Snip]

In a generic SET amp with 300B, it is thus possible to make a triode
driver stage
which makes 0.75% of 2H at the 0.75W output level, but its also not
wise,
since at that low output level most well designed driver stages won't
make that much 2H to cancel anything much. A driver stage naking such a
lot of 2H will struggle
at higher levels, and maybe clip earlier than the output stage.
IMD produced in the driver get passed on and muddy the output spectra.

Why not build a blameless driver stage, and then create the desired 2H
to cancel the output stage 2H by using a pre-distorter network? A
single vacuum diode like half of a 6AL5 and a couple of resistors could
be used to create a pre-distorter that would cancel all the 2H at full
output, as well as at one lower level, without greatly increasing 2H at
the lowest levels. I haven't done the math, but I assume the downside
of this scheme is that it probably increases the amount of odd harmonics
present at higher levels. A simple pre-distorter that wouldn't create
additional odd harmonics could be built, but it would only cancel 2H at
one output level and would increase the 2H at lower levels, although
maybe that would be a feature, creating a euphonious sound. I suppose
the ultimate would be a more complex pre-distorter, probably silicon
based, that would exactly complement the transfer function of the output
stage, eliminating all distortion below clipping, at least into a fixed
resistive load.

Any deliberate attempt to create distortion with diodes is doomed to
failure IMHO.
and perhaps if you tried what you said you'd see what a dismal rewsult
you'd get.

Exactly, I am no fan of such a scheme, which is better reserved for
Television transmitters and the like, my point was to parody the notion
of using driver stage distortion to cancel output stage distortion. I
fail to see a substantive difference between the two schemes, they both
seem like bad ideas to me.

In your third paragraph below you seem to endorse the notion of using
driver stage distortion to cancel output stage distortion, can you
explain why you think this scheme is any better than the "diode" idea?
What criteria would you use to compare the performance of the two
schemes? One problem with both ideas is that the impedance of real life
loudspeakers varies with frequency, which causes the output stage
distortion to vary with frequency whereas the driver stage distortion
doesn't vary with audio frequency, hence you may get good cancellation
at one frequency, but not at others.

Personally I would focus on making the distortion of the separate stages
as low as possible individually, as you describe in the following
paragraph, before you go off the rails and opt for including a
distortion cancellation scheme.

My idea is to linearize the output pentode or tetrode with local CFB
from the OPT
so that its THD at the wanted nominal load for max power, ie, 0.9 x
Ea/Ia reduces to about between 1% to 2%.
The Ra will also fall to less than the Ra if the tube were triode
connected.

Final gain is thus usually less than triode.

THEN one concentrates on a driver triode with resistance load which is
say 10 x Ra
and arranged so it is as linear as can be naturally expected with RL =
10Ra.
So with EL34, and with 125Vrms output with 22k RL due to dc carrying RL
and ac coupled
bias R, the driver THD will cancel the output tube THD because both
produce around say 1.5%
and hence the cancelation of even order products.
At ALL levels of output, the THD cancells well if this regime is
followed.

At low levels, order is very low, and typically the the THD at 5 watts
in an SE pentode amp made for 35 watts at clip
is similar to low levels found in PP amps. And we have not applied any
global NFB.



Hence my solution is to use local CFB from the OPT around
tetrodes/pentodes, and reduce max
output stage THD to say 2% at 20 watts, abd then the driver stage when
loaded with an RL 10Ra
will never struggle or muddy up the sound, and what little 2H it makes
willo
nicely cancel the output stage 2H....and presumably most other even
order products.
The result is beautiful un-muddied SE sound, and because the amps I make
have
over 20 watt capability, there is enough headroom for most ppl
and perhaps 1/10 of the THD/IMD as one may hear with a lone 300B with
average power at 1W.

The odd order junk isn't thus cancelled, but will be a vile residue.
But its at such a low level below what would otherwise be a large 2H
amount, it matter not,
even if you weighted the audibility acording to the Nsquared/4 rule.

So in fact in my amps I *actually do achieve* your quoted 0.03%, but
nobody else seems to.
Most SET amps I have to rewire or teach how to sing and how to behave
are travesties of engineering
because the makers fail so dismally with basic loadings on tubes, and
thd and noise is way above what is
possible.

Because all amps I make have wide bad OPTs giving over 50khz of
bandwidth WITHOUT dependance on global NFB,
when I do apply a bit of NFB, say 9dB, to ensure Rout of the amp is at
least 1/5 of RL,
and preferably 1/10 RL, then the THD and IMD is further reduced and the
net residual artifacts no matter what they
are would be much lower level and far less unpleasant if sent to the
speakers without the music signal present
compared to the rubbish and junk which exists in an average low power
SET amp signal if played a little too loud
and without distortion cancelling schemes either bt way of clever driver
or PP design, and
without loop NFB.

Couldn't you easily meet your 1/5 of RL goal for Rout with only CFB and
a moderately efficient OPT, without resorting to global NFB? I would
think you might even be able to meet 1/10 of RL with an aggressive OPT
design and perhaps a touch more CFB.

The 13E1 with 33% of its primary devoted to a cathode winding
with an OPT for 2.7k:5 ohms has Rout = 0.7 ohms without GNFB.

So the answer appears to be yes, with a well designed output
transformer, CFB alone will meet the 1/5 of RL goal for Rout, giving a
DF greater than 7 without the need to apply overall loop feedback.


Regards,

John Byrns

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

[Patrick Turner]

John Byrns wrote:

In article ,
Patrick Turner wrote:

John Byrns wrote:

In article ,
Patrick Turner wrote:

[Snip]

In a generic SET amp with 300B, it is thus possible to make a triode
driver stage
which makes 0.75% of 2H at the 0.75W output level, but its also not
wise,
since at that low output level most well designed driver stages won't
make that much 2H to cancel anything much. A driver stage naking such a
lot of 2H will struggle
at higher levels, and maybe clip earlier than the output stage.
IMD produced in the driver get passed on and muddy the output spectra.

Why not build a blameless driver stage, and then create the desired 2H
to cancel the output stage 2H by using a pre-distorter network? A
single vacuum diode like half of a 6AL5 and a couple of resistors could
be used to create a pre-distorter that would cancel all the 2H at full
output, as well as at one lower level, without greatly increasing 2H at
the lowest levels. I haven't done the math, but I assume the downside
of this scheme is that it probably increases the amount of odd harmonics
present at higher levels. A simple pre-distorter that wouldn't create
additional odd harmonics could be built, but it would only cancel 2H at
one output level and would increase the 2H at lower levels, although
maybe that would be a feature, creating a euphonious sound. I suppose
the ultimate would be a more complex pre-distorter, probably silicon
based, that would exactly complement the transfer function of the output
stage, eliminating all distortion below clipping, at least into a fixed
resistive load.

Any deliberate attempt to create distortion with diodes is doomed to
failure IMHO.
and perhaps if you tried what you said you'd see what a dismal rewsult
you'd get.

Exactly, I am no fan of such a scheme, which is better reserved for
Television transmitters and the like, my point was to parody the notion
of using driver stage distortion to cancel output stage distortion. I
fail to see a substantive difference between the two schemes, they both
seem like bad ideas to me.

In your third paragraph below you seem to endorse the notion of using
driver stage distortion to cancel output stage distortion, can you
explain why you think this scheme is any better than the "diode" idea?

One CANNOT escape from using distortion cancelling between any two
consecutive
triode casaded amplifier stages.

The use of diodes and deliberate distortion creation in the driving
triode to match the higher
distortion of the following triode ( or pentode/beam tube) is not a good
idea, because
the IMD isn't cancelled, and nor is the inevitable small amount of odd
order crap
accompanying the even order crap.



What criteria would you use to compare the performance of the two
schemes? One problem with both ideas is that the impedance of real life
loudspeakers varies with frequency, which causes the output stage
distortion to vary with frequency whereas the driver stage distortion
doesn't vary with audio frequency, hence you may get good cancellation
at one frequency, but not at others.


Indeed I have pointed out in numerous postings that the load affects the
spectra of
a beam or pentode tube. At low RL, even order 2H, 4H is high and like
triode, but
this falls to zero at some critical load value, then rises again but
with an opposite phase to triode.

But as load rises, the gain also rises, since beam and pentode tubes
have gain = gm x RL approx.
Without any NFB, and with very high RL the pentode&beam tube gain
becomes very high, approaching µ, or gm x Ra.
And the distortion is utterly horrendous.
If you have CFB from the OPT, applied series voltage NFB becomes greater
as load increases and the gain increases,
so the increasing distortion with high RL is reduced.

Where you have a beam or pentode tube connected in UL, the NFB is
applied to the tube via the screen.

But THD in any SEUL with a UL % tap to give neam beam power but a
triode's spectra will
just about always give 5% THD, mainly 2H at clipping.

Where you have a driving triode its impossible to cancel this THD
because the driving triode's THD
is always well under 5% at the grid driving voltage needed for the UL or
triode output tube.
It surely is with a pentode or beam tube, which need only a low voltage
drive.

So there are at least three fundemental approaches to reduce
distortions.

One is to apply NFB from anode of the output tube to cathode of driver
tube.
This always has limitations, and the R needed to transfer enough current
to driver tube Rk
unecessarily loads the output tube.
Its difficult to get a sufficiently effective amount of NFB.

Two is to have a pentode drive tube, and arrange the circuit for shunt
NFB where
the Ra of the driver is the first arm of the R+R shunt NFB network. See
my website for balanced shunt NFB in a power amp, see my schematics
pages.
or read RDH4 on this.

Three is to use regular series voltage NFB applied from the low Z
secondary of OPT back to an input
tube cathode circuit.

All these schemes involve feeding back a large fraction of output
voltage to an input
and generating a fair sized error signal which gives rise to a lot of
second order
IMD products unless large amount of NFB is used.


Four is to have CFB applied from the OPT to output tube cathode and then
have minimal
GNFB.

This way the CFB reduces the THD of the output tube without applying the
distortion around at least a two tube
network.

The result is that you get a beam or pentode tube where the THD at any
load of level up to clip
is limited to under about 2%, yet the closed loop gain is about equal to
a low µ triode,
and Rout is even lower than the triode.

Now the biggest problem with driving speakers is where the Z falls to
below
the rated nominal value, often in the critical band between bass and
midrange
where often the crossover filters pass wasted current in second order CL
and LC networks
at the Xover F.

Where Z is low, the pentode/beam tube produces its highest and worst
distortion.

Fortunately, this very distortion at lowish load values is what we wish
to cancel simply by having a
triode driver stage set up for linear operation, ie, say making 2%
mainly 2H when the amplifier clips.
Its a doddle to therefore get nearly all the 2H to cancel with a 5 ohm
load,
and THD will measure very low.

There is a very useful range of cancelling between 3 and 6 ohms
available if you want it.

The THD will be far lower at all levels for these load values compared
to a triode or UL stage,
or other straight pentode or beam tube with other types of NFB loops
other than the local CFB.

The odd numbered H are insignificant.



Personally I would focus on making the distortion of the separate stages
as low as possible individually, as you describe in the following
paragraph, before you go off the rails and opt for including a
distortion cancellation scheme.

I have pointed out for the umpteenth time that it IS IMPORTANT to
linearize
ALL stages where possible without GNFB applied.

But I have outlined above that UL, triode is prone to 5% at clipping,
and beam/pentode is prone to far greater THD and complex spectra.
See RDH4 for more info on comparisons between beam&pentodes and triodes.

The CFB I am using linearizes the output tube very nicely
so that the unavoidable distortions of the stage are less than 2%,
and the unavoidable 2% from most driver triodes WILL NATURALLY CANCEL
the distortions of the output tube without any "artificial circuitry"
to make sure sufficient 2H is made in a driver stage to cancel that in
an outpuit stage.

There is a catch in tis natural order of things.

The 2H of a drive triode will cancel the 2H of an outut beam or pentode
tube
with a low RL, but not when RL becomes high, and in fact the triode
driver
tube 2H becomes additive to the output tube 2H when the output tube is
loaded
with a high RL, because of the phase reversal of 2H that occurs
above the critical load value which produces zero 2H. But the critical
RL
is a high RL anyway, above the nominal load value for maximum power.
The additive effects of 2H at high values of RL will still give a THD
result which is no worse than a UL or triode stage.



My idea is to linearize the output pentode or tetrode with local CFB
from the OPT
so that its THD at the wanted nominal load for max power, ie, 0.9 x
Ea/Ia reduces to about between 1% to 2%.
The Ra will also fall to less than the Ra if the tube were triode
connected.

Final gain is thus usually less than triode.

THEN one concentrates on a driver triode with resistance load which is
say 10 x Ra
and arranged so it is as linear as can be naturally expected with RL =
10Ra.
So with EL34, and with 125Vrms output with 22k RL due to dc carrying RL
and ac coupled
bias R, the driver THD will cancel the output tube THD because both
produce around say 1.5%
and hence the cancelation of even order products.
At ALL levels of output, the THD cancells well if this regime is
followed.

At low levels, order is very low, and typically the the THD at 5 watts
in an SE pentode amp made for 35 watts at clip
is similar to low levels found in PP amps. And we have not applied any
global NFB.



Hence my solution is to use local CFB from the OPT around
tetrodes/pentodes, and reduce max
output stage THD to say 2% at 20 watts, abd then the driver stage when
loaded with an RL 10Ra
will never struggle or muddy up the sound, and what little 2H it makes
willo
nicely cancel the output stage 2H....and presumably most other even
order products.
The result is beautiful un-muddied SE sound, and because the amps I make
have
over 20 watt capability, there is enough headroom for most ppl
and perhaps 1/10 of the THD/IMD as one may hear with a lone 300B with
average power at 1W.

The odd order junk isn't thus cancelled, but will be a vile residue.
But its at such a low level below what would otherwise be a large 2H
amount, it matter not,
even if you weighted the audibility acording to the Nsquared/4 rule.

So in fact in my amps I *actually do achieve* your quoted 0.03%, but
nobody else seems to.
Most SET amps I have to rewire or teach how to sing and how to behave
are travesties of engineering
because the makers fail so dismally with basic loadings on tubes, and
thd and noise is way above what is
possible.

Because all amps I make have wide bad OPTs giving over 50khz of
bandwidth WITHOUT dependance on global NFB,
when I do apply a bit of NFB, say 9dB, to ensure Rout of the amp is at
least 1/5 of RL,
and preferably 1/10 RL, then the THD and IMD is further reduced and the
net residual artifacts no matter what they
are would be much lower level and far less unpleasant if sent to the
speakers without the music signal present
compared to the rubbish and junk which exists in an average low power
SET amp signal if played a little too loud
and without distortion cancelling schemes either bt way of clever driver
or PP design, and
without loop NFB.

Couldn't you easily meet your 1/5 of RL goal for Rout with only CFB and
a moderately efficient OPT, without resorting to global NFB? I would
think you might even be able to meet 1/10 of RL with an aggressive OPT
design and perhaps a touch more CFB.

The 13E1 with 33% of its primary devoted to a cathode winding
with an OPT for 2.7k:5 ohms has Rout = 0.7 ohms without GNFB.

So the answer appears to be yes, with a well designed output
transformer, CFB alone will meet the 1/5 of RL goal for Rout, giving a
DF greater than 7 without the need to apply overall loop feedback.

One does not need to have GNFB with a pentode output tube
and the final Rout at the OPT sec can be much lower than a triode.


The working of the beam or pentode with CFB and screen bypassed to
cathode needs to be mentioned.
In effct, this case is one of real beam/pentode operation with one loop
of pure series voltage NFB.

Say distortion voltage at cathode = +Vd, and pentode open loop gain =
-30.
( gain is negative, because of the inverting of phase between grid and
anode ).

Then in effect, -Vd is being applied to the grid, and appears as -Vd x
-30 at between anode and cathode
so +20Vd error correction signal exists at anode, and -10Vd at cathode.
This opposes the natural open loop THD of -21Vd and +11Vd at cathode
that would exist
if there was no NFB.

The +Vd appearing at cathode with CFB is also applied to the screen
directly via the bypass cap
and is a loop of positive feedback according to the screen gain, approx
screen gm x RL,
and much lower than control grid gain.

Where the screen is bypassed to ground at ac, the cathode signal +Vd
appears at the screen effectively
as -Vd, and becomes a NFB causing applied voltage.

One must take care that at no part of the wave cycle does the cathode
voltage rise above the
static Vdc of a screen bypassed to ground, or else the tube cuts off.


In my case with SE 13E1 CFB, the 33% CFB winding has a CT, which is
16.5% of the primary.
Bypassing the screen to 0V gave cut off behaviour. But with screen
bypassed to the
16.5% CT of cathode winding there is effectively SOME NFB applied in the
screen circuit
which gives better spectra than with bypassing screen to cathode for
maximal positive FB.

One might be tempted to have equal anode and cathode windings
as I have mentioned in another post re using EL84 where Va and Vk would
be quite low,
and hence Vg would be easy to arrange.
Just how and where one bypasses the screen and at what Vdc you run the
screen at becomes a
critically important issue.

Most folks find all this a pile of BS and all too hard to ever get
right,
and simply settle for triode or plain old UL.

But I know what I'm doing, and my customers hear that the CFB sounds
better.

Patrick Turner.







Regards,

John Byrns

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

[Arny Krueger]

"Iain Churches" wrote in message
i.fi
"John Byrns" wrote in message
...
In article
, "Arny
Krueger" wrote:
"Patrick Turner" wrote in
message

And then there is ordinary real music from instruments.
Presumably a fair amount of IMD is included.

Wrong, because in a live performance there is very
little that mixes the whole acoustic output of the
musicians into a single signal and then puts that
single signal through a strongly nonlinear process.

What about the ear of the listener, isn't IMD produced
there that mixes the whole acoustic output of the
musicians?

Yes indeed. I have experienced this many times. It is not
audible from the audience seats. See my reply to Arny.

Au contraire. If you're talking about the nonlinearity of the human ear
above about 85 dB SPL, its audible everywhere. You just have to know how to
make it audible.

[Arny Krueger]

"Patrick Turner" wrote in message

John Byrns wrote:

In article
, "Arny
Krueger" wrote:

"Patrick Turner" wrote in
message

And then there is ordinary real music from instruments.
Presumably a fair amount of IMD is included.

Wrong, because in a live performance there is very
little that mixes the whole acoustic output of the
musicians into a single signal and then puts that
single signal through a strongly nonlinear process.

What about the ear of the listener, isn't IMD produced
there that mixes the whole acoustic output of the
musicians?

At reasonable listening levels normal ears are reasonably nonlinear. To wit,
we are indeed able to hear the effects of as little as 0.1% nonlinearity.

Indeed ears create artifacts, and as we age the dynamic
range of ears to cope with wide dynamic range is
seriously reduced.

Agreed, but normal ears aren't strongly nonlinear at normal listening
levels.

But in a simple guitar, bass string tension at the bridge
pulls the bridge and other string tensions are
altered slightly, and some IMD must result.

I'm getting impatient who seem to need a Doctoral thesis written on the
meaning of "strongly nonlinear" in order that they not confuse it with "a
little bit nonlinear".

I don't know how linear the stop start air flow in organ
pipes or trumpets might be,
or in bows on violins, but surely they ain't perfectly
linear,
and some IMD products are produced.

The word some admits any finite artifact. We would probably interpret it
today as being any measurable artifact. Given that we can easily measure
nonlinearities below 0.001 %...

Arny suggests there are no non-linearities in musical
instruments, and none in the air,
or caused by the room, so its only the microphone of
other electronics that can create it.

Arny seriously hoped that people could distinguish between "strongly
onlinear" and "less than 0.001%".

I'm not talking about huge amounts as Arny think I am
either.

No use talking to Arny, one gets Kroogerated.

I'm getting my stomach Turnered.

[Arny Krueger]

"Iain Churches" wrote in message
.fi
"Arny Krueger" wrote in message
. ..


John wrote:
And then there is ordinary real music from instruments.
Presumably a fair amount of IMD is included.

Wrong, because in a live performance there is very
little that mixes the whole acoustic output of the
musicians into a single signal and then puts that single
signal through a strongly nonlinear process.

Arny, Try this experiment. Sit amongst an orchestra
during rehearsals or recording. Place your chair at the
back and to the right of the French horn section, where
the microphone would be on a multi-mic setup. Four horns
are good, five horns are better. Sibelius 5, Op 82 Eb is
a perfect example.
Then tell me there is no acoustic IMD.

Cordially,

Iain, as soon as you start signing your little tirades with something that
fits like: "With utter disrespect for common sense", I might consider
responding to them. ;-)

[Arny Krueger]

"Andre Jute" wrote in message
ups.com
On Nov 8, 3:23 pm, "Arny Krueger"
wrote:
"Iain Churches" wrote in message

i.fi

"Andre Jute" wrote in message
ups.com...
Dave wrote:

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

The explanation is simple. Loop NFB causes artifacts
of ever lower magnitude but higher order.

Good example of majoring in the minors. Loop NFB drops
nonlinearity by 20 dB or more. The equipment in question
was not entirely free of higher order nonliner
distortion, and the secondary effect being obsessed over
here typically adds far less distortion than was already
there.OTOH, the loop feedback drops all nonlinear
distortion by 20 dB. The net higher order distortion is
thus dramatically reduced.

We're not talking about the net number, Krueger. We're
talking about the effect of the composition of the
residual distortion.

Well that's *your* problem, Andre.

The net number matters, because its the difference between 10% ("Strongly
nonlinear') and 0.001%.

[Arny Krueger]

"Iain Churches" wrote in message
.fi
"Patrick Turner" wrote in
message ...

Well here I have to agree that sonic differences in
preamp tubes can be heard.
Even when THD and IMD measures below 0.01%, a typical
value where you have a line stage preamp with volume pot before a
generic gain stage using a 6CG7.

I have, with 4 other guys spent an afternoon tube
rolling with 6CG7 samples.
We agreed the NOS Seimans were best, then made in Oz
Miniwatts, then Mullard, and
then very much last were recent Sovtek versions.

Sighted evaluation. :-(

Nice to find that (unlike Arny) others also take
the trouble to listen, and evaluate.

Libel.

To build something better in tubes would be a good project
for Arny. It would also keep him away from RAT for a
*very* long time :-))

I don't even have time to build SS amps - I just buy them.

The tube amp which makes 0.08% at 50W will have
smoothly decreasing THD as output voltage is reduced, so
that at 5W, THD will be perhaps 0.03%, and at 0.5W its
0.01%, and utterly inaudible no matter what the harmonics are.

Indeed.

Any half-ways decent SS amp will have 0.05% at any power level that is a
dB below clipping.

Crossover distortion hasn't been a problem with good SS amps for at least 35
years - its just a red herring that people who circulate old wive's tales
like to trot out to scale small boys.

[Iain Churches[_2_]]

"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
.fi
"Arny Krueger" wrote in message
. ..


John wrote:
And then there is ordinary real music from instruments.
Presumably a fair amount of IMD is included.

Wrong, because in a live performance there is very
little that mixes the whole acoustic output of the
musicians into a single signal and then puts that single
signal through a strongly nonlinear process.

Arny, Try this experiment. Sit amongst an orchestra
during rehearsals or recording. Place your chair at the
back and to the right of the French horn section, where
the microphone would be on a multi-mic setup. Four horns
are good, five horns are better. Sibelius 5, Op 82 Eb is
a perfect example.
Then tell me there is no acoustic IMD.

Cordially,

Iain, as soon as you start signing your little tirades with something that
fits like: "With utter disrespect for common sense", I might consider
responding to them. ;-)

I repeat my request for you to do the experiment.
Iain

[Arny Krueger]

"Iain Churches" wrote in message
ti.fi
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
.fi
"Arny Krueger" wrote in message
. ..


John wrote:
And then there is ordinary real music from
instruments. Presumably a fair amount of IMD is
included.

Wrong, because in a live performance there is very
little that mixes the whole acoustic output of the
musicians into a single signal and then puts that
single signal through a strongly nonlinear process.

Arny, Try this experiment. Sit amongst an orchestra
during rehearsals or recording. Place your chair at the
back and to the right of the French horn section, where
the microphone would be on a multi-mic setup. Four
horns are good, five horns are better. Sibelius 5, Op
82 Eb is a perfect example.
Then tell me there is no acoustic IMD.

Cordially,

Iain, as soon as you start signing your little tirades
with something that fits like: "With utter disrespect
for common sense", I might consider responding to them.
;-)

I repeat my request for you to do the experiment.

Been there, done that, the first time about 50 years ago, more or less.

Iain if you think you're being terribly clever by pointing out that if you
overdrive your ears with excessively loud noises they become nonlinear, then
you are even more arrogant and stupid than I used to think. :-(

[Iain Churches[_2_]]

"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
ti.fi
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
.fi
"Arny Krueger" wrote in message
. ..


John wrote:
And then there is ordinary real music from
instruments. Presumably a fair amount of IMD is
included.

Wrong, because in a live performance there is very
little that mixes the whole acoustic output of the
musicians into a single signal and then puts that
single signal through a strongly nonlinear process.

Arny, Try this experiment. Sit amongst an orchestra
during rehearsals or recording. Place your chair at the
back and to the right of the French horn section, where
the microphone would be on a multi-mic setup. Four
horns are good, five horns are better. Sibelius 5, Op
82 Eb is a perfect example.
Then tell me there is no acoustic IMD.

Cordially,

Iain, as soon as you start signing your little tirades
with something that fits like: "With utter disrespect
for common sense", I might consider responding to them.
;-)

I repeat my request for you to do the experiment.

Been there, done that, the first time about 50 years ago, more or less.

And you did not learn anything?

Iain if you think you're being terribly clever by pointing out that if you
overdrive your ears with excessively loud noises they become nonlinear,
then you are even more arrogant and stupid than I used to think. :-(

You miss the point entirely. When the horns are playing
mezzo-piano the effect is clearly audible. Refer to the full-score.

Iain

[Iain Churches[_2_]]

"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
.fi
"Patrick Turner" wrote in
message ...

Well here I have to agree that sonic differences in
preamp tubes can be heard.
Even when THD and IMD measures below 0.01%, a typical
value where you have a line stage preamp with volume pot before a
generic gain stage using a 6CG7.

I have, with 4 other guys spent an afternoon tube
rolling with 6CG7 samples.
We agreed the NOS Seimans were best, then made in Oz
Miniwatts, then Mullard, and
then very much last were recent Sovtek versions.

Sighted evaluation. :-(

Certainly not in the documented Svetlana tests or the ones
in which I was involved. Patrick can describe his own experiences.

To build something better in tubes would be a good project
for Arny. It would also keep him away from RAT for a
*very* long time :-))

I don't even have time to build SS amps - I just buy them.

But this is RAT, a tube audio hobby group concerned with
tube-craft - building, evaluation, listening and enjoyment. Why
do you come here to talk about SS amplifiers?

I was hoping you would build a better tube amp than I have done,
and then start a thread about its concept, the chassis construction,
the topology, the choice of input and driver tubes, the output pair.
the OPT, tube voicing, test bench results and listening tests etc.
It is pretty easy just to ridicule the efforts of others and do nothing
yourself. Perhaps such a project is beyond you? If so there are
plenty of people here who would be pleased to guide you:-)

At least you still have a very long way to go before you reach
the skill level of your hero Pinky, who could predict the performance
of a tube amplifier by looking at the schematic of another (totally
different) amp by the same maker:-)

Iain

[Arny Krueger]

"Iain Churches" wrote in message
news
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
ti.fi
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
.fi
"Arny Krueger" wrote in message
. ..


John wrote:
And then there is ordinary real music from
instruments. Presumably a fair amount of IMD is
included.

Wrong, because in a live performance there is very
little that mixes the whole acoustic output of the
musicians into a single signal and then puts that
single signal through a strongly nonlinear process.

Arny, Try this experiment. Sit amongst an orchestra
during rehearsals or recording. Place your chair at
the back and to the right of the French horn section,
where the microphone would be on a multi-mic setup.
Four horns are good, five horns are better. Sibelius
5, Op 82 Eb is a perfect example.
Then tell me there is no acoustic IMD.

Cordially,

Iain, as soon as you start signing your little tirades
with something that fits like: "With utter disrespect
for common sense", I might consider responding to them.
;-)

I repeat my request for you to do the experiment.

Been there, done that, the first time about 50 years
ago, more or less.

And you did not learn anything?

Iain if you think you're being terribly clever by
pointing out that if you overdrive your ears with
excessively loud noises they become nonlinear, then you
are even more arrogant and stupid than I used to think.
:-(

You miss the point entirely. When the horns are playing
mezzo-piano the effect is clearly audible. Refer to the
full-score.

Just because the horns are playing mezzo-piano doesn't mean that the level
is insufficient to cause certain ears to be nonlinear.

If the effect is independent of level, then show me a modern commercial
digital recording that demonstrates the same effect.

[Arny Krueger]

"Iain Churches" wrote in message
.fi
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
.fi
"Patrick Turner" wrote in
message ...

Well here I have to agree that sonic differences in
preamp tubes can be heard.
Even when THD and IMD measures below 0.01%, a typical
value where you have a line stage preamp with volume
pot before a generic gain stage using a 6CG7.

I have, with 4 other guys spent an afternoon tube
rolling with 6CG7 samples.
We agreed the NOS Seimans were best, then made in Oz
Miniwatts, then Mullard, and
then very much last were recent Sovtek versions.

Sighted evaluation. :-(

Certainly not in the documented Svetlana tests or the ones
in which I was involved. Patrick can describe his own
experiences.

To build something better in tubes would be a good
project for Arny. It would also keep him away from RAT
for a *very* long time :-))

I don't even have time to build SS amps - I just buy
them.

But this is RAT, a tube audio hobby group concerned with
tube-craft - building, evaluation, listening and
enjoyment. Why do you come here to talk about SS amplifiers?

Oh come on Iain. I only mentioned SS amplifiers in passing. If you are that
hypersensitive to the mere mention of SS amplifiers, how do you survive in
the real world?

[Iain Churches[_2_]]

"Arny Krueger" wrote in message
...
"Iain Churches" wrote in message
news
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
ti.fi
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
.fi
"Arny Krueger" wrote in message
. ..


John wrote:
And then there is ordinary real music from
instruments. Presumably a fair amount of IMD is
included.

Wrong, because in a live performance there is very
little that mixes the whole acoustic output of the
musicians into a single signal and then puts that
single signal through a strongly nonlinear process.

Arny, Try this experiment. Sit amongst an orchestra
during rehearsals or recording. Place your chair at
the back and to the right of the French horn section,
where the microphone would be on a multi-mic setup.
Four horns are good, five horns are better. Sibelius
5, Op 82 Eb is a perfect example.
Then tell me there is no acoustic IMD.

Cordially,

Iain, as soon as you start signing your little tirades
with something that fits like: "With utter disrespect
for common sense", I might consider responding to them.
;-)

I repeat my request for you to do the experiment.

Been there, done that, the first time about 50 years
ago, more or less.

And you did not learn anything?

Iain if you think you're being terribly clever by
pointing out that if you overdrive your ears with
excessively loud noises they become nonlinear, then you
are even more arrogant and stupid than I used to think.
:-(

You miss the point entirely. When the horns are playing
mezzo-piano the effect is clearly audible. Refer to the
full-score.

Just because the horns are playing mezzo-piano doesn't mean that the level
is insufficient to cause certain ears to be nonlinear.

Arny. What the experiment illustrates is the acoustic
IMD produced by four or in this case five French horns,
even at low levels. If you cannot even be bothered to
do the test, I don't see how you can be in a position
to question the results.

Iain

[Arny Krueger]

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John wrote:
And then there is ordinary real music from
instruments. Presumably a fair amount of IMD is
included.

Wrong, because in a live performance there is very
little that mixes the whole acoustic output of the
musicians into a single signal and then puts that
single signal through a strongly nonlinear process.

Arny, Try this experiment. Sit amongst an orchestra
during rehearsals or recording. Place your chair at
the back and to the right of the French horn
section, where the microphone would be on a multi-mic setup. Four
horns are good, five horns
are better. Sibelius 5, Op 82 Eb is a perfect
example. Then tell me there is no acoustic IMD.

Cordially,

Iain, as soon as you start signing your little
tirades with something that fits like: "With utter
disrespect for common sense", I might consider
responding to them. ;-)

I repeat my request for you to do the experiment.

Been there, done that, the first time about 50 years
ago, more or less.

And you did not learn anything?

Iain if you think you're being terribly clever by
pointing out that if you overdrive your ears with
excessively loud noises they become nonlinear, then you
are even more arrogant and stupid than I used to think.
:-(

You miss the point entirely. When the horns are playing
mezzo-piano the effect is clearly audible. Refer to the
full-score.

Just because the horns are playing mezzo-piano doesn't
mean that the level is insufficient to cause certain
ears to be nonlinear.

Arny. What the experiment illustrates is the acoustic
IMD produced by four or in this case five French horns,
even at low levels. If you cannot even be bothered to
do the test, I don't see how you can be in a position
to question the results.

I don't have to do the test today Iain, because I recorded a bunch of French
horns about this time last year. I stood right in front of them during
rehearsal. No IM.

[Iain Churches[_2_]]

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John wrote:
And then there is ordinary real music from
instruments. Presumably a fair amount of IMD is
included.

Wrong, because in a live performance there is very
little that mixes the whole acoustic output of the
musicians into a single signal and then puts that
single signal through a strongly nonlinear process.

Arny, Try this experiment. Sit amongst an orchestra
during rehearsals or recording. Place your chair at
the back and to the right of the French horn
section, where the microphone would be on a multi-mic setup. Four
horns are good, five horns
are better. Sibelius 5, Op 82 Eb is a perfect
example. Then tell me there is no acoustic IMD.

Cordially,

Iain, as soon as you start signing your little
tirades with something that fits like: "With utter
disrespect for common sense", I might consider
responding to them. ;-)

I repeat my request for you to do the experiment.

Been there, done that, the first time about 50 years
ago, more or less.

And you did not learn anything?

Iain if you think you're being terribly clever by
pointing out that if you overdrive your ears with
excessively loud noises they become nonlinear, then you
are even more arrogant and stupid than I used to think.
:-(

You miss the point entirely. When the horns are playing
mezzo-piano the effect is clearly audible. Refer to the
full-score.

Just because the horns are playing mezzo-piano doesn't
mean that the level is insufficient to cause certain
ears to be nonlinear.

Arny. What the experiment illustrates is the acoustic
IMD produced by four or in this case five French horns,
even at low levels. If you cannot even be bothered to
do the test, I don't see how you can be in a position
to question the results.

I don't have to do the test today Iain, because I recorded a bunch of
French horns about this time last year. I stood right in front of them
during rehearsal. No IM.

A bunch? Are you sure they were French horns
and not bananas? :-) The Frech horn is a left-handed
rear-firing instrument. So you need to stand to the rear
and to the right of the section (in the very place one
would put a mic in a multi-mic orchestral set up) just as
I mentioned initially.

I had an e-mail from one of your fellow countrymen,
a student from Berklee College, Sherman Oaks,LA,
a woodwind player who has been following this thread,
and also the discussion with Andre about aural perception.
He was interested to try the experiment I recommended
to you, and states also that he can hear what he calls
"mid notes" (IMD) between two Bb clarinets, the first
playing Eb and the second playing B natural, with
softish reeds at low volume. I shall be interested
to give this a listen next time I have the opportunity.

Iain

[Arny Krueger]

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John wrote:
And then there is ordinary real music from
instruments. Presumably a fair amount of IMD is
included.

Wrong, because in a live performance there is
very little that mixes the whole acoustic output
of the musicians into a single signal and then
puts that single signal through a strongly
nonlinear process.

Arny, Try this experiment. Sit amongst an
orchestra during rehearsals or recording. Place your chair
at the back and to the right of the French horn
section, where the microphone would be on a
multi-mic setup. Four horns are good, five horns
are better. Sibelius 5, Op 82 Eb is a perfect
example. Then tell me there is no acoustic IMD.

Cordially,

Iain, as soon as you start signing your little
tirades with something that fits like: "With utter
disrespect for common sense", I might consider
responding to them. ;-)

I repeat my request for you to do the experiment.

Been there, done that, the first time about 50 years
ago, more or less.

And you did not learn anything?

Iain if you think you're being terribly clever by
pointing out that if you overdrive your ears with
excessively loud noises they become nonlinear, then
you are even more arrogant and stupid than I used to
think. :-(

You miss the point entirely. When the horns are
playing mezzo-piano the effect is clearly audible. Refer to the
full-score.

Just because the horns are playing mezzo-piano doesn't
mean that the level is insufficient to cause certain
ears to be nonlinear.

Arny. What the experiment illustrates is the acoustic
IMD produced by four or in this case five French horns,
even at low levels. If you cannot even be bothered to
do the test, I don't see how you can be in a position
to question the results.

I don't have to do the test today Iain, because I
recorded a bunch of French horns about this time last
year. I stood right in front of them during rehearsal.
No IM.

A bunch? Are you sure they were French horns
and not bananas? :-) The Frech horn is a left-handed
rear-firing instrument. So you need to stand to the rear
and to the right of the section (in the very place one
would put a mic in a multi-mic orchestral set up) just as
I mentioned initially.

I was there too. Still no problems.

[Iain Churches[_2_]]

"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
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...
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John wrote:
And then there is ordinary real music from
instruments. Presumably a fair amount of IMD is
included.

Wrong, because in a live performance there is
very little that mixes the whole acoustic output
of the musicians into a single signal and then
puts that single signal through a strongly
nonlinear process.

Arny, Try this experiment. Sit amongst an
orchestra during rehearsals or recording. Place your chair
at the back and to the right of the French horn
section, where the microphone would be on a
multi-mic setup. Four horns are good, five horns
are better. Sibelius 5, Op 82 Eb is a perfect
example. Then tell me there is no acoustic IMD.

Cordially,

Iain, as soon as you start signing your little
tirades with something that fits like: "With utter
disrespect for common sense", I might consider
responding to them. ;-)

I repeat my request for you to do the experiment.

Been there, done that, the first time about 50 years
ago, more or less.

And you did not learn anything?

Iain if you think you're being terribly clever by
pointing out that if you overdrive your ears with
excessively loud noises they become nonlinear, then
you are even more arrogant and stupid than I used to
think. :-(

You miss the point entirely. When the horns are
playing mezzo-piano the effect is clearly audible. Refer to the
full-score.

Just because the horns are playing mezzo-piano doesn't
mean that the level is insufficient to cause certain
ears to be nonlinear.

Arny. What the experiment illustrates is the acoustic
IMD produced by four or in this case five French horns,
even at low levels. If you cannot even be bothered to
do the test, I don't see how you can be in a position
to question the results.

I don't have to do the test today Iain, because I
recorded a bunch of French horns about this time last
year. I stood right in front of them during rehearsal.
No IM.

A bunch? Are you sure they were French horns
and not bananas? :-) The Frech horn is a left-handed
rear-firing instrument. So you need to stand to the rear
and to the right of the section (in the very place one
would put a mic in a multi-mic orchestral set up) just as
I mentioned initially.

I was there too. Still no problems.

It is not a problem, just an interesting, widely-known
phenomenon.

Iain