What is direct coupled (DC) mean?
Agisthos
too?
I was reading some reviews of a preamp called the Tom Evans Vibe and they
made a big deal out of it being DC. also it was stated the only way they did
this was with their unique lithos regulation of the power supply.
Marketing spiel im sure but ive never heard about DC amps.
David Nicholls
"An amplifier in which the output of one stage is coupled to the input
of the next without the use of a capacitor. This type of amplifier will
amplify Direct Currents and low frequency waveforms." (via Google)
Useful if you want to replay recordings of Blue Whales at their original
frequencies.
Also important if you believe capacitors have a "sound".
DN
Patrick Turner
Agisthos wrote:
DC coupling means that each gain stage of the amplifier is coupled together
without using coupling capacitors and coupling transformers which are a common
feature
of vacuum tubes equipments.
Direct coupling between all the transistors and between the transistors and the
speaker
allows the bandwidth of the amp to be extended down to a very low frequency
of 0.0Hz, or direct current with no frequency content, but then as soon as the
DC level is changed,
it becomes alternating current, or AC.
Often amplifiers have some form of limitation of their bandwidth in the form of
a resistance and capacitance
network at the input of the amp to limit the range of F which can be applied to
th the input to between
say 10Hz to 100kHz.
Direct coupling, or DC coupling is a very common feature of nearly all
amplifiers made today
except tube types.
However it is quite easy to get a tube amp to have a bandwidth of 10Hz to
100kHz,
despite the many R&C couplings and the output transformer which also is a
bandwidth limiting device.
I suggest you read whatever you can find on the basics of amplifier topology
and all about how transistors work.
The full understanding will take considerable time.
Patrick Turner.
Patrick Turner
David Nicholls wrote:
Whale songs could easily be played by a tube amp full of RC couplings and an
output
transformer.
Did you know mice sing to each other at F we cannot hear?
I guess that makes it easier for a cat to chase them.
Cats hear what we can't.
And one I had could hear a pin drop or some slight rustly noise
at 50 feet away. It was quite uncanny what that cat could hear.
Anyway, nearly all airborne or waterborne vibratory communication signals
excluding RF of course
are between 2Hz and 100kHz, and evan a tube amp can be capable of such
a range, although the 2Hz wouldn't be at full power, lest the saturation of the
OPT occur.
But the triode amp designed by D.T.N Williamson in 1947 had a
response between 3Hz and 100kHz at normal levels of use, and
between about 10Hz ant 80kHz at full power.
You don't need direct coupling to get adequately low music reproduction,
but whale sounds that have F below 2Hz might be difficult without such coupling;
and you'd have to have transducer ie, a mic to pick up such low F.
Elephant farts can be reproduced with just about any old amp.
Caps do have a sound in the minds of many folks,
so I ask them "what sound is that?", and the replies have a lot of words in them
and I just agree because its useless to argue.
But I like Wima polypropylene coupling caps in my amps.
I've never had one fail.
If someone wants to rip 'em out and put in Auricaps, then that's their business.
I did hear of a dude who changed the brand and type of caps in his very expensive
SET amp,
and it sounded worse so he went back to the original caps.
Patrick Turner.
>
>
> DN
Jim Gregory
news:4368...@dnews.tpgi.com.au...
isolating transformers between stages.
Result: Much lower frequency pass band, no introduction of phase-angle loss,
tighter slew rate, and maybe less colouration.
But, with no roll-off proviso, somehow any output transformer is going to
corrupt lowest freqs.
Jim
Iain M Churches
"Jim Gregory" <jim....@ntlworld.com> wrote in message
news:SR6af.336$8R6...@newsfe1-gui.ntli.net...
Hello Jim,
Nice to see you posting here. Hope you brought your asbestos
suit with you:-)
Cheers
Iain
Jim Gregory
news:dkb4p5$fgn$1...@phys-news1.kolumbus.fi...
could be a biting, irritating horse-fly.
J
>
Trevor Wilson
> mean/refer too?
**Direct Coupled (DC) simply refers to the fact that a particular circuit
has no coupling capacitors, or transformers, between active devices, or
stages. It is very common in solid state equipment, but rare in valve
equipment. Rare, but not unheard of. The advantages of DC coupling are
tangible, measureable and significant. The human ear is particularly
sensitive to phase errors in systems. A phase shift of a few degrees, can
damage musical information and imaging to those who value such attributes. A
general rule of thumb is that to maintain inaudible levels of phase shift,
at 20Hz, an amplifier needs to have a 3dB rolloff of around 0.2Hz. Clearly,
a response to DC would obviate any possible problems.
>
> I was reading some reviews of a preamp called the Tom Evans Vibe and they
> made a big deal out of it being DC. also it was stated the only way they
> did this was with their unique lithos regulation of the power supply.
> Marketing spiel im sure but ive never heard about DC amps.
**Probably not (marketing spiel). DC coupling is rare, but not unheard of,
in valve products. In every case, I've heard/measured, the results bear out
the manufacturer's claims. The products have managed to eliminate one of the
most glaring faults in all valve preamps - that of excessive phase shift at
LF. The other factor is one which relates to the sound quality of some
capacitors. Many people claim that certain capacitors sound better than
others (there is some science to show that this may be the case, BTW). By
completely eliminating coupling capacitors, the argument is finished. Of
course, most decent SS preamps eschewed the use of coupling capacitors,
several decades ago.
--
Trevor Wilson
www.rageaudio.com.au
Phil Allison
"Jim Gregory"
> Yes, ventured prepared for visiting a regular flak zone, as indigenous
> there could be a biting, irritating horse-fly.
** Well, a horse's arse can * expect * to get bitten by passing
horse-flies.
Its the odour all the "horse shit" you drop that attracts them you know.
........ Phil
Phil Allison
"Trevor Wilson"
> **Direct Coupled (DC) simply refers to the fact that a particular circuit
> has no coupling capacitors, or transformers, between active devices, or
> stages. It is very common in solid state equipment, but rare in valve
> equipment. Rare, but not unheard of. The advantages of DC coupling are
> tangible, measureable and significant. The human ear is particularly
> sensitive to phase errors in systems. A phase shift of a few degrees, can
> damage musical information and imaging to those who value such attributes.
> A general rule of thumb is that to maintain inaudible levels of phase
> shift, at 20Hz, an amplifier needs to have a 3dB rolloff of around 0.2Hz.
> Clearly, a response to DC would obviate any possible problems.
>
( snip rest of TW's spew inducing, ME hype / tripe )
** Kindly post such audiophool crapology on Mr bassett's audio dog bath site
in future.
Or else on "Audioasylum", "rec.audio.opinion" or the " NZ On Line Sheep
Dip" site run by that wacko Kiwi graphic designer.
They are all just hanging out for *horse shit* like TW's.
........ Phil
Bob
Patrick Turner
Trevor Wilson wrote:
> "Agisthos" <ec...@nospam.com> wrote in message
> news:4368...@dnews.tpgi.com.au...
> > From the perspective of amplifier design what does direct coupled
> > mean/refer too?
>
> **Direct Coupled (DC) simply refers to the fact that a particular circuit
> has no coupling capacitors, or transformers, between active devices, or
> stages. It is very common in solid state equipment, but rare in valve
> equipment. Rare, but not unheard of. The advantages of DC coupling are
> tangible, measureable and significant. The human ear is particularly
> sensitive to phase errors in systems. A phase shift of a few degrees, can
> damage musical information and imaging to those who value such attributes. A
> general rule of thumb is that to maintain inaudible levels of phase shift,
> at 20Hz, an amplifier needs to have a 3dB rolloff of around 0.2Hz. Clearly,
> a response to DC would obviate any possible problems.
The negligible phase errors caused by cap coupling does not cause audible
degradation of the sound in from amplifiers.
An order of magnitude MORE phase shift occurs in nearly every speaker due
to the effects of crossoverss and their partially reactive characteristic.
The human ear is remarkably unable to detect phase distortion caused by amps etc
unless that phase problem is a huge one, ie, the leads of your two
speakers are phase reversed thus muddling the stereo image.
The phase shift between the input and output signal of a well designed tube amp
full of
reactance couplings is often no worse than a solid state amp.
>
>
> >
> > I was reading some reviews of a preamp called the Tom Evans Vibe and they
> > made a big deal out of it being DC. also it was stated the only way they
> > did this was with their unique lithos regulation of the power supply.
> > Marketing spiel im sure but ive never heard about DC amps.
>
> **Probably not (marketing spiel). DC coupling is rare, but not unheard of,
> in valve products. In every case, I've heard/measured, the results bear out
> the manufacturer's claims. The products have managed to eliminate one of the
> most glaring faults in all valve preamps - that of excessive phase shift at
> LF.
You are BULLSHITTING AGAIN TREVOR WILSON.
Most well made tube amps have negligible phase shift at LF.
Go refer to the measurements of some decent ampos that you have laying around.
While your'e at it do some blind AB tests and see just how detectable 10 degress
of phase lead is at 30 Hz.
Then get back to us with honest results
.
But I don't expect you to be capable of providing us with the answers that
are right or informative or honest.
Most good tube amps made by Conrad Johnson or ARC who no doubt you are familiar
with have a -3dB point at around 3Hz, and negligibe phase shift
at 30Hz, and they measure as well as the solid state amps you sell.
Most of my customers like the bass of good tube gear in preference to solid
state.
> The other factor is one which relates to the sound quality of some
> capacitors. Many people claim that certain capacitors sound better than
> others (there is some science to show that this may be the case, BTW). By
> completely eliminating coupling capacitors, the argument is finished. Of
> course, most decent SS preamps eschewed the use of coupling capacitors,
> several decades ago.
I agree with everyones point about the differences in capacitors.
It saves an absurd argument.
So where there are no caps, there ia also no argument.
But the absense or presense of caps used in SS amps is not a
big deal.
Sugden manage to keep using caps to couple their amps to speakers
and the sound is revered by the owners of such gear to be second to none.
There is no absolute truth in anything you say Trev.
There are too many examples of gear whose performance demonstrates you are wrong
Patrick Turner.
>
>
> --
> Trevor Wilson
> www.rageaudio.com.au
Trevor Wilson
"Patrick Turner" <in...@turneraudio.com.au> wrote in message
news:436969C1...@turneraudio.com.au...
>
>
> Trevor Wilson wrote:
>
>> "Agisthos" <ec...@nospam.com> wrote in message
>> news:4368...@dnews.tpgi.com.au...
>> > From the perspective of amplifier design what does direct coupled
>> > mean/refer too?
>>
>> **Direct Coupled (DC) simply refers to the fact that a particular circuit
>> has no coupling capacitors, or transformers, between active devices, or
>> stages. It is very common in solid state equipment, but rare in valve
>> equipment. Rare, but not unheard of. The advantages of DC coupling are
>> tangible, measureable and significant. The human ear is particularly
>> sensitive to phase errors in systems. A phase shift of a few degrees, can
>> damage musical information and imaging to those who value such
>> attributes. A
>> general rule of thumb is that to maintain inaudible levels of phase
>> shift,
>> at 20Hz, an amplifier needs to have a 3dB rolloff of around 0.2Hz.
>> Clearly,
>> a response to DC would obviate any possible problems.
>
> The negligible phase errors caused by cap coupling does not cause audible
> degradation of the sound in from amplifiers.
> An order of magnitude MORE phase shift occurs in nearly every speaker due
> to the effects of crossoverss and their partially reactive characteristic.
>
> The human ear is remarkably unable to detect phase distortion caused by
> amps etc
**Oh really?
>
> unless that phase problem is a huge one, ie, the leads of your two
> speakers are phase reversed thus muddling the stereo image.
**Duh.
>
> The phase shift between the input and output signal of a well designed
> tube amp
> full of
> reactance couplings is often no worse than a solid state amp.
**Often? Nope. Sometimes? Yes.
>
>
>
>>
>>
>> >
>> > I was reading some reviews of a preamp called the Tom Evans Vibe and
>> > they
>> > made a big deal out of it being DC. also it was stated the only way
>> > they
>> > did this was with their unique lithos regulation of the power supply.
>> > Marketing spiel im sure but ive never heard about DC amps.
>>
>> **Probably not (marketing spiel). DC coupling is rare, but not unheard
>> of,
>> in valve products. In every case, I've heard/measured, the results bear
>> out
>> the manufacturer's claims. The products have managed to eliminate one of
>> the
>> most glaring faults in all valve preamps - that of excessive phase shift
>> at
>> LF.
>
> You are BULLSHITTING AGAIN TREVOR WILSON.
**Er, no, I'm not.
>
> Most well made tube amps have negligible phase shift at LF.
**Duh. Focus on the words: "well made".
>
> Go refer to the measurements of some decent ampos that you have laying
> around.
**Zero degrees pahse shift, from DC to 50kHz. What's your point?
>
> While your'e at it do some blind AB tests and see just how detectable 10
> degress
> of phase lead is at 30 Hz.
**Done. Critical listeners can hear it.
>
> Then get back to us with honest results
> .
> But I don't expect you to be capable of providing us with the answers that
> are right or informative or honest.
>
> Most good tube amps made by Conrad Johnson or ARC who no doubt you are
> familiar
> with have a -3dB point at around 3Hz, and negligibe phase shift
> at 30Hz, and they measure as well as the solid state amps you sell.
>
> Most of my customers like the bass of good tube gear in preference to
> solid
> state.
**Good for them.
>
>
>> The other factor is one which relates to the sound quality of some
>> capacitors. Many people claim that certain capacitors sound better than
>> others (there is some science to show that this may be the case, BTW). By
>> completely eliminating coupling capacitors, the argument is finished. Of
>> course, most decent SS preamps eschewed the use of coupling capacitors,
>> several decades ago.
>
> I agree with everyones point about the differences in capacitors.
> It saves an absurd argument.
> So where there are no caps, there ia also no argument.
**Precisely.
>
> But the absense or presense of caps used in SS amps is not a
> big deal.
>
> Sugden manage to keep using caps to couple their amps to speakers
> and the sound is revered by the owners of such gear to be second to none.
**The last few Sugden amps I worked on were DC coupled. Only the very early
ones were capacitor coupled.
>
> There is no absolute truth in anything you say Trev.
**Then feel free to prove me wrong.
>
> There are too many examples of gear whose performance demonstrates you are
> wrong
**No. There are many examples of equipment which proves I am right.
--
Trevor Wilson
www.rageaudio.com.au
Patrick Turner
You replied
> **Er, no, I'm not.
>
You continue to bullshit on.
Trevor Wilson
**Lack of proof, duly noted.
--
Trevor Wilson
www.rageaudio.com.au
Phil Allison
"Trevor Wilson"
>> "Patrick Turner"
>> You replied
>>
>>> **Er, no, I'm not.
>>
>> You continue to bullshit on.
>
> **Lack of proof, duly noted.
** The only proofs needed that TW is **bullshiting** is that his lips are
moving or his fingers typing.
TW lives and breathes bullshit.
BTW
The lebanese family next door to TW at number 6 Somerset Street Hurstville
don't know he considers them to be sub humans.
Time somebody told them.
........ Phil
Doug Flynn
news:4369...@news.comindico.com.au...
By completely eliminating coupling capacitors, the argument is finished. Of
course, most decent SS preamps eschewed the use of coupling capacitors,
several decades ago.
Hi
I recently re-engineered my tube preamp and tube power amp so that there are
no caps in the signal path (and that includes the bias circuits). I did
this by replacing them with interstage transformers. In theory transformers
also introduce their own phase problems, but the sound is so much better
with the transformers. OK, transformers do make LF sine and square waves
look bizarre, but I can't deny what my ears are telling me. Doug
Eiron
>>While your'e at it do some blind AB tests and see just how detectable 10
>>degress
>>of phase lead is at 30 Hz.
>
>
> **Done. Critical listeners can hear it.
Can anyone give an example of an audible phase shift?
Either pointers to the wav/mp3 files or a reference for the music and
the filters used.
I haven't tried it at very low frequencies where a phase shift corresponds
to a large time shift, which I accept could be audible, but I've never
been able to hear a difference caused by phase shift (obviously the same
on both channels).
--
Eiron
I have no spirit to play with you; your dearth of judgment renders you
tedious - Ben Jonson.
Iain M Churches
"Eiron" <e1...@hotmail.com> wrote in message
news:3sudnhF...@individual.net...
> Trevor and Patrick argued:
>
>>>While your'e at it do some blind AB tests and see just how detectable 10
>>>degress
>>>of phase lead is at 30 Hz.
>>
>>
>> **Done. Critical listeners can hear it.
>
> Can anyone give an example of an audible phase shift?
> Either pointers to the wav/mp3 files or a reference for the music and
> the filters used.
> I haven't tried it at very low frequencies where a phase shift corresponds
> to a large time shift, which I accept could be audible, but I've never
> been able to hear a difference caused by phase shift (obviously the same
> on both channels).
>
> --
> Eiron
>
Morjens Eiron.
Just a while ago, I bought an adjustable phase oscillator
by Feedback Electronics UK, to look into the effects of
phase shift, with regard to my own home-brew valve amps.
http://www.kolumbus.fi/iain.churches/Pics/FeedbackVPO602.jpg
http://www.kolumbus.fi/iain.churches/Pics/FeedbackPhaseMeter.jpg
The example quoted by Trevor above of 10 degrees lead at 30Hz
seems to be quite extreme, so perhaps if it can be heard
by a critical listener. But where does it come from?
My own 50W tube amp had 3 degrees at 30Hz, and <10 degrees
at 10Hz. As a reference, I measured a Radford STA100 which was
one degree better than the above figs.
I have a feeling that the phase distortion in a loudspeaker might
be considerably more. (puts on asbestos suit, glances nonchalantly
over left shoulder, and exits into the night)
Iain
Arny Krueger
> Can anyone give an example of an audible phase shift?
> Either pointers to the wav/mp3 files or a reference for
> the music and the filters used.
Eiron
Thanks Arny. Can anyone hear the difference between your samples?
Arny Krueger
> Arny Krueger wrote:
>
>> "Eiron" <e1...@hotmail.com> wrote in message
>> news:3sudnhF...@individual.net
>>
>>
>>> Can anyone give an example of an audible phase shift?
>>> Either pointers to the wav/mp3 files or a reference for
>>> the music and the filters used.
>>
>>
>>
>> http://www.pcabx.com/technical/LR-300-3K/index.htm
>
> Thanks Arny. Can anyone hear the difference between your
> samples?
Some of them, yes.
Patrick Turner
Doug Flynn wrote:
Transformers and capacitors are quite good passing square waves if the time
constant
with the resistance elements is large enough.
I've made plenty of OPTs with FULL POWER bandwidth from
10Hz to 300kHz, and a 1kHz square wave looks like a square wave.
A 10 Hz or a 300kHz square does not. So what?
The square wave performance indicates the bandwidth and the response
to transients.
By analysing the square wave with a glance we can estimate a lot about
the operation of a circuit.
Each and every amplifier is effectively a bandbass filter;
Only a limited range of F can pass through.
If your coupling trannies have enough bandwidth, and the frequencies of interest
between 20Hz and 20Khz pass through the amps in a flat response,
then you don't have much to worry about; the -3 db points would then be
say about 12Hz and 60kHz
Even if the -3dB points were 20Hz and 20kHz, or 12kHz, i doubt you'd hear any
difference.
What your amps are doing between 50 and 5kHz is the most critical.
I know you don't like NFB, so I assume you don't have any in your amps.
Then to get good BW each and every tranny would have to have a wider BW
than the one you want to finish up with.
So if you had 4 trannies in the signal path, and each had -3dB poles at 20Hz &
20kHz,
then the BW after 4 stages would be a lot less than 20Hz to 20khz.
But unless you actually measured it you would not be sure that's how it was.
And trannies need to have the correct termination to stop them
producing a peaked response between 5kHz and 50kHz, caused
by parallel resonances that are very common in many coupling trannies.
Its almost impossible to use NFB in a loop around any amp with both an OPT
and an interstage transformer.
The problem is that the leakage L and shunt C cause a rapid phase shift
at HF and the shunt inductances create a rapid phase shift at LF
so if the phase shift is 180 degrees and the open loop gain above 1.0,
then the amp will become an oscillator.
So tube amps need to have a wide bandwidth before NFB is applied,
and so ISTs have dissappeared from amplifiers, and besides,
an R&C is a lot cheaper.
There isn't anying magical about the sound using transformers.
But using good ones means the tubes or SS devices can get on with the business
quite ok.
D.T.N. Williamson proved you could have an amp
which was stable into any load, and have 20 dB of NFB, and have low Ro
of approx 0.2 ohms, and have BW = 3Hz to 100kHz, and have 0.1% noise&thd,
and have negligible phase shift, in 1947.
((By 1949 McIntosh went a bit further and he had a total of about 35dB NFB,
and got figures which are still considered good today,
although there is a fetish for removing zeros.
Halcro have tried to make amps that cannot be found to have distortion
because nobody has gear good enough to measure it.))
But Williamson used an OPT, and had two RC coupled stages.
If ppl were not told, and did not know, an AB test comparison
between a 15 watt Williamson and some modern SS direct coupled class B amp
of 15 watts, or a new digital amp of 15 watts would show that they all
could play music and many ppl would not hear the slightest difference,
even after hours of test music.
But to some they'd say that amplifer X as opposed to amplifier Y or Z
did seem to sound warmer and maybe more detailed and smooth
and in effect, listenable.
Probably amp X had funny glass things in it.
I have no argument with ppl who prefer higher thd, more noise,
higher Ro.
These are only things we measure, and need only be low enough in the system we
have to make the
music sound well; there are limits.
We don't go fishing to measure the fish; we go because we are hungry.
So I heard you have horns now, so all you need is a poofteenth of a watt to
produce quite loud music, and in this case niether the amp nor speaker procduces
much
distortion, although the amps need to be quiet, lest we hear the noise all the
easier
because horns are sensitive creatures.
As for the phase shift in horns, well, I never heard anyone complain
about a well done folded horn such as a Lowther.
But their top end is direct from the cone, or the whizzer cones.
These are made to be sensitive; its easier to make a sensitive HF unit
than a bass unit, so Lowther decided to horn load the rear of the speaker to
make it more efficient
at LF.
If you DID want to use NFB around an amp with all iron wound
couplings, then it IS possible with the proviso that the time constants are all
long
enough, but unfortunatly in tube amps the plate resistances and load resistances
are all such
high values of ohms that the amount of inductance needed to get a pole of
say 2Hz at each LR interface is enormous.
And inductance changes with signal level.
So a circuit with a tranny operating at low levels has a poorer BW than when it
operates at a higher level; Williamson recommended no less than 100H
for his primary in his OPT even though the plate resistance anode to anode
of two KT66 in triode was a rather low 3,200 ohms.
If less than 100H is present in a Williamson design amp
then it will oscillate at LF, since the amp becomes a phase shift
oscillator.
The OPT may have 600H at 10 watts though; the higher voltage applied to the
tranny
makes it appear the inductance has increased.
Indeed it effectively has increased.
Now since the primary inductance shunts the load in tube amps,
and beacuse the value of the ohms of reactance changes between low level
anf high level, then there is a difference in amplifier gain between the two
levels of operation.
Its not a very big difference in practice, and can be ignored.
Even within an individual large value sine wave there is a slight
change to the inductance; its less around the zero crossing point and higher
away
from it, and thus the load seen by the tube changes during each cycle.
The type of distortion produced is mostly 3rd harmonic, and
the % is usually well below what is produced by the tubes.
In amps with SE OPTs and SE coupled stages, add in 2H to the mix.
But with 4 trannies, you get 4 consecutive lots of 3H and 2H.
The % of 3H produced by the iron is worst when the trannies are used at their
low range
of voltages in PP circuits and it is rather like the crossover distortion you
get in
pentode PP tube amps which are underbiased, ( used now commonly in guitar amps )
and the 3H phase is such that it makes the sine waves more peaked, rather than
flattened.
I think that sounds worse than the flattening phase of 3H.
SE OPTs and coupling trannies are gapped, and thus you cannot ever get the
optimum
ratio of 100H/3.2k of load without using an enormous number of turns,
and that's what you have to do which everybody else didn't want to do
when trannies were popular for coupling back in 1930.
I don't use any trannies for coupling because its so hard to get
all the attributes you want, high primary L, low leakage L, and low
self capacitance and low stray capacitance, and therefore get
abundant bandwidth.
Any coupling with a tranny is a combination of R plus lots of L as well as C.
At least with CR coupling there is no L involved, and its a whole lot easier
to get the good sounding time constants.
But using L rather than C as the main reactive elements in an amp
does mean that the loads due to the L rise with F, so a typical
triode such as a 6SN7 loaded with a tranny with 200H of inductance
will have a load of very high impedance at the mid frequencies which are most
important.
Thus the tube operates more nearly as if loaded by a constant current source
and hence produce the least possible distortion;
0.1% at 10Vrms isn't uncommon, and entirely adequate
in a preamp;
if the tranny is made such that the distortion is low,
and it is lowest when the plate resistance is lowest, then the stage with a
tranny
in a preamp should sound very healthy.
A 6SN7 has an Ra at moderate Ia of about 10k, which is
about low enough for use of trannies.
With a pentode, forget using a tranny unless a lot of FB is contemplated
to get the circuit to act as if the tube were a triode.
There's more I could say about tranny coupling.
But we are supposed to be talking about direct coupling.
And BTW, you can make a tube amp considerd to be truly
direct coupled; its the Loftin White amp, invenetd about
1930 because ppl didn't like paying for trannies; L was always expensive,
and the caps of that time were very unreliable, being only wax, paper, and
foil concoctions.
Because there NPN and PNP, we can have direct coupled SS amplifiers without
having to stack the supplies on top of each other as in the Loftin White
design to get direct coupling; ( or as it was also done in scientific
DC amplifierswhen tubes were all they had to use ).
To get away from cap coupling or tranny coupling in tube amps,
we would need to have tubes capable of controlling current
like a PNP bjt, but nobody has invented it,
mainly because they have figured its impossible to invent,
( for technical reasons ).
Patrick Turner.
Doug Flynn
Thus the tube operates more nearly as if loaded by a constant current source
and hence produce the least possible distortion;
0.1% at 10Vrms isn't uncommon, and entirely adequate
in a preamp; if the tranny is made such that the distortion is low,
and it is lowest when the plate resistance is lowest, then the stage with a
tranny in a preamp should sound very healthy.
A 6SN7 has an Ra at moderate Ia of about 10k, which is
about low enough for use of trannies.
With a pentode, forget using a tranny unless a lot of FB is contemplated
to get the circuit to act as if the tube were a triode.
There's more I could say about tranny coupling.
But we are supposed to be talking about direct coupling.
And BTW, you can make a tube amp considerd to be truly
direct coupled; its the Loftin White amp, invenetd about
1930 because ppl didn't like paying for trannies; L was always expensive,
and the caps of that time were very unreliable, being only wax, paper, and
foil concoctions.
Patrick Turner.
Thanks Patrick
I agree that the *only* way to load a triode is with a constant current
source, but not a solid state variety (the experiments I have done with SS
CCS were not promising). IMHO nothing beats a transformer to load a triode,
and it has the added benefit of eliminating a coupling cap AND the grid
resistor of the following stage. In my experience the grid resistor is just
as audible as the coupling cap. You can also use the secondary of the
transformer to apply the bias voltage, thereby eliminating the traditional
RC bias network.
This is basically what I've done with my 3 stage 300B amp. It's 6J5GT -->
SE transformer --> 45 --> SE transformer --> 300B. All tubes are fixed
bias. No feedback anywhere thankyou very much.
The preamp is a paralleled 6SN7 per channel to push RP down and current up
(always a good thing in my book) into a 6K6 : 100R SE transformer. The end
result is certainly the best sound I've heard in nearly 10 years of amp
building.
Cheers. Doug
Ayn Marx
Patrick Turner wrote:
> Snip of a lot of tech stuff I don't begin to understand and some sewage from you know how..........
>
> > The other factor is one which relates to the sound quality of some
> > capacitors. Many people claim that certain capacitors sound better than
> > others (there is some science to show that this may be the case, BTW). By
> > completely eliminating coupling capacitors, the argument is finished. Of
> > course, most decent SS preamps eschewed the use of coupling capacitors,
> > several decades ago.
>
in the power supply are part of the amplification chain and therefore
claims that many SS eschewe coupling capacitors doesn't tell us the
whole story?
Trevor Wilson
"Ayn Marx" <mdh...@iprimus.com.au> wrote in message
news:1131158744.8...@g44g2000cwa.googlegroups.com...
**Not quite. There are several issues here:
* Power supplies may use regulation elements, which effectively remove caps
from the equation.
* Capacitors in power supplies are MUCH larger than any coupling caps.
* SS amps can (usually) amplify direct current as easily as they can amplify
AC.
--
Trevor Wilson
www.rageaudio.com.au
Ayn Marx
Trevor Wilson wrote:
> "Ayn Marx" <mdh...@iprimus.com.au> wrote in message
> news:1131158744.8...@g44g2000cwa.googlegroups.com...
> >
> > Patrick Turner wrote:
> >> Snip of a lot of tech stuff I don't begin to understand and some sewage
> >> from you know how..........
> >>
> >> > The other factor is one which relates to the sound quality of some
> >> > capacitors. Many people claim that certain capacitors sound better than
> >> > others (there is some science to show that this may be the case, BTW).
> >> > By
> >> > completely eliminating coupling capacitors, the argument is finished.
> >> > Of
> >> > course, most decent SS preamps eschewed the use of coupling capacitors,
> >> > several decades ago.
> >>
> > Forgive my ignorance Patrick but isn't it the case that capacitors used
> > in the power supply are part of the amplification chain and therefore
> > claims that many SS eschewe coupling capacitors doesn't tell us the
> > whole story?
>
> **Not quite. There are several issues here:
plenty, don't all ampilifiers modulate the power supply, doesn't "not
quite" imply they do.
>
> * Power supplies may use regulation elements, which effectively remove caps
> from the equation.
aren't regulation elements amplifiers?
> * Capacitors in power supplies are MUCH larger than any coupling caps.
and maybe slower due to L in the foil windings. isn't the primary
intention
to control ripple due to rectification of ac. yet the signal must pass
through them to get to the load.
Ayn Marx
Doug Flynn wrote:
Snip<
OK, transformers do make LF sine and square waves
> look bizarre, but I can't deny what my ears are telling me. Doug
I don't doubt you hear what you hear . These kinds of observations, if
backed by ABX results, could prove the interface between electronics
and psychoacoustics is as yet to be properly joined. In other words,
if I may disturb the objectivists, we don't yet have all the answers.
Phil Allison
"Ayn Marx" <
>>
>> * Power supplies may use regulation elements, which effectively remove
>> caps
>> from the equation.
>
> aren't regulation elements amplifiers?
** Audiophool crapology.
>> * Capacitors in power supplies are MUCH larger than any coupling caps.
>
> and maybe slower due to L in the foil windings.
** Audiophool crapology.
> isn't the primary intention
> to control ripple due to rectification of ac. yet the signal must pass
> through them to get to the load.
** Audiophool crapology.
.......... Phil
Trevor Wilson
**Not quite. If an amplifier uses a well regulated power supply (such as a
preamp, for instance), then that power supply modulation will be
immeasurably low in level.
>
>>
>> * Power supplies may use regulation elements, which effectively remove
>> caps
>> from the equation.
>
> aren't regulation elements amplifiers?
**Sort of.
>
>> * Capacitors in power supplies are MUCH larger than any coupling caps.
>
> and maybe slower due to L in the foil windings. isn't the primary
> intention
> to control ripple due to rectification of ac. yet the signal must pass
> through them to get to the load.
**There are a variety of methods to eliminate ESL in caps. One can use a
large number of parallel caps, or parallel smaller, low ESL caps, or a
combination of methods. If you think of the power supply capacitance as a
battery, it may assist with the analogy. With a large enough capacitor bank
on the power supply, then that supply acts as a 'perfect' DC source. Again,
consider the action of those capacitors in a highly regulated preamp.
--
Trevor Wilson
www.rageaudio.com.au
Phil Allison
"Ayn Marx"
> Doug Flynn wrote:
> Snip<
> OK, transformers do make LF sine and square waves
>> look bizarre, but I can't deny what my ears are telling me.
Doug
>
> I don't doubt you hear what you hear .
** Audiophool crapology.
>These kinds of observations, if
> backed by ABX results,
** Drivel & audiophool crapology.
> could prove the interface between electronics
> and psychoacoustics is as yet to be properly joined. In other words,
> if I may disturb the objectivists, we don't yet have all the answers.
** Audiophool crapology.
............ Phil
Ayn Marx
Phil Allison wrote:
>
> ** Audiophool crapology.
> ** Drivel & audiophool crapology.
>
> ............ Phil A
Thank you for your constructive contribution.
Phil Allison
"Ayn Marx" <
>
>> ** Audiophool crapology.
>> ** Drivel & audiophool crapology.
>> ** Audiophool crapology.
>
> Thank you for your constructive contribution.
** Yes - I make then all the time.
Not ** sickening audiophool snake oil shit ** YOU post on behalf of the
CRIMINAL SCUM you claim to associate with who are all rightfully too
scared to post on any NG.
PISS OFF - you vile autistic moron.
The Bassett Hound is wagging his tail in anticipation of your crapology.
........ Phil
Ayn Marx
* *
You're very, very close to the edge dear.
Phil Allison
"Ayn Marx"
>
> * *
> You're very, very close to the edge dear.
>> Thank you for your constructive contribution.
...@...................com
<phila...@tpg.com.au> wrote:
>
>"Ayn Marx"
>>
>> * *
>> You're very, very close to the edge dear.
>
>>> Thank you for your constructive contribution.
>
>
>** Yes - I tried hard then.
>
>Not ** sickening crap that I usually post
>because I am descended form CRIMINAL SCUM (my ancesters were convicts).
>
>I need to PISS OFF - ybut i'm lonely.
>
>Bassett's new group is waiting for you.I am jealous because I'm banned
>from posting there.
>
>shame really
>........ Phil
>
>
Yes it is sad for you Phil...and a party for the rest of us!!
woo hoo!
Ayn Marx
Trevor Wilson wrote:
>
> **Not quite.
Not quite? Then how much>
If an amplifier uses a well regulated power supply (such as a
> preamp, for instance), then that power supply modulation will be
> immeasurably low in level.
>
> >
> >>
> >> * Power supplies may use regulation elements, which effectively remove
> >> caps
> >> from the equation.
> >
> > aren't regulation elements amplifiers?
>
> **Sort of.
Sort of ? This is getting way too vague , even for me.
>
> >
> >> * Capacitors in power supplies are MUCH larger than any coupling caps.
> >
> > and maybe slower due to L in the foil windings. isn't the primary
> > intention
> > to control ripple due to rectification of ac. yet the signal must pass
> > through them to get to the load.
>
> **There are a variety of methods to eliminate ESL in caps.
Don't you mean ESR?
> One can use a
> large number of parallel caps, or parallel smaller, low ESL(?) caps, or a
> combination of methods. If you think of the power supply capacitance as a
> battery, it may assist with the analogy. With a large enough capacitor bank
> on the power supply, then that supply acts as a 'perfect' DC source. Again,
> consider the action of those capacitors in a highly regulated preamp.
>
I'm waving the white flag & declaring myself way out of my depth here,
besides, the prawn , squid, scallop & trout risotto is calling loudly
from the kitchen.
Patrick Turner
Doug Flynn wrote:
I know your preferrence for iron and wire; I do like them used
in many situations.
But a CCS with a single bjt or fet does have its merits where a choke won't
quite do.
I quite like loading gain stages and cathode followers with a bjt in CCS mode.
In this way the the CCS topology stipulates that the bjt entirely give up its
voltage distorting
properties and become a completly co-operative current slave to the tube's every
desire for current.
It is entirely impossible for a bjt based CCS to impart any sonic signature, and
I know you would
say that your ears don't tell you that.
Using a CCS is like using a 30 megohm resistor taken to some
mythical high supply voltage; the actual current change in a 1Vrms signal is
almost unmeasurable, so how can the CCS influence what the tube does
dynamically?
The current is constant. The only current change in the tube is due to miller
effects and
the cap coupled resisance or tranny coupled following stage, and such items will
affect the performance of the tube MANY times more than a CCS.
I don't like using bjts as voltage amps. Their thd profile is like a pentode's.
Their collector resistance is uselessly high, and their input resistance low.
The can only survive on vast amounts of NFB.
The triode however has the unique properties of mainly even order thd.
When its load becomes many times the plate resistance the thd is minimised
The reason why the thd falls to such a low value when the load is a high value
is because
that's the situation when the electrostatic feedback operating within the triode
is maximally applied between the anode and the flow of electrons.
This feedback isn't to be confused with the miller effect; it operates at all F,
and for example as the grid goes +ve to increase Ia, the anode voltage goes -ve,
and a -ve going anode voltage
tends to reduce Ia, so the Ia depends on the result of TWO electrostatic
forces on the electron flow happening simultaneously.
Put another way, if a +ve distortion voltage should appear at the anode, its
effect tends to increase the Ia, which cause the load voltage to increase, so
the anosde voltage tends to go more -ve because the voltage across the load
is applied between the fixed B+ supply and the anode.
bjts and fets and pentodes don't have this natural FB capability.
The FB capability is put into every triode when it is conceived in the factory
by the God Of Triodes,
and if you don't like NFB in the triodes delevered to you by a well meaning God,
then
use a pentode/bjt/fet, because its screen grid between the control grid we have
talked about
and the anode prevents the electrtostatic NFB from affecting Ia, so
pentodes have much more natural distortion than triodes,
and with a far grreater number of odd and even numbered harmonics.
Anyway, none of what I am saying about the nature of the devices explains the
differences we do hear
in preamp tubes when different brands of the same tube type are swapped around,
with all other factors staying the same.
Its not unusual for a typical triode preamp which
consists of nothing more than a volume pot and gain stage, say a
6SN7 in common cathode direct coupled to an output cathode follower buffer
and with both triodes loaded with 47k to produce 0.015% at
all levels when used with a typical power amp sensitive so
20 watts come from a volt of input.
You could endlessly change the triodes in such a pre-amp and
never see more than 0.015% thd, nearly all 2H, with 3H maybe
15db below the 2H at 0.003%.
Such levels of thd give rise to negigible and totally inaudible IMD,
so blaming triode preamps for poor sound quality due to inherent
SET high distortion levels is complete and utter BS.
Changing the tube brands around reveal sonic signatures you would not
think were possible.
I don't care that we cannot quantify such sonic changes.
> IMHO nothing beats a transformer to load a triode,
> and it has the added benefit of eliminating a coupling cap AND the grid
> resistor of the following stage.
I don't believe tranny coupling is superior sounding to say a 0.22uF and a 470k
R,
with DC supplied to the triode via a bjt CCS.
My clients like amps built this way.
The effective load on the triode is thus the cap coupled 470k.
The load remains high over a wide band of F, and there is no iron distortions.
But well thought out tranny coupling is fine.
> In my experience the grid resistor is just
> as audible as the coupling cap.
I have never detected any audibility of such things myself.
The tube sonic characteristics due to the tube type/choice/brand and
circuit topology are an order of magnitude more important
than bias R and C.
> You can also use the secondary of the
> transformer to apply the bias voltage, thereby eliminating the traditional
> RC bias network.
Yes, this is a real benefit which prevents a grid that has decided to generate a
positive voltage on it with respect to the applied grid voltage supply
from ever goin into runaway due to bias failure.
But the IST usually MUST have some resistance termination
or an RC zobel across the secondary in order to flatten the response and
avoid the typical 6dB peak in the response between say 5kHz and 30kHz somewhere
depending on the LC resonant effect between the shunt C and leakage L which
together
limit BW by forming a second order LC LPF, and if not damped critically
by the right value of shunt R and the Fo of the LC filter, a peak occurs.
Its very basic engineering to get this right, and it stops an amp
acting like a tone control with the treble turned up.
>
>
> This is basically what I've done with my 3 stage 300B amp. It's 6J5GT -->
> SE transformer --> 45 --> SE transformer --> 300B.
Plus the OPT after the 300B.
This will be fine if you have the response flattened.
> All tubes are fixed
> bias. No feedback anywhere thankyou very much.
Except the huge amount in each of the triodes you are using.
The GOT put it there, and one should resist argument with a God who
is in charge of a lot of high voltages.
God inspired NFB is quite OK, the man made stuff
with loopos of resistances etc may be seen as evil sounding
but my clients prefer moderate NFB.
I believe the NFB removes the unwanted artifacts, and lets the
tubes shine at their best.
But any more than about 15dB, and you could say you have not
got the concept right.
In your case with your MF/HF horns and sensitive large old reflex bass boxes
with their fairly constant impedance and the low amount of power you need, say
0.1watts for thunderingly loud sound, SET power is entirely adequate and
will shame many other forms of amplification.
And the 300B can be used with a 5,000 : 4 ohm opt, but
still with say a 16 ohm bass speaker, and the 300B then effectivley
has a 20,000 ohm load, so it operates with utterly negligible thd,
and any argument used to discredit an SET flops miserably.
The damping factor under such circumstances
is also excellent.
The anode resistance of 800 ohms
is 25 times lower than the load resistance in this case.
Used with my ordinary speakers of only 88dB/W/M the 300B isn't my choice,
but I know ppl who do like the 300B with only 8 watts max, wind permitting,
even with VAF I66!
>
> The preamp is a paralleled 6SN7 per channel to push RP down and current up
> (always a good thing in my book) into a 6K6 : 100R SE transformer. The end
> result is certainly the best sound I've heard in nearly 10 years of amp
> building.
Its difficult to make a 6SN7 sound crook.
Patrick Turner.
>
>
> Cheers. Doug
Patrick Turner
Ayn Marx wrote:
I really don't want a long argument about the effects of capacitances in power amps.
The bigger value in uF, the better for the power supply is my motto.
I don't believe low capacitance values of oil filled caps do better in PS
along with high value filter chokes.
That's the old fashioned way to make PS but it just doesn't
stand up to my scrutiny because the amp ends up
being connected to a high output impedance
which rises as F reduces and one that is sometimes resonant.
IMD that could be avoided is the result, and there can be unecessary
LF instability.
Quad II amps have only 16 uF connected to anchor down the
CT of their OPT.
When measuring them the distortion IMD coming as a result of the
PS about equals the THD, which Peter Walker thought was quite acceptable,
and it may be for many ppl but I like to
remove the tube rectifier, replace with silicon diodes, and
have a 100uF , then 200 ohm resistor, then 470uF as the supply elements
prior to the CT connection.
This about eliminates any IMD which results from the PS.
A 16uF has 100 ohms of impedance at 100 Hz,
but 470 uF has only 3.4 ohms.
So the saw tooth ripple noise of 17Vrms that appears at the CT in the original amps
is reduced by an enormous factor, not just by using a 470 uF cap instead of
16uF, but because there is a 3 element CRC filter inplace of a lousy
single 16 uF cap. And the "CLC" supply is non resonant.
While the DC impedance of the supply isn't improved because there is still a
200 ohm R between the Si rectifiers and the amp, one must
remember such amps operate in class A and don't need a
stiff DC voltage output.
PP amps also have the added benefit of CMMR noise rejection.
With all SET amps a CRC or CLC with huge cap values is best imho.
Large supply caps are also beneficial in SS amps for the same reasons.
I don't believe coupling caps and bias resistors spoil the sound.
Some will claim sonic differences, but I have NEVER seen the results
of these people's well carried out AB tests, so I always just agree
with their claims when I hear them claiming.
If they claim cap type X is better, then of course it is, ( to them ).
If they condemn coupling caps altogether, then I'd say they are
sub opimally life experienced or informed.
I have build SS amps with both RC coupled stages and with an OPT and
operating in class A with mosfets and bjts, and with CCS and various loops of
NFB and the sound was indetectably different to a tube amp full of
RC couplings and an OPT with about the same total amount of FB, about 18dB.
I have had ppl here to try to hear any difference, but in my AB tests
while they didn't know which pair of amps was between the
preamp and speakers they could not tell any sound difference,
unless either of the pair was set to a slightly higer level, and then they
always picked the better amp which was 1 dB louder.
I could easily trick them either way.
Both lots of amps used lots of C; the 100 watt class AB tubie
has 1,500 uF at the CT, the 50 watt class A mosfet has 45,000 uF at its CT.
Don't anyone try to tell me oiler caps are better; or that large polypropylene
motor start caps of 40 uF are better than the garden variety Jamicon electrolytics
which at 470uF and 450V rated are 1/3 the size of the 40uF oiler/motor start cap.
The electros made today in their millions are routinely better than they ever have been
because they have to be; they are used almost everywhere in everything,
so nobody like electro failures..
They bypass well up to a high enough F and we have the
history of the SMPS to thank to give rise to some really blameless
electros that when used in a tube amp are working
under very easy condition compared to their intentional
hard life in a SMPS.
And No, I don't think Black Gate are superior.
If someone insists I use exotica, I do, but I have always got
stunning sound quality from caps chosen for their circuit effectiveness
rather than snob value.
I cannot hear any change when i drive a tweeter through a Jaycar
bought bi-polar 3.3uF for $2 or a fancy Wima polypropylene 3.3 uF for $10,
or someother exotica for $50.
I use the Wima so nobody can poke muck at me.
There is serious current through such a cap compared to any coupling cap where
the current is several orders of magnitude less, so the distortion probably
is too, and if I can't hear the cap distortion with a speaker, then i won't
hear it with a coupling cap.
Patrick Turner.
Patrick Turner
Ayn Marx wrote:
Yes they are.
Their purpose in life is to amplify the minute supply changes
to oppose such a change, and they are used routinely to save on the bulk and thus
cost of a large
passive RC filtered supply.
But one rarely ever sees regulation used in any power amps.
>
>
> > * Capacitors in power supplies are MUCH larger than any coupling caps.
>
> and maybe slower due to L in the foil windings. isn't the primary
> intention
> to control ripple due to rectification of ac. yet the signal must pass
> through them to get to the load.
The DC output of a PS does not pass though the caps.
But the AC appearing across the cap is reduced according to
the value of capacitance.
The inductance of the foils used isa negligible impedance
in caps used for their intended bandwidth of bypassing.
Placing a 0.47 uF plastic cap in parallel across a 470 uF PS electro cap
can extend the bandwidth of bypassing up to many MHz.
Patrick Turner.
Patrick Turner
Ayn Marx wrote:
We don't need the ultimate answers to be all spelled out in numbers.
We do need enough appropriate numbers.
We just need good music.
Its possible via a variety of solutions, but guesswork
by the pure subjectevists isn't the way to build sound gear.
Patrick Turner.
Patrick Turner
> Don't you mean ESR?
> > One can use a
> > large number of parallel caps, or parallel smaller, low ESL(?) caps, or a
> > combination of methods. If you think of the power supply capacitance as a
> > battery, it may assist with the analogy. With a large enough capacitor bank
> > on the power supply, then that supply acts as a 'perfect' DC source. Again,
> > consider the action of those capacitors in a highly regulated preamp.
> >
> I'm waving the white flag & declaring myself way out of my depth here,
> besides, the prawn , squid, scallop & trout risotto is calling loudly
> from the kitchen.
Well happily Ayn, you've never come the raw prawn with me...
Patrick Turner.
Jim Gregory
Caps in DC power supplies are not used for AF amplification purposes but for
smoothing and energy.storage . Whatever next?
And some electrolytics in the active circuits are not used for
amplification, either, but allow decoupling and stability, and reduce HF
x-talk if more than one active channel is served..
Trevor Wilson
>
> Trevor Wilson wrote:
>>
>> **Not quite.
>
> Not quite? Then how much>
**It's not a matter of how much. As students of electronics, we all learned
that the power supply caps are part of the signal path. However, in the real
world, this is not quite correct. It is a theoretical concept only. As I
previously stated, one could use a massive bank of filter caps (such as what
might be available to a preamp, f'rinstance) and treat the capacitors more
like a battery. IOW: The capacitors ARE the power source. For musically
relevant periods, anyway.
>
> If an amplifier uses a well regulated power supply (such as a
>> preamp, for instance), then that power supply modulation will be
>> immeasurably low in level.
>>
>> >
>> >>
>> >> * Power supplies may use regulation elements, which effectively remove
>> >> caps
>> >> from the equation.
>> >
>> > aren't regulation elements amplifiers?
>>
>> **Sort of.
>
> Sort of ? This is getting way too vague , even for me.
>>
>> >
>> >> * Capacitors in power supplies are MUCH larger than any coupling caps.
>> >
>> > and maybe slower due to L in the foil windings. isn't the primary
>> > intention
>> > to control ripple due to rectification of ac. yet the signal must pass
>> > through them to get to the load.
>>
>> **There are a variety of methods to eliminate ESL in caps.
>
> Don't you mean ESR?
**The previous post (which, I presume was not written by you) spoke about
ESL. Please refer to that, if you wish. ESL = Equivalent Series Inductance.
>> One can use a
>> large number of parallel caps, or parallel smaller, low ESL(?) caps, or a
>> combination of methods. If you think of the power supply capacitance as a
>> battery, it may assist with the analogy. With a large enough capacitor
>> bank
>> on the power supply, then that supply acts as a 'perfect' DC source.
>> Again,
>> consider the action of those capacitors in a highly regulated preamp.
>>
> I'm waving the white flag & declaring myself way out of my depth here,
> besides, the prawn , squid, scallop & trout risotto is calling loudly
> from the kitchen.
**Then refer to the writer of the previous post.
--
Trevor Wilson
www.rageaudio.com.au
Ayn Marx
Trevor Wilson wrote:
>> >>
> >> **There are a variety of methods to eliminate ESL in caps.
> >
> > Don't you mean ESR?
>
> **The previous post (which, I presume was not written by you) spoke about
> ESL. Please refer to that, if you wish. ESL = Equivalent Series Inductance.
>
Doug Flynn
>> IMHO nothing beats a transformer to load a triode,
>> and it has the added benefit of eliminating a coupling cap AND the grid
>> resistor of the following stage.
>
> I don't believe tranny coupling is superior sounding to say a 0.22uF and a
> 470k
> R, with DC supplied to the triode via a bjt CCS.
> The load remains high over a wide band of F, and there is no iron
> distortions.
>
> But well thought out tranny coupling is fine.
I will stick to my guns and state that tranny coupling is the ultimate.
I've demonstrated this to myself several times. Yes, it costs lots of money
to do right, but when one is pursuing ultra-fi it's worth it.
>> In my experience the grid resistor is just
>> as audible as the coupling cap.
>
> I have never detected any audibility of such things myself.
>
> The tube sonic characteristics due to the tube type/choice/brand and
> circuit topology are an order of magnitude more important
> than bias R and C.
My power amp only has 1 resistor per channel in the signal path, so any
change to those resistors is very noticeable. For example, going from metal
film to carbon film gives the amp a whole new character. If the circuit is
overly complex then you won't notice the difference.
>> You can also use the secondary of the
>> transformer to apply the bias voltage, thereby eliminating the
>> traditional
>> RC bias network.
>
> But the IST usually MUST have some resistance termination
> or an RC zobel across the secondary in order to flatten the response and
> avoid the typical 6dB peak in the response between say 5kHz and 30kHz
> somewhere
> depending on the LC resonant effect between the shunt C and leakage L
> which
> together limit BW by forming a second order LC LPF, and if not damped
> critically
> by the right value of shunt R and the Fo of the LC filter, a peak occurs.
> Its very basic engineering to get this right, and it stops an amp
> acting like a tone control with the treble turned up.
Oh no it doesn't! I agree that on the scope the square wave response looks
a little better with a load on the interstages, but it destroys the sound
completely. Well-made interstages (like the Lancroft and Lundahls I'm
using) don't have serious ringing problems. I've experimented extensively
with terminations, and I like my setup mo' better au naturale.
>> This is basically what I've done with my 3 stage 300B amp. It's
>> 6J5GT -->
>> SE transformer --> 45 --> SE transformer --> 300B.
>
> Plus the OPT after the 300B.
>
> This will be fine if you have the response flattened.
You'd be surprised just how flat the response is in my replay chain, given
the 4 sets of transformers per channel!
> Used with my ordinary speakers of only 88dB/W/M the 300B isn't my choice,
> but I know ppl who do like the 300B with only 8 watts max, wind
> permitting,
> even with VAF I66!
Dude, you really do need to delve into the world of high efficiency. It
frees you from being a slave to the Watt.
Doug
Mr.T
> > **The previous post (which, I presume was not written by you) spoke
about
> > ESL. Please refer to that, if you wish. ESL = Equivalent Series
Inductance.
> >
> Inductance is spelt with an 'L' ?
The symbol used is L, many other units use the greek alphabet. Nothing to do
with spelling though.
>I really am way over my head.
Yes, but no need to worry. I assume you are not going to be an engineer any
time soon.
MrT.
David Nicholls
> "Ayn Marx" <mdh...@iprimus.com.au> wrote in message
> news:1131227015.8...@g43g2000cwa.googlegroups.com...
>
>>>**The previous post (which, I presume was not written by you) spoke
>
> about
>
>>>ESL. Please refer to that, if you wish. ESL = Equivalent Series
>
> Inductance.
>
>>Inductance is spelt with an 'L' ?
>
>
> The symbol used is L, many other units use the greek alphabet. Nothing to do
> with spelling though.
Probably relates to Lenz, of Lenz' Law fame, which is about opposing
magnetic fields induced in conductors, and because 'I' was already used
for current, because 'C' was already used for capacitance...
DN
Ayn Marx
can't understand why you insist on slumming it with some of the
creatures who haunt this place.
Each to their own I suppose.
I can't imagine anyone being silly enough to try and build something
like an amp by guesswork. But come to think of it there was someone
hanging around here who was intending to do very peculiar things with
high voltages. I wonder if he made the wrong guess? ZZZZZZZZZZZT!
S Roby
Arent there many many many caps in the signal path in the recording process
Does this make the whole concept of direct coupled a nonsense??
Phil Allison
"S Roby"
** Absolutely.
The "direct coupled is best coupled " scam has a VERY long history - back
40 or 50 years.
Designers of valve hi-fi amps could eliminate the two capacitors normally
needed to drive the grids of output valves by " direct coupling" the driver
valve. Absurd claims were made for the idea.
At the same time, others were espousing the mysterious virtues of one or
other type/ brand of paper /oil capacitor in this position.
The editors of "radio TV and Hobbies" magazine got so fed up with all the
crapology - they created a new column in the mag called "Let's Buy an
Argument" with the first subject being the one of coupling capacitor
foolishness.
......... Phil
Trevor Wilson
"S Roby" <em...@gooble.gooble> wrote in message
news:ezebf.1061$xD6....@news.xtra.co.nz...
> Arnt there some rather largish caps (& inductors) in the speaker xover
**Not necessarily.
> Arent there many many many caps in the signal path in the recording
> process
**Not necessarily.
> Does this make the whole concept of direct coupled a nonsense??
**No.
--
Trevor Wilson
www.rageaudio.com.au
Phil Allison
"Trevor Wilson"
>
> "S Roby"
>> Arnt there some rather largish caps (& inductors) in the speaker xover
>
> **Not necessarily.
** Wanker's reply.
>> Arent there many many many caps in the signal path in the recording
>> process
>
> **Not necessarily.
** Wanker's reply.
>
>> Does this make the whole concept of direct coupled a nonsense??
>
> **No.
** ME dealer scam artist & wanker's reply.
> Trevor Wilson
> www.outrageaudio.com.au
** Racist pig.
........ Phil
Patrick Turner
Doug Flynn wrote:
> "Patrick Turner" <in...@turneraudio.com.au> wrote in message
> news:436CCF77...@turneraudio.com.au...
>
> >> IMHO nothing beats a transformer to load a triode,
> >> and it has the added benefit of eliminating a coupling cap AND the grid
> >> resistor of the following stage.
> >
> > I don't believe tranny coupling is superior sounding to say a 0.22uF and a
> > 470k
> > R, with DC supplied to the triode via a bjt CCS.
> > The load remains high over a wide band of F, and there is no iron
> > distortions.
> >
> > But well thought out tranny coupling is fine.
>
> I will stick to my guns and state that tranny coupling is the ultimate.
> I've demonstrated this to myself several times. Yes, it costs lots of money
> to do right, but when one is pursuing ultra-fi it's worth it.
What is your idea of a lot of money?
$5 at a sale where someone is selling off some
second hand old ISTs?
ISTs and OPTs that one buys around the traps
which were made in ancient times are usually crap.
The only way to get decent ISTs or OPTs is to buy from
people who really know how, which excludes Hammond, but may include
Lundahl, Plitron, perhaps Sowter and a few others.
But then you could wind the tings yourself like i do but that takes REAL
dedication, and you have to be preapared to write off some of the ISTs
due to any technical knowledge deficit that you may have, but after
4 attempts and a very disciplined measurement regime you just might get
something
that has what you want.
GOSS and wire is about $12 per Kg at the moment, but you must buy 50Kgs of iron
as a minimum order, and $50 worth of wire; that's real money for a hobby.
Plus GST.
>
>
> >> In my experience the grid resistor is just
> >> as audible as the coupling cap.
> >
> > I have never detected any audibility of such things myself.
> >
> > The tube sonic characteristics due to the tube type/choice/brand and
> > circuit topology are an order of magnitude more important
> > than bias R and C.
>
> My power amp only has 1 resistor per channel in the signal path, so any
> change to those resistors is very noticeable. For example, going from metal
> film to carbon film gives the amp a whole new character. If the circuit is
> overly complex then you won't notice the difference.
I have never noticed any sonic difference between metal film or carbon
resistors.
> >> You can also use the secondary of the
> >> transformer to apply the bias voltage, thereby eliminating the
> >> traditional
> >> RC bias network.
> >
> > But the IST usually MUST have some resistance termination
> > or an RC zobel across the secondary in order to flatten the response and
> > avoid the typical 6dB peak in the response between say 5kHz and 30kHz
> > somewhere
> > depending on the LC resonant effect between the shunt C and leakage L
> > which
> > together limit BW by forming a second order LC LPF, and if not damped
> > critically
> > by the right value of shunt R and the Fo of the LC filter, a peak occurs.
> > Its very basic engineering to get this right, and it stops an amp
> > acting like a tone control with the treble turned up.
>
> Oh no it doesn't! I agree that on the scope the square wave response looks
> a little better with a load on the interstages, but it destroys the sound
> completely.
But all my experience shows that many ISTs have a peaked response resulting
in a horrible harsh top end.
Unless you measured carefully, you may not be aware of the phenomena.
I have never noticed complete destruction of the sound due to resistors.
They are one of the most blameless element of amplifier design.
But I realize you have noticed all these things.
> Well-made interstages (like the Lancroft and Lundahls I'm
> using) don't have serious ringing problems. I've experimented extensively
> with terminations, and I like my setup mo' better au naturale.
The ringing, or square wave overshoot is of little concern as long as you don't
get a peaked sine wave response within or close to the audio band.
Every transformer is effectively a BPF, and the rate of attenuation at their
top end of the band is due to shunt C and leakage L acting together
but usually there are several L and C elements acting in a complex randomly
functioning LCR filter, so a steep roll off is normal.
The slope of the roll off is the steepest with the lowest Ra of the triodes you
are using;
the higher the Ra, the gentler the slope, since the Ra is in series with the
LC filter and the damping is purely by the Ra, and not on a shunt R that may be
across the secondary.
Square waves will always look ragged with some ring on nearly every tranny.
Its a normal reaction to resonant circuits being excited bt the transients in a
square wave.
But usually the transients in a square wave have much faster rise times than
you'll
ever measure in the audio waves, so there is no cause for alarm
if there is some ring; a flat sine wave response is all that need worry you.
But many old samples of ISTs were quite poor; some with a 6dB peak at 10khz.
You are on the right track with Lundahl, I dunno about Lancroft;
a colleague said all his trannies were rather roughly wound.
> >> This is basically what I've done with my 3 stage 300B amp. It's
> >> 6J5GT -->
> >> SE transformer --> 45 --> SE transformer --> 300B.
> >
> > Plus the OPT after the 300B.
> >
> > This will be fine if you have the response flattened.
>
> You'd be surprised just how flat the response is in my replay chain, given
> the 4 sets of transformers per channel!
If you are within 1dB from 30Hz to 15khz, maybe it sounds ok.
But don't be too worried. every system I have ever measured with a mic
reveals SPLs varying +/- 5 dB at various places along the band.
Rooms and speakers maul the flat response.
So if one tranny was a bit peaked, and another a bit saggy,
then the response would end up flat.......
> > Used with my ordinary speakers of only 88dB/W/M the 300B isn't my choice,
> > but I know ppl who do like the 300B with only 8 watts max, wind
> > permitting,
> > even with VAF I66!
>
> Dude, you really do need to delve into the world of high efficiency. It
> frees you from being a slave to the Watt.
I just have not heard ANY high efficiency system that is as good as my own.
I waited years until i finally heard a 1/2 decent system that I helped our
friend Joe set up with Altec and JBL horms and large bass reflexes.
he still has more work to do since he is tri-amping, and has no
measurement system to get the levels right or the crossovers adjusted
properly.
I've heard plenty of horn systems that were simply expensive firewood.
I still like my own system better, at the moment its a horror story
for you, 100 watt PP amps with 6 x 6CA7 outputs in UL
with loop FB, and all SEAS drivers in well made boxes,
and a preamp using all SET tubes in ΔΎ-follower mode with a fet front end for the
phono.
I listen without tiring, and the bass is particularly realistic.
When i build all the amps i do build it is a lotta work, but it don't
seem like too much work.
The amps are no more stressed than your 300Bs would be
with your horns, so there are negligible artifacts, and its creamy accurate
sound.
Watt never worried me, and I don't believe he prevented me
from hearing good music.
Patrick Turner.
>
> Doug
Patrick Turner
Ayn Marx wrote:
> Patrick Turner wrote:
> > Ayn Marx wrote:
> >
> > > Doug Flynn wrote:
> > > Snip<
> > > OK, transformers do make LF sine and square waves
> > > > look bizarre, but I can't deny what my ears are telling me. Doug
> > >
> > > I don't doubt you hear what you hear . These kinds of observations, if
> > > backed by ABX results, could prove the interface between electronics
> > > and psychoacoustics is as yet to be properly joined. In other words,
> > > if I may disturb the objectivists, we don't yet have all the answers.
> >
> > We don't need the ultimate answers to be all spelled out in numbers.
> > We do need enough appropriate numbers.
> >
> > We just need good music.
> >
> > Its possible via a variety of solutions, but guesswork
> > by the pure subjectevists isn't the way to build sound gear.
> >
> Patrick, you really are one of the sanest people posting here.
Allison thinks i am demented, but who cares about that slimy excuse for a
person?
> I just
> can't understand why you insist on slumming it with some of the
> creatures who haunt this place.
> Each to their own I suppose.
I have never found a better place to discuss things at the depth i try to go
to,
other than rec.audio.tubes, and here.
All the little groups are mainly do-little people;
few can wear a soldering iron out in a year like I do.
I am not an extremist audiophile, and I tire of small talk.
If you listen to Parliment being broadcast you quickly become aware of
how mainly men carry on in a public forum.
This is no different.
I don't expect to have a dream run.
I expect to get opposed by people left right and centre because its natural for
ppl to be competitive, and the more one says, the bigger the target you become.
My father was in Kuringai Council for a very long time, and was the mayor
for years in the 1960s.
I grew up hearing all about the damn fool arguments that went on all the time.
I am a hopeless public speaker. But I think I know my tube craft.
I am not afraid of getting dirty from hard work and if that
means getting shitty when handling the Phil's of this world then so be it.
>
>
> I can't imagine anyone being silly enough to try and build something
> like an amp by guesswork.
People do though.
One can have only the vaguest of notions and still build amplifiers.
When i was 16 I had built a radio telephone for speaking to a mate of mine.
We used 6V6 and 807s for the Xmitter outputs
We canobolised some marvellous old radios to make transmitters.
all illegal, but I knew enough to do it.
All I had was a volt meter; no CRO, no sig gene, no
other gear; probably my transmitted signal had harmonics all over the bands.
kids will be kids.
I gave up for about 30 years for a different career, then
started building sound gear.
It was as if the whole solid state revolution that was just beginning
in the 60s had never happened.
> But come to think of it there was someone
> hanging around here who was intending to do very peculiar things with
> high voltages. I wonder if he made the wrong guess? ZZZZZZZZZZZT!
I have had a lot of shocks from working on boxes full of voltages.
I have never wanted to build amps using transmitter tubes with
high voltages. One shock from 1,200V can be the last....
Maybe the shocks have charged me up, lest I go flat.
Patrick Turner.
Patrick Turner
S Roby wrote:
Its foolish to claim that direct coupling is solely responsible fot the good
music we hear.
The fact is that in the process of recording music to listening to it later
from speakers,
numerous L, C, and R elements were in the signal path,
several digital manipulations, lots of NFB, and many various active devices,
and its a wonder the music makes it through the jungle.
Patrick Turner.
Doug Flynn
>> I will stick to my guns and state that tranny coupling is the ultimate.
>> I've demonstrated this to myself several times. Yes, it costs lots of
>> money
>> to do right, but when one is pursuing ultra-fi it's worth it.
>
> What is your idea of a lot of money?
> $5 at a sale where someone is selling off some
> second hand old ISTs?
>
> ISTs and OPTs that one buys around the traps
> which were made in ancient times are usually crap.
>
> The only way to get decent ISTs or OPTs is to buy from
> people who really know how, which excludes Hammond, but may include
> Lundahl, Plitron, perhaps Sowter and a few others.
> GOSS and wire is about $12 per Kg at the moment, but you must buy 50Kgs of
> iron
> as a minimum order, and $50 worth of wire; that's real money for a hobby.
I use Lundahl ISTs which set me back $280 AUD a pair. AEM Cores in SA will
make GOSS C-cores in any quantity you want - as long as you agree to pay the
shipping costs they'll make it.
> I have never noticed any sonic difference between metal film or carbon
> resistors.
You've probably got too much crap clogging up the circuit. I only have one
resistor per channel in the entire replay chain, so it's noticeable.
> But all my experience shows that many ISTs have a peaked response
> resulting
> in a horrible harsh top end.
Not the Lundahls. They have decades of winding experience, and judging from
the measurements I have done on them, they seriously know their stuff.
> I have never noticed complete destruction of the sound due to resistors.
> They are one of the most blameless element of amplifier design.
>
> But I realize you have noticed all these things.
Yes, and the differences weren't subtle either.
> You are on the right track with Lundahl, I dunno about Lancroft;
> a colleague said all his trannies were rather roughly wound.
I have several Lancroft OPTs and plate chokes - they are very well made.
They are no longer trading, so it's a moot point.
Cheers. Doug ;-)
Phil Allison
"Ayn Marx"
>
> Patrick, you really are one of the sanest people posting here.
** Pot tells kettle - "you are no blacker than me "
Puke, puke .........
......... Phil
Ayn Marx
Phil Allison wrote:
> ** Audiophool crapology.
> ** Drivel & audiophool crapology.
> ** Audiophool crapology.
>
>
>
> ............ Phil
paul packer
<tre...@SPAMBLOCKrageaudio.com.au> wrote:
>
>"S Roby" <em...@gooble.gooble> wrote in message
>news:ezebf.1061$xD6....@news.xtra.co.nz...
>> Arnt there some rather largish caps (& inductors) in the speaker xover
>
>**Not necessarily.
>
>> Arent there many many many caps in the signal path in the recording
>> process
>
>**Not necessarily.
>
>> Does this make the whole concept of direct coupled a nonsense??
>
>**No.
Disagreeing with Phil, Trevor? You must enjoy being called bad names.
Trevor Wilson
"paul packer" <pac...@iprimus.com.au> wrote in message
news:436ee675...@news.iprimus.com.au...
**Phil's response does not suggest he is disagreeing with me.
--
Trevor Wilson
www.rageaudio.com.au
Patrick Turner
Doug Flynn wrote:
> "Patrick Turner" <in...@turneraudio.com.au> wrote in message
> news:436E0D2B...@turneraudio.com.au...
>
> >> I will stick to my guns and state that tranny coupling is the ultimate.
> >> I've demonstrated this to myself several times. Yes, it costs lots of
> >> money
> >> to do right, but when one is pursuing ultra-fi it's worth it.
> >
> > What is your idea of a lot of money?
> > $5 at a sale where someone is selling off some
> > second hand old ISTs?
> >
> > ISTs and OPTs that one buys around the traps
> > which were made in ancient times are usually crap.
> >
> > The only way to get decent ISTs or OPTs is to buy from
> > people who really know how, which excludes Hammond, but may include
> > Lundahl, Plitron, perhaps Sowter and a few others.
> > GOSS and wire is about $12 per Kg at the moment, but you must buy 50Kgs of
> > iron
> > as a minimum order, and $50 worth of wire; that's real money for a hobby.
>
> I use Lundahl ISTs which set me back $280 AUD a pair.
That's cheaper than making your own.
I have no bad reports in about Lundahl.
> AEM Cores in SA will
> make GOSS C-cores in any quantity you want - as long as you agree to pay the
> shipping costs they'll make it.
Try investigating Eilor Cores made in Israel and sold here by O.H.O'Briens.
at Smithfield in Sydney.
The quality of the cores are better than any of the roughly made C-cores from
AEM.
>
> > I have never noticed any sonic difference between metal film or carbon
> > resistors.
>
> You've probably got too much crap clogging up the circuit. I only have one
> resistor per channel in the entire replay chain, so it's noticeable.
Well as far as I am concerned, what clogs up the listening experience
is that I am not listening to it live; there is the WHOLE recording process
along the way.
Hundreds of pn transistor junctions, a total of maybe 1,000 dB of NFB
applied at many opamps, countless R&C&L components and
non audiophile cabling.
All this if the recording was totally in the analogue realm.
If you have a 1960 vinyl its most likely all the
process was done using tubes, so there were many trannies, and many pentodes,
and all that FB around every device used.
Thern they used a shirtload of FB at the cutting head amp etc........
But meanwhile we can achieve something to keep the sound clean at home
and if you like to leave out R and instead insert L then go fo it.
>
> > But all my experience shows that many ISTs have a peaked response
> > resulting
> > in a horrible harsh top end.
>
> Not the Lundahls. They have decades of winding experience, and judging from
> the measurements I have done on them, they seriously know their stuff.
I have never measured one.
But if well made they shouldn't need termination R.
Its a result of using enough interleaving to get leakage L low
and also keeping the windings apart to reduce C.
All the parasitic resonances are then moved to a frequency well
above the audio band.
>
>
> > I have never noticed complete destruction of the sound due to resistors.
> > They are one of the most blameless element of amplifier design.
> >
> > But I realize you have noticed all these things.
>
> Yes, and the differences weren't subtle either.
>
> > You are on the right track with Lundahl, I dunno about Lancroft;
> > a colleague said all his trannies were rather roughly wound.
>
> I have several Lancroft OPTs and plate chokes - they are very well made.
> They are no longer trading, so it's a moot point.
Lancroft retired.
Many older craftsmen have to hang up the soldering iron sometime.
You could make all your own chokes if you wanted to very easily.
Patrick Turner
>
>
> Cheers. Doug ;-)
Arny Krueger
> Forgive my ignorance Patrick but isn't it the case that
> capacitors used in the power supply are part of the
> amplification chain and therefore claims that many SS
> eschewe coupling capacitors doesn't tell us the whole
> story?
Yes and no.
First off, there are all sorts of amplifiers around that are
truely DC coupled - most of them are some kind of test
equipment, whether for electronic gear or biomedical
instruments which are essentially test equipment for people.
With no known exceptions, this equipment is either
line-operated via power supplies with power supply
capacitors in them, or they are battery-operated and still
may have capacitors in them related to power.
So, just because something has capacitors in its power
supply, does not mean that it does not run effectively down
to DC.
However, there are a few power amps around whose low
frequency response is limited by their power supply caps.
Arny Krueger
>>> Forgive my ignorance Patrick but isn't it the case that
>>> capacitors used in the power supply are part of the
>>> amplification chain and therefore claims that many SS
>>> eschewe coupling capacitors doesn't tell us the whole
>>> story?
>>
>> **Not quite. There are several issues here:
> plenty, don't all ampilifiers modulate the power supply,
> doesn't "not quite" imply they do.
Most power amplfiers have quite a bit of immunity to the
properties of their power supplies. Under normal conditions
almost all power amps will have several volts of ripple on
its power supply when heavily loaded. This is applied
directly to the supply rails of the power amplfier, which
rejects it.
>> * Power supplies may use regulation elements, which
>> effectively remove caps from the equation.
>
> aren't regulation elements amplifiers?
Yes they are, and power amplifiers can be used as regulation
elements.
That's why power supply rejection is an important internal
power amplifier parameter. It's often on the order of 60 dB
or more, or about 1000:1 or more.
>> * Capacitors in power supplies are MUCH larger than any
>> coupling caps.
Yes, but the size of a capacitor does not matter nearly as
much as the other circuit parameters related to it. Power
supply caps work in a low impedance domain, so they have to
be large to be effective.
> and maybe slower due to L in the foil windings. isn't the
> primary intention
> to control ripple due to rectification of ac. yet the
> signal must pass through them to get to the load.
The old problems problems of inductance and resistance in
capacitors has been studied and addressed for decades.
>> * SS amps can (usually) amplify direct current as easily
>> as they can amplify AC.
Indeed - if you bypass the input DC blocking capacitor and
use a servo to replace the function of a capacitor commonly
used to provide bias stability ( a feature already
incorporated in many power amps as part of the origional
design) a power amp could be used as a DC power supply or a
battery charger.
IOW there are from one to two capacitors in most power amps
that keep them from being proper DC amplifiers.
Arny Krueger
news:ezebf.1061$xD6....@news.xtra.co.nz
> Arnt there some rather largish caps (& inductors) in the
> speaker xover
Yes, not to mention the fact that most speakers and
microphones are incapable of response down to DC.
When you're counting caps you're being overly-specific. What
you really want to do is called "counting poles" which
includes things that have properties that are much like
capacitors, but are not exactly capacitors like mics,
speakers, and digital filters.
> Arent there many many many caps in the
> signal path in the recording process.
Typically a minimum of a half-dozen. Likely more. This
number has decreased with the increasing use of digital
processing.
>Does this make the whole concept of direct coupled a
>nonsense??
Of course.
I like PA's phrase - "By themselves an argument".
paul packer
<tre...@SPAMBLOCKrageaudio.com.au> wrote:
>> Disagreeing with Phil, Trevor? You must enjoy being called bad names.
>
>**Phil's response does not suggest he is disagreeing with me.
Not if you happen to be a wanker and racist pig, no. :-)
Trevor Wilson
**Not quite. He is certainly being characteristically abusive, but he is not
disputing my words.
--
Trevor Wilson
www.rageaudio.com.au