"Stewart Pinkerton" wrote in message
...

Well, to be precise, he used excellent output transformers. The
amplifier topology itself was pretty much standard.


To be even more precise: he designed these transformers,
and they were wound in his own factory.

If you recxall the launch of the STA100 at the APRS mid sixties,
you will remember that it was considered rather special.
100W over three valve stages was not commonplace then.

Iain

"Dave Plowman (News)" wrote in message
...
In article ,
Iain M Churches wrote:

Flat response doesn't seem to be a problem.
Audio amplifiers don't need to be DC to daylight.

Troo. But it would be nice if they were flat within the human audio
spectrum, something apparently near impossible with valves...

Come on, Dave. If you are talking about +/- 0.5dB then you know
that 15Hz to 50kHz is not difficult to achieve,
even in a glow-in-the-dark amp.
I can't speak for SS amps, but I know that valve amps
often measure better than their specifation. Those from China
are probably an exception.


Iain

"Stewart Pinkerton" wrote in message
...
On Fri, 29 Oct 2004 15:31:22 +0300, "Iain M Churches"
wrote:
Flat response doesn't seem to be a problem.
Audio amplifiers don't need to be DC to daylight.


"Stewart Pinkerton" wrote in message
. ..
Quite so. The valve amp designer would be laughing in an embarrassed
way, because of his inability to achieve a flat response............
--
They do however need to be flat +/- 1dB *at full power* from 20Hz to
20kHz. This is *very* challenging for a valved design.

I am surprised that as a proper engineeer you did not use the term
"power bandwidth" but nevermind.

Presumably you are referring to the limitations of the output
transformer.

I have just looked at the spec of the STA100 and the STA25
which are the two amplifiers best known to me.

Both have a power bandwidth in excess of the figure you quoted.
My own humble 50 watt amp has a FR of 10Hz-60kHz and a power
bandwidth of 20Hz-45kHz.

If you wish to confirm this, I can let you have the transformer type
numbers, and you can check with Sowter UK.



Iain

On Sat, 30 Oct 2004 08:03:03 +0300, "Iain M Churches"
wrote:


"Stewart Pinkerton" wrote in message
.. .
and I believe him to be the inventor of
the transmission-line loudspeaker.

Nope, that was around for decades, indeed the tapered transmission
line speaker was patented by STC in the '30s, being 'prior art' which
confounded B&W's attempt to patent the 'Nautilus' design. The modern
implementations are generally held to be descended from the work of A.
R. Bailey, as published in Wireless World in 1965. The well-known
Radford and IMF designs are definitely descended from Bailey's work.

Arthur Radford and Dr Bailey worked in close co-operation.
I am told they share a patent from the mid sixties.

Quite so, and Bailey also helped improve the STA series amplifiers.
The original patents for the transmission line speaker do however stem
from the '30s, when it was described as an 'acoustic labyrynth'. I
suspect that the Bailey/Radford patent was restricted to the UK,
whereas B&W were after world-wide recognition for the Nautiluis.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Sat, 30 Oct 2004 08:10:03 +0300, "Iain M Churches"
wrote:

"Stewart Pinkerton" wrote in message
.. .

Well, to be precise, he used excellent output transformers. The
amplifier topology itself was pretty much standard.

To be even more precise: he designed these transformers,
and they were wound in his own factory.

If you recxall the launch of the STA100 at the APRS mid sixties,
you will remember that it was considered rather special.
100W over three valve stages was not commonplace then.

Indeed yes, I've always supported the STA series as good examples of
classic valve design, having few of the usual valve amp foibles. As
ever, God is in the details................
--

Stewart Pinkerton | Music is Art - Audio is Engineering

"Iain M Churches" wrote in message

"Dave Plowman (News)" wrote in message
...
In article ,
Iain M Churches wrote:

Flat response doesn't seem to be a problem.
Audio amplifiers don't need to be DC to daylight.

Troo. But it would be nice if they were flat within the human audio
spectrum, something apparently near impossible with valves...

Come on, Dave. If you are talking about +/- 0.5dB then you know
that 15Hz to 50kHz is not difficult to achieve,
even in a glow-in-the-dark amp.

Perhaps the firebottle amp will do that into a resistive load. However
things tend to fall apart if you are silly enough to attach a speaker to
it...

In article , Ian Molton
wrote:
Stewart Pinkerton wrote:

Well, to be precise, he used excellent output transformers.

A fair few of which may well have been wound by my dad...


Tell me more. :-)

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Keith G wrote:
"Tat Chan" wrote in message
...

Keith G wrote:


that's the whole point, isn't it?
'wire with gain'



No, not with me it isn't. My systems are 'sound producers' in their own
right. I play records for *that* sound - I'm not too bothered how it relates
(in the nth degree) to what went down at the time of recording, which was
before I was born in some cases.




snip system pairing of valves and speakers

OK, that's good - how about then if these opinions and preferences are
expressed in 'non-engineering' terms, as mentioned above??

I don't have a problem with that, as should be the case with everyone
else. After all, you are expressing opinions and preferences, and not
technical details.

Thank you - it ain't hard is it? (Easy to turn it in to a punch-up though,
if that's what you are really wanting....)

nope, not after a prolonged argument here.

On the other hand, 'high fidelity' would be a scientific claim ...

Yes, but still so subjective as to be virtually useless.

no, not subjective in terms of electronics (i.e. source and amp). If the
electronics manage to produce an exact copy of the signal on the source
and feed it the to speaker terminals, then that is by definition, 'high
fidelity'. What happens when the amplified signal reaches the speaker terminals
on the other hand, is a different matter. Speaker measurements are an entirely
different thing of which I am do not have much knowledge on.

I have often said I
don't like the term 'hifi' here in the past (ignored by those who found it
more useful, so to do) as it really only ever was a marketting term used to
sell audio gear.


If 'fidelity' was to have any meaning in the sense of a
quantifiable relationship between input and output signal than some figure
would need to be produced to allow scientific comparison, don't you think?
(Percentages perhaps?)


see my reply above. Within an audio context though, the definition of fidelity
can be loosened a bit, as some distortion of the input signal can be allowed as
human hearing can pick up changes below a certain threshold (0.5, 1 dB?)

snip

That's the whole point - who TF has *ever* made any such claim? There are
those (spot the 'tact' here) who *choose* to interpret the word better as
fake, scientific claims for the purposes of showing off and exercising
their 'debating skills' to make up for a boring day or summat.

You snipped out my smiley ... the last definition of 'better' was an
attempt at scientific stereotyping ...



No, I saw the smiley - the remark I made wasn't directed at you - sorry if
it appeared it was.



Ah, OK.


What is especially laughable is the suggestion that a 'ruler flat' FR
graph means *anything* at all in the real world. I could give you the
phone number of a valve amp designer who will laugh his arse off if you
start arguing 'ruler flat' anything!!!

I would have to disagree here (and the technical posters can correct me if
I am wrong).



No, **** the 'technical posters' - I'm interested in *your* viewpoint here,
not theirs.


well, I gave my viewpoint which is what I believe to be correct. If someone else
points out that it was wrong, than I am prepared to look at what I said that was
wrong.



Having a flat frequency response means no frequency component is
attenuated or amplified disproportionaly to othe frequency components,
which means that the ouptut waveform is just a larger version of the input
waveform. If the FR graph isn't ruler flat, then certain frequencies would
be exagerrated during playback.



Yes, agree entirely but my point is that no FR is truly 'flat' and I suppose
I'm trying to match opposite and oposing deficiencied to create an
artificial 'compound flatness'..??

yes, no FR is truly flat, but I guess 'flat enough' means the changes from the
flat response are small enough that the human hearing system can't detect those
changes.


But as I have said before, like others I am more interested in the 'end
product sound quality' than any relationship (real or imagined) it may (or
may not) have to the 'original', recorded sound.

sure, at the end of the day, you are the one listening to your audio system.


A poor analogy, but think
of a fantastic oil painting, stand back far enough and compare with a
photograph of the same image. What do you want - 'information' or a 'deeply
satisfying emotional experience'??

Depends on how I feel, but I would like to know which of the two I am experiencing.

Keith G wrote:

"Tat Chan" wrote

Is my regular and frequent use of 'digital' also noted? Let's see if we
can straighten you out Tat, it would be a start.

yes, you have stated lots of times that you play CDs regularly as well,
but you have stated that you prefer vinyl to CD.


Is that a problem?



Not at all.


Have you *never* seen me post 'valves are not for everyone'...???

(Before your time?)


I can't remember if you did, but a search through the archives should
bring it up.

Off you go then.


Found it in the thread you started called 'The main reason valves & vinyl is
better...' but I didn't get too far into the first post as there was a fair bit
of aggro in it.

Glenn Booth wrote:

Hi,

In message , Tat Chan
writes


out of curiosity Glenn, what speakers are you using at the moment?


Sore point. At the moment I'm switching between Kef Q35s (which just
don't work in this room) and an ancient pair of Heybrook HB1s (original
version, very bright sounding but they do work in the room).

Bugger. Hate it when that happens.

I've been
holding off on an upgrade as we're moving house sometime soon. Wifey
gave me an "IOU" birthday present, which I intend to trade in for a pair
of ESL63s once we find a house.

nice one. My partner didn't like the idea of me getting a pair of Mission 774
floorstanders on the cheap. Oh well, someone else did beat me to them in the end.


I'm pretty happy with my amp, and the next big upgrade for me would be
a better pair of speakers and listening environment!


Speakers make all the difference, IMO. Room treatment can also make a
very big difference - I decorated my room a while back, and it ruined
the acoustics somehow.


what decorations did you put in? Maybe extra damping was needed after the revamp.