Ian Molton wrote:

Did he work at Ashton Vale? I went there a couple of times.
Everything, including transformer winding and chassis metalwork
was done in house.

He worked in Bristol. No idea where Ashton Vale is though.

It's in Bristol, just south of the river from the main part of the city

"Iain M Churches" wrote in message
...

"Dave Plowman (News)" wrote in message
...
In article ,
Iain M Churches wrote:
I am not trying to pass the buck here, but don't you agree
that the main problem is the shifting impedance of some
loudspeakers at various points within the frequency spectrum?

Perhaps you'd have a go at designing one where this doesn't happen? ;-)

Alas. 'Tis a task for better men than I :-))

Though come to think of it, I did once get
quite a good sound from two National Health
Dried Milk tins, connected with a length of
wet string:-))

Iain


Must be tweaking? Dry string for milk tins as telephones and wet string for
antenna ;-)

In article , Iain M Churches
wrote:

"Dave Plowman (News)" wrote in message
...
In article , Iain M Churches
wrote:
I am not trying to pass the buck here, but don't you agree that the
main problem is the shifting impedance of some loudspeakers at
various points within the frequency spectrum?

Perhaps you'd have a go at designing one where this doesn't happen? ;-)

Alas. 'Tis a task for better men than I :-))

Actually "in principle" [1] it is "easy" sic. You just measure the
speaker's impedance/frequency pattern, then work out the conjugate, and
connect them together. ta-daa! a resistive load.

Snag 1: easier said than done.

Snag 2: usually means a lower load impedance and a lower efficiency. Thus
making *more* work for the amp designer.

Slainte,

Jim

[1] This term is a trademark used by academics. You may encounter other
trademarks like "it can be shown that", and "it is obvious from first
principles that", etc... ;-

--
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

In article , John Phillips
wrote:


It's certain that even moderate quality modern vinyl has more dynamic
range than many people think.

It becomes difficult to quantify this for various reasons. e.g. distortion
tends to rise rapidly as you go above 0dB ref level, and also varies with
cartridge, etc, as well as frequency, etc, etc. e.g. Once the distortion
goes above, say, 20% is the result much different from being clipped?

However a single figure does not give the
whole story - see for example the noise floor plots in
http://users.bigpond.net.au/christie/comparo/part4.html.

As I understant it, the vinyl noise floor above 1 kHz can certainly take
the dynamic range of a good tape recording. However what puzzles me is
the effect on ambience of the steeply rising noise floor ("surface
noise"?) below 600 Hz or so.

Fortunately (for LP), human hearing tends to become less sensive as the
frequency goes below the order of a 100Hz.

It is my understanding (maybe this is faulty) that the much prized
ambience ("air" etc.) of a recording has a rather large and important
component at low frequencies. While (from a non-expert point of view)
the situation indeed appears to be that good detail above 1 kHz may be
reproduced without using compression, I am puzzled about the effect of
the surface noise on ambience if you do not use compression. This is
especially so as vinyl is often said to be better than CD in this
respect.

For me, the snag here is that I am not at all sure that the term "air" is
being used to mean the same thing (in terms of signal properties) by all
those who use the term. Hence we may have to clearly agree the meaning of
the term in a way that can be related to the characteristics of the signal
in an appropriate way before we can deal with the question you raise.

FWIW I don't personally associate 'air' in this context as being the
natural background sounds you get when the specific instrument is not being
played. I associate it with a natural sound for the 'acoustic' in terms of
the reverberation and apparent room acoustic induced by the instrument
itself.However I am far from sure that this is the kind of definition most
people would be assuming.

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

"Iain M Churches" wrote in message

"Arny Krueger" wrote in message
...
"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

Surely, no one tests into a purely resistive load any more.

It's the law in the US for consumer home amps.

It's the standard way that power ratings are defined.

It's often a more severe test of power supplies and heat sinks than
speaker-like load testing.

I am not trying to pass the buck here, but don't you agree
that the main problem is the shifting impedance of some
loudspeakers at various points within the frequency spectrum?

Reactive load testing is far more of a problem for fire bottles than modern
solid state.

On Sat, 30 Oct 2004 08:15:18 +0300, "Iain M Churches"
wrote:


"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.

Yeah, riiiiight.

Those from China
are probably an exception.

Okeley Dokeley. Quote me one valve amplifier from any manufacturer,
which is specified at 15 Hz to 50kHz, even to 1dB *at full power*. Not
a problem for any decent SS amp, but unheard of with valves.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Sat, 30 Oct 2004 08:31:25 +0300, "Iain M Churches"
wrote:


"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.

I'm not surprised that a slider jockey would be unaware that the term
'power bandwidth' implies -3dB, but never mind.

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

Generally, that does indeed set the limit, especially at the low end.

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

There are better nowadays, but those indeed remain excellent examples
of their type.

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.

See above. A full-power bandwidth of 20-20kHz +/- 1dB implies a -3dB
'power bandwidth' of 10-40kHz. The low end is always a weakness with
valves.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Sat, 30 Oct 2004 12:58:15 +0300, "Iain M Churches"
wrote:

"Stewart Pinkerton" wrote in message
news
Quite so, and Bailey also helped improve the STA series amplifiers.

My recollection is that the STA series II and III were
established before the co-operation between Arthur
Radford and Dr Bailey began.

Check out Woodside Audio, also Wireless World in the '60s. Definitely
a joint venture.

I also recall that on a visit to Ashton Vale,
we listened to and were impressed by a
transistor amplifier that Dr Bailey had designed.

I
suspect that the Bailey/Radford patent was restricted to the UK,
whereas B&W were after world-wide recognition for the Nautiluis.

It would be intersting to know for certain.
Do you have the time to do a liitle
research?

Nope, I'd have to spend money to access the relevant patents! :-)
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On 30 Oct 2004 09:52:35 GMT, John Phillips
wrote:

In article , Iain M Churches wrote:

"Stewart Pinkerton" wrote in message
...
On Thu, 28 Oct 2004 21:14:57 +0300, "Iain M Churches"
wrote:
Please do not give the impression to people that music has to be
compressed
for disc cutting, This definately not the case, especially in the case of
classical
music which rarely needs any treatment whatseover, perhaps a dB or two of
peak limiting but no more.

Were it not the case, then we wouldn't have people claiming that they
can hear low-level detail on vinyl that they can't hear on a CD of the
same performance, now would we?

If they say then can, then we must assume they can. One cannot cannot get
inside aonther listener's head, as it were.

But please do not use compression as an explanation.

It's certain that even moderate quality modern vinyl has more
dynamic range than many people think.

No, it isn't.......

However a single figure does
not give the whole story - see for example the noise floor plots in
http://users.bigpond.net.au/christie/comparo/part4.html.

Note that her work has been extensively discredited, and is very shaky
at best.

As I understant it, the vinyl noise floor above 1 kHz can certainly take
the dynamic range of a good tape recording.

Not really, since the replay response drops at -6dB/octave above 2
kHz.

However what puzzles me
is the effect on ambience of the steeply rising noise floor ("surface
noise"?) below 600 Hz or so.

It is my understanding (maybe this is faulty) that the much prized
ambience ("air" etc.) of a recording has a rather large and important
component at low frequencies.

Yes, it does, and phase response ids particularly imprtant.

While (from a non-expert point of view)
the situation indeed appears to be that good detail above 1 kHz may be
reproduced without using compression, I am puzzled about the effect of
the surface noise on ambience if you do not use compression. This is
especially so as vinyl is often said to be better than CD in this respect.

It is only so said because compression lifts what *should* be
low-level detail, and there are lots of midrange phase problems, which
give a *spurious* impression of 'ambience' to LP. If you do any live
recording, compare and contrast with a real master tape, which can be
essentially perfectly transferred to CD-R but may sound rather 'dry'
to those who are used to vinyl.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Wed, 27 Oct 2004 18:10:17 +0300, "Iain M Churches"
wrote:


"Dave Plowman (News)" wrote in message
...
I envy you your collection of unusual discs - I'm more into
tape. Can play/record pretty well any mono or stereo format ever -
including 8 track cartridges and Elcassette. No multi-track beyond 4,
though, - the machines are too large. ;-)

I thought the Elcassette was an excellent format in the applications for
which it was intended. Great shame it didn't catch on.
Like Betamax it was the better of two formats on offer at the
time I think . Oh God. Am I going to get showered with Anglo-saxon
vocabulary:-(((((

Elcaset was indeed technically excellent when compared with
Musicassette. However, Betamax was *not* the best of the available VCR
technologies. I still have a Philips Video 2000 recorder...... :-)
--

Stewart Pinkerton | Music is Art - Audio is Engineering