In article ,
Tat Chan wrote:
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?)

Although it's easy to ascertain the minimum level change the ear can
discriminate against, working out the same thing for a change in harmonic
content ain't. Extremely subtle changes in these relationships are very
difficult to quantify although apparent to the ear.

--
*I took an IQ test and the results were negative.

Dave Plowman London SW
To e-mail, change noise into sound.

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. 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.

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.

--
John Phillips

"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.


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?


Iain

"Tat Chan" wrote

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.


OK, that reads like a personal 'you' again - it's a general 'you' (ie not
*you* personally.... ;-)


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.


Exactly, speakers are the last word in any system after which the room takes
over, which is why I'm not ****ing blood worrying *too much* about the nth
degree of 'fidelity' which is most likely way beyond my hearing/perception
anyway.....

rest snipped - no time

"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.
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?


Iain

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? ;-)

--
*What was the best thing before sliced bread?

Dave Plowman London SW
To e-mail, change noise into sound.

In article , Iain M Churches
wrote:

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

Yes and no. :-/

If you can face reading some of the current audio magazines you will find
that they tend to either:

A) do no measurements at all.

B) only check the power into a few resistive loads, or just into 8 ohm
resistors.

Some 'reviews' go further, but many do not. Others now simply call
themselves 'auditions' and use this as a way of washing their hands of
doing any measurements that might tell anyone other than the writer
concerned anything that might help them decide if the amp (or speakers)
might be suitable for anyone other than the person writing the 'audition'.

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?

Yes and no. :-)

It may become a 'problem' when the amplifier does not maintain a low source
impedance, or can't deliver high currents without limiting, or can't handle
some loads without instability.

The above is one of the factors that can make commercial design of power
amps a nightmare. You can be sure that all kinds of weird loads will be
connected to the output, and have to try and ensure that the amp still
works OK in as many cases as seems feasible.

Hence this is partly the LS designer's responsibility, and partly the amp
designer's. Alas, since the amp designer knows what boogers some LSs are,
they feel obliged to try and cope... This then encourages LS designers to
come up with even wierder loads. 8-]

Snag is, that it is not much use to customers for the designers to try and
pass the parcel as to who is responsible. They just want their amp to work
with their speakers.

Then, having spent time and effort on all this, and made an amp that deals
with all sorts of loads, the magazine reviews makes no attempt to check
this area, and instead recommends another amplifier which has not been
developed in the same way, and may have all kind of interaction problems.
:-/

Alternatively, if the designers of a specific amp go out of their way to
point out their design is good in these areas, it may be tested for them.
But then there will be no real comparison results for many competing
designs...

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

"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

Iain M Churches wrote:
"Ian Molton" wrote in message
...

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...


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.

Jim Lesurf wrote:
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. :-)

As the story I remember was from when I was bout 10 I thought I'd ring
and ask him...

Apparently he had nothing to do with the audio ones, but did wind some
6V ones. I also recall something about some monster transformers used to
melt ice in drainpipes (this in the days when drainpipes conducted
electricity) by shorting the drainpipe across the secondary.

He was in a hurry so I didnt have time to talk much. Apparently one of
his mates new the girl that would most of the opts.