In article , Java Jive
wrote:
On Tue, 08 Nov 2011 17:26:03 +0000 (GMT), Jim Lesurf
wrote:

In article , Java Jive
wrote:

I've only ever found one actual figure for the THD of vinyl
production, and it was a little suspect in that it didn't come from
an authoritative source, but IIRC it was around 7%.

Actually, it's a bit more authoritative than I remembered:
http://www.hometheaterhifi.com/techn...e.html?start=1

I'd be interested to hear your opinion, Jim, if you have time.

I'll have a look at that and some of the other items you mentioned when I
get a chance. I'm in a bit of a 'publication time panic' at present. :-)

You can find some simple measurements on

http://www.audiomisc.co.uk/HFN/LP4/NewLampsForOld.html

but that relates to 'best case' in many ways.

Very interesting read, but, with respect to both your undoubted
expertise and my original point, like the article I referenced (as it
has turned out now that I've found it again), that is only the playback
part of the process. To get the full figure, we need to know the THD
introduced in cutting the master and pressing the vinyl as well.

You may be overlooking the fact that the test LPs I used were also cut and
pressed. But I agree that these may have been made with much more care than
ye olde EMI knock-outs.

The figures *do* need to be seen with caution, though. For example, they
were done with a track well away from the center of the LP. So avoid
end-of-side problems. And HF difference (L-R) modulation often gives *much*
higher values unless the modulation level is very low. And HF/LF intermod
can be very high at the end-of-side for the same reasons. Not good for
something like stereo massed strings and other instruments at an orchestral
climax.


I've not had any access to academic libraries or other technical
resources for some time. Apart from the article linked above and now
your own, I've not been able to find much from authoritative sources
online.

Alas overall the AES and its members has long lost interest in LP. The
closest you get is people using things like laser scanners and optical
systems to read old discs and process them into audio. But there were many
measurements and sets of analysis in the past. The bottom line, though, is
that it varies a lot from one LP to another - to the point pun that which
stylus/cart/geometry works best for one LP won't be best for another. Not
just a matter of cutting angles, etc. Also questions like the elasticity
and elastic limits of the specific 'vinyl' sic used for that LP.

One of the reasons most AES members stopped taking an interest in
'analogue' is that they got very aggressive abuse from some audio
enthusiasts when they showed they doubted what some 'golden ears' and
'high end' makers claimed.

Perhaps I should out on my (long) 'to do' list a review of what was
measured and published in the past about topics like LP distortion. I did
deal with noise and dynamic range, but that is easier to summarise.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

I haven't seen a "is vinyl magical" flamewar for ages.

Makes me almost nostalgic.

Almost.

BugBear

On 08/11/2011 22:37, Java Jive wrote:
snip

At the end of the day, I consider all analogue recording processes to
be obsolete, that those who prefer them are misguided (but their
preference is their own affair), and that those who claim that they
are somehow better than digital are at best deluding themselves, at
worst fraudulent, and that the wider interests of science and
technology lie in exposing these latter whenever they are encountered.

What do you mean by 'exposing'? How can a preference be wrong, or a lie
(etc.)?

Rob

On 08/11/2011 19:37, Steve Thackery wrote:
Rob wrote:

Distortion doesn't cover a variable yet to be discovered. And please
don't ask me what that might be :-)

Sorry, mate, but you can't get away with that old chestnut in a proper
argument. :-)

It's like Christians asserting that the existence of God can never be
established scientifically, because He is beyond the realm of scientific
enquiry.


Well, that's not such a good example because God is a human construct.
Sound isn't.

My position is quite simple. I think, in large part, that analogue
recording and replay is preferable to digital. Obviously, I'm not alone.
Many artists prefer the sound, and demand for analogue media and
hardware has if anything increased in recent years.

I simply want to know why that preference exists. I'd love to do without
the faff of vinyl.

You see? It's a self-serving argument that leads nowhere. It is up to
you to offer a vaguely feasible suggestion as to what this mysterious
variable is. It is up to Christians to demonstrate why God might be
beyond the reach of scientific enquiry (which, so far, appears to have
no in-built limits).


If I get the time or I stumble across a decent explanation I'll let you
know!

By the way, does this variable of yours have to comply with the known
laws of physics? If so, then you're going to struggle. The science and
mathematics of analogue and digital signals are extremely well established.

If not, then you've got an even bigger job on your hands. :-)


Doubt very much it'll be my job. But don't be surprised if I report 'I
told you so" and some time not too distant :-)

Rob

In article ,
Steve Thackery wrote:
Dave Plowman (News) wrote:

Before you can do any subjective comparisons, you would need to hear a
single live instrument in a room and record it with a mic close to
your ear - then reproduce with a loudspeaker in the same room.

Even that is questionable. Assuming your electrical bits are
"perfect", then you want the microphones to be placed where the
loudspeakers will be during playback. Thus the loudspeakers can
reproduce exactly what the microphones heard, at exactly the same place.

You site the speaker where the instrument is.

I suppose microphones placed at your ears would require loudspeakers
placed at your ears - open-backed headphones, maybe?

That's one other way.

--
*Where do forest rangers go to "get away from it all?"

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

"bugbear" wrote in message
o.uk...
I haven't seen a "is vinyl magical" flamewar for ages.

Makes me almost nostalgic.

Almost.

"Valve amps better than transistors" next.

How about "horn loudspeakers better than cone speakers"?

--
Max Demian

In article ,
Jim Lesurf wrote:
Never mind. I'm currently trying to write a sort of 'potted history' of
the use of PCM/NICAM for BBC radio. That may help people to discover
just what has been done during the last few decades. It is quite a
remarkable story, and shows how good the BBC engineers were! Alas, now
largely forgotten by the public *and* the BBC itself!

BBC Engineering Training Department at Evesham had a device which allowed
you to select the various options for A to D and D to A conversion. Most
arrived at the same conclusion as those who specced NICAM - that the
figures chosen were where only very few thought there was a difference. Of
course many would have wished they'd gone a couple of steps higher than
that to be sure to be sure. But overall costs were an issue then as now.

--
*In "Casablanca", Humphrey Bogart never said "Play it again, Sam" *

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

In article , Dave Plowman (News)
wrote:
In article , Jim Lesurf
wrote:
Never mind. I'm currently trying to write a sort of 'potted history'
of the use of PCM/NICAM for BBC radio. That may help people to
discover just what has been done during the last few decades. It is
quite a remarkable story, and shows how good the BBC engineers were!
Alas, now largely forgotten by the public *and* the BBC itself!

BBC Engineering Training Department at Evesham had a device which
allowed you to select the various options for A to D and D to A
conversion. Most arrived at the same conclusion as those who specced
NICAM - that the figures chosen were where only very few thought there
was a difference. Of course many would have wished they'd gone a couple
of steps higher than that to be sure to be sure. But overall costs were
an issue then as now.

FWIW The NICAM '2' experimental system did try 14 companded into 11 bits
per sample. But the links of the time couldn't fit that in with the
required number of channels, and it was decided that 10 was fine anyway.
Hence NICAM 3.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

In article , Jim Lesurf
wrote:
In article , Java Jive
wrote:


Actually, it's a bit more authoritative than I remembered:
http://www.hometheaterhifi.com/techn...e.html?start=1

I'd be interested to hear your opinion, Jim, if you have time.

Three quick comments.

They used the same test LP as I did for distortion. FWIW I'd recommend it
over the alternatives I tried. However I chose the bands that step or sweep
the frequency or level to probe how that changed the distortion.

Making tests with a single tone isn't that revealing. It would make more
sense IMHO to use a set of tones that would represent something like an
equal-tempered chord. (i.e. with no simple integer ratio between all the
components). That helps get away from the idea that the distortion must be
pleasing as it is 'just second harmonic'. Yes, that does just tweak the
harmonics for a single note on an idealised instrument. But in reality,
music isn't so simple. :-) Alas, no-one makes an appropriate test LP.

If you test *difference* component (i.e. vertical motion) you may well find
the result isn't mainly second-order. As with FM, stereo makes a lot of
difference pun. ;-

However it is very hard to predict this as it varies such a lot from one
example to another. What did seem sad to me was that an ancient V15 should
do so well compared with modern designs.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

"Java Jive" wrote in message
...

Very interesting read, but, with respect to both your undoubted
expertise and my original point, like the article I referenced (as it
has turned out now that I've found it again), that is only the
playback part of the process. To get the full figure, we need to know
the THD introduced in cutting the master and pressing the vinyl as
well.

The distortion in cutting the master and pressing the vinyl seem to be
included in Jim's measurements.