"Don Pearce" wrote in message

On Fri, 12 Nov 2004 15:14:33 +0000 (GMT), Jim Lesurf
wrote:


At what level, and at what distortion? I'd also wonder what the cut
squarewave might look like after a few dozen playings...

Worth remembering that a square wave recorded on vinyl will be - in
physical groove terms - a triangular wave, which may not be too bad
from a tracking point of view.

Since the playback device is veolcity sensitive, a triangle shaped groove
would produce a square wave output from the cartridge seems intuitively
clear. However, the idea that the groove is a triangle presumes no RIAA
pre-emphasis. The RIAA playback curve can be approximated by an
integrator. Therfore, the groove shape has to be something like a
differentiated triangle, no?

"Jim Lesurf" wrote in message
...
In article , Trevor Wilson
wrote:

"Tat Chan" wrote in message
...


**16/44 digital can't even reproduce a decent 5kHz square wave. Such a
feat is a doddle for a good vinyl system. Do you think you can hear the
difference between a 5kHz square wave and a 5kHz sine wave? Hint: You
probably can.

What definition of 'decent' are you using here? Just been looking at some
reviews that show 1kHz squarewaves and these show all sorts of ringing,
rounding, droop, etc. Some of which is reported as cutter produced.

**The square waves from my CBS test disk are excellent (when played on the
right equipment). Far better than any CD player I've tested (at 5kHz).



Vinyl only has (at best) 70 - 78 dB of dynamic range, which equates to
12 - 13 bits resolution, and I am sure vinyl is bandwidth limited as
well (cuts off at 16kHz?).

**Nope. In fact, a good vinyl recording can go well past 50kHz. The
mighty Dynavector 10D-II can operate to 60kHz. The square wave
performance of this very fine cartridge is exemplary.

At what level, and at what distortion? I'd also wonder what the cut
squarewave might look like after a few dozen playings...

I don't have info on the 10D/II to hand, but I'm looking at squarewaves
for
the 20A/II and DV100R. No idea how similar these are, but the results do
show a wide bandwidth, albeit with an overshoot and ultrasonic ringing.
Not
clear how much of this is due to the cutter or a matching resonance with
the preamp, though.

**Sorry Jim. Brain fart. I meant a Dynavector 17D-II.



Isn't the extra "frequency content" associated with vinyl a byproduct
of the mechanical replay system?

**In poor systems, yes. In good systems, no.

Depends what you mean. The dynavectors I just mentioned seem to have THDs
similar to most others. i.e. order of 1% around 0dB/1kHz and rising with
both frequency and amplitude, as well as worse as you approach the inner
groove. Hence I would expect them to produce some ultrasonic components
due
to nonlinearity. (This is one reason we have to treat squarewave tests
with
care as the distortion may be making the shape look 'sharper' than a
linear
response sweep would confirm if filtered to remove distortion products. My
experience is that these sorts of things in cartdidges are subject to the
same sort of 'pass the parcel' tweaking as the distortion, etc, in FM
receivers. You can make some measures look nicer by allowing others to
degrade, or by choosing specific circumstances with care.)

**All good points. I'll dig out some 'scope shots for you.


--
Trevor Wilson
www.rageaudio.com.au

On Wed, 10 Nov 2004 19:12:05 -0000, "Keith G"
wrote:

A while back I made a reference to a woolly memory of something I had read
in HFW to do with Tim de P's views on bitrates and their vinyl equivalents
and said I would post a reference to it, if it ever appeared. Well it's
popped up out of the blue and is, of course, nothing like I remembered it.

It's on 2 pages of the April 2004 edition:

http://www.apah69.dsl.pipex.com/keit.../article01.jpg

plus the top left paragraph he

http://www.apah69.dsl.pipex.com/keit.../article02.jpg


The 'bitrates' are nothing to do with vinyl it seems - simply Tim De P's
idea of a minimum requirements for digital to come even close.

And we're all well aware that 'crazy Tim'is not fully resident on
planet Earth. Typical valvie, on current evidence............

Now, having said all this, I still have another memory that there are some
pretty impressive figures somewhere that compare vinyl 'information flow'
very favourably with digital bitrates, but I've no idea where from and have
no intention of trying to find out.

Commercial vinyl has a dynamic range of 75dB on the best day of its
life, and a bandwidth of less than 20kHz, regardless of what the
cartridge *could* respond to. This may be fully captured by a 13-bit
digital sampling system running at 40k samples/sec, so in fact the
'information density' is significantly less than that of CD.

- I don't need to, I *know* there's more
detail in vinyl played on decent equipment.

Sure you do, dearie, and you've been told just how this *trick* is
done....................
--

Stewart Pinkerton | Music is Art - Audio is Engineering