"Goofball_star_dot_etal" wrote in message
...
On 3 Jan 2004 05:52:39 -0800, (John
Atkinson) wrote:
No, Mr. Krueger, I have plenty of test LPs. But there is no way of
knowing
a) that the signal source used to prepare the master was set precisely
to
the specified frequency and b) that the cutting lathe was turning at
precisely
the correct speed. All the reviewer can do, therefore, is specify the
test
record used and the result obtained. A strobe, BTW, indicated that the
Linn
did turn at 33.33 rpm.
This is not actually true. You don't need to know the frequency of
the signal source _and_ the speed of the cutting lathe. You _just_
need to know the number of cycles/ revolution and this is something
that can easily be measured using just the LP and a soundcard and some
sort of audio editor. The sound card does not need an accurate
timebase either. If you don't follow, you could search google groups
for "John's dad say : "Ratiometric measurement lot better than kick in
balls."
You can't tell rotational accuracy if the test record has more w/f than the
table under test.
I think that this may well be the case, we are talking about very small
values here. The strobe may also not be accurate enough.
The only way to do this would be to set up some kind detector on the platter
itself and this could measure the accuracy of rotation. The effects of the
tone arm, and cartridge however cannot be determined this way.
The crux of the problem is that turntable performance can only be measured
in a partial way. Even if the exact same test record were used to compare
tables, the combination of effects could mask defects, or exaggerate them.
The net result however is as you say, a lot better than a kick anywhere
Carl