John Byrns wrote:

In article ,
Eiron wrote:


John Byrns wrote:


In article ,
Eiron wrote:

You have that graph upside down. HF is boosted for disc cutting
and reduced on playback to reduce noise (among other reasons).


No, I have the graph exactly the correct way around. The RIAA disk
cutting curve reduces the high frequency groove amplitude by roughly 12
dB using a shelving equalizer with time constants of 318.3 usec. and 75
usec. You are the one that has his RIAA groove amplitude graph upside
down, I suggest doing a little homework before making further comment so
as not to embarrass yourself in public.

I suggest doing a little homework before making further comment
so as not to embarrass yourself even more in public.
And just to get you started:
http://en.wikipedia.org/wiki/RIAA_equalization



It is always best to read the Wikipedia with a jaundiced eye. In this
case they have omitted an explanation of some of their unstated
assumptions. The first two paragraphs are OK, but the graph and the
following paragraphs can't be correctly interpreted without
understanding the assumptions made by the Wikipedia article. The
primary problem is that the article fails to mention that they are
assuming a velocity responsive pickup that gives an output that rises at
6 dB/octave with increasing frequency, for a constant recorded groove
amplitude. If you compensate the playback curve graph shown in the
Wikipedia article for this effect you will end up with a playback curve
that is exactly the complement of the recording curve I described, where
in playback the groove amplitude must be compensated by boosting the
high frequencies by approximately 12 dB.

I know from past discussions here that the nature of the groove
amplitude cut on an RIAA equalized LP is a difficult concept for most in
this group to get their minds around, but if you drop your prejudices,
and take some time to do your homework as I suggested, understanding can
be achieved.

Your previous answer to Serge Auckland explains your confusion.
The rest of the world is not wrong and understands perfectly that
the signal is represented by the stylus velocity, not its displacement.

--
Eiron.

May contain traces of irony.