[BC] CD vs LP

[RichardBJohnson at comcast.net]

I seriously doubt that this urban legend is true. The original
CD format used the exact same PCM used in ".wav" files
and, in fact, are ".wav" files. However, the CD/DVD players
won't allow you to view them as files. Nowadays there are
other kinds of formats being used including very poor MP3
compressions. They are used so that you can have
more recordings on the disc.

The PCM format uses two 16-bit signed integers, the first
for the left-channel, the next for the right channel. Sixteen
bits provides about 96 dB dynamic range if viewed as
a peak value --which is actually meaningless. However,
because it is a signed number you don't get 0 to 65535
values. Instead you get +/- 32767 codes with 0 in the
center. This gives you:

0.707 * 32767 =  23,166 (convert peak level to RMS)
20 log10 (23,166) = 87 dB

Eighty-seven decibels dynamic range  is much greater than
typical analog audio circuitry that almost never exceeds
80 dB over a 20 kHz bandwidth, that it should not be the
limiting factor in a high-fidelity system.

What is the limiting factor is the crap compression and
the more modern MP3 that takes compressed audio
and quantizes it into about 8-bit steps. The result is
only about 40 dB of dynamic range in which the
total information bandwidth is compressed into the
top 4 bits.

Now, if you train your listeners that this is the "correct"
sound, they will believe you when they hear a live
performance through multiple horns driven at 120 dB
by kilowatt amplifiers.

If they were ever forced to sit at Symphony Hall
they might quickly vomit and leave. It's all in perception.
Even some modern elevators now have artificial noise
generators so that people believe that they are working
when climbing and descending tall structures.

--
Cheers,
Richard B. Johnson
Read about my book
http://www.LymanSchool.org


 -------------- Original message ----------------------
From: "Dana  Puopolo" <dpuopolo at usa.net>
> The CD format chosen (44.1, 16 bit) was chosen in anticipation of car CD
> players and picked so the media could fit in a slot between the knobs on the
> car dashboards of the time. 
> 
> So I heard at an AES meeting in the early '90s by a person from Sony.
> 
> -D
>