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I use custom built Ortofon moving coil cartridges.  These
indeed will pick up more than 20 kHz.  But I'm NOT trying to
detect audio signal above 20 kHz - instead the transducer responds
to noise differently than it does respond to music.  This
makes it possible for DSP algorithms to better distinguish noise
from signal - the signal generated by a percussion instrument will
look dramatically different from the noise generated by a scratch
or crack in the record.  You can then remove the noise without
affecting the signal.

When using a Shure M44-7 cartridge, the signal from a percussion
instrument and the noise generated by a scratch or crack look
nearly the same, so when removing the noise you end up also
removing a little bit of signal.  This is because the M44-7
does not generate supersonic (inaudible high frequency harmonics)
that the moving coil transducers do.  And you need the higher
sampling rates to capture all of the noise so that the DSP
algorithms can work better.

Just to be extra clear - the higher sampling rates are not used to
get a better AUDIO signal.  They, together with the right
transducers, are used to get a better NOISE signal.  Because
ultimately, you want to separate and remove the NOISE from the
AUDIO signal.

Eric Jacobs
The Audio Archive


-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:[log in to unmask]]On Behalf Of Goran Finnberg
Sent: Saturday, June 25, 2005 3:51 AM
To: [log in to unmask]
Subject: Re: [ARSCLIST] 2GB limit for audio file formats


Don Cox:

> The more detailed recording makes it easier for declicking software to
distinguish
> between clicks and music.

With a Shure M44 as a source?

So what is the source giving us above 20 kHz??

BTW, as the source is bandwith limited then a more "detailed" recording
does not make for a sharper risetime from what is already slow risetime
limited.

Also a greater sampling frequency doeas not make a more detailed
recording.

--
Best,

Goran Finnberg
The Mastering Room AB
Goteborg
Sweden

E-mail: [log in to unmask]

Learn from the mistakes of others, you can never live long enough to
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