Re: [ARSCLIST] Advice for filtering surface noise

[Don Cox <doncox@xxxxxxxxxxxxxx>]

On 28/09/04, Steven Smolian wrote:
> 78 grooves are of no uniform width.  Anywhere from 2.5 to 3.5 mils are
> usual.
>
> If you are playing through a stereo cartridge, one source of noise is
> the vertical signal on lateral cut records, the opposite for most
> Edisons, Pathes, etc. The solution involves wiring the cartridge
> proerly or having the appropriate switch on your preamp, should it
> have one.

This reduces the noise by 40%.

An alternative aproach is to listen in stereo. The music is then in the
centre, between the speakers, and the noise is spread from left to
right. This helps the brain to separate them.

Of course, if you have a good computer program to reduce impulse noise
without affecting the music, that helps too, but it is very
labour-intensive.

The most important thing to realise is that you cannot remove hiss or
clicks by operations in the frequency domain, as both contain all
frequencies. "Turning down the treble" just makes it harder for the
brain to separate noise from signal. The effective software identifies
the wave form of each individual click and removes it, by interpolation
or smoothing.

However, percussion and muted trumpet can give false positives.

Regards
--
Don Cox
doncox@xxxxxxxxxxxxxx