phono PreAmp Studio USB (English)
21
6. Descratcher
The
Descratcher
function effectively removes pops and crackling noises from old vinyl and
shellac records as well as from audio files in which the tone quality has been decreased dur-
ing recording because of switch noise, digital crosstalk or thyristor humming.
The
Descratching algorithm
consists of two components: the
Declicking filter
and the
Decrack-
ling filter
. While the
Declicking filter
is running, usually to remove relatively loud clicks and
pops from old vinyl records or switch noise from digital or analog audio devices, the
Decrack-
ling filter
removes any remaining, usually quiet but dense crackling.
The higher you set the
Declick
parameter, the more cracking noise is removed. When it is set
to 0, the filter lets through nearly all cracking noises. To remove cracking noises from soiled
vinyl records, a
Declick
value
of about 50 is good in most cases.
A typical popping noise in a signal from a vinyl record (left) and the reconstructed signal (right).
The higher you set the
Decrackle
parameter, the more crackling noise is removed from the
original. The highest setting, nearly 100, dampens the actual input signal. In general, this pa-
rameter can be set to 80 without resulting in any audible depletion of the original sound. In
some cases, an extremely high setting, even up to 100, can be used to improve the quality of
the audio material.
To minimize the depletion of the original sound in the
Descratching
procedure, you should
listen very carefully to the effects of the
Declick
and
Decrackle
parameters at various points of
the recording before deciding on their final values. In doing so, the
Difference
function in the
Playback area
will certainly be a great aid. It allows you to set the parameters in a very intui-
tive manner. With it, you can switch between the original input signal and the input/output
signal difference, i.e. the part that has been removed by the
Descratching
algorithm. Nor-
mally, you do not want the signal difference to contain any part of the original signal that you
want to keep. For more notes on optimizing the settings of the
Declick
and
Decrackle
parame-
ters, see to the Application Notes.
Note also that the
Difference
functions can be applied to the
Descratcher
and
Denoiser
func-
tions simultaneously. If you want to run the
Descratcher
only, leave the sliders (
threshold
and
reduction
) for the
Denoiser
set to 0.
