The noise (rumble) is the sum of all
disturbances that accompany the signal provided by the cartridge and that do
not belong to the musical message. It is caused by all kinds of vibrations that
occur in every movement and are captured by the magnetic cartridge, which is
sensitive to vibrations. Hearing these noises fog the music and make a presence
as a background purr.
This noise annoys more or less depending on the level of
the signal that is recorded on the disc. Thus, it is noticed more in a
pianissimo than in a part of great orchestra, for which it is necessary to look
for a fixed term for the comparison of the noise.
It is therefore necessary to
indicate the signal to noise ratio is measured in dB. That is, how many dB
below is the noise relative to a fixed signal recorded at 1000 Hz and with a
speed of 10 cm/sec on the disc for the DIN norm. This DIN norm requires between
35 and 55 dB minimum, with values ranging from 40 to 60 dB and the highs
reached by high performance turntables between 50 and 70 dB.
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