In regard to this discussion it should be realised that the output from the magnetic cartridge of a record player rises at 6 dB per octave. This must be compensated on reproduction using (these days) standard RIAA equalisation, nominally at -6dB per octave. Actually its a little more complicated than that as there are three time constants in the equalisation curve. RIAA equalisation can be achieved in a single (low noise) op amp with a feedback network providing time constants of 3180us (50Hz), 318us (500Hz) and 75us (2122Hz). Recording without equalisation would produce sound with high treble and low bass, sounding 'tinny'. Of course equalisation could be done digitally within software. However I looked at the menu of Audacity and, although there is reference to high and low pass filters, I could find no reference to RIAA equalisation. Perhaps the Audacity software mentioned has RIAA provision. Pardon me if all this is known. I have recorded my old vinyls to CDs uisng hardware that provides both RIAA equalisation and circuitry to remove clicks and plops. Most of this noise is noticeable on the first 20 mm of track where the velocity is greatest. I've heard that there is software to do all this. Geoffrey
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