Vinyl noise and the 'Devinyliser'

摘要

In a letter in the December 2015 issue of HFN, Patrick Wallace pointed out that vinyl signals always come with a background of low-frequency noise due to non-flat discs. He also argued that a good deal of this noise is vertical with respect to the stylus, and therefore appears out of phase. The result is that it cannot be localised by the ears. Mr Wallace also suggested that this noise might therefore be interpreted by the ear as 'surround sound' ambience on the recording. This was the first hypothesis I had come across that gave a near-plausible reason why vinyl, with its inescapable limitations, might be preferred to digital. I thought a good test of this idea would be the removal of anti-phase low-frequency noise by means of crossfeed at low frequencies, converting the signal into mono at the bottom end. This has often been suggested as a way of removing turntable rumble without losing low frequencies, as the bass content of stereo recordings is almost always panned centrally to make vinyl discs playable and ensure the best use of two amplifier channels.