I gather from Michael's post that this digital fix won't remove the
vertically read surface noise picked up by the stereo wired cartridge.
I'm curious about what the professional remastering people on the
list do when faced with early mono-LPs and 78s. Transferring stereo
seems to offer better impulse noise reduction possibilities, while
tranferring with a cartridge wired for lateral-only, and thus mono only,
reduces surface noise. What pros and cons go into deciding which
cartridge to use?
A transformer-based circuit for deriving sum and difference signals is
in various books, but nowadays it would be easier to digitise the
signals. Then you can invert one and subtract.
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