[Phil Allison[_4_]]

Nil wrote:



I want to digitalize a mono LP. I record it to the computer as a stereo
WAV file. What's the best way to make it a mono WAV file? My usual
practice has been to pick the best-sounding/least-noisy channel and
eliminate the other. But I recall someone here recommending doing
something like inverting one channel and then summing them in order to
cancel out more noise. That's not it, but something like that.


** Stereo LPs are cut using a 45 /45 degree system that puts Left and Right channel signals on opposite sides of the grove. Also, the phase of one is reversed so that a mono signal results in purely lateral excursions of the cutter. This ensures mono compatibility and is put right by internally reverse wiring one channel of stereo pickups.

The problem with mono cut LPs is that they have mostly *stereo* noise on them because contamination & damage to each side of the groove is not identical.

Summing reverse phase, L and R signals from a mono LP removes the sound and what remains is an out of phase mix of the previous two noises. Summing this with a L + R signal may cancel one of them, but boost the other.

Worth a try maybe.


..... Phil





Simply summing L and R signals will cancel low frequency rumble from the turntable.