[Edi Zubovic]

On Mon, 5 Oct 2015 16:33:11 -0400, "None" wrote:

"Nil" wrote in message
.. .
This was discussed here some time ago, I believe, and I thought I
saved
the instructions, but I can't find them, so I hope for some
advice...

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.

Can someone please steer me in a good direction?

If you make sure the two tracks have the proper polarity and
time-alignment, and you sum them, you get essentially the same signal,
6 dB hotter. Noise that's not correlated between the two tracks will
typically yield an average of 3 dB hotter when summed. So by summing
the tracks, you typically get a 3 dB improvement in S/N, for those
types of noise. Noise that's the same in both tracks, such as noise
from a mono master recording, will not be improved, it will increase
by the same 6 dB as the signal. For noise that is is in one track
only, you get 6 dB improvement in S/N by summing, but if you take only
the track without the noise, even better.

It pays to do some investigation on the kinds of noise that exist, and
how they do or do not correlate between channels.

It's about differences, some are correlated and some not. A simple
summing up is not sufficient enough for me, that's why I prefer stereo
cartridges for mono records. Even for 78RPM, Shure has its M78S, I use
its green stylus in the body of a V15. It's a 0,75 mil stylus I think,
a good all-rounder for 78s
Record stereo, do the m/s matrix and then sum it up. There's an old
Waves tool, I think "S1 - No Shuffler", a part of their DirectX
bundle. There is also a m/s matrix tool. You can do all kinds of
summing up with it, usually with "Width" = 0 and "Asymmetry" either
center or -90, you can invert with "Input Mode" etc. Very handy for
experimienting with.

Edi Zubovic, Crikvenica, Croatia