Posted by: "Dan Dugan"
> What is optimum? A level that produces a theoretically better
> signal-to-noise ratio but no improvement in practice, or a level that
> plays back in a natural balance without adjustment? My argument is
> that turning up the S channel for better saturation might have had
> some meaning in analog tape days, but isn't necessary with the
> available dynamic range of digital.
Optimum is whatever you would set if you were recording with just the
one mic, mono, not stereo. It does vary from individual to individual
but most have a consistent setting system they use. Mostly a matter of
choice of headroom on your metering. You might want to ask as well
what's a natural balance? Bet it differs considerably depending on who's
mixing. I hear considerable variation in M/S mixed by different people.
I operate with 15dB on average for headroom, so that's what my mid will
be set at (and for some sites it might be as low as 25dB or more, it's
based on my estimate of the probability of a louder call). I've found
the side to balance right with as much as 30dB below the mid upon
occasion, depending on the site, may have used even more at times, can't
remember just now. That's a total possible setting on the side under
your system of 45dB down. That is a lot, particularly as I do still
record with a 16bit system and don't expect that to change anytime soon.
Wasn't Rob giving us a talking to a little while back about how much we
lost recording that low? Particularly in 16bit. About how the lower half
of the range did not resolve as well as the upper half? Maybe should
resolve that issue before going down there as a standard practice? If we
record in the bottom 60dB of the dynamic range of a digital recorder
will the recording be as good as if we did so in the top 60dB?
You can get around your argument for 100 years in the future by
archiving your decoded M/S too. Once you have decided on the exact mix
you like. Which you archive is your choice. I often try several
different ratios before deciding what I want, not something to be
fiddling with while you have good calling in the field.
I asked this question when I first started recording M/S. And I also
experimented both ways of setting, I actually started setting to optimum
stereo mix by adjusting the ratio in the field. From others who did a
lot of M/S the consistent advice then was to set for optimum on each mic
and mix later. And from my own experiments my recordings were more
consistent if I recorded at optimal setting for each mic. I do what
works best for me, and that's not what I expected before I started
recording M/S. Before I started I thought I'd be mixing the stereo in
the field, why I bought the MP2. Since the best sounding mix can vary
minute by minute that sort of fiddling just did not work out well for me.
Walt
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