Re: [F_MINOR] Bach D minor concerto

[Robert Merkin <bobmerk@earthlink.net>]

Yo Bill Larson, et omnes,

I tossed your query to my Audio Engineer / Sound Recording Engineer Pal,
who actually Knows Stuff. His top-tier career began in the Analog Age of
Vinyl, though a bit after the end of the Mono Era.

He previously contributed to f_minor with a post from his Toronto sister,
about the CBC GG studio recording, from which the barely audible
announcers' play-by-play of a nearby Leafs hockey game could not be
isolated and removed -- so the CBC released the recording with the
play-by-play commentary, and in the liner notes, the date, visiting team's
name, and final score of the game.

Here is his reply:

===================

To be compatible with mono, some stereo formats (e.g.: FM stereo, vinyl
disks) use M/S, not left/right encoding. (The "M" and "S" refer to "mid"
and "side", not "mono" and "stereo." An equally valid description is "sum"
and "difference.") The groove on a mono vinyl disk is symmetrical: the
wiggles represent the "mid", "sum", or monaural waveform. The groove on a
stereo vinyl disk is asymmetrical, including the additional "side" or
"difference" signal. The wiggling now includes a rotational component.
(Does asymmetrical rotational wiggling have anything to do with the answer
to your doggie-style question?) Considering where (or when) in the
performance the signal appears to change to stereo, it's possible there's a
spiraling groove on the disk: the groove pitch is intentionally coarser --
the grooves are farther apart -- to permit visual cueing. Adjusting the
cutting lathe's pitch may have mechanically altered the groove geometry so
the result sounds like stereo. Or maybe not. One of the mysteries of life.
As you've been known to say: "Free advice: worth every penny."

=========================

> [Original Message]
> From: Bill Larson <wwlarson@JUNO.COM>
> To: <F_MINOR@EMAIL.RUTGERS.EDU>
> Date: 3/2/2005 12:40:47 AM
> Subject: [F_MINOR] Bach D minor concerto
>
> This is my first post to the list, and it's a rather odd inquiry.  I've
> long enjoyed the Bernstein recording on the Great Performances record,
> but the vinyl has exhibited a strange characteristic that raises a
question.
>
> The recording is, of course, in mono.  However, the very last chords of
> the first and third movement pan out to stereo-- especially noticeable
> through headphones (go listen and see if I'm nuts).  This means one of
> three things, I think:  the recording was mastered in stereo, and panned
> to mono throughout, with a careless engineer putting the pan pots back
> into their regular position a bit prematurely; the tape at the last
> notes was in such bad shape that a contemporary stereo recording was
> cross-faded to mask tape dropouts; or fake stereo/reverberation was
> added, just at the end, to mask aforementioned dropouts.
>
> This has bugged me for years, and I would love to learn that a stereo
> master exists (1957 wasn't that early in the stereo game--RCA recorded
> stereo masters starting in 1954).  Has anyone else noticed this?  Does
> it happen on the Great Performances cassette and CD issues?
>
> By the way, if anyone is in Baltimore on April 10, I'll be playing the
> Goldbergs at the First Unitarian Church downtown at 2 p.m.
>
> Bill Larson, in Pittsburgh, PA

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