Jody,

Mark Fontana wrote me a note requesting information regarding the
Marantz recording technology.  I thought my response might be of
interest to a larger group than just Mark himself, so I am posting my
response through Foxtail.

 - - -

Mark,

As it turns out, I have a good deal of knowledge relating to the
Marantz recordings and recording equipment.  I was not directly
involved in the design and construction of the mechanisms, but I knew
the engineers well and I followed the progress with interest.  The
Marantz facility was about 20 miles from my home, so visiting did not
pose any difficulties for me.

Your statement that you have heard that the Marantz recording piano
used mercury to sense dynamics is disheartening.  I am shocked and
dismayed to learn that we have yet more myth masquerading as fact.  I
have no idea how it happens that mercury has taken on such a
particularly important place in people's thinking; after all, it is not
gold or platinum, and it has no place in the list of precious metals.
Nevertheless, each and every discussion of recording technonology seems
to center around a discussion of a "mercury trough" and "prongs" that
"dip" into the mercury.  Mercury has become the Holy Grail of
reproducing piano technology, and it seems that no narrative of
recording technology is possible without it.  How all this came to be
is a mystery, although there are some clues.

Let me assure you that there was no mercury in the Marantz recording
piano, not in a "trough" and not anywhere else.  There were not even
any mercury switches of the type one finds in German vorsetzers.  I
examined the instrument on several occasions.  I made test recordings
myself at the keyboard, and I had lengthy discussions with the
designers and engineers.  I know from direct experience what was in the
recording piano and what was not.  Here is a brief description:

The keyboard activity was sensed by a set of optical switches (that is,
light-emitting diodes and phototransistors), one for each note.  These
optical switches were placed above the hammer shanks in such a way that
a shutter, attached to the shanks, would interrupt the light beam when
the key was depressed.  This idea was originally mine, and the
fundamental patent on it bears my name.  The patent is now assigned to
the Yamaha Corporation, and modern Disklavier instruments use this
scheme.  (Yamaha later acquired what was then the Pianocorder Division
of Marantz. )  There were no sensors under the keys.  Pedal activity
was sensed in a simple on-off fashion.

The computer used to process and store the keyboard data was an Intel
MDS-800.  The sample rate was in the vicinity of 35 hertz.  The storage
medium was 8-1/2 inch floppy disks conforming to the Intel "double
density" standard, with 128 bytes per sector and 52 sectors per track.
(Single density disks had 26 sectors per track.)  There were 77 tracks
per disk.  The data was stored in raw, open frames, without data
compression of any kind.  As you might expect, this limited the playing
time that could be stored on a single floppy disk.

The original roll transfers were made using a Welte-Mignon vorsetzer
modified for the purpose.  There was a drum attached to each of the two
expression pneumatics.  Each drum was equipped with 32 silver wire
contacts and a common buss bar in such a way that as the expression
pneumatic closed the individual contacts were connected to the buss bar
in sequence.  A separate circuit converted this "walking code" into the
5-bit binary (32 level) code used for the bass and treble halves of the
Pianocorder solenoid stack.  In addition, there were two switch boards
attached to the primary valve chest in place of the ordinary secondary
valves used to play the vorsetzer.  The bass switch board had 43
contacts, and the treble switch board had 37 contacts.  These were
connected to auxiliary circuit boards that provided the necessary
interface.

The positions of the 32 silver wires on each of the expression drums
were adjustable, and were adjusted by ear for optimum results.  As you
would expect, the wires were closer together at the position
corresponding to softest play than they were at the position
corresponding to loudest play.

At a later time, this original mechanism was replaced with a number of
roll "readers" built primarily by Joe Gaide of Cee-Jay Machine in Sun
Valley, California.  Joe later retired, and the word on the street is
that he subsequently went into the pornographic film business.  He has
since dropped out of sight.

I hope this description clears up a few points for you.  On an entirely
different subject, I am happy that you are taking a close look at
View.  Please let me know your response and suggestions.

With best regards, I remain

Sincerely Yours,

Wayne Stahnke