The interesting correspondence from Tom Jansen [010112 MMD] tends to
confirm my theory that modern experts have lost sight of this clever
yet simple technique.  It is, after all, merely a matter of adjustment
of the regulator spring and few restorers or technicians would leave it
unusually weak unless they were aware of this idea.  I trust you will
agree this effect is not a figment of my imagination.  I was quite
surprised at the expression which appeared when I wrote this
experimental software.  The program is very primitive yet, musically,
the results are a big improvement.

I am in no doubt that Hupfeld used this technique in a deliberate and
controlled manner but have always wondered if other manufacturers
around the world also knew of it.  I have processed scans of some of
the more boisterous QRS rolls using the same algorithm and they
certainly produce expression which is, in most cases, an improvement
on the "constant volume" sound.  Is it possible that US manufacturers
might have used the same trick ?

The discussion about the Animatic Clavitist is another issue.  I was
never certain what was inside the "orchestra" box and a xylophone does
make sense.  The scale is well documented and I attach a scan of what
is probably an "S" roll.  My piano had the ingenious mandolin system
mentioned and also used pneumatic logic gates characteristic of
Hupfeld.  For example, the "motor off" track cut the motor but, when
opened in combination with the "soft pedal" a special latch operated
which initiated reroll.

One aspect which neither of your experts mentions is the use of square
and round punches on the same roll.  This would have been a major
manufacturing complication and there must have been a good reason for
doing it but I wonder what it was ?  I attach a pictorial scan of a
small section.  These rolls are fully of mysteries.  The use of the
themes is surprising in the musical sense.  In addition, many of the
"snakebites" are out of position.

Having examined the rolls more closely, I'm beginning to revise my
opinions about the quality.  Physically they are superb but there are
several bouts of "lumpiness" in the tempo and this, together with the
misplaced themes, makes me suspect that these rolls are copies which
might be several generations old.

I attach (1) a pictorial scan of part of one of the rolls; (2) a MIDI
file of one tune; all tracks are intact, only the webbing has been
removed; (3) a MIDI file as above but processed with my algorithm
which increases volume in accordance with an estimation of the vacuum
demand at any instant.  The control tracks have been removed.

Best wishes

Richard Stibbons

 [ Thanks, Richard.  I'll place your article and the accompanying
 [ files at the MMD Sounds site, http://mmd.foxtail.com/Sounds/
 [ -- Robbie