Replying to Craig Smith's inquiry about my patents on a solenoid stack,
the two patent numbers are:

  5,081,892   Solenoid Mounting Systems For Player And Reproducing
              Pianos, and
  5,081,893   Striker Solenoid Assembly For Player And Reproducing
              Pianos

Both patents are dated January 21, 1992.  The patents contain my early,
less successful designs, as well as the ones I regard as most practical,
so reading them would not explain everything, but my previous
description of the rail should do so as regards the mounting system.

In the mounting system patent, the claims cover mainly the shapes of
the framework comprising the solenoid mounting rail, as well as methods
whereby the solenoids are affixed to it.  Both factory and retrofit
designs are covered.

The design of the solenoids themselves, the subject of the second
patent, is an entirely different issue and is too complex to discuss
here.  In any case, although we clearly solved the problem of invisibly
mounting a solenoid stack as early as 1992, of the three companies
I know which manufacture solenoid playing actions for grand pianos,
only Yamaha has thus (invisibly) bothered to mount one; the others
still hang down, for some reason.  Perhaps it was felt that this could
not be achieved without patent infringement, I don't know.

The tragic thing about this is that, since the publication of this
patent at the beginning of 1992, thousands of pianos have had their
original pedal mechanisms needlessly ripped out and replaced in many
cases with a Rube Goldberg mess of rods, latches, pillow blocks, angle
iron, strap iron, and untold hundreds of feet of raw steel bar stock.

Had either company been willing to work with me, installers of their
wares would not have had to disturb the original pedal trap work of
pianos in which their actions were installed.  Moreover, under certain
circumstances, instead of weakening the keypads, they could have been
strengthened in the course of installation.

These solenoid and stack patents were the result of an original
suggestion made by Jim Miller, a brilliant inventor and innovator
(and one of the finest craftsmen I have ever known), that a solenoid
stack which did not "depend," or hang, from the bottom of a grand
piano, would be a significant improvement which the average consumer
would appreciate.

Until that time it was just "assumed" that all playing actions
in grands would have to hang down, as in the pneumatic action days;
the first commercially successful solenoid action, the Pianocorder,
required a rather large box to be constructed to cover the protruding
solenoid rails, and its descendants, the PianoDisc and then Pianomation
as well as the Disklavier of the time, followed its example.  Jim and
I therefore set about to build the first such "invisible" solenoid
device ever, and we completed it just in time to demonstrate it in
a piano at my booth at the winter National Association of Music
Merchants (NAMM) show, in January, 1991.

Based on the tremendous success of the demonstration solenoid unit
at the NAMM show and the enthusiasm it generated, I decided to offer
an "invisible" solenoid action to Pianomation customers and installers,
as an after-market alternative to the one supplied.  Baldwin Piano and
Organ Company  asked me to build one for them, and I was sent to Conway,
Arkansas, to install my first production prototype.

Jim's solenoid design, although it worked superbly when installed
just right, was rather fragile and required much precision machining.
My rail design, likewise, needed further development.  I therefore set
about to develop a simple, robust and economical-to-produce action.

At the time, we had been very enthusiastic about the original,
then-new Pianomation action developed by Wayne Stahnke, and Wayne
shared my booth at the show so that he could demonstrate his new
software stored on an audio CD format.  Wayne said that the result
of the show was that we had proved two things about the "invisible"
action: first, that it could be done, and second, that the public
evidently likes and wants it.

Equipped with our improved solenoids, the original Pianomation action
played, in the opinion of many including Jim and myself, incredibly
well, even as well as the Boesendorfer SE much of the time, despite its
relative simplicity.  Unfortunately, this original mechanism design was
scrapped by QRS, due to business disagreements with Wayne Stahnke.  QRS
then developed its own new Pianomation mechanism, still being produced
today.

After an immense amount of research and many failures, I developed what
I still regard as the best design to date.  Evidently Yamaha agrees,
because the present design for their top-of-the-line Disklavier sole-
noid action in my opinion is, in effect, the same as the one I patented
in 1992, although perhaps there are sufficient differences in details
of construction to avoid infringement, I don't know.

Baldwin asked me to build them a second action a few months later, and
this time I was able to send it in a mailing tube and they installed it
easily with no help from me.  This received highest marks from manage-
ment and the manufacturing plant, which was "no small compliment coming
from our plant managers," I was told.

Until one has attempted to design around an existing piano action,
he would be unlikely to appreciate the difficulties involved in
accommodating existing components which cannot be changed (at least,
in the retrofit model), crammed into a small space, and of their doing
work in that space under significant constraints of range of motion and
geometry.

I developed a new respect for the designers of the old pneumatic
systems.  There are many areas in which there are simply not many
alternate ways to do something, and sometimes there is only one
solution.  All of this experience served me well in designing the
PowerRoll, as I had already made many of the usual errors in such
projects.

I mentioned previously that I can build new Disklavier stacks for any
scale, if given the vital keybed and action data, PC driver boards from
an original stack, and a set of coil bobbins wound with wire.  Recently
I have also again been thinking of possibly manufacturing "invisible"
solenoid stacks on an aftermarket basis, for use with the Pianomation
and PianoDisc retrofit units.  These would be used by the installer
instead of the one supplied by the manufacturer and possibly would
incorporate components from them.

It seems to me that many purchasers of these retrofit solenoid systems
would be interested in spending a little extra to prevent damage to and
strengthen their pianos during the installation, and enable the result-
ing installation to be undetectable from the outside of the piano.  If
the manufacturers would like to offer these deluxe stacks or install
them in factory units, this might be worked out with me after things
get going.

I would be interested in feedback about these ideas.

Incidentally, readers may also be interested is looking up another
patent, written mostly by me, on an invention by Jim Miller, to which I
am licensee (not "assignee," as is erroneously printed on the patent).
I did considerable development work on this device, which was at one
time, in conjunction with my solenoid developments, intended as the
basis for a complete solenoid-type reproducing piano system:

  5,237,123  Velocity, Position And Direction-Tracking Sensor
             For Moving Components of Musical Instruments

This sensing scheme has, in our opinion, significant advantages over
every other method of recording piano action data with which we are
familiar.  In fact, a working one note model incorporating the Miller
recording system and my solenoid innovations, was demonstrated both to
Steinway and Baldwin management, and received very high praise.  The
data acquired by it impressively shows events occurring within the
strokes of the hammer and key, in units of time as small as
microseconds.

Larry Broadmoore, Broadmoore Research Corporation
1709 First Street, Unit "C", San Fernando, CA 91340
tel: (800)497-4266 ; (818) 365-6231 ; fax: (818) 361-0911
http://www.erolls.com for PowerRoll information.