Disklavier

I'm taking the liberty of quoting (under fair use, I hope) from a Yamaha 
maintenance document.

--------------------------------

. . .   The core
plungers of the pedal drive units are not
separate items, but instead, are built into the
traditional pedal system, and the plunger
moves each time the pedals are moved. It is
fairly easy to see that a solenoid has to have a
certain opening or "gap" while at rest to provide
the correct amount of movement when the
current is applied. For example, if the gap is
less than it should be, the amount of travel of
the solenoid plunger is decreased by that
same amount, and might not be enough to
move the pedal action to the correct position. It
could also close completely causing a noise as
the solenoid core reaches the end of its travel.

Another issue is that by its electrical nature, if
the solenoid core is stopped before the job is
completed, the computer will continue to send
extra current trying to get the job done. This
extra current causes the temperature of the
coil to rise, and could shut down the entire
system rather than overheat. It is obvious that
the solenoid needs to have a specified gap at
rest to function properly.  . . .

------------------

Thus, too small a solenoid gap could result in a thump when the pedal 
goes full down--both when being played or during reproduction.  The 
adjustment of the gap will require the tech to find or make a gauge and 
to get down on the floor with the gauge, a pair of wrenches, and perhaps 
even a penlight.

That gap, if misadjusted, however, could not account for the thump when 
the pedal is released, which probably comes from 88 dampers 
simultaneously striking the strings and abruptly transferring energy 
from the damper mechanism's fall.

The broad principle is standardization--all DKVs ought to play in the 
same manner.  That's why pedal regulation ought to be checked and 
adjusted before before trying to compensate with MIDI pedal values.

-- 
Robert Welcyng
Anchorage, Alaska

The physical adjustment of the pedals is different for uprights than it is
for grand pianos.  There can never be any standardization that would work
for both models.  What started this whole thread about annoying pedal
thumping has more to do with trying to deal with MIDI data on files from the
internet rather than  Yamaha PianoSoft files optimized for Disklavier use.

It is more a difference in the physical properties of the different piano
models.  There is a reason the U1 costs more than the M500 models.  It has
to do with design.  The trade-off is appearance versus function and
stability.  The MX500 is a noisier piano than a DU1A.  The pedals have
different solenoids.  The solenoid gaps are different.   The Disklavier
software is different.  The ROM is different.  The price is different.

For upright pianos, the damper pedal must lift 66 or so damper levers from
one end of a rod suspended by 4 hangars.  Furthermore, when you press the
pedal down, you are pulling down on one end of a seesaw; the other end is
rising and pushing up a rod that lifts one end only of another rod that
swings out moving the 66 damper levers away from the strings.  In a
Disklavier, a solenoid is built into the pedal rod.

In grand pianos, the dampers are much more efficient.  To start with, they
are located at the strike point of  the hammer on an ideal node that is 1/8
the speaking length of the string.  Either the hammer or the damper is
striking the string.  (Obviously you can't do this on a upright as the
hammers would always hit the dampers on the way to the strings. Therefore
the dampers are placed below the ideal position on the node.)  When you push
the damper pedal down on a grand piano the energy follows a more direct
path.  The back of the pedal pushes up a rod that pushes a lever with a
small pitman rod connected to the center of a tray that pushes up the 66 or
damper levers.

Because of the felt bushings, wear and tear can flatten their dimensions
creating a wrong size gap in the solenoid.  This adjustment needs to be
checked form time to time to keep the pedal solenoids from overheating and
shutting down the system.

Yamaha Disklavier is the only system that uses in-line solenoids on their
pedals.  No other system works as well.  In fact, the QRS folks have
modified their MIDI files (called continuous pedaling) to hold down the keys
longer so you don't even need a pedal solenoid at all.  However, the
difference in pedal nuance would drive a DKV owner crazy!

Just remember that Yamaha is NOT responsible for whatever data is contained
in third party files.  If your Disklavier plays PianoSoft files properly,
then your DKV is working just fine!

Carol Beigel

Greetings Robert, Carol and Group,

You quote from the manual confirms my suspicion that proper adjustment
will eliminate pedal thumping. I found it difficult to believe that
Yamaha would sell pianos that could not be adjusted properly. It is
just the same with the old reproducing pianos and with any other
straight piano too. The quality of the performance is directly related
to the adjustment and maintenance that the instrument receives.

I was interested in making a program to modify midi files if it would
help with certain models and certain music but I do not want to do
this if it encourages people to leave their instruments incorrectly
adjusted.

Regarding the playing of music other than Yamaha's, I have to
disagree. There is no excuse for not supporting standard MIDI
conventions. It is unreasonable to expect everyone to make special
versions of their music to work with the current and future models and
their peculiarities. If Yamaha feels that they can produce better
results with their own music by taking advantage of features of their
system then that puts their music at an advantage and it should
increase sales for them as long as their recordings are good in other
respects. To design their systems to play other standard formats in an
inferior way is manipulative and sleezy.

I am thinking about buying a DKV or a Pianodisc so that I can play a
variety of music from piano rolls and other sources. I have several
customers who have done just this and most of them have chosen
Pianodisc over DKV for this very reason.


-- 
Best regards,
Spencer Chase        mailto:spencer@...
67550 Bell Springs Rd.
Garberville,  CA 95542    Postal service only.
Laytonville, CA 95454    UPS only.
Spencer@...
http://www.spencerserolls.com
http://www.spencerserolls.com/MidiValve.htm
(707) 984-8356