Bob Fitterman (bobf@ilx.com) writes:

> I own a Disklavier MX100B (an upright) and am very pleased with it, both
> as a piano and for its ability to reproduce performances. I have owned it
> for about 5 years and believe it is one of the better purchases I have
> made in recent years.
>
> The system, however, is not perfect. I have had problems with the
> instrument not being able to play *extremely* fast sequences of repeated
> notes. Before the action is in a resting position, the solenoid fires
> again and the later note does not play properly.
> ...
> I am suspicious that the inherent differences between an
> upright and grand action may account for the problem, but it's just a
> hunch.

I think your suspicions are correct.  An upright piano action cannot
repeat notes as rapidly as a grand piano action.  It takes more time
for an upright action to recycle and return to a resting position.
Larry Fine's "Piano Book" covers this in some detail.  There is a
modern invention, the Fandrich action, which claims to repeat faster
and you could conceivably retrofit your upright with it, but who knows
what affect that would have on the Disklavier mechanisms.

Richard Gillmann