Yamaha U1 regulation problem

[Isaac OLEG]

Hi Ron,

I had the same problem in a jazz club, not really beginners, the
repetition was poor, no way to regulate with a normal letoff, as the
hammers did not "drop", the jack was not moving enough far of the butt
when the hammer goes in check.

Having a shorter stroke did not help at all because the catching was
even near the strings then.
Larger letoff only disturbed the repetition too much (Boogie Boogie
playing expected).

A mix of minimal but real aftertouch, maximal checking, somewhat large
letoff (3mm) and a precise regulation of the lost motion was the
solution).

If not enough lost motion, under the stroke the hammer is propelled
too early and it comes in check when the jack did not finish it's
course, I noticed that on the U series from Yamaha's, it is also due
to the compression of the jack's rest cushion, that give us a false
appreciation of the good lost motion point
Then, we tend to close too much the jack's butt contact, and the jack
don't reengages/hammer don't drop.

If you check while looking at the top of the jack , by knocking
lightly the back of the key with the handle of the tool (to reset the
system in its natural neutral position) while testing with a light
finger on the playing part of the key at the same time, then one can
really regulate the lost motion, taking in account the natural
compression of the felts ( I leave may be 1/10 mm, but not 'hole' felt
at the key, just avoid the immediate propulsion sensation that mean
the system  is compressed since the start).

You can see then that the jack comes in a perfect "no lost motion"
position while you believe at first you are having too much. Anyway
that little moment at the beginning of the stroke is hardly felt by
the player as the real lost motion that we should avoid, only some
springiness, then the propulsion.

And the hammer take frankly its full velocity and stroke, it is not
delayed like when lost motion exist.
While the immediate start of the action mean a lot of power for the
attack of the tone, I am not sure it produce the most manageable tone.
All piano action need some "air".

The rest cushion from Yamaha is very bouncy ,more than usual too.

As having a larger checking add strength to the tone to some point,
this approach is useful and it compensate well for the little loss of
strength due to larger lost motion. The tone is more open then .

Beside, I like these actions a lot, they react almost as grand action,
telling us when they are properly regulated by a specific tone
quality.

There is a point I did not investigate there and it is the geometry of
the short lever of the jack on the button. May be some motion is lost
because of their relation, (angle or position of the button) and the
forward move of the jack can be too slow in some configurations.

BTW, on verticals, having less stroke does not help repetition, as the
hammer is more vertical then and less prone to come back to rest I
guess.

That's all folks ....

Best Regards.


Isaac OLEG

Entretien et reparation de pianos.

PianoTech
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94400 VITRY sur SEINE
FRANCE
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> -----Message d'origine-----
> De : pianotech-bounces@ptg.org
> [mailto:pianotech-bounces@ptg.org]De la
> part de Ron Nossaman
> Envoye : vendredi 7 mars 2003 15:28
> A : Pianotech
> Objet : Re: Yamaha U1 regulation problem
>
>
>
> >             I know bobbling hammers can be a problem on
> Yamaha verticals
> > and I ve worked on hundreds of these, but I can t shorten
> blow any more
> > and as I mentioned, keydip-aftertouch are correct. I m
> hesitant to
> > increase lettoff back to its original excessive amount,
> so esteemed
> > colleagues ---Any suggestions? I m going back next week.
>
> This has always been a problem with these actions with
> beginners, kids, and
> folks with a tentative touch. To me, it seems to be a
> design thing. The
> ratio of jack length to tail length is high, so any drag of
> the jack at the
> but translates to increased resistance at the tail. As the key is
> depressed, the pianist picks up resistance from the damper
> spring first,
> then hits added resistance at letoff. They just don't push
> through the
> letoff and finish the stroke, which makes the hammers
> bobble. Bottom line
> is that the person playing the piano needs to learn how to
> work it and the
> "problem" goes away. Since that isn't likely to happen
> immediately, I find
> the quickest and most easily reversible cheap trick is to
> bend the letoff
> rail brackets down a tad to make that letoff about 1/4" -
> maybe more. There
> will be a point where even the most relentless and
> determined soft paw
> won't be able to make the hammers bobble. That's where to
> leave it. Feels
> funny? No power, no control? No sweat. If they were capable
> of power and
> control, the problem wouldn't have come up in the first
> place. Next year,
> when they've learned to work the piano and complain about
> the lack of power
> and control (or not), these same brackets can be bent back
> up to get the
> letoff close enough to even it out quickly without having
> had to crank all
> the buttons down, then up again. Sure, I hate to compromise
> the action to
> accommodate someone's inability to work it, but they aren't
> going to change
> until (and if) they change, so all that's left is
> minimizing the damage
> until, and if, they do.
>
> That's my take.
>
> Ron N
>
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