[CAUT] Black on Black... (Jack alignment)

[Marcel Carey]

One thing that was not mentioned yet is the fact that when the jack is
positioned as far forward as possible it could bounce on it's rest felt and
then cheat on fast repetition. I've watched the Kawai high speed film and
remember seeing the jack bouncing back and forth on it's rest felt. 

I guess there must be good reasons for manufacturers to recommend the jack
adjustment with the back of the core.

Marcel Carey, 
Sherbrooke, QC

-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of
Douglas Wood
Sent: 13 août 2007 13:40
To: College and University Technicians
Subject: Re: [CAUT] Black on Black... (Jack alignment)

I was urged, in The Basement, to keep the jack aligned with the back of the
knuckle core so there would be no cheating on the loundest, hardest, fastest
repetition. As it's been pointed out, a failure here is much worse than
having the action feel just slightly heavier.

Their contention was that overall the repetition was actually better with
the jack aligned with the back of the core.

It's been my experience that there are other issues at work with a
"constitutionally slow" instrument.

Doug Wood
University of Washington


On Aug 10, 2007, at 5:08 PM, Fred Sturm wrote:

> On 8/9/07 6:31 PM, "Tim Coates" <tcoates1 at sio.midco.net> wrote:
>
>> Fred,
>>
>> I would be interested in knowing if you experience the same issues I 
>> think Chris Soliday eluded to:  the jack back versus the jack forward 
>> affects speed.
>> I agree that .5mm is a great deal of discrepancy and should not be 
>> there.  I deal with a number of Van Cliburn finalists and students 
>> from TCU (yes here in
>> the Dakotas).  One of their obsessions is speed of repetition.   I  
>> see how
>> what you are doing can be used with my methods.
>>
>> I am always trying to tweak the performance instruments in my care 
>> and I find jacks to be critical to the condition of the piano.
>>
>> Thanks,
>>
>> Tim Coates
> Hi Tim,
>     I don't think jack alignment (within normal parameters) affects 
> repetition. It doesn't matter whether it gets back in contact with the 
> stop (ie, its regulation button felt contacts that metal upright) or 
> not during that fast repetition action, just that it gets under enough 
> at the right moment to stay there and not cheat out during the next 
> stroke. What matters, I think, is the stop felt at the end of the rep 
> window, and the amount of aftertouch. Felt being closer, and 
> aftertouch less, means faster repetition.
>     Looking at those high speed videos, what strikes me is the 
> bouncing of the jack against the knuckle, often several times and long 
> bounces during very fast repetition. Repetition will fail if the jack 
> happens to be in one of its bounces at the wrong time. So I figure the 
> less bouncing, the better the repetition. You'll get less bouncing if 
> your stop felt is closer in, and if you aren't pushing the jack as far 
> away from the knuckle with the key.
> You push the jack farther with the key if you have more aftertouch.
>     These aren't the only factors. Obviously rep spring strength, 
> friction, etc come into play. But my sense is that aligning your jacks 
> outward won't improve repetition speed. It will make the feel of 
> letoff smoother and less noticeable, which will affect the touch, and 
> there may well be many fine pianists who prefer that feel.
> Regards,
> Fred Sturm
> University of New Mexico
>
>

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