I haven't been following all of this thread, but thought I'd chime in on
this interesting side of the discussion.
Some years ago Kawai's laboratory experimented with the sound of a piano
with and without pin bushings. The test went something like this . . .
- Finish up a normal new Kawai EX concert grand with pin bushings, voice it
and prepare for a recital in Kawai's recital hall at the Ryuyo factory.
- Hire a pianist to perform a recital for the staff, which was recorded.
- After the recital, they quickly lowered the tension, pulled the pins,
removed the bushings, then put the same pins and strings back into the
piano. The next morning the strings were tuned and settled and re-fitted to
the hammers, and the piano was tuned multiple times by the same person who
had tuned for the recital the day before.
- That afternoon the same pianist came back and played the same recital,
which was recorded again.
Their conclusion: The sound was clearly different. Everyone heard it,
including the pianist. This was apparently borne out with the recordings as
well, although they haven't made them available to me yet (I'd love to have
them and be able to play them at a PTG convention).
Note, I didn't say the sound was better or worse, only different. Some of
our MPAs said better, others not as good. It wasn't so different as
sounding like 2 different pianos, but there was a change.
In the absence of hearing the recordings I have asked them to describe what
was different. The answer, usually something like "hmmm, different, but
hard to describe." Mostly a more lively tone, not so much brighter as
having more energy and color, similar to the change from muting or unmuting
the aliquot scale. Also they said there seemed to be a little bigger,
fuller tone, and the tonal envelope gave better sustain just following the
attack.
The Kawai EX has a fully doweled and mortised pinblock / stretcher design
also, and they said that a rigid front end on the piano is probably required
to hear the difference.
In my own comparison of these pianos with and without bushings, I noticed a
few things. I don't have the benefit of hearing the same piano with and
without, but different examples of the same model with and without. I found
that the resonant frequency of the tuning pins is lower, and I have no doubt
that these contribute in a small way to the sound of the piano. You can
hear them by dragging your fingernails across the tops of the pins.
Another factor, only supposition on my part, is that the pin panel itself is
a little more flexible without bushings. If the plate / pinblock /
stretcher structure is not rigid the added flexibility might be a bad thing,
while striking the right balance of flexibility (and in the right direction,
maybe) with a mortised stretcher might give the best balance of rigid
vibrational support of the plate without eating up the vibrations in a bad
way. This is what an overly "floppy" front end of the piano seems to do.
This is an awfully complicated topic, fraught with all kinds of variables,
so it's hard for me to make clear conclusions about what is better.
Relating to the pin size: Kawai pianos usually have 6.9mm tuning pins. The
first unbushed EX pianos we received were strung with 6.9mm or 7.0mm pins,
and I suggested that they try it with 7.15mm pins, that it would be easier
to tune stably for concerts. The laboratory agreed and changed the pin
size, but I never heard from them if they felt that this affected the sound.
It definitely raised the pitch of the tuning pin "ring," but not as high as
the 6.9mm pins in a bushed plate.
A side benefit of this research is that Kawai found a good way in production
to make the front of the piano more rigid while still keeping the stretcher
removeable, which is important to our production method. So the new Shigeru
and GX grands all have a thick and stiff stretcher bar that overlaps the
pinblock. The pinblock extends out from under the plate towards the pianist
a couple of centimeters, and there is a row of screws holding the stretcher,
along with screws and dowels holding the pinblock to the inner rim and
screws holding the stretcher to the outer rim at each end. The pinblocks
are also butted up against the plate flange. All of this added stiffness to
the front of the piano, which gave a little more power and sustain to the
tone. These pianos still have bushed plates, though, and will likely
continue to.
The technicians who usually tune Kawai pianos with bushings don't like the
feel of the unbushed pianos, and complain about the added flexibility of the
pins. For me, having cut my teeth on American pianos mostly, I am very
comfortable working with the flex of the pin when tuning. As long as the
string coils are not way high and the string friction isn't excessive, I
think they tune well.
Ah, another overly long post . . . .
Don Mannino
Original Message------
David Love wrote:
"There are obviously other factors that go into a how well a block tunes but if the plate is designed for bushings I'd certainly not leave them out. There can be no real benefit."
Why is it then, that some companies such as Yamaha have gone from using tuning pin bushings to not using them in their top pf the line pianos?
I am not arguing - I am honestly curious. I have heard that there is a difference in tone and that Yamaha finally copied its greatest competitor. Can this be? If not, why would they have changed this?
If I am correctly informed, Yamaha used a small pin, 7.00 mm (# 1, I believe) with their bushed plates. When they went to un-bushed plates, they continued to use the thin pins. These were thinner and more flexible than #2 pins used by Steinway and others, and prone to a lot of flag poling and resultant tuning issues. I do not know what pin size they use today in un-bushed plates. Does anyone have accurate information?
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Jurgen Goering
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