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Bernhard, Stéphane .
Thanks for this analysis and the nice presentation.
I write as I see we are in the high spheres of piano conception and analysis
there so we have lost most of the passengers during the fly !
<G>
Joke apart I've heard the change in the spectra between the 2 samples also.
That remember me of something we found on some pianos (brand undefined) <H>
. It is well possible that it is considered related to hammers because the
voice try to mask that parasitic noise, and finish with an overnnedled
suspension .
I understand it can be called "kissing noise" but I try to stay more
discrete when kissing !
Can't the longitudinal waves modify the hammer contact ratio , and is it
considered in Minimens ? (because I relate this effect also to a "cardboard
tone" where I feel a less efficient spectra, with more impact noise.
Isaac OLEG
P.S.
<H> stand for "Helmet" like in Flame Suit
-----Message d'origine-----
De : Stéphane Hanriat [mailto:stephane.hanriat@free.fr]
Envoyé : mercredi 21 avril 2004 22:25
À : Bernhard Stopper; Pianotech; oleg-i@noos.fr
Objet : Re: Longitudinal partial on Kawai G-23 string
Hello Bernhard,
Thanks a lot for the analysis.
I'll try to get more accurate measurement for the string. I'll try to find
out a micrometer tool, or may be
I'll ask my Kawai tech if he can provide us with precise numbers.
I would be interested to look at the graphics for the diameters you are
recommending for comparison.
Actually, the parasitic noise is clearly a whistling, as you pointed out.
I think it is worth to go deeper in the study, although I would be surprised
that Kawai made such a
design flaw, but who knows.... If this is the case, I can predict that this
subject might make some "noise" !
Greetings,
Stephane
----- Original Message -----
From: Bernhard Stopper
To: Stéphane Hanriat ; Pianotech ; oleg-i@noos.fr
Sent: Monday, April 19, 2004 12:21 AM
Subject: Re: Analysis of plain wire string/wound wire break on
aSteinwayModel Bwith MiniMens 1.0.6
Dear Stephane,
After i entered the string measures that you sent me, MiniMens reports
clearly that this a problematic string length/diameter setting. The
Longitudinal wave matches very close the 13. transversal partial, what
results in a strong resonance effect. (speaking length 1058 mm, 0,975, plain
wire, copper 0,5 mm)
The three pointers in the "Longitudinal Freq." meter representing the
first 3 longitudinal partials in the transversal partial spectrum
(represented by the meters scale, transversal partials reported from partial
Nr. 12-48, the first longitudinal partial has a frequency of 1290 Hz.
The meter indicates, that the longitudinal partial matches slightly above
the 13. transversal partial.
Physically, longitudinal partials near to Odd transversal partials produce
a strong resonance with 2 times the frequency of the odd transversal
partial, what means in this example, the 1. longitudinal partial has a
resonance with the 26. transversal partial. Due to inharmonicity of the 26.
partial, this occurs if the frequency of the longitdunal partial is slightly
above the 13. transversal partial.
In the sound simulation produced by the MiniMens Simulator one can clearly
here the whistling produced by the longitudinal resonance.
listen to the sound by clicking the link:
http://www.piano-stopper.de/dl/Kawai_G23_0,975_0,5.wav
a solution would be to change the diameters to 1,0 mm for the core wire
and 0,475 mm for the copper diameter.
(inharmonicity must be checked with the neighbour keys)
what would sound like this:
http://www.piano-stopper.de/dl/Kawai_G23_1,0_0,475.wav
Regards,
Bernhard Stopper
info about the MiniMens Simulator:
www.piano-stopper.de
----- Original Message -----
From: Stéphane Hanriat
To: Bernhard Stopper ; Isaac Oleg
Sent: Sunday, April 18, 2004 9:15 PM
Subject: Re: Analysis of plain wire string/wound wire break on
aSteinwayModel Bwith MiniMens 1.0.6
Hello Bernhard,
Please find hereafter the measurements I made for the note G23 (the note
for which the kissing noise is the most audible):
- speaking length : 1058 mm
- steel diameter : between 0.9 & 1.0 mm (may be 0.95 mm) - section looks
square where covered with copper.
- total wire diameter (includin copper wraping) : 1.9 mm (copper should
then be around 0.5 mm diameter)
- strike point : 133 mm from the agraffe.
Hope you'll be able to sdo something with those information.
All the best,
Stephane
----- Original Message -----
From: Bernhard Stopper
To: Pianotech
Sent: Friday, April 09, 2004 10:06 PM
Subject: Re: Analysis of plain wire string/wound wire break on
aSteinwayModel Bwith MiniMens 1.0.6
Hello Stephane,
is it possible for you to send me length and diameters for the keys
that causing the problems?
I will do a dynamic simulation and a sound simulation with the
Minimens to find out what might be the case. Please let me know also what
kind of steel wire Kawai is using. MiniMens can do a sound simulation that
reports also the longitudinal waves. I rather think it is a problem caused
by the longitudinal waves (as Isaac Oleg metioned also earlier), but to do
an exact simulation, it is necessary to know the value of youngs modulus of
the core wire. (I actually only have it for Röslau steel, it varies from 201
to 207 kN/mm² depending on the diameter). I "measured" youngs modulus of
Röslau steel by simulating different diameters with the Minimens Simulator
and measured inharmonicity on real instruments with same settings until the
spectra fit.
I don´t think that the problems are caused by the multiple contacts,
because they are normal for the lower keys. on the lowest octave the hammer
does bouncing with the string up to 3 or 4 times, thats normal.
Best regards,
Bernhard
----- Original Message -----
From: Stéphane Hanriat
To: Pianotech
Sent: Friday, April 09, 2004 8:21 PM
Subject: Re: Analysis of plain wire string/wound wire break on a
SteinwayModel Bwith MiniMens 1.0.6
Hello Bernhard,
Very interesting post. I'm wondering if the "contact ratio" has
something related to the "kissing noise" effect I've observed on most of the
Kawai piano I've played. Please see below the post I sent to the list on the
subject. I've working with Kawai Europe & Japan to try understanding the
root cause, but they were not able to explain this parasitic noise to me,
just saying that this is well known and likely due to hammer condition ???
I've never been convinced about that explanation, since only very few notes
are impacted (few first notes below the break tri-cord/bi-cord) and only on
the 1.78m and 1.86m piano...
Personnally, as an engineer, I already made the hypothesis of
multiple contacts with the strings in that range, creating this parasitic
noise (see below)...
I would be very much interested to have your feedback on this point.
Cheers,
Stephane Hanriat - Owner of Shigeru Kawai SK3
______________________________________________
Hello List,
I'm back with another topic I would like to share with you.
During the process of selecting my Shigeru piano, I played a lot of
Kawai instruments, and I found a strange noise impacting very few notes, but
always the same notes : 23, 24 and 25. The noise looks like a whistling
appearing at the attack, and is very easy to ear when playing a non legato
trill at pianissimo. This noise is clearly audible on most of RX-2, SK2
(1.78 m), RX-3 and SK3 (1.86 m). Very difficult to ear it on larger
instrument. RX-6 or SK6 (2.12 m) do not have it. - sorry for the metric
unit -:)
I had extensive discussions on that with our french MPA who is now
an expert to determine whether an instrument is having the noise or not. We
have contacted Kawai in Japan. They replied that this is well known as
"kissing noise" and that mostly all prestigious brands are facing this
problem that originates from hammer conditions. Kawai also told us that
Steinway has extensively studied the topic without identifying the root
cause ; and when the problem is creating inconvenience at playing, Steinway
is replacing the hammers...
We made some experiments at the french Kawai show room on some RX,
without being capable to find a reliable fix. Some pianos were not having
this kissing noise, but most of them had it in the showroom.
When I play grand pianos in this size range, I always discreetly
check the stuff... but I've not seen this kissing noise as present as on the
Kawai. I can tell you I've been cautious when selecting my Shigeru, so it
took me 2 years to find an SK3 almost free from kissing noise (but not
completely free).
If some of you have an explanation and/or a fix, I would be very
excited to learn this (and lot of MPAs too, believe me).
Cheers,
Stephane Hanriat, the french guy who loves the Shigeru's.
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