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Frequency Change

  • 1.  Frequency Change

    Registered Piano Technician
    Posted 8 days ago

    Hello, esteemed Listees.  This question was asked by a member who is not on this list, and I didn't know the answer.  I thought maybe someone could enlighten us both.  Thank you for your replies!   

    When tuning using a hard test blow, the frequency of the string increases, but then gradually lowers as volume decreases.

    Why does this happen given that the length, tension and mass of the string does not change?

     



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    Clark Sprague
    Bowling Green OH
    [csprague4@gmail.com]
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  • 2.  RE: Frequency Change

    Registered Piano Technician
    Posted 8 days ago
    A less than fully educated answer: the tension DOES change. When you set a string into motion, it changes shape as it travels and takes up a greater distance than the speaking length when it is still and in a straight line. As soon as it moves, it literally has more tension on it. This is why strings break more often when people play loudly holding the sustain pedal down: the hammer will occasionally hit the string when it is already at it's maximum distance from the hammer, and this puts so much tension on it that it breaks.

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    Maggie Jusiel, RPT
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
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  • 3.  RE: Frequency Change

    Registered Piano Technician
    Posted 8 days ago
    PS: I wouldn't recommend tuning this way, but if one must, please use ear plugs. This WILL damage your hearing. If you don't believe me, watch a decibel meter while you work.

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    Maggie Jusiel, RPT
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
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  • 4.  RE: Frequency Change

    Registered Piano Technician
    Posted 8 days ago
    When the hammer strikes the string,the energy imparted moves it away from its equilibrium position, which increases the tension. With each zero-crossing, the tension reaches zero momentarily, but the string's momentum carries it beyond the zero point, again increasing the tension momentarily. This continues as long as momentum remains, until the string has no more energy. At the moment of attack, the force moving the string is greatest, and so is the increase in tension, thus the increase in pitch. As the momentum decreases, so does the pitch. 

    Mark Schecter
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  • 5.  RE: Frequency Change

    Registered Piano Technician
    Posted 8 days ago
    That was worded much better. Thanks! 😁

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    Maggie Jusiel, RPT
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
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  • 6.  RE: Frequency Change

    Registered Piano Technician
    Posted 8 days ago
    The question then becomes, "When do you read the pitch?" when using an ETD. Wait for it to stabilize (a few seconds) or on the attack, knowing it will fall in pitch.
    Paul McCloud
    San Diego


    Margaret Jusiel
    That was worded much better. Thanks! 😁

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    Maggie Jusiel, RPT
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
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  • 7.  RE: Frequency Change

    Member
    Posted 8 days ago
    The attack does not contain organized pitch, except in what I consider my "grail tone"..."grail tone" is rather rare, I'm afraid, in most pianos.  So, that means, if you tune into the attack, the point where pitch is disorganized, what are you tuning into???...disorganized pitch???   Wait for the pitch to become discernible, and that will be a musically useful pitch to tune to. Each piano I think will organize pitch at its own pace, so, one has to listen to the individual piano, to decide when pitch has organized itself.

    This is interesting, because folks often council to tune into the attack...I almost never do, for the reason stated above.

    ETD's sample much slower than the ear, so maybe its an interesting point, to try and decide, with an ETD when in the tone to go for the target.

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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
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  • 8.  RE: Frequency Change

    Registered Piano Technician
    Posted 8 days ago
    I've been using Pianometer lately, after using the Accutuner for many years. The Pianometer display shows much more information, with spinners for several partials. What I had failed to see on the Accutuner, which is the initial bump in frequency, is easily seen on the Pianometer. I think there must be some kind of display smoothing on the Accutuner, because it is almost instantaneous on the display and mostly remains steady, whereas the Pianometer shows everything in real time, first sharp, then flat, sometimes going flat after a few seconds. And of course, it does depend upon how hard you play the note. Thus, it takes me longer with Pianometer because I have to wait and see what is happening, sometimes several times to be sure it's correct.
    I"ve also heard to tune the treble on attack, and the rest on decay. I'm not totally on that train of thought, tho. Depends..
    Paul McCloud


    Jim Ialeggio
    The attack does not contain organized pitch, except in what I consider my "grail tone"..."grail tone" is rather rare, I'm afraid, in most pianos. So, that means, if you tune into the attack, the point where pitch is disorganized, what are you tuning into???...disorganized pitch??? Wait for the pitch to become discernible, and that will be a musically useful pitch to tune to. Each piano I think will organize pitch at its own pace, so, one has to listen to the individual piano, to decide when pitch has organized itself.

    This is interesting, because folks often council to tune into the attack...I almost never do, for the reason stated above.

    ETD's sample much slower than the ear, so maybe its an interesting point, to try and decide, with an ETD when in the tone to go for the target.

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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
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    Reply to Group Online View Thread Recommend Forward Mark as Inappropriate



  • 9.  RE: Frequency Change

    Member
    Posted 8 days ago
    A test blow is not needed if you have the proper hammer technique. Using the Verituner, I have noticed pitch fluctuation thru the decay and found that Steinways and most pianos can be tuned just after the initial attack, leaving the spike. Whereas, Yamahas tend to need to be tuned in the attack or to the spike.

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    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
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  • 10.  RE: Frequency Change

    Registered Piano Technician
    Posted 8 days ago
    Interesting observation, Jon. Any idea why the difference between Yamahas and other pianos in this respect?

    Alan

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    Alan Eder, RPT
    Herb Alpert School of Music
    California Institute of the Arts
    Valencia, CA
    661.904.6483
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  • 11.  RE: Frequency Change

    Registered Piano Technician
    Posted 7 days ago
    The SAT III is a good ETD but suffers from what I call The Dreaded Octave 5. On many pianos, it just reads dirty (can you say Young Chang?). Tuning the extreme decay for that octave works best in many cases, but it certainly takes additional focus. Some interval testing is a good idea. Once I hit octave 6 - life is good again. .

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    Randy Prentice RPT
    Tucson AZ
    520-749-3788
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  • 12.  RE: Frequency Change

    Posted 8 days ago
    Same answer, different words:
    When a string is struck the hammer pushes it which puts more tension on it which increases the pitch. But also pushing or displacement of the string by the hammer makes it longer in length thus lower the pitch. So, both happen at the same time although a small spike of unorganized pitch will be at the attack.

    Somewhere I was reading that if our ears heard the same recorded note from, let's say, 5 different instruments, and the recorded chunks were half a second, then it would be difficult for us to distinguish which instrument was which if the attack of each instrument was removed from each recorded chunk.

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    Cobrun Sells
    cobrun94@yahoo.com
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  • 13.  RE: Frequency Change

    Registered Piano Technician
    Posted 8 days ago
    The partials of all sounds are exactly alike. IOW if you deconstruct each sound (no matter what it is) and listen to the individual partials separately, they all sound the same (i.e. 1st, 2nd, 3rd etc partials of a dog bark sound exactly the same as 1st, 2nd, 3rd etc partials of an elephant's blast or a cat's meow). The difference of each is in the relative presence/absence/intensity of all the partials. That unique combination is what we recognize as a specific sound.

    If you remove one partial from that sound it will change it significantly. Therefore as noted, if you could disect the attack sound (the partial[s] responsible for the attack) each of those tones would doubtlessly found more or less similar.

    We hear with our brains...not our ears. The ears are highly engineered collection and transmission devices...the brain does all the heavy lifting to decide what things are or are not.

    Don't know if that is relevant or not but it's an interesting factoid.

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 14.  RE: Frequency Change

    Posted 8 days ago
    You raise an interesting question.

    Do the partials move with the fundamental? 

    All of us have probably considered the tension to rise as a significant amount with high displacement strong vibration. But someone mentioned that the vibrating length gets longer. Um . . . This gets complicated. The physical length between the nodes is fixed (subject to soundboard vibration causing a virtual node beyond the bridge). We can see that at maximum vibration deviation the tension increases so leading to increase in pitch. In a loudspeaker a voicecoil going outside the magnet gap would introduce harmonic distortion as a sinewave would cease to be pure. On a strong string displacement the tension would be altering during the vibration and be non-negligibly changing within each cycle. Is the physical lengthening of the string relevant or is it inherent in other considerations of the analysis? And will those string tension changes at the periodicity of the fundamental be equally relevant to the harmonics?

    Somewhere I saw an analysis of the step-wave function of a hit string, and the component frequencies separating out on each subsequent termination reflection.

    A related phenomena occurs in the acoustic of an organ in a large acoustic where on each reflection a wave is lost leading to a diminishing frequency in the reverberation and a chord sinking flat. Perhaps it might be possible to hear this on https://www.youtube.com/watch?v=wSf7-4t_SWc which is a famous perfect organ acoustic but touring YouTube no doubt others are audible. https://www.youtube.com/watch?v=vPGDiA3fidA at Albi is another.


    Best wishes

    David P  

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    David Pinnegar, B.Sc., A.R.C.S.
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    +44 1342 850594





  • 15.  RE: Frequency Change

    Member
    Posted 7 days ago
    The problem with piano covers and DC systems is once the piano is opened, the strings are exposed to the conditions in the room. Opening the piano breaks the micro-environment in the piano.  For conditions such as this, I request that the piano be opened a few hours if not the day before to allow the strings to acclimate and not replace the cover or close the lid until after the performance, especially if there is air conditioning. Do not remove the bottom board on verticals with a DC either, it's bad enough having the a/c affect the bass and tenor strings above the keybed.

    Even if there is no DC  but a cover, I request the early opening.

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    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
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