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Very high partial in plain string?

  • 1.  Very high partial in plain string?

    Registered Piano Technician
    Posted 06-05-2020 17:34
    Hi everyone,

    I have two customers with the same issue. A VERY high partial prominently ringing to the degree it is loud and irritating. 

    One piano is a Kawai small grand. The note is C6. And the other piano is a 1920's Steinway S restrung in the 80's. These strings are at the bottom of the plain string scale just before they turn to brass wound. Both pianos are in pretty good shape. 

    But I cannot not get rid of it! 

    Here is what I have done so far.
    1. Swapped adjacent hammers. Ring stays with the string NOT the hammer. 
    2. Front Duplex: muted it, pushed strings back and forth to remove any possible burrs under the V bar. No change. 
    3. Seated the string at bridge. No change. 
    4. Drive bridge pin in a little. No change. 
    5. Needle voiced a little just in case. No change to partial just overall tone. 
    6. Perfected the unison tuning. No change.
    7. Looked for sympathetic vibration of other strings. None.
    8. On Steinway I could NOT test the agraff for scratches. 
    9. Pressed all over the soundboard from underneath while customer played note. No change.
    10. Muted back duplex. No change. 

    Any ideas? 
    Can plain strings have longitudinal nodes like wound strings? 

    Thanks!
    Daniel

    ------------------------------
    Daniel Achten
    Chattanooga TN
    423-760-2458
    ------------------------------


  • 2.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-05-2020 17:40
    Sometimes this can be caused by a damper down in the bass section that is not seated correctly. Play a note up higher and it sympathetically generates a corresponding partial in that lower note that the damper isn't catching. Try gently pressing down on the dampers throughout, just enough to force them to seat entirely, and see if you can locate the one that is leaking.

    ------------------------------
    Geoff Sykes, RPT
    Los Angeles CA
    ------------------------------



  • 3.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-05-2020 18:11
    Daniel, I had a problem on a M&H BB. Turned out it was the long plate strut. Try touching everything inside the piano.

    ------------------------------
    Larry Messerly, RPT
    Bringing Harmony to Homes
    www.lacrossepianotuning.com
    ljmesserly@gmail.com
    928-899-7292
    ------------------------------



  • 4.  RE: Very high partial in plain string?

    Posted 06-05-2020 20:58
    There's a good chance the low tenor one is a longitudinal mode.  Can't get rid of that without major work...its very common in the that area in small pianos. does it beat loudly, but the beating does not change with tuning changes?

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 5.  RE: Very high partial in plain string?

    Posted 06-05-2020 21:00
    yep...plain wire can have longitudinal modes. Jim Ellis wrote a whole book on this phenomenon. i am re-reading as we speak...trying to understand it better than i did the last time I tried to read it.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 6.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-05-2020 22:22
    Thank you guys for your thoughts!

    Would replacing the string take care of the issue?

    ------------------------------
    Daniel Achten
    Chattanooga TN
    423-760-2458
    ------------------------------



  • 7.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-06-2020 00:07
    Wouldn't you have to move the hammer to hit in a slightly different position/location?

    ------------------------------
    Maggie Jusiel
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
    ------------------------------



  • 8.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-06-2020 00:05
    Jim! You just diagnosed a problem I was having! It was doing it on LOTS of strings, though. Thanks!

    ------------------------------
    Maggie Jusiel
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
    ------------------------------



  • 9.  RE: Very high partial in plain string?

    Posted 06-06-2020 08:01
    O.K. guys, here's the thing: If you want to understand longitudinal modes, go to the PTG store, buy Jim Ellis's book on longitudinal modes and read it, all 78 pages. It's very well written and not so hard to understand.
    I would call it required reading for the 21st century piano technician.
    Jim's book is the first analysis and explanation of this phenomenon in pianos. It opens a new area of understanding in our work. Ed McMorrow has done some very creative work involving longitudinal modes as causes of string noise in the high treble, but the first step is to read Jim Ellis's book.

    Like many piano noises, longitudinal modes have always been there, perhaps unnoticed, then once you hear it, it won't go away. some big name pianos have them in the low tenor.
    Just as hypothesis, if the sound is extremely distressing, there is a chance that changing the gauge or material of the string may eliminate it. This may introduce other voicing or tuning problems, but they may be more amenable to needling. Please note all the hypotheses. This would be a very trial-and-error approach. If you had a monochord like Jim's you could test different strings off the piano!

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



  • 10.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-06-2020 10:04
    Ed! I have that book & forgot I had it. Thanks!  And...the string...duh. Thanks again! :-)

    ------------------------------
    Maggie Jusiel
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
    ------------------------------



  • 11.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-06-2020 08:03
    Daniel, 

    I have had some success with this type of issue as in your Sty by changing th e TYPE of wire in that region. Specifically Puresound SS wire or Paulello wire. If it is in fact a LM problem, simply replacing the wire with a new identical type will only  "fix" it temporarily and it will come back. You must change the fundamentals of how the wire behaves in order to eliminate it, thus a change to a different type of wire. Remember that the wire that piano was strung with originally was not the same as today's cast wire, thus problems like this can arise with restringing. 

    Now, with that said, it might not be LM, but rather the edge of a damper resting directly on a node thereby producing the offending frequency. If the piano was restrung, then it also got redampered and some changes might have occurred in that dept. THAT is where I would look first...then wire change. 

    Pwg

    ------------------------------
    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
    ------------------------------



  • 12.  RE: Very high partial in plain string?

    Posted 06-06-2020 08:25
    The longitudinal coupling is dependent both on velocity of longitudinal vibration in the actual string material and speaking length. Jim E does say changing wire manufacturers wire will result in some small change in longitudinal velocity.  Peter's point is interesting, as other tensile strength wires were not available, when Jim did his research, and according to the comment regarding different manufacturer's wires being slightly different, different tensile strength wires may mitigate the problem somewhat.  bass strings are where i find l modes a real pain, personally. these can be fixed by scaling the wraps differently. He does mention that changing strike point may help mitigate it somewhat, but there are other gotcha's that may be involved in moving the strike point.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 13.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-06-2020 09:35
    ...and just in case the damper felts did NOT get replaced as part of the restringing, then they are even MORE likely to be the source of your problem. Whether or not the dampers are the culprits, it is always prudent to take a few minutes to consider the simpler diagnoses and remedies before the more invasive/time consuming/expensive ones.

    Alan

    ------------------------------
    Alan Eder, RPT
    Herb Alpert School of Music
    California Institute of the Arts
    Valencia, CA
    661.904.6483
    ------------------------------



  • 14.  RE: Very high partial in plain string?

    Posted 06-06-2020 10:46
    Straightforwardly the longitudinal waves should be dependant only on the tension of the string and the speed of sound in that string. Changing from one type of string to another I'd not have thought to be significant if the speed of sound in the material. Poor damping of other strings appears to be to me the more likely of the explanations. There's a lot of information about longitudinal modes on https://asa.scitation.org/doi/10.1121/1.4916708 and the bibliography there, and https://pubmed.ncbi.nlm.nih.gov/25920829/ quotes https://pubmed.ncbi.nlm.nih.gov/29092614/ Best wishes David P

    ------------------------------
    David Pinnegar BSc ARCS
    Hammerwood Park, East Grinstead, Sussex, UK
    +44 1342 850594
    "High Definition" Tuning
    ------------------------------



  • 15.  RE: Very high partial in plain string?

    Posted 06-06-2020 11:20
    <longitudinal waves should be dependant only on the tension of the string and the speed of sound

    This is incorrect. They do not respond to changes in tension...you cannot tune them out. As Jim Ellis states, in piano strings, the coupling from the transverse mode to the longitudinal is dependent on the speed of the longitudinal wave in the given material, and on speaking length.

    I am not knowledgeable enough about this to say what the difference between speed of sound, presumably in air,  and speed of a longitudinal wave is. i also don't know how or whether the longitudinal wave is expressed by the soundboard, and if so, how it is physically reaches and is perceived by the ear.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 16.  RE: Very high partial in plain string?

    Posted 06-06-2020 11:43
    https://ccrma.stanford.edu/~jos/pasp/Longitudinal_Waves.html  states that they are only weakly dependant on tension. 

    Research appears to focus on an intermodulation between the transverse and the longitudinal waves. 

    Unless the speed of sound varies between different steels used in different strings then changing the strings doesn't look as though it's going to make the difference. 

    The research suggests that the longitudinal waves occur at sum and difference frequencies between harmonics, so amplifying harmonics and inharmonicities.

    But rather than looking through an ectoplasmic mist of complications, in my opinion the suggestion of incomplete damping of lower strings might sound to me a better area to investigate as first recourse.

    Best wishes

    David P 

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





  • 17.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-07-2020 21:29
    Thank you everyone for the discussion on LM. I read Jim's book a while ago but don't remember much from it. Time to read it again!

    I did look for sympathetic vibrations in other strings as mentioned and could not eliminate the partial. 

    I also did mate the hammer to the string and all the rest of the hammers as well. 

    Based on what I have done and the suggestions here it seems that my only chance of fixing the issue is to attempt a string change using a different brand. My customer is very concerned about a tonal change in the note, however. So I am apprehensive. 

    Peter, where can I get Puresound SS or Puallelo wire? I only have a small stockpile of the wire Shaff sells. But I have been interested in trying other brands ever since I read a post by Jim Ialeggio on rescaling. Jim feel free to offer brand suggestions as well. 

    Thanks! 


    ------------------------------
    Daniel Achten
    Chattanooga TN
    423-760-2458
    ------------------------------



  • 18.  RE: Very high partial in plain string?

    Posted 06-07-2020 23:33
    don't worry too much about tonal change in the note. if this is a short piano, chances are very good that you will hear tonal improvement in the wire change. probably switching to Paullelo, type 1, which has a lower tensile strength than modern roslau or mapes gold. post the speaking length and note number, and we can take a look at what the options may be. (sorry for lack of capitals and lack of paragraphs...my enter and shift keys died friday)

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 19.  RE: Very high partial in plain string?

    Posted 06-07-2020 23:34
    forgot to ask...does the nasty high partial beat prominently?

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 20.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-07-2020 23:41
    Hi Jim,

    The nasty partial happens at the moment of attack and dies off at about 1 full second. In other words it does not sustain with the rest of the note.  And it does not have a beat like a false beat or out of tune unison if that's what you mean when you ask "does it beat prominently".

    ------------------------------
    Daniel Achten
    Chattanooga TN
    423-760-2458
    ------------------------------



  • 21.  RE: Very high partial in plain string?

    Posted 06-08-2020 07:35
    hmmm...it might be the strike point. have you tried moving the action significantly in or out, to see if changing strike point reduces it?

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 22.  RE: Very high partial in plain string?

    Posted 06-08-2020 15:55
    Question for Daniel A.: I know it can be difficult to describe a particular unusual sound such as this. Your mention of the sound happening at the attack and then dying off in a second sound like a noise I have heard. Does the sound have what might be described as a bell-like quality?

    ------------------------------
    Terry Farrell
    Farrell Piano Service, Inc.
    Brandon, Florida
    terry@farrellpiano.com
    813-684-3505
    ------------------------------



  • 23.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-08-2020 18:28
    A couple of observations. You are talking about two instruments with a similar problem but in different sections of the pianos. They may not have the same cause. Tenor sections are problematic because they tend to run out of room, even going up to very heavy wire will still leave them at lower than optimal tension. It might be worth double checking the string size on the restrung Steinway. 
    The other piano has the problem on C6 and you call it "a very high harmonic", how much higher can it be from C6? This one seems to be the better candidate for a sympathetic tone from further down the scale. However, some Kawais' have exceedingly high tensions in their treble sections, so it's  possible the wire itself is distorted. Does that piano have a history of treble wires breaking? If the extraneous tone stops the instant the string is damped (with a finger) then that weighs against a sympathetic vibration, and conversely...

    Fun trick re. longitudinal waves: tie a stout rope, 20-30' to a tree, fence, your house, hold it taught with arm strength and give it one quick rotation-1' diameter circle. You will see the longitudinal wave travel to the terminus and echo back at you, when it gets back to you, you will see how much power it retains. To me it illustrates why its period is a function of length, not tension, and gives one an idea of how much havoc it can wreak on the normal harmonic mode of vibration that is going on simultaneously.

    ------------------------------
    Steven Rosenthal
    Honolulu HI
    808-521-7129
    ------------------------------



  • 24.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-09-2020 15:48
    Daniel,

    Jurgen has some I think (till his supply is exhausted). I have a bunch, and I think Ed McMorrow has some too. 

    You will need to remember too that both PS and Paulello are in metric gauges (almost .001" smaller than ASW gauges) and plan accordingly. What is useful though is that you can often increase the diameter of your wire (down there in the trouble zone) raising your tension, but not producing the annoying tubbiness that would occur if you tried it with conventional wire. 

    Interestingly, when I was in DC I took care of a Bosie concert instrument that got rehammered and shanked (but not by me) with factory direct pre-hung parts. It appeared to be a fine job with nothing to complain about. However, I distinctly recall that upon returning to tune it after the job was done, I noticed one note (right in the middle...possibly right next to the first treble break I think) that had a clear high pitched pulsating ringing to it, which HAD NOT been there before. IOW a classic LM issue. The piano had not restrung but simply hammers, thanks, regulation. 

    What did I do about it?  I fiddled with strike point fir a short period but ultimately i did NOTHING, as no one was complaining about it. However I definitely noticed it because I knew the piano inside and out and I knew it was NEW as a result of the work. (In the end I moved back to NH so it then became someone else's potential problem).

    I know of at least one other case where an LM problem was "fixed" by replacing some of the strings, only to resurface a couple of years later just like before. 

    The point here is that tracking down the SOURCE of this kind of problem is clearly not a clear straight path.  And Jim Ellis (as I recall) never really published a true FIX for it either. (I read the book long ago).  James Arledge has some good stuff on it too. 

    This all ASSUMES that your problem is in fact LM and not a damper issue. 

    Pwg


    ------------------------------
    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
    ------------------------------



  • 25.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-09-2020 16:06
    I am scheduled to return to my customers home this coming Friday; the Kawai. I plan to double check everything that has been mentioned. I would like to prove it is NOT one of the simpler solutions before replacing the string. Other than the high partial he note sounds great.  

    On the Kawai the note is C6 and the partial is C8. On the Steinway the partials are 6 octaves up from the offending tenor notes. 

    Keep the ideas coming if anyone anyone has any more thoughts. I'd be happy to test them this Friday. 

    Oh, and Terry, I don't know if I would call it a bell like tone. It's clearly a partial that I can measure and it is in the noisy annoying side of sound quality. Unfortunately it is annoying enough to make my customer cry. She is a piano teacher and said, "it ruins her musical experience." 

    Thanks Peter for where to find the wire. And everyone for your explanations and ideas! 


    ------------------------------
    Daniel Achten
    Chattanooga TN
    423-760-2458
    ------------------------------



  • 26.  RE: Very high partial in plain string?

    Posted 06-10-2020 07:06
    Daniel-

    1) Paulello's website gives lots of information about Paulello wire. https://www.stephenpaulello.com/en/cordes  
    The typogram let's you calculate the correct kind of wire for the pitch and string length. You will need accurate metric measurement of string lengths.

    2) Pure Sound wire is not available because it was a technical and commercial failure and its sole maker, Juan mas Cabre has disappeared. Pure Sound has a low break point. Juan claimed it could be used to rescale modern pianos, and provided scales for Steinway M's among other pianos. I, and others, liking the sound of the wire on historic instruments at low pitch, tried it on 20th century instruments with colossal failure. Capo section wires broke spontaneously in a few days. Tenor wires, which sounded beautiful, began to break at the bridge pins after a few months' playing.
    Paulello wire, Malcolm Rose wire and Stephen Birkett's P wire are better replacements for modern or historic instruments as appropriate.

    3) Longitudinal modes occur around the 13th to 15th partial of the string, not two octaves above. for C6 I'd suggest searching the back scale and tapping the plate, looking for a sympathetic tone. I have found clear tones in Kawai plate struts, not enough to require fixing, though years back someone wrote of adding weight to a Kawai plate strut to dampen a tone. You might try lightly damping the C6 strings and playing the note to see if anything sounds.

    4) Good luck and let us know what you find!

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



  • 27.  RE: Very high partial in plain string?

    Posted 06-10-2020 07:32
    Another thought might be also to pluck the string with a plectrum rather than it being hit with a hammer.

    A remote possibility might be a mad thought of a resonance within the hammer shank.

    Best wishes

    David P


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





  • 28.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-14-2020 00:55
    Ok, here we go. 

    I returned to my customer on Friday morning and spent another 1.5 hours trouble shooting this with all the suggestions. 

    The problem is definitely in the string or at least that note. But I did NOT fix the issue. I did manage to mask it by voicing the note weaker than the rest but the irritating partial is still there, just overall quieter note. It was an acceptable compromise for my client. 

    Also, it is a Kawai GE-1

    Here is what I did.

    1. Not a bell tone. More brittle and irritating. 
    2. Moved strike point for and aft. No change. Also shifter the keyboard. No change. 
    3. Double checked mating. No problem. Perfect.
    4. Front duplex. Touched speaking part and smithed grooves in vbar. No change. 
    5. Back duplex. No change.
    6. Seated bridge pins. No change.
    7. Seated strings. No change.
    8. Double checked for leaking damper in lower register (and everywhere else). Not it.
    9. Sound stops when I touch offending string. Confirms it's in that note.
    10. Touched all around in the belly: plate struts etc. and all cabinet parts, hinges, sound board etc.
    11. The partial does NOT beat loudly. It's just loud. 
    12. It Sustains for about one second. While the notes Sustains for about eight usable seconds.
    13.  When I pluck with my finger nail the high partial is still there no matter where along the string of pluck.
    14.  When I rub my finger up and down the string  defending partial is the natural residence of the string that I hear. 
    15.  The same thing is going on subtly with the three notes below this one. But not above it or any further below. 
    16.  Changing the pitch of the string up or down as much as 15 cents does not make any difference. 
    17.  It does not make that partial at pianissimo. It shows up at mezzo. Making me think it was a voicing issue. Or a resonance issue that is triggered by the volume. 
    18. I voiced the shoulders. No change. Voice the crown no change. Voiced zone 2 under the strike point. No change. 
    19. And it is not a sympathetic vibration from something in the room. 

    Is it safe to conclude that it's just an anomaly within this piano? 

    Daniel

    ------------------------------
    Daniel Achten
    Chattanooga TN
    423-760-2458
    ------------------------------



  • 29.  RE: Very high partial in plain string?

    Posted 06-14-2020 09:15
    This is interesting, and the kind of thing that often leads me to learn something unexpected and highly useful.  Do you have any idea what the partial's frequency is?  Your list above did not include trying to find a place to damp the plate, I don't think. Did you try damping the struts by flexing a piece of wood in between various struts at various locations?  


    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 30.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-14-2020 09:55
    #1) release tension, try pulling the bridge pin. If it's loose, tighten it (CA glue in the hole). At least turn it so the string bears on a different spot on the pin.
    #2) replace the string with better quality wire. Mapes or Renner's best, or Paulello if appropriate. Exactly the same gauge as you're replacing.
    #)3) Remember, it's a GE-1. Not quite Shigeru, not even a KG-1!​​​

    ------------------------------
    Patrick Draine
    Billerica MA
    978-663-9690
    ------------------------------



  • 31.  RE: Very high partial in plain string?

    Posted 06-14-2020 10:04
    Every piano is an anomaly!
    What comes to mind is how, in many Steinway pianos, somewhere in octave 5 notes "deconstruct" into a burst of higher partials which quickly fizzle away leaving a very weak fundamental.
    It would seem that somehow the piano cannot reflect and sustain the fundamental, or that something responds so well to the second partial that it "steals" a lot of the original energy.

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



  • 32.  RE: Very high partial in plain string?

    Posted 06-14-2020 10:47
    Ed, this phenomenon, which in my opinion all pianos exhibit, is one of the  three reasons I became a technician. s&s has it really bad, but they all do it, new boards or old. It drives me absolutely bonkers. In my covid induced creativity of the last few months, I am close to fingering the culprit, and have come up with a unique coupling fix, and at least a working hypothesis, which is outside the usual explanation. Proving the hypothesis will cost more money than i have or than a foundation grant will support, unfortunately...which of course means the hypothesis will remain unproven, with only circumstantial empirical evidence.

    I don't think it has as much to do with the soundboard or its modes as we have assumed it to be.   More on this in a little while in a separate thread, if tomorrows experiment confirms earlier experiments.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 33.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-14-2020 11:08
    All sound waves in gasses, (the air is a gas), are longitudinal. It is because air has equal degrees of freedom in all directions. Strings are much more of a two dimensional wave medium.

    Ellis had as a goal of his research to derive a formula for predicting L-mode frequency in piano strings. He found that unsolvable to any degree of accuracy because the L-modes in piano wires are, (in my own words), leaky and sneaky.

    L-modes can move past termination points constructed to define transverse modes.

    My theory of why "softer" types of piano wire, (and the pure sound and Paulello type O,1, and 2 wires are definitely softer than Mapes international gold wire), can influence tone is the softer wire carries or propagates less energy into the L-mode. Ellis did test a sample of Pure sound wire and it had a lower natural L-mode frequency than the modern wire of the same size and tension. He did not test whether softer wires also produce less energetic L-modes for a given displacement compared to modern wire. But it only makes sense that softer wire would have more internal damping than modern wire since experience shows that hard tool steel sounds brighter when impulse excited than softer mild steel.

    I believe the mixing of L-modes and T-modes contributes much to the conditions that produce false beats. Even in the highest treble where the L-mode frequencies are all beyond the range of human audibility. The L-modes can "distort" the bridge movement enough to "beat" with the T-modes so to speak.

    Ed


    ------------------------------
    Edward McMorrow
    Edmonds WA
    425-299-3431
    ------------------------------



  • 34.  RE: Very high partial in plain string?

    Registered Piano Technician
    Posted 06-14-2020 11:19
    Have you contacted Kawai tech support yet? I would be interested to hear what their take on this is.

    ------------------------------
    Geoff Sykes, RPT
    Los Angeles CA
    ------------------------------