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Interesting and weird high treble effect

  • 1.  Interesting and weird high treble effect

    Posted 12-09-2018 10:49

    Behavior of the high treble can be downright weird. Take this observation. Chinese grand makeover I just finished and sold. In the rush to get it up and running for a chapter technical I was doing on the piano, the top half octave, which needed mating, got ignored until after the technical...no time.

    Later, at my leisure, I went to mate these hammers, no.83-88. I use this notation when mating hammers, per unison:  oxX, =  "o"left string no contact. "x"middle string contacting but weaker than the right, and "X" right string contacting well.
     
    88's mating pattern was oxX.  Proved by striking the note with the key driven hammer, and muting individual strings. Ok...so I thought "right string is sounding the loudest, so I have to take some off the X, middle string is sounding but weaker than the right, so I have to take a little off the x, and left string is not sounding, so I take none off the "o". I do that, and the strike pattern gets worse...still oxX but worse. I repeat the removal of felt logical that seems logical several more times, until the crown is noticeably tilting down to the right side...the side supposedly striking the string. The tone of the entire unison starts to get noticeably worse. 

    There was one puzzling observation I made while messing about in the proceeding paragraph that I didn't mention. Though the original "un-corrected" no.88 had a striking sound profile of oxX, the carbon paper visual evidence said Xxo...the opposite. I scratched my head, but didn't think about it initially, assuming the carbon paper was giving a bogus result for some reason.

    However I soon realized a bizarre thing...the carbon paper was absolutely correct. "X" the loudest sounding struck note, and the note with nice tone, was indeed not being struck at all by the hammer...not at all.  "x" was striking but not firmly, and "o" the string producing no sound at all, was the only string that was actually being firmly contacted by the hammer. This was confirmed both by the carbon paper trails, and by raising the hammer carefully to the strings and plucking the notes. 

    I went on to confirm this weird behavior in the entire top half octave, at which point we seemed to exit the worm hole and return to normal results.

    My theory is that that hammer is completely damping the vibration, and the only good tone came from vibrations initiated at the bridge. no. 88 hammer is 3.7g (not SW, but HW) Hammers are light, though this set was heavier than usual for me, as the last piece of wood used in the moulding was very dense. Usually I can get them down to 3.2-3.0 gm. Leverage was slightly elevated with hammer weight adjusted for touch. WNG shanks. Regulation and letoff functioning well. 2mm letoff with drop a touch higher than letoff...but definitely no blocking at drop. I push shank friction in the treble up to 4g measured at 20mm from the center.

    David Love's comment on hammer rebound time (COR) made me think about this. I have been thinking about how I could have increased rebound speed up at 88 where there is little felt to serve as a serious spring, and requirements of stiffness in the hammer are greater than lower in the scale.  88 was well juiced, as the factory 49mm SL which I did not get into changing on this instrument,  was challenging tension up there to start with. When re-scaling I have been pushing SL's up there to 55mm for a while, and getting good results with the higher tension. I have not noticed this weird behavior before though...but I will certainly pay attention in the future.

    But yeah, how to cut rebound time when my specs are already geared to reducing that time?  





      



          ​



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


  • 2.  RE: Interesting and weird high treble effect

    Registered Piano Technician
    Posted 12-09-2018 11:24
    JIm,

    What response pattern -- if any -- do you see when plucking L, C, R without the hammer in contact?  Do they respond and decay equally? Any pronounced false beats, and if so, any pattern to them?

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    John Rhodes
    Vancouver WA
    360-721-0728
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  • 3.  RE: Interesting and weird high treble effect

    Posted 12-09-2018 11:36
    John,

    I delivered the piano last week, but will visit it in 2 weeks. Plucked, all there strings were similar, meaning no Xxo differential at all.  

    Regarding falseness, there was more falseness than is usual for me in the treble in general, since I did not replace the cap. However, its a pleasant and sparkly falseness, not a wild noisy falseness.  I just repinned with slightly oversized pins. I will check for obvious differentials in false beating between individual strings.

    Why do you ask about falseness?     


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



  • 4.  RE: Interesting and weird high treble effect

    Posted 12-09-2018 12:31
    Jim
    If you muted X and x, and played the note, did o sound or not?

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



  • 5.  RE: Interesting and weird high treble effect

    Posted 12-09-2018 12:49
    "o" did not sound.  The weird part was that "o" was the only string the hammer was actually contacting.

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



  • 6.  RE: Interesting and weird high treble effect

    Posted 12-09-2018 13:24
    Wait, I read that wrong. 
    I meant, what if you muted o and x, holding the wedge so there's no transmission of the impact through o and x to the bridge.
    Would X sound then.
    I'm wondering is there a twist when the hammer strikes, or is X responding to the jarring of the bar right next to it, perhaps a resonance in the capo bar?
    [Something like this requires some extreme imagining.]

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    Ed Sutton
    ed440@me.com
    (980) 254-7413
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  • 7.  RE: Interesting and weird high treble effect

    Posted 12-09-2018 16:48
    Ed, I would say that the bridge still has movement initiated even if o&x are muted. I will check when I see it.

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



  • 8.  RE: Interesting and weird high treble effect

    Registered Piano Technician
    Posted 12-09-2018 13:01
    Jim,

    I haven't encountered what you describe, and I don't know what might be going on.  But mechanisms which can couple energy from one string to another are involved, and terminations are integral to that.  Plucking and listening for false beats might provide a clue.  If plucking response seems normal, and hammer response is weird, that would implicate the hammer.

    I'd also look for anything unusual about the capo termination.  Try plucking the front scale to see how the speaking portion responds.  And compare (in as many ways you can think of) the trouble notes to those down-scale where things seem normal.  If you have a spare hammer, you could juice it until it resembles concrete and see if that eliminates the trouble.  If the defect is still there, then look for something other than contact time being the cause. 

    Please keep us informed of your progress.  And good luck!

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    John Rhodes
    Vancouver WA
    360-721-0728
    ------------------------------



  • 9.  RE: Interesting and weird high treble effect

    Member
    Posted 12-09-2018 15:45
    I had some strange sounds coming from a church piano that I traced back to loose center pins in the hammer flanges. I think it is worth rebushing and repinning a few of the problem hammers as well as travelling the hammers and seating and levelling strings. You probably did this but its never a bad idea to try it again. Also swapping out a hammer for one in the octave below can help pinpoint if its the hammer or the strings . Another thought is to play around with the action position to see if a different strike point on the strings is better or worse...

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    James Kelly
    Pawleys Island SC
    843-325-4357
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  • 10.  RE: Interesting and weird high treble effect

    Posted 12-10-2018 13:36
    What do the strike points feel like.  Is the hammer soft? Does it need firmed up?

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    Jeffrey Gegner
    Tipton IN
    765-860-5900
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  • 11.  RE: Interesting and weird high treble effect

    Registered Piano Technician
    Posted 12-10-2018 15:46
    Thanks so much for your post, Jim. I recently experienced for the first time the symptoms you have described. It is totally counter-intuitive, and I have no explanation speculation to offer. Looking forward to us collectively getting to the bottom of this apparent mystery.

    Alan

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



  • 12.  RE: Interesting and weird high treble effect

    Registered Piano Technician
    Posted 12-10-2018 18:12
    A good example of how notions of profitability can be dashed, in terms of hourly rates, when these mysteries occur. Or sometimes just fumbling around with a troublesome screw for 10 or 15 minutes. 
    One long shot that comes to mind is the possibility that an odd sized wire got thrown into the mix?

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    Steven Rosenthal
    Honolulu HI

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  • 13.  RE: Interesting and weird high treble effect

    Posted 12-10-2018 20:46
    Alan,  Does this mean I have not actually entered the twighlight zone, yet...or does it mean we both have entered it? 

    Can you share some specs on your patient.


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



  • 14.  RE: Interesting and weird high treble effect

    Posted 12-10-2018 21:08
    Wouldn't having a key pounding machine eliminate the human error part?  There could be a misdiagnosis of the carbon paper lines, removing too much felt, etc.
    The design I came up with is pretty easy to make. Mine cost less than $20, whereas WNG is $1800. It only takes an hour to mate the hammers to the strings.
    Piano Key Pounder Version 3
    YouTube remove preview
    Piano Key Pounder Version 3
    Worked out the bugs of the first two pounders. Added a central guide to the slide support legs. Increased the size and density of the camshaft. Went from 5/8" fir dowel to a 1" hickory dowel. That fixed the torque problem. Used hardrock maple to make the cams out of.
    View this on YouTube >


    -chris




    ------------------------------
    Maker of the Worlds Best Piano Soundboards.
    chernobieffpiano.com
    grandpianoman@protonmail.com
    865-986-7720
    ------------------------------



  • 15.  RE: Interesting and weird high treble effect

    Registered Piano Technician
    Posted 12-11-2018 10:49
    Chris --

    Loved the video. Especially the audio part. Wonderful how the sound changes as you move around. Essence of Steve Reich.

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    Geoff Sykes, RPT
    Los Angeles CA
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  • 16.  RE: Interesting and weird high treble effect

    Registered Piano Technician
    Posted 12-11-2018 08:54
    Jim,

    Far be it from me to be able to tell you if I am just a fan of the Twilight Zone or am actually living in it, much less diagnose your own status in this regard. If you figure that one out, please do share your realization with the group!

    What I can tell you is that we encountered the mating conundrum you describe on a Falcone 7' 4". Don't recall the exact note, but it was also in the top half octave (A or A# below the highest C come to mind). When last working on that piano, we ran out time before resolving the issue. Can't wait to find out from you what we should do next ;-).

    Alan

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



  • 17.  RE: Interesting and weird high treble effect

    Registered Piano Technician
    Posted 12-15-2018 04:14
    Maybe it was actually the leftmost string of #88 (in more firm contact with the hammer, and hence probably lower) which was precisely the culprit responsible for a quicker hammer rebound speed that allowed the rightmost string to speak louder during your striking sound profile test.

    Then, it would make very good sense how the carbon paper profile suggests Xxo, while simultaneously the striking sound profile suggested oxX.

    I like your notation system a lot!

    Essentially after it has been well mated, we're persuading the hammer contact time per string, or rebound response per string, to become more equal among each wire in the unison.  

    So perhaps this discrepancy between the Xxo and oxX test results has less to do with string coupling phenomena.

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    Adrian Carcione
    Simi Valley CA
    805-578-8941
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  • 18.  RE: Interesting and weird high treble effect

    Posted 12-15-2018 11:06
    Adrain....so I would need a way to test your theory. 

    If I understand you correctly, 88's right string, the one that sounds nice in the oxX key driven hammer test, as evidenced by the discrepancy in the carbon paper test, is still being hit, but later than the right and center...maybe only grazed by the hammer. I suppose a way to test that would be to file the right side of the hammer such that it was way below the string at strike, to make sure it never hits the string at all...confirm there is no grazing of the right string

    I did kind of do this by mistake at first when I mis-diagnosed the strike pattern. I did note that the when really making the hammer lopsided, perhaps taking the right string out of the equation at the hammer, the sound got worse. Though the way I did this also reduced the middle string's contact, as I filed the strike point in a straight, though lopsided line. Perhaps the test is to get the strike so I have the original ox for left and right, and only take the right string out of the picture, by filing it aggressively all by itself. I will try to mess with this on friday when I see it...though its much harder to mess around like this once the piano is on-site.

    If this theory were true though, I still think it will leave an essential frustration for me. Filing all to equal as we normally try to do, will leave all three with equal strike, and equally too long contact time. When doing the final prep on this piano, I elected to leave the unequal condition, because it sounded better up there...but I will revisit my impressions now that I have some perspective, not having the piano in my face in the shop for a couple of weeks..
    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 19.  RE: Interesting and weird high treble effect

    Registered Piano Technician
    Posted 12-15-2018 21:15
    Jim: Yes. Interesting example of another unmusical "foolish consistency"?  If I understand you correctly left and center is what you meant in line 2.


  • 20.  RE: Interesting and weird high treble effect

    Registered Piano Technician
    Posted 12-16-2018 13:04
    Jim,

    Thanks for posting. I can't think of anything profound to add, but wanted to address a couple of specs that jumped out at me. I generally don't try to nail the action in at prescribed numbers, but these did stand out. Maybe my own misunderstanding.

    You said that you set letoff at 2mm and drop just above. I typically get the letoff higher as I go up the scale and end up closer than 2mm at the top, as long as I can assure that the hammer is not interfering with the string deflection. Also, I can't reconcile setting drop above letoff, which seems like it wouldn't give the hammer anywhere to go and might cause it to linger within the deflection envelope. Am I missing something here or just displaying my ignorance?

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    Dave Conte
    Owner
    North Richland Hills TX
    817-581-7321
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  • 21.  RE: Interesting and weird high treble effect

    Posted 12-16-2018 13:35
    Jim-
    I intentionally raised let-off and blow distance so that A7 blocked firmly against the strings.
    Pressing the una corda to clear the left string, the sound sustained when the key was played.
    Holding a big mute between the two right strings, there was no sustain sound when the key was played with the una corda.
    This partly supports your idea that the sustain sound comes by reflection from the bridge.
    The same test could be done with an uneven topped hammer. Maybe groove the middle so a tilting hammer blow is ruled out.

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



  • 22.  RE: Interesting and weird high treble effect

    Posted 12-16-2018 14:56
    Where drop ends up, for me, is determined by the stack and action parts in each particular piano. I set drop by synchronizing the instant when the drop screw is first touched by the balancier and the instant when the jack toe first touches the letoff button. This is done by "feel". Where drop ends up relative to letoff is a result rather than the target. The snychronization is the target, and occurs mid stroke somewhere, at the beginning of the letoff event. Setting drop this way is not dip dependent, as the synchronization happens in mid-stroke. The end point of drop at full dip is where it ends up. One just has to be sure that at full dip, drop is not so high that it hits the strings in the excursion zone.

    I used to set letoff higher, but with lighter, less dense hammers, I found the control high letoff seeks is automatically achieved by lower inertia (sometimes higher leverage) in the hammer lever itself...much bigger bandwidth of high functionality.  l often found previously, that if letoff is too high, I had to sacrifice synchronicity often as the synchronization required a slightly elevated drop,relative to letoff.  


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



  • 23.  RE: Interesting and weird high treble effect

    Posted 12-16-2018 15:12
    Ed,  good idea on the test. It corroborates my own observations.

    I would add to Ed's partial conclusion, that the blocked center and right strings are still allowed to vibrate somewhat, because the string, being blocked at the strike point is being blocked at a node. The center and right string are not allowed to vibrate with the large mute, because the mute is not located at an efficient termination point.  

    My take on this observation has been, that in proving what at first seems to be the exception, the observation actually sheds some very interesting light on the complex interactions that may be going on in the weird, extreme high end of this beast. 

    If anyone out there can challenge Ed's partial conclusion, ie that his experiment points to indirect excitement of his left string by the bridge, please chime in, and we can try to challenge the hypothesis.  I think there is something practical to be learned here regarding voicing and tone regulation of the high treble. I submit, that there is much more available up there, than we usually get, because the damn hammer is shutting down a huge percentage of the vibration...even with light hammers (relative to modern weight standards and modern leverage standards).

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



  • 24.  RE: Interesting and weird high treble effect

    Posted 12-17-2018 07:35
    If your rep lever upstop screw leaves the hammer higher than Let Off, then your actual LO is where the rep lever elevates the hammer. The jack will trip out but the rep lever supports the hammer until disengaged. It's a combination of dip and action geometry as to how far the whippen is elevated.

    I too set the jack engaging the LO button and the rep lever touching the upstop screw simultaneously. You can lift the jack tender to touch the button and adjust the upstop screw to touch the rep lever, I watch the back end of the rep lever for motion. If the 'drop' is higher, then dip or maybe hammer blow distance can be corrected.  I usually find it to end up less than a mm below LO with the key fully depressed or just about at LO. But more important, is to have the whippen elevated to a point such that the jack ends up to just clear the knuckle at full dip.

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    Regards,

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



  • 25.  RE: Interesting and weird high treble effect

    Registered Piano Technician
    Posted 12-17-2018 10:27
    Always something to postulate. 

    At the risk of appearing "me too", I shoot for a simultaneous double escapement moment of contact. I find there are objectives to meet in several directions. Simultaneous feels different than a slight deviation does under the fingers, less rebound of the hammer leads to higher risk of bobbling if regulation tolerances are kept tight (so often there needs to be fudging somewhere else accordingly), and there is inevitably a tonal difference. Another item that occurs to me is that if the rep lever is taking over work from the jack when in motion, than variation in velocity force will make the behavior of the lever dynamic according to how much the spring is being taxed, whereas the jack is not affected by it. I don't profess that to be good or bad, but just for consideration.

    ------------------------------
    Dave Conte
    Owner
    North Richland Hills TX
    817-581-7321
    ------------------------------