[pianotech] finding the strike line

[Gene Nelson]

Thanks Dale,
I have really spent considerable time at the listening thing. I can set the hammer at note 68 to about 1/9th and get a great tone - strong fundamental with definite pleasing upper partial and great sustain. Then push the hammer close to the string so I can see the strike point, then pluck the string in many places on both sides of the strike point and not really hear any decernable change in tone - that is unless I extend my plucking more than 5 or 6 mm. 
I suppose that I will need to just choose the best strike line and hang the hammers based on what I am hearing.
Gene
  ----- Original Message ----- 
  From: erwinspiano at aol.com 
  To: pianotech at ptg.org 
  Sent: Sunday, February 08, 2009 12:44 PM
  Subject: Re: [pianotech] finding the strike line


   Hi Gene
    I teach a class on this but it is not based on math. All my work is skilled listening. I do however think that there is a math model involved but it either doesn't' work.  OR.. Perhaps too many miscalculations or compromises were made to expedite the ease of production. Ie straight hung hammers.
    98 % of my experience lie with the strike lines on Steinway models prior to the 1990's.
   I have proven it to my own satisfaction that Steinway models both grand & some upright have strike line issue that effect & degrade the sustain,tone color & loudness of the sound in the 5 th & 6 octaves. All of my pianos going out have had the strike lines altered & it makes a huge difference. I had occsion to speak with a former Steinway restoration center employee ( 1995 to 2000) & he stated they changed the strike lines on all the rebuilds but it was kind of a hush hush thing. 
    Don't ask... don't tell.
    I have posted about this before but I do not call to what extent I detailed my protocol for finding the optimum sound but it is ultimately a sound driven protocol, & ultimately the ear is the one that dictates what is right. The math would be great if a new bridge body were to be fashioned correctly to accommodate a straight hammer line. Tw'd be Sooo much easier.
   More recent B & D plates manufactured since Stwy bought Kelly plate seem to have the problem solved or mostly so. The others I haven't had the opportunity to check out.
    
    Dale



  Hello list,
  I am curious if anyone uses a math model for finding the strike line and arrives at a line that gives the best tone. 
  Also, if listening is included in the model, exactly what are we listening for in what part of the piano?
  I have read Wolfenden's technique that says to start with 1/8th at the lowest note and graduate to 1/9th at 52, 1/10th at 64, 1/12th at 76 and 1/14th at 88.
  The original strike line on my Knabe was not even close.
  (It is now restored with new board, bridge, strings and hammers.)
  My samples are notes 1, 47, 68 and 88.
  Note 1 sounds much better at 1/8th and is farther toward the bridge than original by about 4.5mm. Note 47 also sounds much better at 1/8th and is about 2.5mm longer than original.
  Note 68 and 88 are a bit more elusive. I move 68 from the original fore and aft 1 to 3mm and can hear very little audible difference - it sounds good anywhere in there. Actually, the closer the hammer comes to binding on the belly rail the better it sounds. Note 88 appears to be good enough at about 3.3mm about 1/16th - it just is dead at 1/14th.
  It is clear that listening is a key part of this but are we really trying to hit a node and eliminate the odd partials like 5,7 and 9?  Wolfenden says and it makes sense, this is not really an issue in the upper section above middle C.
  On a side note: I did alter some speaking lengths for a couple of reasons: note#1 was shortened by only 1mm and note #88 was lengthened by 5.3mm and I used 1.05 as a multiplier to correct speaking lengths down to about note 60 and after that I lengthened speaking lengths as much as practical to get the tensions higher down to about F3. These were small changes but were improvements. So I know that the strike line should conform to a more ideal math model and certainly would differ from original. Now I struggle to fined this strike line.
  Anyone care to share their technique or thoughts?
  Certainly this all will change the action geometry as well.

  Thanks 
  Gene
  Gene



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