You can engineer the soundboard down to the ninth decimal. You can analyze the action geometry until it's better than new. You can rescale the treble wire. You can (and should) order the bass strings from JD Grandt. You can have hammers made from the wool of only the most contented sheep. But if you can't hear that the hammers are hitting in the wrong place you are destined for unhappiness. Your prized rebuild sounds like a concert grand through the first 4 1/2 octaves but is a dead ringer for a Wurlitzer spinet in octaves 5 and 6. My most recent project, a model M from 1930, was one of these. I've attached pictures of the revised hammer line. It was moved a full 6mm distal (hung at 124mm) at note 61. After checking and rechecking I also re-hung notes 72 thru 88 with 88 ending up at 129mm from the shank center pin. My first clue this would be needed was that the adjustable strike point mechanism in the treble cheek block had been set all the way forward back in 1930. The keyframe was even with the front of the cheek block. This is very unusual and I'm pretty sure that nobody had moved it since the piano was built. I initially hung the hammers at 130 mm like the original set. After the action was regulated and the hammers shaped and rough fit to the strings I tuned the instrument a couple of times and there was a clear deficit in tone quality from about note 57 up through note 73 or 74. I taped a piece of notebook paper to the keybed with one of the lines directly under the front edge of the keyframe in front of the offending notes and pulled the action forward until the tone improved and then marked the paper. This let me know how far I needed to move the hammers. Once I knew what was needed it was just a matter of re-hanging the hammers and checking the escapement and re-setting the backchecks. I also had to trim the inside of the hammer tails to keep them from hitting the backs of the repetitions. On paper I know I changed the leverage by moving the payload but in practice the notes with the moved hammers don't feel any different from the ones hung at 130mm. While this was a pretty extreme example it was by no means the first time I've needed to customize the strike line when tone regulating a grand piano. I've found it necessary on Steinways and Bosendorfers and a number of other makes. What moved me to share this was a call I had recently from a technician who had a similar problem on the same model a decade or two newer than my project. He had consulted with experts and installed riblets and was beginning to think that the soundboard needed to be replaced. After we spoke he returned to the piano and moved the action forward a few mm and the tone in the first capo section improved dramatically. ¡Que milagro! I know that others have written about this more eloquently and completely (Dale Erwin) but just hoped that someone out there might find this useful.
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Karl Roeder
Pompano Beach FL
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