This is a multi-part message in MIME format. ---------------------- multipart/mixed attachment Roger Jolly wrote: > Thanks Del, > I completely agree with your comments on rear duplexing, the > amount of extra power and tone colour gained is questionable. Actually I don't think that the practice of tuning the rear duplex gives any extra power at all. In my view most such schemes detract from the acoustic power output by restricting the motion of the soundboard. > Having said this, the piano in question has a crude quality casting at > best. > the forward and rear pressure bars are a long way from being parallel, and > there is a quite an audible pitch difference on all three of the duplex > unisons. In this case for sure I'd be grinding off what is there and placing some half-round or half-oval bars in the most advantageous spot possible. > Trying to assess a potential outcome, with worn hammers, tired strings, > and badly grooved bars, is as much gut feel as opposed to science. Your > point on the angle of the string through the pressure bars is well taken, > visually it looks quite steep, and with the tuning hammer there seems to be > lots of drag in setting the string, but this is probably due to grooves, > tired strings, and no lubricant. If you can figure out how to do so, measure the deflection angle before destringing. In my opinion you want to end up with at least 20 degrees. And that's assuming that you can keep the duplex length down to less than 40 mm or so. If it must be longer than that, then I'd try for a deflection angle of closer to 22 degrees. > Since this is not a customers piano I can indulge myself with some > experimentation, so I think I am going to give it a shot. > Thanks once again for your help > Kind Regards. > > Roger Jolly > University of Saskatchewan > Dept. of Music. Good luck. -- ddf ---------------------- multipart/mixed attachment A non-text attachment was scrubbed... Name: vcard.vcf Type: text/x-vcard Size: 402 bytes Desc: Card for Fandrich, Delwin D Url : https://www.moypiano.com/ptg/pianotech.php/attachments/6c/7b/ab/a0/vcard.vcf ---------------------- multipart/mixed attachment--
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