Ric, Sorry, I would define it as killer octave syndrome in this piano-- short sustain on one note in particular and generally lacking power in the upper half of the 1st treble section. (Mr.) Bill Ballard told me about using a riblet with great results in the treble of a rebuilt Chickering (if I remember correctly). If he's reading, perhaps he'll chime in about the sound before and after. Barbara Richmond, RPT near Peoria, Illinois ----- Original Message ----- From: "Richard Brekne" <ricb at pianostemmer.no> To: <caut at ptg.org>; <pianotech at ptg.org> Sent: Monday, September 24, 2007 3:29 PM Subject: [CAUT] Riblets > The Riblets yes.... definitely interesting and worth a try. Let me know > how they work on the Seiler... as I have a similar Seiler with what sounds > like exactly the kind of sound you refered to in the same place. Not > exactly a killer octave syndrom is it.. ?... just a weakish (tubby??) > thinned out sound. Not particularly percussive or short sustain... just > not very nice and full. Anyways... to my own idea. > > Seems to me that the idea behind these and other schemes... if it is about > adding stiffness... is that it really is about the downbearing pressure of > the strings... both in static and in vibrational modes. I mean where are > these riblets installed yes ??... > > I'm not an engineer... but the idea I had was to use opposing neodymium > magnets... very powerful things. Two opposing 45 mm Ø 5 mm thick magnets > will support about 50 kilos at 2-3 mm distance. Anyone figuring how much > load support there is right under the bridge by any given rib will quickly > understand that an added 50 kilos for what amounts to about 10 grams of > mass tops is quite a bit. > > I did do a very coarse experiment a couple years back on one of these > little Knudsen pianos we have all over the place here... very easy to > access the back. At the time I was more interested in looking at what > kind of pitch change they would cause when adjusted closer or farther > apart as part of the whole pitch change for season change discussion.... > so I didnt pay so much attention to what kind of sound difference there > was created. Wrong kind of instrument for that anyways me thinks. In any > case... strikes me that opposing magnets might have an even better result > then riblets or other such devices... and to boot one can actually > <<tune>> their effect by simply adjusting the distance between them. One > magnet screwed into the soundboard directly under the bridge... the other > on a cross beam attached to the bracing so that one can adjust the height > of the magnet from underneath with a simple screw. > > Worth a try anyways... > > Cheers > RicB > > > > Well, since my boss, Ed Sutton, has spoken up, here's a sneak peek > at a TT & T item from the November Journal. > > If you are going to make riblets, Darrell Fandrich has modified the > design (see picture)--he reported to me that by stepping off the > back they perform better than the originals (with the curved back). > > Barbara Richmond, RPT > near Peoria, Illinois
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