[CAUT] Riblets

[Richard Brekne]

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