Julian Cossmann Cooke

Conforming f-hole templates to arching between c-bouts

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1 hour ago, Marty Kasprzyk said:

The A0 frequency is proportional to the f hole area A to about the one fourth power  A^.25.  

The width distortion reduction might be around ten percent from a 3d projection to 2d so 0.9^.25 = 0.974 so your A0 frequency would be only 97.4%

If your A0 goal was 280Hz you would end up with only 273Hz.  I doubt any body could notice this difference.

I've found you have to make a massive change in f hole widths to notice anything changing.

Sounds like I may be focusing on the backside of a gnat here.  Thanks, Marty.

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18 minutes ago, Jim Bress said:

At the VSA, Joseph Curtin, Fan Tao, and Marilyn Wallin  (I don't have my notes in front of me) gave a lecture on a viola study with 25 violas made from identical outlines (cnc forms).  Part of Oberlin acoustics lab I believe.  One thing they noted from the mountain of data that they are still wading through is that a trend is surfacing from the preliminary data that the area between the f-holes (f-hole length and distance apart) has a major affect on tone.  Smaller area = brighter more focused; vs. larger area = darker less focused tone. 

Also that AO depends on length of f-hole, body of instrument (internal volume?), and stiffness of top.

Again, this is from memory not my notes.  

-Jim

I really do feel that changes in A0 have a surprisingly small influence on perceived tone.

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10 hours ago, Jim Bress said:

At the VSA, Joseph Curtin, Fan Tao, and Marilyn Wallin  (I don't have my notes in front of me) gave a lecture on a viola study with 25 violas made from identical outlines (cnc forms).  Part of Oberlin acoustics lab I believe.  One thing they noted from the mountain of data that they are still wading through is that a trend is surfacing from the preliminary data that the area between the f-holes (f-hole length and distance apart) has a major affect on tone.  Smaller area = brighter more focused; vs. larger area = darker less focused tone. 

Also that AO depends on length of f-hole, body of instrument (internal volume?), and stiffness of top.

Again, this is from memory not my notes.  

-Jim

The viola study was done by the Oberlin makers group not the acoustics group.  

I'm anticipating they will find a lots and lots of scatter.  Scatter in everything: listener preferences vs. player preferences, geometry and materials correlations with sound character and so on.  In fact if you study this stuff hard enough you eventually become scatter brained. 

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