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F holes and outline


~ Ben Conover
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Hi Jim,

'' The Upper Wing Tip angle & breadth seem a little out-of-whack with the

Lower Wing ''

_ Yes, the upper wing has a different angle and width to that of the lower one, as is normal with most f holes. The angle is not so steep and the width is narrower.

Also, the finished angle of the upper corners is not shown on that drawing.

Those f holes you linked are charming but very different to each other.

Your thoughts on why they might work better 'acoustically' ?

Cheers.

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Those f holes you linked are charming but very different to each other. ... Your thoughts on why they might work better 'acoustically' ?

I'm just sayin' Mateo Gofriller also had f-holes without the severe Upper Wing mismatch [mainly 'breadth'].

If it were me, I'd go with a symmetrical pair of f-holes.

'Acoustically'? ... it has to do with the way f-hole shape/location handles compressed & rarefied air.

Enough said. :)

Jim

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Try some specifics then :

How many templets do you other makers use.

How do you decide which ones to use.

What effect - if any - do F holes have on sound.

Etc.

Oded points out to me that the ring mode of a back is closed with the center curved.. According to an earlier discussion of bending stiffness vs stretching stiffness, it seems that stretching stiffness would be especially important in mode 6.

I have noticed something about tops. If the final 2mm or so of an f-hole is left uncut and the rest of the hole is cut before final graduations, the ring tap tone does not drop very much. I did not actually use a glitter/speakervibration test, but it would seem that the ring-shaped nodal line is pretty much still thee.

If then the ends of the f-holes are then cut, the mode 5 drops suddenly. (I mean the mode had when holding at a cheek and wrapping the center) This seems to show me that a sudden release of that stretching degree of freedome loosens up the plate for at least mode 5.

It is interesting. Perhaps somebody else will be able to use this. for example, before cutting through the ends, perhaps the ring nodal line could be adjusted somewhat thorugh graduation. This might be hard to make sensible, becuase the nodal line will be drawn automatically to the ends of he f-holes before they are cut through. But perhaps some other aspect of the shape of this nodal line could say something.

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Leaving the centre thickness of the table constant right to the edge gives some violins a particular sound, Filius Andrea for exapmle.

Guadagnini sometimes left his tops thicker than his backs.

Would a Strad with Guarneri F's sound differerent ?

Would a Guarneri with Strad F's sound different ?

If anyone could make sense of these variables would it make choosing an F hole easier ?

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Leaving the centre thickness of the table constant right to the edge gives some violins a particular sound, Filius Andrea for exapmle.

Guadagnini sometimes left his tops thicker than his backs.

Would a Strad with Guarneri F's sound differerent ?

Would a Guarneri with Strad F's sound different ?

If anyone could make sense of these variables would it make choosing an F hole easier ?

Some of those awkward Guarneri f's with the pointy ends certainly make it look like he was trying to enlarge the free center portion of the top. Do others see it this way?

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Try some specifics then :

How many templets do you other makers use.

I use none. I locate the upper and lower holes, drill them, then sketch in a rough f-hole pattern, then start cutting till they are right.

What effect - if any - do F holes have on sound.

I have an experiment hat hopefully will provide some information on this but currently I am using my data aquisition system on another more vital project so the f-holes have to wait.

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'' Some of those awkward Guarneri f's with the pointy ends certainly make it look like he was trying to enlarge the free center portion of the top. Do others see it this way? ''

Pointy Guarneri's are rather like the Brescian Da Salo or Magginni, they look gothic.

I see the f's as being a component of design aesthetic and the limits of the outline you have.

You can't put Guadagnini f's on a Del Gesu outline because they just won't fit, etc.

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Ben,

There was a discussion a while back, on using longer (larger) F's on a smaller pattern viola to give it more bass. It seems from extrapolation that different F's would indeed change the sound. The 10 million $ question would be what combo get what. No help on that im afraid ive only made cellos. :)

Jesse

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To add that I changed my f hole design from Goffriller to J.B. Guadagnini.

Just wondering what you think of the combined outline and f hole shape.

Does it work ?

Thanks.

http://www.flickr.com/photos/benconover/se...868769292/show/

I really enjoyed your talent with the Flicker slideshow using your photography and the new F holes. Much better looking, I think.

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