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ff hole outline details


Alex_E

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The varous books and literature I have on ff holes give diagonal lengths, distances between the upper holes and distance of lower holes from plate edge but not much info on the actual hole size diameters, or width at the widest point between the holes.

I've been making the upper holes 6mm, bottom holes 8-9mm and widest point at the bridge line, 6mm.

I've noticed recent posts have mentioned that making the ff holes too small tends to give a nasal sound and too large muffles the sound.

Are there any optimal sizes (as in the 61-64mm for total body thickness) that are recommended for better sound/tone production?

I've just drilled the pilot positioning holes for the ff 'holes' on the front plate of my magnesium bodied prototype and want to give it the maximum sound potential possible.

I'm planning on using 11mm from edge to bottom hole and 41mm between the top holes

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I don't know if you are refering to my post sometime ago

about f-holes. I am not a luthier per se but I was quoting

what W. Oakes' book said. There is an optimal ratio,ratio of area of the hole to inside air volume. If you copy f-hole

without consideration of its air volume you might lose the optimal.

I think it is very logical. But some expert here put a resevation sign of this idea. (to me it is obvious,if you think a bottle f water half-full,and blow air on top,you can change the level of water at will to experiement sound would be different. I am not a luthier,please remember. I am not saying to find the ratio,it is silly to do that. I am saying the observaton of its change of power)

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It seems to me that varying the amount of water in a bottle would correlate to changing the internal volume of the violin, not necessarily the f-hole size. To determine anything about f-hole size using a blown bottle, you'd have to be able to change the diameter of the bottle's neck opening without changing its volume.

If you really want to see what f-hole size does, perhaps you could just tape off part of an f-hole on a violin that sounds good and see how it sounds with the size effectively reduced. Use drafting tape or masking tape you've stuck on your pant leg and peeled off to reduce the adhesive. That will help prevent damage to the varnish.

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That is exactly NOT my point to make. Let me try it again.

If you lower the level of water in the bottle,i.e. to increase the volume of air in the bottle, while the mouth of the bottle unchanged. So the ratio indeed changes ( ratio =( volume of air )/ (area of the mouth) ). Right?

Taping the plate you are in disregard the volume of the box. Are you? I am not saying Mr. Oakes theory is correct, I am not qualified or in a position to say. If you accept the idea of the existence of such optimal ratio then this is an obvious consequence. Does this (ratio) matter to violin making?

It depends on how you make your violins, I think. Like Oakes, he (a luthier of 1889)

used trial-and-error if the violin not good (not optimal)he just took it apart re-do it. He believed Strad had an optimal ratio in mind. If someone make his violin based on a Strad then he has nothing to worry, does his best to copy, the best ratio in the Strad was built-in already (he is copying both

volume and area of f-hole). I am not making judgement but keeping an open mind on his explanation of violin making theory.

(possible nonsense?)

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The basic issue here is whether the ratio matters. Just because a ratio exists, that doesn't automatically make it important. There are a lot of unproven assumptions floating around in violin making. F-holes affect the tone, however the generalizations I've heard here are speculative, not proven, and don't even have the strength of consensus. Most of the fall squarely in the hot-air square.

Even Kevin's test isn't a good one: it's been scientifically proven that the thickness and sharpness of the edge of the f-hole have an effect on the tone, so Kevin's experiment is messing not only with size but with those other issues.

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Another extreme case, the bottle almost full, little power either. So, Mr.Oakes, he reasoned that there must be something in between. He said also that smaller holes would result more nasal sound. Of course, there are other parameters, like thickness along the f-hole, or things like that which are more than I would be able or like to understand.

I respect highly your thoughts and expertise and you made great violins. (verybody knows, public knowlege now)

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Back on track here, the numbers you want are 6mm or 7mm for the upper eyes, depending on the model, and about 9mm for the lower ones. For total length, 64mm center to center on the eyes, and that, or 63mm in some cases, is about right for every Cremonese model--variations in f-length happen *around* that placement (by which I mean that the holes don't move, but the loops approaching them the wings, everything that's not the hole placement can be longer or shorter, making the total top-to-botton length vary around the normal 76-79mm length), which almost never changes. Since a "normal" post is from 6.0mm to 6.3mm, you probably want the width at the nicks to be 6.3mm or so.

We could fight all day about the theory involved, and I'm sure the various people who might pontificate on it haven't actually tried what they might suggest, but the f-holes on about 95% of the world's best violins fit the description above, so there doesn't really seem to be an issue to discuss, anyway.

A good spacing is 39-41mm for the top holes (I'm sure some people will have lots of theories they themselves have never tried on this one, too--suffice it to say that really great violins have been made with the fs nearer at the top than 39mm, which is the del Gesu norm, but fewer of the really great ones stretch beyond 42mm or so. For the lower holes, 128mm between the *outsides* of the bottom holes works well. One danger sign that something's not right is when the inner edge of the f in the area just above the nick leans out relative to a grainline there. In is OK, aesthetically, but out rarely is. You may have difficulty finding the growth rings in aluminum, but I'm sure they're there. :-)

If you want to be snobby about it, you can do all the location the way the Cremonese did:

[Alex, when I e-mail you my mail always bounces.]

flocation.jpg

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Michael, if the locations of the sound holes are solely determined by the positions of

the lower corners, how do I reconcile with the requirement of 195mm stop length. Does

that mean when I design the mould I must place the lower corners in such a way that

in finished top plate I would have 195 stop length. But when shaping the corner blocks,

sometimes I grind it off more, sometimes less, and my stop length will vary accordingly.

Hans Weisshar went into extreme and said if your stop length is not 130/195, musician

would not play the violin. I think in the classical times, the stop length is not fixed

(or standardized). It varies from del Gesu's 192 to Maggini's 200.

BTW, how do you determine the placement of sound holes in a cornerless violin?

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On classical period Cremonese violins the stop length varies a bit, that's right. The Cannone is 199 on one side, and the Baltic 189.5; Strads wander similarly--I've seen 193 to 197, and maybe 198, if I'm remembering right, on Strads.

When I wrote my article, I didn't know what Francois Denis was doing--he's got a plan that nails the lower corners down according to proportions, so they're required to be in a very definite place. I'm really looking forward to seeing his book.

I let the stop fall where it may, and try to keep it within 2mm of 195mm. That means keeping the lower corners in control. Then I can put the bridge at 195mm, and still keep to the rule that the nicks have to fall within the thickness of the bridge.

Hans was pretty close to right: the less a violin costs, the less a player will accept a strange stop, so it's really mandatory for new makers to keep things in order.

Real violins always have corners, so that's not a problem. :-)

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The roughed out ff holes have come in close to parameters with the only deviations being 41.5mm between top hole inner edges and 130mm between bottom hole outer edges.

The grey colour is the factory finish after rolling and annealing, before the final polish.

Mag%201.jpg

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Hi Mr. Darnton,

Here an amaturer's (me) question : Is there any evidence that Strad did adjust the ratio (volume/ area) of a f-hole by cutting the hole larger to get "his optimal ratio" after the top was attached ? (Are there asymmetrical f-holes

not by choice, but by neccessity) Thank you in advance.

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Nice work on the shaping of that piece Alex. As I think I may have mentioned at one time, I also have some history working with shaping of metal, which helps in the appreciation of what you have been doing. Most of the metal shaping I was involved in was shaping of parts (mild steel) for customizing of porsches and maseratis, and shaping of aluminum for repair of Rolls Royce and Bentley automobiles.

How do you anneal the magnesium? For normal aluminum, I would just cover the surface with soot from the torch and then burn it off. The temperature required for that process was the same as the temperature required for annealing, so it was a quick-n-dirty way to go about it. I still don't completely understand how a violin made of metal would function, but it would seem that you would want to leave certain areas in their hardened state (created by the shaping) and others would be best served if they were annealed - but that's just an assumption.

Please keep us posted as I think others here find your work as interesting as I do.

Tim

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