sospiri

Rib Taper hypothesis #43,759

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1 minute ago, Bruce Carlson said:

That's one among the various theories.

It's an awfully compelling one methinks.

And I tried the balance point thing out too.

The results were: everything I tried balanced around the f hole position. 

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20 minutes ago, sospiri said:

Very true. Concert pitch in times gone by was quite arbitrary. 

I also wonder what people think they mean when they attribute mystic meaning to certain keys; "the dark key of G minor" ....what is that supposed to mean?

Any mood is implied in the composition and the playing. And it's all an acquired taste anyway.

Not exactly on point, but on piano (and probably other fixed pitch keyboards) different keys have different feels (to me at least, when I could still hear).  On recorder, keys creating lots of cross fingerings have complex range of tone color, more than simple keys without complex fingerings.  This I can hear, and the sweat pouring off the soloist might indicate the key really is tortured!   On guitar, I imagined that some keys would tend to excite the unstopped strings more than other keys, but I couldn't tell any difference.

As to what is dark v. light, I now admit to having little idea what people are referring to.  So many opinions.

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16 minutes ago, Stephen Perry said:

Not exactly on point, but on piano (and probably other fixed pitch keyboards) different keys have different feels (to me at least, when I could still hear).  On recorder, keys creating lots of cross fingerings have complex range of tone color, more than simple keys without complex fingerings.  This I can hear, and the sweat pouring off the soloist might indicate the key really is tortured!   On guitar, I imagined that some keys would tend to excite the unstopped strings more than other keys, but I couldn't tell any difference.

As to what is dark v. light, I now admit to having little idea what people are referring to.  So many opinions.

I would be interested to learn what pitch horns were tuned to before valves were invented?

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1 hour ago, Bruce Carlson said:

The central pin is a conical hole, larger on the inside of the back. 

Couldn't the hole be what is left after the screw was removed after carving the plate exterior?  Just bolt the plate/wedge to a wider piece of plank from underneath, clamp down and commence to carving. 

Seems easier than using a cradle.

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17 minutes ago, sospiri said:

I would be interested to learn what pitch horns were tuned to before valves were invented?

415 or less than that if you go back to roman times.

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1 hour ago, uncle duke said:

Couldn't the hole be what is left after the screw was removed after carving the plate exterior?  Just bolt the plate/wedge to a wider piece of plank from underneath, clamp down and commence to carving. 

Seems easier than using a cradle.

Sounds like a good idea but if I were going to screw the plate to a plank I would make sure the screw stops well before the outside arch to avoid hitting it with my gouge.  

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1 hour ago, uncle duke said:

415 or less than that if you go back to roman times.

Historical "A" has been all over the place (even as high as 567 in one old church organ) and often varied by location or city.

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1 hour ago, uncle duke said:

Couldn't the hole be what is left after the screw was removed after carving the plate exterior?  Just bolt the plate/wedge to a wider piece of plank from underneath, clamp down and commence to carving. 

Seems easier than using a cradle.

If this were the case, I would use two screws to avoid the rotation of the piece instead of one in the center. Then the consistency of the position where the pin is found would not make much sense and they would be more random.

 

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He found his own theory to justify the pin and if nothing else it gives it a practical value in its construction method, even if it doesn't convince me too much:). But I don't have a better alternative to contradict it.

 

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2 hours ago, sospiri said:

I would be interested to learn what pitch horns were tuned to before valves were invented?

This is an easy one. You need to buy and read the book "History of Performing Pitch; The Story of A".  https://www.amazon.com/History-Performing-Pitch-Bruce-Haynes/dp/0810841851

The answer is that horns were tuned to the pitch of the local organ, and that there were two organ standards, one for brass, one for strings, and that those pitches varied all over the place from in the 300s to the 500s. Generally, strings and horns didn't play together.

Valves don't determine tuning pitch; slides do.

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The balance point of the top plate and its center of mass are slightly different concepts.

As Bruce pointed out, it is possible to balance the plate on the point of a pencil. This is the balance point.

The center of mass would have the same position in some flat plane, say, defined by the plate edges, but would be located some distance below the point of the pencil on which the plate was balanced. How far down along the pencil would be a function of the arching as well as how the plate was thinned.

One can use Newton's Laws of Motion and some non-trivial mathematics to compute the location of the center of mass, but that is beyond the scope of this forum.

Physically, an object that is pushed at its center of mass will travel without any rotation. If it is pushed at a point away from its center of mass, it will move as if was pushed at its center of mass, but with a rotation about the point. This is a useful concept for figuring out the interactions of many moving machine parts, movements of planets about each other and the sun, and just about anything that can be treated as basically an array of rigid bodies.

Most of the movement of a violin plate, once it is attached to the body, is due to bending deformation. Rigid body motion probably contributes very little to violin response.

For vibrational modes, there are concepts called modal participation factors and effective mass which basically measure how much of the plate participates in a vibrational mode. This participation is one of the reasons that design just by matching vibrational modes can be misleading, especially free plate tuning without a bass bar and sound post.  One can work hard to match a vibrational mode frequency, but do so in such a way that only a small amount of the plate participates in the vibration. So the mode would contribute little to the violin tone and power.

 

 

 

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2 hours ago, MikeC said:

Sounds like a good idea but if I were going to screw the plate to a plank I would make sure the screw stops well before the outside arch to avoid hitting it with my gouge.  

Always leery of going through I am careful.  My dimensions for the board is 29" long x 13.5 " wide though for easier working I need to lose three inches in the width to 10" wide.  1/2" thick mdf is all it is.  

The 29" width works well for clamp room and forearm resting while carving, gouging and chiseling.

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2 hours ago, Davide Sora said:

If this were the case, I would use two screws to avoid the rotation of the piece instead of one in the center. Then the consistency of the position where the pin is found would not make much sense and they would be more random.

 

I use three screws one placed 100mm from the neck edge, 173mm at the middle area and 250mm for the back half.  By the time I'm through carving they are coming loose.  It's just a method I thought would work before I found Maestronet.  I carved exterior arching for 28 -30 plates so far, seems o.k. to me. 

With the D.G. plates - are there any signs of more than one pin location like around the 95 -100mm area and 245 - 270 mm area on the glue line measuring from neck towards the end?  That would be between the upper bout widest and upper corners and well behind the bridge area for the other.

I should mention that I trace around the inner form with ribs glued onto the flat board so that placement is consistent everytime for the plates or in other words the screws are always in the same location no matter the build.   It just seemed a simple thing to do.

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Actually Peter's explanation is shown in an earlier video as a point where the scrape tones of the top edges matches the scrape tones of the bottom edge and the distance of the central point varies from 182 mm to 197 mm.  If Guarnieri used this as central pivot point for thickness circles from his primary mold there is too much variance and his thicknesses  are not really circles.   Here

 

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On 11/14/2020 at 9:10 AM, Bruce Carlson said:

As you demonstrated to me a while back, the balance point does not necessarily prove equal area above and below. The shapes are too different. Of those I have tested the balance point is usually further towards the upper bout from the bridge position. I've never found one that balanced right on the line of the inside bridge notches. Same for 'del Gesù'.

It's usually nearer 190 mm. In addition you have with or without bars, possibly some regraduation, cleats and doubling that could skew the test.

Thank you for sharing your observations.

If you follow David Beard's simple rectangle proportions of the violin with the bridge dividing the length into 4 units long for the bottom rectangle and 5 units long for the upper rectangle and their width proportions of 5 units wide for the bottom rectangle and 4 units wide for the upper one then the two rectangles have the same area. The bridge is on the boundary of these two rectangles.

But the balance point for even this simple two rectangle assembly is calculated to be 0.25  proportion units above the bridge line.  If a violin size is used then the balance point is about 10mm above the bridge line.  This is in the same direction to what you observed for real plates having more complicated shapes.

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3 hours ago, Michael Darnton said:

This is an easy one. You need to buy and read the book "History of Performing Pitch; The Story of A".  https://www.amazon.com/History-Performing-Pitch-Bruce-Haynes/dp/0810841851

The answer is that horns were tuned to the pitch of the local organ, and that there were two organ standards, one for brass, one for strings, and that those pitches varied all over the place from in the 300s to the 500s. Generally, strings and horns didn't play together.

Valves don't determine tuning pitch; slides do.

Oh so ya think it's easy do ya?

Go on then, define pitch?

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2 hours ago, sospiri said:

Oh so ya think it's easy do ya?

Probably. Look into borrowing the book from your local library. If your local library doesn't own that particular book, they probably participate in some sort of inter-library lending program and can hook it for you that way.

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Old discussion of musical keys having different 'color' or 'character' are mostly assuming actual tempered scale systems still being used.  In temper tuning, actual specific interval vary from key to key.

But, even in an equal tempered environment, musical context tends to associate the introduction of flats with lowering tones, and sharps with raising.  So, on some level notions of sharp keys being bright and flat keys tending sweet or dark or cloying somewhat live on.

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20 minutes ago, David Burgess said:

Probably. Look into borrowing the book from your local library. If your local library doesn't own that particular book, they probably participate in some sort of inter-library lending program and can hook it for you that way.

So you think you can give me trumpet lessons?

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3 hours ago, Marty Kasprzyk said:

Thank you for sharing your observations.

If you follow David Beard's simple rectangle proportions of the violin with the bridge dividing the length into 4 units long for the bottom rectangle and 5 units long for the upper rectangle and their width proportions of 5 units wide for the bottom rectangle and 4 units wide for the upper one then the two rectangles have the same area. The bridge is on the boundary of these two rectangles.

But the balance point for even this simple two rectangle assembly is calculated to be 0.25  proportion units above the bridge line.  If a violin size is used then the balance point is about 10mm above the bridge line.  This is in the same direction to what you observed for real plates having more complicated shapes.

There's something that does hold across many examples that relates to what you're saying here.

But it's not near as simple or straightforward as what you've asserted here.  As I said earlier, the details of what you're touching on lay very deep in the woods.  I'm not prepared to engage in this full conversation yet.  More of the basic elements of the system need to be shared and accepted first.

 

Also Marty, you're miss quoting me.  I said that 4/9th provides a lower boundary guide to bridge location, which is in most cases actually found somewhat above this boundary.

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8 hours ago, Davide Sora said:

He found his own theory to justify the pin and if nothing else it gives it a practical value in its construction method, even if it doesn't convince me too much:). But I don't have a better alternative to contradict it.

 

I've watched all his videos and I'm not very convinced either.   I certainly can't hear what he claims to be hearing.   Strads don't have the pin hole do they? 

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