reciprocity video

[Oded Kishony]

Some folks have been asking me to explain string reciprocity so I've made a short video.

This is the first time I've tried making a video so I hope I'm forgiven any shortcomings.

There are some minor errors and misstatements in the video but I think the basics are all there and more or less correct.

I'm posting it here so I can answer questions about the process. Keep in mind that I'm just an ignorant violinmaker and not a physicist.

http://www.youtube.com/watch?v=dK3rh1KtMvg?hl=en&fs=1%22%3E%3C%2Fparam%3E%3Cparam

[Jacob]

Some folks have been asking me to explain string reciprocity so I've made a short video.

This is the first time I've tried making a video so I hope I'm forgiven any shortcomings.

There are some minor errors and misstatements in the video but I think the basics are all there and more or less correct.

I'm posting it here so I can answer questions about the process. Keep in mind that I'm just an ignorant violinmaker and not a physicist.

http://www.youtube.com/watch?v=dK3rh1KtMvg?hl=en&fs=1%22%3E%3C%2Fparam%3E%3Cparam

Oded, you're THE MAN.

That video is very much appreciated.

[Marijan Radaljac]

Keep in mind that I'm just an ignorant violinmaker and not a physicist.

http://www.youtube.com/watch?v=dK3rh1KtMvg?hl=en&fs=1%22%3E%3C%2Fparam%3E%3Cparam

Luckily. That makes things understandable . Any chance for part 2, with a little more detailed view on practical use of string reciprocity principle.

Thanks for that!

[C.B.Fiddler]

I am unable to view the video. Anyone else?

[Roger Hill]

Very useful, Oded. Thank you for taking the time to do this. Will part 2 explain how to find the location of the anti-nodes on the surface and show the scraping process? I hope so.

[lvlagneto]

Fun video... thank you!

Sometimes when I sing next to my guitar or violin, the body responds. These are sympathetic vibrations?

[JimMurphy]

Good one, Oded.

If different E-string types are tested, I wonder if the resonant frequency 'moves'.

Thanks,

Jim

[Oded Kishony]

Very useful, Oded. Thank you for taking the time to do this. Will part 2 explain how to find the location of the anti-nodes on the surface and show the scraping process? I hope so.

When you tap on the nodes the strings either stop vibrating or vibrate less. The strings vibrate most at the antinodes.

Oded

[Oded Kishony]

Good one, Oded.

If different E-string types are tested, I wonder if the resonant frequency 'moves'.

Thanks,

Jim

Doesn't matter what type of string you use the frequency will not move.

The only difference might be how loud the harmonics might be between steel, nylon and gut E strings.

Oded

[Oded Kishony]

Sometimes when I sing next to my guitar or violin, the body responds. These are sympathetic vibrations?

That's odd when I sing only the dog starts to howl, do you think it's unsympathetic vibrations? ;-)

[Andres Sender]

Thanks very much for taking the time to do this Oded.

[Dean_Lapinel]

Nicely done Oded!

It took a bit of time for me to be able to view the video. Do you have a direct link or search word on the you tube page for those that are having trouble?

Incidentally, you present yourself well and you have a knack for visuals when describing concepts. I look forward to a part two

Question: (partly related to the singing question)

Why is it that the violin or guitar corpus rings at a variety of frequencies? I'm certain this can be found by anyone holding the instrument near a speaker. I don't know if it works with hip hop though, as I encase, cover and hide my instruments when someone plays hip hop in my house

[Anders Buen]

Some folks have been asking me to explain string reciprocity so I've made a short video.

This is the first time I've tried making a video so I hope I'm forgiven any shortcomings.

There are some minor errors and misstatements in the video but I think the basics are all there and more or less correct.

I'm posting it here so I can answer questions about the process. Keep in mind that I'm just an ignorant violinmaker and not a physicist.

http://www.youtube.com/watch?v=dK3rh1KtMvg?hl=en&fs=1%22%3E%3C%2Fparam%3E%3Cparam

A very nice presentation, Oded. No fuzz, just plain useful information.

What are the highest pitched note you have identified using your method?

Can you track the f-hole wing modes e.g.?

[violins88]

Some folks have been asking me to explain string reciprocity so I've made a short video.

This is the first time I've tried making a video so I hope I'm forgiven any shortcomings.

There are some minor errors and misstatements in the video but I think the basics are all there and more or less correct.

I'm posting it here so I can answer questions about the process. Keep in mind that I'm just an ignorant violinmaker and not a physicist.

http://www.youtube.com/watch?v=dK3rh1KtMvg?hl=en&fs=1%22%3E%3C%2Fparam%3E%3Cparam

Oded,

Thank you very much. It was important to actually see you doing it.

[DrTodd]

Shouldn't there be 3 air modes since there are three dimensions? I had read to get A0 by blowing across the f-hole like you're playing a flute or a coke bottle. This seems very close to blowing obliquely in east-west direction which would give the third air mode? I guess that mode hasn't been determined to be useful?

[Wm. Johnston]

Shouldn't there be 3 air modes since there are three dimensions? I had read to get A0 by blowing across the f-hole like you're playing a flute or a coke bottle. This seems very close to blowing obliquely in east-west direction which would give the third air mode? I guess that mode hasn't been determined to be useful?

Actually one dimension would give you a whole series of air modes just by itself, but three dimensions will cause even more! There is a mode called A1 which is a standing wave with antinodes at the neck and tailblocks. It can be heard when you are very near to the violin but it radiates poorly so it's probably only important to the player's impressions. As far as I know A0 is the only one that radiates strongly. That's all I will say about it here, don't want to derail the topic.

[Marijan Radaljac]

Shouldn't there be 3 air modes since there are three dimensions? I had read to get A0 by blowing across the f-hole like you're playing a flute or a coke bottle. This seems very close to blowing obliquely in east-west direction which would give the third air mode? I guess that mode hasn't been determined to be useful?

If I recall correctly, length and depth of the body, and the size of the f-holes openings are the measurements which set the resonant frequency of the body. Width has an impact on the power of the output or amplitude. Similar to the square profile organ pipes. Two pipes with same length and depth, but with different width will share the same frequency. Or simple wooden block, same length and thickens will result in same frequency at different widths.

[NewNewbie]

I am unable to view the video. Anyone else?

Thank You Oded!!!

Does that help?

Here is OdedKishony's channel at YouTube.

odedkishony

If there are any future videos should be found most likely found here.

[Jacob]

Good one, Oded.

If different E-string types are tested, I wonder if the resonant frequency 'moves'.

Thanks,

Jim

What's the difference between different and different?

[richardz]

Thank you for doing this Oded. Excellent and informative presentation.

[JimMurphy]

What's the difference between different and different?

Voice inflection.

Jim

[Oded Kishony]

Marijan writes

If I recall correctly, length and depth of the body, and the size of the f-holes openings are the measurements which set the resonant frequency of the body.

You are combining too many things together. As stated in the video the resonant frequency is determined by three things stiffness, mass and damping this translated in the body of the violin to the wood properties, the arching and the graduations. The shape (or model) also contribute to the resonances by changing stiffness and mass determined by relative size of the lower middle and bottom bouts etc. The F hole openings have mostly to do with how the air moves in and out of the corpus when the surface vibrates the wider the hole the higher the frequency. You can hear the effect of the first (lowest) air mode by covering the treble side F hole, humming a C# into the bass side F hole then opening and closing the treble side F hole with your hand. It will sound as f you are turning the switch on and off. Now try the same thing with a different note and you will hear...nothing. The air mode only amplifies a very narrow range of frequency, usually around C# (on the G string)

Width has an impact on the power of the output or amplitude.

Not as far as I know.

Similar to the square profile organ pipes. Two pipes with same length and depth, but with different width will share the same frequency. Or simple wooden block, same length and thickens will result in same frequency at different widths.

In terms of violin air modes this analogy doesn't really apply.

Oded

[Oded Kishony]

I should also add that I didn't mean to imply that modes can only be in phase or out of phase, in fact there are many degrees (~180) between in phase and out.

A few other small errors in the talk which I'll clarify as I spot them.

Oded

[Janito]

Good video. Now I can read and understand what you are saying.

Why did you chose the E string if it is tuned down considerably? Might the A work also?

[Oded Kishony]

Good video. Now I can read and understand what you are saying.

Thanks. Yes, it's a lot more interesting when you know what people are talking about.

I chose the E string because it is the lightest and will respond most easily, but you can use any string. I haven't tried it but I bet gut strings would work well.

One of the details I did not mention is that the range of frequencies that you get depends on the hardness of the object that you use to strike the bridge or tap the surface. If you are interested in high frequencies then use a hard object, I use the back of a chinrest key. Midrange use something like a hard plastic, I like a toothbrush handle. Low frequencies something soft like a pencil eraser. You can strike very lightly if your hearing is very good and it's probably best not to try this on an old and valuable instrument. ;-)

The highest frequency you can get is equal to the highest harmonic of the highest string at the highest pitch. The limit is mostly the ability to hear such high frequencies. Someone asked if the F hole wings are in this range-they are.

If you want to use the fingerboard to raise the pitch it is best if you press the string with your finger nail, other wise the fleshy part of your finger dampens the vibration too much.

One of the things you can do is actually map out nodal lines. To do this you need a marker that will safely leave a mark on the surface. On an unvarnished violin I simply use a piece of chalk. First locate a resonant frequency of the violin ( but not an air mode)by tapping the side of the bridge and raising the pitch of the E string, leaving the string at the same pitch now tap the surface, when you hear the humming of the strings drop, make a dot with the chalk. After you have made several dots start to connect them and before you know it you will have a set of nodal lines just like the fancy computer generated pictures you see on the net. I don't generally draw nodal lines of the whole instrument but I will take a section that I'm interested in and draw out a few of the nodal lines. Of course you will not get the same level of detail as a computer generated picture but it's a lot easier and cheaper ;-)

Oded