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GerardM

Tap Tone or Plate Tuning Equipment

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On 9/18/2018 at 3:54 PM, David Burgess said:

Prior to dropping some big bucks on Spectra Plus software, and learning  how to use it, I'd say that most of my earlier efforts didn't amount to much more than a waste of time.

Ditto!

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If you use a freeware sound capture program, like Audacity, you can measure Q as follows.

Pluck a string and capture the sound.

Expand the Audacity wave form plot until you can clearly see the repeating, decaying patterns.

Pick an peak... any peak.

Count how many cycles it takes for that peak to decay to 50% of its height.

Multiply the number of cycles by 4.53.

For example, if it takes 10 cycles for the peak to decay to half its amplitude, then Q = 10 x 4.53 = 45.3

 

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That will capture the Q of the string.  I don't see much point of that.  If you want the Q of a body resonance, you'd need to do a sine burst input with a bridge driver.

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It captures the Q of the entire violin, string and body. For sine burst into the bridge, one supposes the bridge would need to be supported by the strings, so the damping of the strings would still come into play. I would need to think a bit about whether or not the results would be different between the two tests.

The point of any of this really depends on what the OP is trying to accomplish. If one is trying to judge the effect of wood treatments or construction techniques on the Q of the body, then some burst sine input into an unstrung violin might be the way to go.

Q values are frequently frequency dependent, so that adds an extra complication into figuring out what any of this means.

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16 hours ago, ctanzio said:

If you use a freeware sound capture program, like Audacity, you can measure Q as follows.

Pluck a string and capture the sound.

Expand the Audacity wave form plot until you can clearly see the repeating, decaying patterns.

Pick an peak... any peak.

Count how many cycles it takes for that peak to decay to 50% of its height.

Multiply the number of cycles by 4.53.

For example, if it takes 10 cycles for the peak to decay to half its amplitude, then Q = 10 x 4.53 = 45.3

 

In my experience it was not that easy - sadly.

some problems

- the peak ( in your experiment) also includes the extension of string- harmonics ( having most probably different [faster] decays)

- especially at the beginning the signal also includes corpus - "side"-energy ( from strong corpus modes, exited by the pluck- action 

I tried to purify the contaminated pluck signal by eliminating the harmonics ( with  eq.), so that only the fundamental part should remain and should give a better reading. After this I wondered, that the decay of the fundamental oscillation was not regular. So I made an FFT of the remaining (fundamental)signal. There was to see, that this fundamental signal was still contaminated by a closely adjacent oscillation, obviously a corpusmode, exited by the pluck signal. I don´t know if the crazy shape of the decays was caused only by the neighbourhood-corpusmodes or whether there are additional some other effects. Even there could be a timedepending different composition of the amounts of radiation-damping / internal(wood-structure)damping / left-hand-finger-damping ( if not open string) or string-damping. One should really do some pizzicato-records and look at the decays - one rubbes one´s eyes ! 

I think, the procedure, used by Don is much better, because it at least avoids to exite harmonics or neighboured corpus-resonances. It could give better chances for a suitable reading.

 

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1 hour ago, Danube Fiddler said:

I think, the procedure, used by Don is much better, because it at least avoids to exite harmonics or neighboured corpus-resonances. It could give better chances for a suitable reading.

Reading, yes.  Useful, no... unless you want to verify all the things that are not of use.

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5 minutes ago, Don Noon said:

Reading, yes.  Useful, no... unless you want to verify all the things that are not of use.

Who knows......

Why didn´t bring the spectral approaches much more than found by Meinel and Dünnwald. So many decades have passed and there was no further real progress. I think, the truth must be somewhere else. Why not in the decays ?  Seen with the eyes of players : Which are the most difficult points of time while playing ? I.m.o. often these are the beginnings and endings of notes. Would it be so unlogical to assume the main-field of quality exactly here ?

 

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That's exactly what I think too.  If measurements so far haven't seen much difference between good and great (bad or good or what ever) it means that we're not measuring the right things.  The starting and ending transients (decays) should be looked at more carefully.

41 minutes ago, Danube Fiddler said:

Who knows......

Why didn´t bring the spectral approaches much more than found by Meinel and Dünnwald. So many decades have passed and there was no further real progress. I think, the truth must be somewhere else. Why not in the decays ?  Seen with the eyes of players : Which are the most difficult points of time while playing ? I.m.o. often these are the beginnings and endings of notes. Would it be so unlogical to assume the main-field of quality exactly here ?

 

 

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13 hours ago, Marty Kasprzyk said:

That's exactly what I think too.  If measurements so far haven't seen much difference between good and great (bad or good or what ever) it means that we're not measuring the right things.  The starting and ending transients (decays) should be looked at more carefully.

I know that some years back, Sam Z. was intensely focused on starting transients.

Assuming that transients are a big deal, and you get the measurements to show the difference between good and bad... there's still the tiny little problem of figuring out what you need physically in the construction to get there.  I think it would be even more difficult than the problem of matching the known frequency response of a "good" instrument.  And I don't mean just signature modes.  As far as I know, this has never been done very accurately.

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1 hour ago, Don Noon said:

I know that some years back, Sam Z. was intensely focused on starting transients.

Assuming that transients are a big deal, and you get the measurements to show the difference between good and bad... there's still the tiny little problem of figuring out what you need physically in the construction to get there.  I think it would be even more difficult than the problem of matching the known frequency response of a "good" instrument.  And I don't mean just signature modes.  As far as I know, this has never been done very accurately.

While I agree with your sight of the problems  May be, Sam Z. has found something, which is of practical use - we can´t claim, that his violins would be unsuccessful.

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3 hours ago, Danube Fiddler said:

While I agree with your sight of the problems  May be, Sam Z. has found something, which is of practical use -

Quite possible. One could easily argue that Sam doesn't share everything he knows. Why would he?

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4 hours ago, Danube Fiddler said:

May be, Sam Z. has found something, which is of practical use - we can´t claim, that his violins would be unsuccessful.

My discussion of transients with him was several (9?) years ago, and there were some technical problems with the measurements he was trying to get, and no clear path to usefulness.

I'm not aware of any known improvements in his violins since then which would indicate he found something enlightening, and in my several meetings with him, the only thing he's been less than open about is varnishing... perhaps that's because it's an endless topic full of infinite details and variations.

I'm fairly certain his success is based on talent for woodwork and vast experience with high level violins and violinists... not some secret gimmick or technical discovery. 

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14 hours ago, Adam Edwards said:

When I talked to Sam Z. I walked away thinking he was a lot more generous with his knowledge than most makers I’d met 

I think, one problem of many makers could be, that they don´t have much special (describable) "knowledge". They can´t share much, at least nothing, one could tell or write down. These makers probably have a more intuitive approach with a lot of sensivity in working with woods but couldn´t describe it. So they have to be silent, even if they would like to share. 

On the other side, Sam Z. surely has such a huge amount of knowledge - he easily could talk many hours about making and acoustical science, even if he would like to bypass the things, in which he really believes or what he considers as really important. 

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8 hours ago, Danube Fiddler said:

I think, one problem of many makers could be, that they don´t have much special (describable) "knowledge". They can´t share much, at least nothing, one could tell or write down. These makers probably have a more intuitive approach with a lot of sensivity in working with woods but couldn´t describe it. So they have to be silent, even if they would like to share. 

On the other side, Sam Z. surely has such a huge amount of knowledge - he easily could talk many hours about making and acoustical science, even if he would like to bypass the things, in which he really believes or what he considers as really important. 

I think that violinmaking is necessarily based on intuitive "science", but reaching certainties in this way is very difficult and leaves room for denials or different opinions as there is not only one way to make good violins.

I am inclined to think that the tendency is to share the aspects of which we are reasonably certain (or convinced we are) and to be reluctant to talk about aspects that are more uncertain and with the possibility that they will be changed as a result of development of new ideas or personal researches of the violin maker.

That's why it is so difficult to talk about varnishes or aspects related to the acoustic response, where much remains uncertain and that perhaps will always remain so because of the nature of these things.

The risk is that every admission made by a luthier is considered as definitive, while often these are only temporary ideas linked to the current state and subject to changes.

Not everyone is willing to accept this risk, preferring to suggest the existence of "shop secrets" to avoid being denied sooner or later, not considering that "only the dead and the stupid never change their opinion";)

Just my evening thoughts.

 

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46 minutes ago, Davide Sora said:
 

I think that violinmaking is necessarily based on intuitive "science", but reaching certainties in this way is very difficult and leaves room for denials or different opinions as there is not only one way to make good violins.

 

I am inclined to think that the tendency is to share the aspects of which we are reasonably certain (or convinced we are) and to be reluctant to talk about aspects that are more uncertain and with the possibility that they will be changed as a result of development of new ideas or personal researches of the violin maker.

 

That's why it is so difficult to talk about varnishes or aspects related to the acoustic response, where much remains uncertain and that perhaps will always remain so because of the nature of these things.

 

The risk is that every admission made by a luthier is considered as definitive, while often these are only temporary ideas linked to the current state and subject to changes.

Not everyone is willing to accept this risk, preferring to suggest the existence of "shop secrets" to avoid being denied sooner or later, not considering that "only the dead and the stupid never change their opinion";)

 
Just my evening thoughts.

 

This seems to be a good description of the things. I would have to add, that I would not be able to tell much in my art ( of playing the violin ) outside of giving intensive violin lessons. 

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I been using this tool to hear the tap tones, I find it very useful because I have a hard time hearing.. getting old 

StroboSoft  it has the new tap tunning setting

20180103_030955_r.thumb.jpg.5a66f192cd006c29977bdb0eda18d6f9.jpg

 

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