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GerardM

Tap Tone or Plate Tuning Equipment

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Hello  have downloaded a tone generator app onto my iPad. So I now need to connect an amplifier to it plus a speaker. Has anyone already done this ,and if so would you be kind enough to suggest what amp and speaker. I am assuming I can go this route, or will I need a laptop and different software.  The iPad app produces the frequency’s needed for the various modes required but not loud enough. Thanks in advance for any advice. Gerard

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What about ordinary PC speakers (or bluetooth speaker if you don't have connector)... I used to have old square PC speakers with soft fabric screen just about prefectly sized to place violin or mandolin plate onto without need of supports. Worked great for me.

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1 hour ago, GerardM said:

Hello  have downloaded a tone generator app onto my iPad. So I now need to connect an amplifier to it plus a speaker. Has anyone already done this ,and if so would you be kind enough to suggest what amp and speaker. I am assuming I can go this route, or will I need a laptop and different software.  The iPad app produces the frequency’s needed for the various modes required but not loud enough. Thanks in advance for any advice. Gerard

On  www.platetuning.org   is told some equipment.

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Search for "mini amplifier" on Amazon or eBay, and you'll find a ton of them under $20.  I have a  bunch of them for various things... TV sound, shop stereo, and acoustic testing.  Some of them don't come with a 12V power supply, so you might have to buy one separately, or look for a package deal.  Caveat:  I don't use these for vibrating free plates, so I don't know how much power you need.  I guess these go loud enough.

For speakers, there are even more cheapo choices.  Probably anything 4" - 6" diameter is what you'd want.  Easily scavenged from old computer speakers or trashed radios.

If you want to see chladni patters as well as frequencies, I guess you'd need this stuff.  I don't bother... just getting the taptone frequencies is enough for me, and much quicker and easier.

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If you just want to see the frequencies of the modes, a simple response spectrum app on a smart phone works fine with knuckle tapping, fingernail scratching and blowing across the f-holes.

You can also use a free computer program, like Audacity, to capture and analyze mode frequencies.

If you are also interested in tuning the mode shapes, like chladni patterns, then a more sophisticated tone generator setup is needed and some way to mount the plates over the sound source.

 

Edited by ctanzio
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3 hours ago, Don Noon said:

Search for "mini amplifier" on Amazon or eBay, and you'll find a ton of them under $20.  Caveat:  I don't use these for vibrating free plates, so I don't know how much power you need.  I guess these go loud enough.

Excatly! 

"Cavear: I don't .............. ........... "

So why did you post :)

(BTW, They are load enough, so is ones ear)

ps. 

Ignore my post

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23 minutes ago, 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.

Although not specifically stated, the inference is that Spectra Plus is NOT a waste of time.  Are there important things that it does that zero bucks Audacity can not do?

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5 minutes ago, Don Noon said:

Although not specifically stated, the inference is that Spectra Plus is NOT a waste of time.  Are there important things that it does that zero bucks Audacity can not do?

It's much more precise... But this ain't rocket science so Audacity is good enough, IMO. Few Hz here or there doesn't count as the frequencies of wooden parts are sensitive to humidity. Main problem is that AFAIK no one succesfully tracked the modes of parts into succesful instrument.

Here is pic of my old rig... ordinary passive speakers connected directly into SB16 soundcard (that was early 90's when some soundcards had powered output besides headphones output). I read specs that SB16 had 0.7W per channel...  still enough to get mandolin plate moving (I don't think I ever needed to go close to full volume). So for this all you need is any speaker(s) loud enough to fill small room... or get old used cheap guitar amp at pawnshop.

mando07-chladni.jpg

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9 hours ago, GerardM said:

Has anyone already done this ,and if so would you be kind enough to suggest what amp and speaker.

1st tried just a garage sale stereo amplifier. Not enough. Then put a preamplifier ahead of that cheap  amplifier and then the combo had adequate volume.

But key also is the speaker, which has to be powerful enough

to deliver the [considerable] output volume needed. And BTW, don't forget the ear covers.

    But all that said, my experience is, as Don said, that you can get more or less equally

useful information from just the tap tones alone, plus some good software. There are various software options,

or you can write your own, and tailor it to the tasks of making stringed instruments.

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23 minutes ago, Don Noon said:

Although not specifically stated, the inference is that Spectra Plus is NOT a waste of time.  Are there important things that it does that zero bucks Audacity can not do?

Much higher detail and resolution. That might matter to some, and not to others. It mattered to me.

Anyone can experiment with it on a temporary and free trial basis, by downloading from  http://www.spectraplus.com/

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Thanks for all the information. I am not a violin maker, I’m a apprentice trained cabinet maker. Making reproduction furniture. Veneering, marquetry, inlay etc. Bin doing it for nearly 50 years. Happened to read an article about violin acoustics while waiting in the dentists, got me thinking about trying it out in the work shop. Might even consider making a violin. Any books you would recommend,  have seen some but they appear to be aimed at the diy person with not much woodworking skills. Anyway thanks for all the information Gerard

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1 hour ago, Don Noon said:

Although not specifically stated, the inference is that Spectra Plus is NOT a waste of time.  Are there important things that it does that zero bucks Audacity can not do?

I write scripts for Spectra Plus that change settings, measure peaks, bandpasses, etc. However, I recommend Audacity for 95% on MN who would never use these features. 

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13 hours ago, 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.

 

2 hours ago, francesco piasentini said:

I find George Stoppani's spectrum analyzer more practical than audacity, especially in acquisition.

You can find it in his website (goggle stoppani technical).

Would any of both software allow to do peak analysis - curve fitting ( for damping calculations ) ?

 

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Hi.

You can do it when fitting modes, using the other application of Stoppani.

I don't think you can do it right with "Spectrum Analyzer".

Another valid alternative is working with packages such as Matlab or Scilab.

At least if you used it during your studies you can capitalize on some of your previous experiences.

I found libreoffice spreadsheet embarrassing when dealing with more than 100 raws. Matlab home edition is not so expensive. You can theoretically make modal analysis, but I'm happy with George's suite.

 

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8 hours ago, francesco piasentini said:

Hi.

You can do it when fitting modes, using the other application of Stoppani.

I don't think you can do it right with "Spectrum Analyzer".

Another valid alternative is working with packages such as Matlab or Scilab.

At least if you used it during your studies you can capitalize on some of your previous experiences.

I found libreoffice spreadsheet embarrassing when dealing with more than 100 raws. Matlab home edition is not so expensive. You can theoretically make modal analysis, but I'm happy with George's suite.

 

Thanks for advices !

I did some peak-analysis with free-software, however it was very cumbersome and sadly no calc - routine for peak-width at half-height. All comfortable curve-fitting packages seem to be quite expensive ~ 1000 $. Good to know of matlab, but in a short view I am not sure, if it does a comfortable peak-analysis.

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On 9/18/2018 at 3:41 PM, GerardM said:

I am not a violin maker, I’m a apprentice trained cabinet maker. Making reproduction furniture. Veneering, marquetry, inlay etc. Bin doing it for nearly 50 years.

That's a very good place to come from.

The book "Stradivari's Genius: Five Violins, One Cello, and Three Centuries of Enduring Perfection" by Toby Faber makes what is, to me, a convincing case that Antonio Stradivari was not apprenticed to Nicolò Amati, as is generally believed (and as he claimed on his first surviving violin), but instead was originally an apprentice woodworker, who did work on Amati's decorated violins - but who later was apprenticed to another violin maker to learn violin making.

The book speculates that this maker might have been Francesco Rugeri. It doesn't state what feature Stradivari's violins had in common with his, but I later learned from elsewhere it was the absence of a small mark in the center of the back and belly from the pivot point of a compass used in gradation.

As for books to help you with making your violin: yes, books for the beginner will often concentrate on teaching woodworking skills. But there are things about the violin, such as which woods it is made from, that aren't obvious from how it looks, and have to do with its acoustic function.

"Violin-making as it was and is" is an old book available free online, although a rather old one, and it might be a place to start.

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56 minutes ago, francesco piasentini said:

Why do you want to perform such a peak analysis?

Some physicists (e.g. Güth, who had written "Physik im Geigenbau" [ " physics  in violin-making" ] ) assumed, that damping could play an important role in the violin acoustics. However often was told, that damping is extremely difficult to measure. If one has luck, a responsive-curve / spectral peak has a shape, which is fittable to a Lorenzen - function. Then the damping ( = 1/Q) can be calculated as 

damping  = F(peak) /( F( right side at half-height ) - F (left side at half-height ) )

The problem is, that many peaks don´t have a sufficient fittable shape. So I think needed is a comfortable tool for a fast peak-analysis - if a peak is not suitable, you didn´t loose much time and you can change something to improve the peak or look for the next peak. Using freeware I need at least 5 min for one peak ( import from audacity / cutting out the wanted spectral area / curve-fitting itself / calculating the damping from the half-height-points ) - that´s too cumbersome and results in the fact, that I will forget it.

 

 

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It’s a fascinating subject this violin acoustics, never gave it a thought till reading the article. I have quarter sawn pine in stock. Will make a violin belly with some of it, then do the tea leaf test and carve away to watch the effects. I have also downloaded an app that tells the pitch of a tapped sound. So will be playing around with that also. Is the idea to have  the same pitch in all areas of the belly?  I realise that the pine I have ( it’s not spruce , it’s yellow pine cannot recall the Latin name ) may not be ideal acoustically but I will certainly learn a lot from testing. Have been tapping pieces of it and seems to make a reasonable noise, having said that not shure what I should be hearing. It’s good to learn new skills , so will more than likely go on to construct a violin. Meany thanks again Gerard 

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