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Old 03-09-2018, 08:05 AM
Picker2 Picker2 is offline
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Originally Posted by KevWind View Post
Just so I am understanding correctly you state AP's claim that if you pluck the E5 @ the 12 fret the guitar will also generate at 329 and 320 is not true .....
But you claim to offer proof of this by setting up a recording of the body resonance produced by tapping on the bridge, (which is not the condition or criteria stated by AP). The reason you give for recording the tap instead of the string pluck, does not stand up to objective analysis, and also has nothing to do with conditions in AP's statement . The reality is that ,,,,, at same time that you recorded the the bridge tap you could have recorded and graphed a string pluck at the 12 Fret E string and would have then actually and directly addressed the condition in the AP statement, you claim is not true .
It is always allowed to reach conclusions by scientific reasoning plus observations of one experiment to predict observations of another experiment - as long as you stick to generally accepted scientific principles.

In this particular case I don't get why AP stated that if you fret the high E at the 12th fret (659 Hz), the fundamental will also resonate (329 Hz). It doesn't, and it never will. That's the whole point of fretting a string. I assume it was just a slip of the pen, or maybe he meant it the other way around: if you hit the open E string (329 Hz) the first harmonic (659 Hz) will sound along with it. This is indeed true.

The recording of the body resonance after tapping the bridge may seem to be an odd thing to do, but it is a well-known method to capture the properties of acoustic systems (room ambiance, echo's, but also the tone of stringed instruments). The method is widely applied in digital audio processing, e.g., convolution reverb. It's a standard method and there are countless text books describing it.

There is no point in recording the string pluck to test the body resonance. The string pluck will only generate a very limited number of frequencies. It's like taking a picture through a couple of narrow slits - you will only see a small part of the total scenery. A short tap, however, generates all audible frequencies in one go and feeds them to the top. The top will then resonate with those frequencies it supports. Since the tap contains all audible frequencies, you can be sure you never miss one.

Regardless all of the above, my most important statement is that body resonant frequencies in a guitar are always so short and so unspecific that they will never interfere with the frequencies generated by the strings as they ring out. Since this is what the whole "better-in-tune-ness claim" of V-bracing is about, this claim makes no sense to me.
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Last edited by Picker2; 03-09-2018 at 08:47 AM.
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