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Old 03-09-2018, 11:34 AM
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KevWind KevWind is offline
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Quote:
Originally Posted by Picker2 View Post
OK, I see your point. Your proposed experiment will not provide additional information, but it probably gives better insights in this matter. And it's fun! So, especially for you , I went through the trouble to spend another three seconds, TWICE, to produce the measurements below.

This is the spectrum of the open E string of my Taylor GC BTO, plucked with my fingernail:



As you see, there is the narrow peak at 329 Hz (the fundamental), the first harmonic at 659, and many more higher harmonics. And... WAIT, there are 'subharmonics' too! One at 190 Hz and even one at 108 Hz!

Wrong.

These are not subharmonics. This is the fundamental resonant frequency of the guitar's top (108 Hz) and another resonant frequency of the top at 190 Hz. I can verify this by tapping on the bridge, this time with my fingernail:



See? There they are again, at exactly the same positions. As I explained earlier in this thread, plucking the string generates a shock wave in the string, which propagates through the string to the bridge. The effect of this is essentially the same as tapping the bridge. This causes the 'subharmonics' in the upper graph, except these are not caused by the string, but by the body. So they are not subharmonics, they are body resonances.

If you perform a real-time measurement of the plucked string, you will see that the body resonance peaks only last a short time. They appear, and are gone within half a second. The peaks caused by the string last as long as the string rings out - much, much longer.

This is the reason I conclude that body resonances don't 'fight' or interfere with the vibrations of the string. Because, and I repeat:

1. They last very short
2. They don't produce a distinct tone, but a 'thud' sound.

Stating that body resonances interfere with the 'in-tune-ness' of a guitar, like Taylor does, is like stating that the bass drum in a band interferes with the notes produced by the piano. (Hey, that's a good one! I'm gonna put it in a bold font. )
I appreciate your spending an additional 3 seconds doing a test just for me. So Thanks
And yes I see that the frequencies below the fundamental with a rise look to be in the same location as those with the bridge tap, which very interesting and speaks to your point . So I am guessing you are predicting the same would occur if you plucked the E string fretted at the 12
.. but we have only made it halfway to what I was suggesting . Where is the graph pluck with the E string fretted at the 12 th as per AP' statement ?
Kinda interesting to note the string pluck open high string you did does appear to generate the "Full spectrum" as you called it, and even produces rises below what the tap on the bridge does (which looks like "additional information") HUMMMMMM ????? It appears you were perhaps mistaken as to that being a reason not to test it . :


Also it's great that you bolded your statement but the inference in your statement does not appear to be what AP actually said....
To clarify .......What he said (according to what you quoted him as saying) was ------

Andy wrote:
As an example, the E5 note on the high string at the 12th fret has a frequency value of about 659 Hz. An octave below is the open high E string at 329 Hz. If a guitar has a natural resonance hot spot around 320Hz, it will vibrate whenever either of these E naturals are played. But what we’ll hear is a mix of 329 or 659 and 320. That’s going to have a detrimental effect on what we get to listen to.

I don't know or particularly care if what he is saying is true, but I am a bit of stickler for refuting what is actually said.


BTW I have been meaning to mention your "White Lighting" piece is outstanding
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Last edited by KevWind; 03-09-2018 at 12:56 PM.
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