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  #76  
Old 03-08-2018, 10:50 AM
Picker2 Picker2 is offline
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Originally Posted by KevWind View Post
Ouch... that guitar clearly has no V-bracing...!
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  #77  
Old 03-08-2018, 10:55 AM
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Yes, it does. That's an artifact from the device that captured the strings. It bugs me all the time when people post these vids on Youtube to demonstrate how strings vibrate.
"Yes it does" What ? Not quite clear .

I understand what an artifact is, and that an artifact may not be accurate... And so to clarify you are suggesting the "artifact" is the occasional irregular movement of the strings and is not accurate ? Which I suppose is possible
But even if we assume that is an inaccurate artifact and has completely changed the appearance from regular to irregular , I wonder if it is any less credible than an animation of a guitar string movement ?
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  #78  
Old 03-08-2018, 10:58 AM
Purfle Haze Purfle Haze is offline
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I have rarely heard a guitar so badly out of tune. Must need some V-Bracing!
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  #79  
Old 03-08-2018, 10:59 AM
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Yes KevWind, this is a very fundamental principle of physics and mathematics. You have to frequency-transform the string's audio signal (sounds complex but it's a standard procedure), multiply it by the graphs shown in this thread, and then back-transform to an audio signal. That will give you the sound of that string as if it were mounted on the guitar that produced the graph.

This is the way they add reverb to audio files. You go to a large church, record the reverb of a short click, and then you can use that recording to add the church's acoustics and reverb to any audio recording made anywhere else.
Yes thanks I already understand the basics of convolution reverb.

So why not simply measure and graph the sting pluck ?


And while I would agree there should only be objective science, but even then it can be selective about one specific independant element , it can be more inclusive and be about interdependent related elements , etc. And then there is (yes I agree mistakenly claimed as science) but is agenda driven , selective out of context and Pseudoscience .
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Last edited by KevWind; 03-08-2018 at 11:13 AM.
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  #80  
Old 03-08-2018, 11:00 AM
Inyo Inyo is offline
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Consider this, if you will:

Note that the traditional X-brace has not one, but FOUR V-shaped brace shapes in its configuration: two Vs orientated along the vertical axis, and two Vs aligned along the horizontal axis.

Ergo--The traditional X-brace is four times better than the V-brace.
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  #81  
Old 03-08-2018, 11:03 AM
Picker2 Picker2 is offline
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"Yes it does" What ? Not quite clear .

I understand what an artifact is, and that and artifact may not be accurate And so to clarify you are suggesting the "artifact" is the occasional irregular movement of the strings and is not accurate ? Which I suppose is possible
But even if we assume that is an inaccurate artifact and has completely changed the appearance from regular to irregular , I wonder if it is any less accurate that the animation of a the guitar string movement ?
It (the string) does always look like a polygon while it vibrates.

The video you showed demonstrates what they call a violation of the Nyquist condition. In essence, the camera is too slow to capture the speed of the string. It's like the wheels of a post coach in a Western movie turning backwards while the coach moves forward.

In addition, this camera sampled the video frames line-by-line, and successive lines captured a different moment of the vibrating string. That's how all the wiggles are created, it's a well-know artefact of digital video cameras.
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  #82  
Old 03-08-2018, 11:04 AM
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Originally Posted by Purfle Haze View Post
I have rarely heard a guitar so badly out of tune. Must need some V-Bracing!
I was faster than you with that one!
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  #83  
Old 03-08-2018, 11:07 AM
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Originally Posted by KevWind View Post
So why not simply measure and graph the sting pluck ?
Because the string only produces a limited series of frequencies: its fundamental and the overtones. So the spectrum you would measure would cover only a small part of the response of the guitar body.

A short tap contains all audible frequencies, and generates a full spectrum.
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  #84  
Old 03-08-2018, 11:10 AM
robj144 robj144 is offline
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Originally Posted by KevWind View Post
"Yes it does" What ? Not quite clear .

I understand what an artifact is, and that an artifact may not be accurate... And so to clarify you are suggesting the "artifact" is the occasional irregular movement of the strings and is not accurate ? Which I suppose is possible
But even if we assume that is an inaccurate artifact and has completely changed the appearance from regular to irregular , I wonder if it is any less credible than an animation of a guitar string movement ?
It's an artifact called a rolling shutter. It does really move regularly. Here it is captured properly:

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  #85  
Old 03-08-2018, 11:13 AM
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Originally Posted by Purfle Haze View Post
I have rarely heard a guitar so badly out of tune. Must need some V-Bracing!
Haha. That is WAY out of tune.
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  #86  
Old 03-08-2018, 11:15 AM
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Originally Posted by robj144 View Post
It's an artifact called a rolling shutter. It does really move regularly. Here it is captured properly:

THANKS for this clip. This video shows the same behaviour as shown in my computer simulation (phew...!). However, you see that the wire's stiffness shaves of the sharp angles after a few reflections. This is the decay of the higher harmonics, which always goes faster than the decay of the lower frequencies (you can verify this easily by careful listening to a guitar string ringing out).

My computer simulation did not show this effect (although the simulated sound did).
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  #87  
Old 03-08-2018, 11:22 AM
Sagebrush Tom Sagebrush Tom is offline
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Originally Posted by Inyo View Post
Consider this, if you will:

Note that the traditional X-brace has not one, but FOUR V-shaped brace shapes in its configuration: two Vs orientated along the vertical axis, and two Vs aligned along the horizontal axis.

Ergo--The traditional X-brace is four times better than the V-brace.
Inyo if it wouldn't be a problem could you either e-mail me or PM me. I would like to discuss Inyo County and/or music with you. Sorry not really interested in this discussion.
Thank you, Tom
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  #88  
Old 03-08-2018, 11:23 AM
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Originally Posted by Picker2 View Post
Because the string only produces a limited series of frequencies: its fundamental and the overtones. So the spectrum you would measure would cover only a small part of the response of the guitar body.

A short tap contains all audible frequencies, and generates a full spectrum.
Wait back up a second . I never said record and graph the sting in isolation..... However are you placing your recording device , if it records the all the audible frequencies and generates a full spectrum for the tap, it will do the same for a string pluck. So why not measure that .


Not to mention when playing the acoustic guitar we are not hearing the string vibration in isolation we are hearing the string vibration transduced by the body.......... again why not measure that ?
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  #89  
Old 03-08-2018, 11:26 AM
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Originally Posted by robj144 View Post
It's an artifact called a rolling shutter. It does really move regularly. Here it is captured properly:

OK I get that the camera in the sound hole might be showing artifacts
And I am not saying a picked guitar string does not move regularly..... BUT
the above clip only shows a string that is pulled up and let go
It does doesn't show a picked guitar string which is usually picked in both a sideways and up or down picking motion directions .
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Last edited by KevWind; 03-08-2018 at 02:29 PM.
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  #90  
Old 03-08-2018, 11:27 AM
HodgdonExtreme HodgdonExtreme is offline
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Originally Posted by Picker2 View Post
The video you showed demonstrates what they call a violation of the Nyquist condition. In essence, the camera is too slow to capture the speed of the string. It's like the wheels of a post coach in a Western movie turning backwards while the coach moves forward.
For sure. Note the video title indicates it was captured at 60FPS. That's slow.

Also note only the treble strings (higher pitch/frequency) exhibit the odd wiggles. The bass strings appear much more "normal".
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