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  #151  
Old 03-10-2018, 04:46 AM
jessupe jessupe is offline
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Originally Posted by gitarro View Post
This is wonderful. Who would have thought that Taylor v bracing would lead to einstein and quantum physics and the dualistic nature of light being discussed???

I reckon that to solve the grand unified theory problem, Taylor needs to release the Z class bracing next year an d say how it is even better than v class bracing at intonation LOL
this makes sense, as 11 is to 10 z is to y, it's that, click, one more, when you really need to crank it up
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  #152  
Old 03-10-2018, 04:54 AM
Picker2 Picker2 is offline
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Right , because you never know when an E8 quasicrystals 432 verdi tuned 4 D projection displays that dark is information and faster than light, blocked information is information, just ask a holographic voxelated projection...or taylor

you know it's funny, I was reading articles the other day about this Dutch physicist who apparently did stints on "Baywatch" , has interesting theories, the real funny thing is you're that Dutch physicist , the crop circle guy, cool beans dude...

the gravitron wave that came by, it's F sharp , check it on your tuner at 432, surely it means AP is wrong
What kind of paint thinner have you been sniffing to come up with THAT?
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  #153  
Old 03-10-2018, 05:01 AM
jessupe jessupe is offline
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Yes. The “phase and interference” argument was also brought up a few times by Taylor. Most modes of self-resonance of a guitar top have different parts of the top vibrate in opposite phases. For example, every time the bottom half moves inwards, the top half moves outwards. This means that the sound wave emerging from the bottom half is always half a wavelength out of phase with the sound wave created by the top half. As a result, these two waves cancel each other out, which could - in theory - result in complete silence for that particular frequency. In practice, the interference is one of the components that shapes the guitar’s top response.

It is also one of the reasons why it’s so hard making a good audio recording of an acoustic guitar. Different parts of the sound come from different positions, so it’s as if the sliders of your equalizer make random jumps every time you move your microphone.

However, I fail to see how this fits into the Taylor in-tune-ness story. The only way to reduce this interference effect, is to make sure the top can only move in and out as a whole. That’s the low E string. Higher notes will always cause bipolar modes and higher, along with the inherent interference effects. V-bracing will definitely modify the response curve, and hence the tone, but I see no reason whatsoever why this would improve “in-tune-ness”.
I was merely speculating as to what AP may have been talking about. as far as it goes the only way I see it pertaining is that it may be related to generating 'wolf notes' which when on the cusp of being 'wolfy' tend to make things sound "out of tune"

while wolf notes do exist on guitars they are generally much more of a problem on bowed instruments, but, if a wolf is present on a guitar and then that note is sounded in a chord, it can sound very out of tune.

So my thinking about bringing it up was that AP's v brace magically creates pure crystal harmony with no deconstructive frequency, and or that's what he may have been saying, but of course being a forum, i came up with that before I actually read what he wrote,
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  #154  
Old 03-10-2018, 05:05 AM
jessupe jessupe is offline
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What kind of paint thinner have you been sniffing to come up with THAT?
paint thinner! I'll have you know we inhale nothing but the finest, methyalated alcohol !

also, wow, great playing, really awesome style, love that track you have embeded
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  #155  
Old 03-10-2018, 05:54 AM
B3N B3N is offline
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Not entirely true. It makes people think. :-) But you do have a point of course, so please read below.



Herb, please read below!



Can you please elaborate on what you mean exactly? What is a “new” harmonic? Why would such a harmonic generate lower level frequencies (which I assume are subharmonics)? (I’m an expert in laser physics, non-linear optics and magnetic resonance imaging. I grew up with Fourier Analysis and understand it in every little detail. As a physicist, I have a pretty good understanding of basically all technical aspects of the world around us, with specific interest in guitars. So don’t be shy!)

The only way I see subharmonics are generated by a guitar string is by the attack, not by the decay. The attack generates a wide frequency spectrum, which may excite resonant frequencies in the body that are dissonant with the harmonics of the decaying string. This is, however, no big deal. The dissonant
attack lasts only a short while and has a very low Q (= a wide peak in the frequency curve, which corresponds to a ‘hissing’ sound). It’s like the ‘thud’ sound when you tap the bridge. You don’t perceive it as an harmonic distortion or ‘out-of-tune-ness’.

With bowed instruments it’s a different story, because the bowed string feeds white noise into the body continuously, which may excite a dissonant body harmonic at high volume. These are the infamous wolf tones. But this does not happen on plucked string instruments.

The way I see it, the best way to construct a guitar is to prevent or reduce resonant peaks in the frequency response curve. Just like room acoustics in a recording studio. But that’s another story.
Actually, when you play two notes, they are generating a sub harmonic together. For instance if you play a G# (13th fret g string ) and a D (15th fret Bstring) if you listen closely you will hear a B (14th fret a string) pop off. Works better with reeds, horns and voices. And on electric guitar with a over driven sound. Give it a try
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  #156  
Old 03-10-2018, 06:08 AM
Picker2 Picker2 is offline
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While wolf notes do exist on guitars they are generally much more of a problem on bowed instruments, but, if a wolf is present on a guitar and then that note is sounded in a chord, it can sound very out of tune.
Oh yes, on bowed instruments wolf notes are as real as wolves! Have you ever played a cello? However, there is a huge difference between wolf notes on bowed instruments, and 'wolf notes' on plucked instruments.

Both the 'pluck' and the 'bow' will generate a signal that contains all audible frequencies. Mathematicians and physicists figured out a long time ago that the frequency spectrum of a very short pulse is very wide, and that the same applies to a typical 'hissing' sound (they call it 'white' noise, or other colours). Hissing sounds contain all audible frequencies at the same time. Now the 'pluck' will feed a very short pulse into the string, and the 'bow' will feed a hissing sound into the string.

Because the frequency content of both the pluck and the bow are the same, both will cause resonance in the instrument body. After all, resonance means 'vibrating along with a matching frequency' and since both the pluck and the bow contain all frequencies, there will always be a matching one.

There is, however, a crucial difference between the 'bow' and the 'pluck'. The bow will feed the wide-spectrum noise into the instrument body continuously, and so can sweep up body resonances at very high volume, even at the same level as the strings. If this body resonance is close to the note being played, you get the sound of a honky tonk piano, with massive beating. Half of it comes from the string, the other half comes directly from the body. It sounds pretty bad.

The pluck, on the other hand, only lasts a very short time. It's like a tap on the bridge. The body resonant frequencies decay very rapidly after the tap. The string will ring out a hundreds times longer. If you listen carefully to the sound of a string being plucked, you can very clearly recognise this 'tap on the bridge' sound at the very beginning, every time your pick or your finger touches the string. But I would not call that a 'wolf note', because, as I explained before, it's just a short 'thud', not a clear tone.
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  #157  
Old 03-10-2018, 06:43 AM
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Actually, when you play two notes, they are generating a sub harmonic together. For instance if you play a G# (13th fret g string ) and a D (15th fret Bstring) if you listen closely you will hear a B (14th fret a string) pop off. Works better with reeds, horns and voices. And on electric guitar with a over driven sound. Give it a try
OK, I tried it and I failed... I don't hear the B. In order to check if I was tone deaf, I recorded the spectrum of both. In the graph below the green(ish) curve is the G#/D combination, and the blue curve is the B as you told me to play them.



You see the blue peak of the B at 246 Hz, but you also see that the green curve (G#/D combination) does not have a peak there. So no subharmonic is created. This can maybe be explained by the fact that if you do this experiment, you have to make sure you mute all strings that you don't pluck. Otherwise you could hear the resonance of another string.

Or maybe you mean 'beats'. Two frequencies played at the same time, say f1 and f2, will indeed create a tone of the average frequency, which is modulated at the difference of the two frequencies. This causes beating, a rapid modulation of volume. So 100 Hz and 102 Hz, played simultaneously, will sound like a 101 Hz note beating at a frequency of 2 Hz (this is how they tune pianos - turn the knobs until the beat goes away).

So if you would have 300 Hz and 500 Hz together, you can say the result is a 400 Hz tone, modulated at 100 Hz. And that 100 Hz could then be perceived as a 'subharmonic'.

In practice, however, our ears and brains will perceive two distinct tones, without a modulation beat, as soon as the two frequencies are too far apart. You can try this out yourself on your guitar by tuning down the high E to a B, pluck both strings and tune the high E up and down a bit. You go from 12-string to honky tonk piano to two separate notes.
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  #158  
Old 03-10-2018, 08:46 AM
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  #159  
Old 03-10-2018, 08:56 AM
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Q: If Schroedinger's Cat played a guitar in his box, would it be X braced or V braced?

A: Yes.

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  #160  
Old 03-10-2018, 09:02 AM
Golffishny Golffishny is offline
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As far as scientific analysis, much of carbon dating is now found to be in error. You don't know what hasn't been discovered and proved yet. Testing methods are always advancing. Some folks were even ridiculed for saying the Earth revolved around the Sun, or the Earth was not flat. I'll wait until I hear the V bracing in person and make my own mind up. I will not be indoctrinated either way.
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  #161  
Old 03-10-2018, 09:03 AM
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One thing is clear, a Taylor is definitely not in someones future.
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  #162  
Old 03-10-2018, 09:06 AM
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Originally Posted by Picker2 View Post


Would you mind telling me the name of iPhone App are you using to generate this graph ?


Also why does it look like a different GUI in your previous posts ?




I searched the App store under "iPhone Microfoon" and did not find anything. Thanks Kev
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Last edited by KevWind; 03-10-2018 at 09:11 AM.
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  #163  
Old 03-10-2018, 09:28 AM
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Sorry for taking a while getting back, I was cooking supper and thought I would add to my reply but events took over my evening. Before I get to the book I would like to comment on the body resonance and the thought that it only occurs for the first half second and then are gone. That may be true for notes up the scale but notes in the vicinity of the resonances keep feeding the resonance until the note stops vibrating. So it is still a concern if you are playing bass notes and treble notes together. Playing one not and using that as a justification that the body resonances do not matter does not take into account how the guitar is played.

The Gore & Gilet book is pretty handy source for the person who takes the scientific or engineering approach to building guitars.

4.7.2 A second source of intonation error

A second source of intonation error arises due to body resonances. For this source to be problematic , the guitar needs to be reasonably efficient and responsive (have high monopole mobility). An overbuilt guitar with a heavy soundboard (i.e. the typical guitar available in a main street shop) will rarely suffer problems due to this source of intonation error. This source of intonation error could almost be regarded as a penalty for building a good guitar, but one that is not quite good enough.

The problem arises due to the string resonance coupling with the body resonance when a body resonance happens to fall close in frequency to a scale tone. In section 1.4.4 et seq. we discussed at length why major body resonances should be designed to fall precisely between scale tones. We learnt that coupled that coupled resonances repel, the consequence for the string being that a fretted note will play off its target frequency, in bad cases as much as 25 cents. Fretted notes pitched above the body resonance will play sharp and those below will play flat. In bad cases the effect will be apparent for notes pitched two or three frets above and below the pitch of the body resonance.

Fixing this type of intonation problem is considerably more involved than simply applying the conventional 12th fret method. The technique we have developed is one we use most frequently on instruments built by other guitar makers who are less pedantic than us about where they pitch the body resonances. This not only fixes (as well as can be fixed ) the intonation issues due to resonances but also address the first source of intonation error.

Section 1.4.4 goes through the issue of coupled resonators and their moving the resonant frequency. It is one of the more valuable pieces of the guitar making puzzle in the books (set of two) and help to justify the $300 cost to me. The authors go though the mathematical theory why the resonators behave as they do and offset the string's frequency creating an out of tune note. The book goes on, I did a quick search on the net to see if I could find something to point to rather than me retyping the mentioned chapter. Lot of straw making finding the needle tedious. That is about as much time as I have this morning, got to go.
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  #164  
Old 03-10-2018, 09:30 AM
B3N B3N is offline
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OK, I tried it and I failed... I don't hear the B. In order to check if I was tone deaf, I recorded the spectrum of both. In the graph below the green(ish) curve is the G#/D combination, and the blue curve is the B as you told me to play them.



You see the blue peak of the B at 246 Hz, but you also see that the green curve (G#/D combination) does not have a peak there. So no subharmonic is created. This can maybe be explained by the fact that if you do this experiment, you have to make sure you mute all strings that you don't pluck. Otherwise you could hear the resonance of another string.

Or maybe you mean 'beats'. Two frequencies played at the same time, say f1 and f2, will indeed create a tone of the average frequency, which is modulated at the difference of the two frequencies. This causes beating, a rapid modulation of volume. So 100 Hz and 102 Hz, played simultaneously, will sound like a 101 Hz note beating at a frequency of 2 Hz (this is how they tune pianos - turn the knobs until the beat goes away).

So if you would have 300 Hz and 500 Hz together, you can say the result is a 400 Hz tone, modulated at 100 Hz. And that 100 Hz could then be perceived as a 'subharmonic'.

In practice, however, our ears and brains will perceive two distinct tones, without a modulation beat, as soon as the two frequencies are too far apart. You can try this out yourself on your guitar by tuning down the high E to a B, pluck both strings and tune the high E up and down a bit. You go from 12-string to honky tonk piano to two separate notes.
Oh it is nice that you tried!

I did that by muting the strings. That b is really low in terms of volume !

I don't know the terms, but if you try with two reeds/horns, it is really perceivable. I agree that it is barely there on a acoustic guitar so probably irrelevant in a way that it could make a guitar intonation "dirty".

I don't know if it's a subharmonic but it's wavy and flabby and quite indistinct. I think that is one thing that gives overdrive a character, when you play double stops.

Thanks a lot for the input!

Ps it's probably not exactly a B, maybe a little flat...
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  #165  
Old 03-10-2018, 09:56 AM
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But now I have some new questions. First it appears you are using an iPhone app which one ? Because I now would like to see how my guitars graph
Not because I care about AP statements one way or the other, just curious about the body resonance .

Also after looking at the graphs and (understanding that an iPhone mic and graphing app. may not be the most accurate ) If that's what you are using ....

But couple anomalies appear to have arisen.

One: on the open E string pluck graph, Is the L Peak : number in the upper left , showing the fundamental or does (L) simply mean "loudest" ? ..If the fundamental, then why is it showing 331 instead 329 ? I certainly hope that does not mean your guitar is inaccurately intonated by 2 Hz ???? Maybe you need V bracing just kidding , I assume the (L) means loudest ??

Because in the new graph with the 12th fret pluck the L Peak is showing 1324 assuming that is twice the fundamental, if it's the fundamental, that would make that 662 Hz ..... so why is the octave above tone louder than the fundamental by what appears to be 3 or 4 db ?????????
I'm using an app called "Analyzer" You can find it in the AppStore. There are zillions of similar apps in the AppStore, but this one is very good. Simple and complete. The microphone of my iPhone X is surprisingly good (sound recordings are excellent), but you are right - if you want ultra-high precision you have to use calibrated microphones.

In the graph you referred to, L means 'loudest' indeed. And yes, my guitar was a little sharp at 331 Hz. I never use electronic tuners.

In the graph of the 12th fret pluck you are right: the first harmonic is louder than the fundamental. There are various reasons this can happen. It may have to do with where you pluck the string, but also in which direction. If you pluck sideways, the string's fundamental will reduce and a tone of twice the fundamental will become more dominant. This has to do with the longitudinal tension in the string. But that would be food for another thread. In any case the fundamental does not always need to be the loudest frequency - its the lowest frequency.
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