#151
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#152
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#153
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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. 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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http://www.jessupegoldastini.com/ |
#154
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also, wow, great playing, really awesome style, love that track you have embeded
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http://www.jessupegoldastini.com/ |
#155
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Thomas Féjoz 7-strings MD - Jura spruce / Madagascar Eastman E20-D |
#156
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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
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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
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#159
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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. |
#160
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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
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One thing is clear, a Taylor is definitely not in someones future.
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Steve |
#162
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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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Enjoy the Journey.... Kev... KevWind at Soundcloud KevWind at YouYube https://www.youtube.com/playlist?lis...EZxkPKyieOTgRD System : Studio system Avid Carbon interface , PT Ultimate 2023.12 -Mid 2020 iMac 27" 3.8GHz 8-core i7 10th Gen ,, Ventura 13.2.1 Mobile MBP M1 Pro , PT Ultimate 2023.12 Ventura 12.2.1 Last edited by KevWind; 03-10-2018 at 09:11 AM. |
#163
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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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Fred |
#164
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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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Thomas Féjoz 7-strings MD - Jura spruce / Madagascar Eastman E20-D |
#165
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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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