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  #211  
Old 03-13-2018, 05:46 AM
Trevor Gore Trevor Gore is offline
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Originally Posted by KevWind View Post
Unfortunately French Brubaker did not test all the same series of Taylor guitar , which may have directly addressed my question better.. (which I thought I made clear) about a standardized per build series and body shape model, with the same materials throughout . Oh well .........

Interesting to note and perhaps should be clarified that the French Brubaker tests , done at Taylor Guitars in 2007, were appearently testing 32 guitars from 7 different series , with 7 different back and side species materials, AND 2 different kinds of spruce top materials = Engelman and Sitka . Using what appears to be a handheld, modal impact hammer ...

And thus the variations in the test results appear to be as much or more derived from being and spread out over 7 different variables of body/side material and two different spruce tops . (and not testing the variations within the same back, sides and top materiels ) Which is not surprising and which would seem to make the term "Significant difference " less significant

"Significant" being ..... 2.24 hz variation and 2.23 % of the mean, ... spread out over the two different types spruce tops and 7 different body/side species ....

...While the French Brubaker is interesting it does actually address my original question. But again it doesn't really matter because I am content to wait to play one.
Regarding "the test results appear to be as much or more derived from being and spread out over 7 different variables of body/side material and two different spruce tops" we can see from your chart that Ovangol bodies give results ranging from 95Hz to 103Hz and rosewood from 97 to 103Hz, so still significant variation even within body species.

Whilst the top wood may be Sitka or Engelmann, an oft quoted phrase is "spruce is spruce" meaning that the mechanical and acoustical properties of the spruces overlap so much that very similar properties can be found in either species, so a species tag tells you very little about acoustical performance. Unless the species are sorted by particular values of their measured properties, they are essentially all from the same population.

It is worth considering how large a difference in resonant frequency needs to be to make a "significant difference" in performance for a truly responsive guitar. To minimise over-coupling problems (and hence possible intonation problems) resonances need to be placed as far as possible from scale tones. At main air resonance frequencies a semitone interval is ~6 Hz. To get within 1 Hz of target frequency demands quite a bit of accuracy. Checking against your chart, no more than a dozen of the 32 would pass that test for that particular resonance. For most of the 32 to pass that test, the standard deviation in first resonant frequency would need to be better than ~0.3%.

The proof of this pudding is inevitably in the hearing, and whether people like the sound of V bracing or not, I doubt that the intonation will be any different from previous offerings.
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  #212  
Old 03-13-2018, 07:46 AM
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KevWind KevWind is offline
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Originally Posted by Trevor Gore View Post
Regarding "the test results appear to be as much or more derived from being and spread out over 7 different variables of body/side material and two different spruce tops" we can see from your chart that Ovangol bodies give results ranging from 95Hz to 103Hz and rosewood from 97 to 103Hz, so still significant variation even within body species.

Whilst the top wood may be Sitka or Engelmann, an oft quoted phrase is "spruce is spruce" meaning that the mechanical and acoustical properties of the spruces overlap so much that very similar properties can be found in either species, so a species tag tells you very little about acoustical performance. Unless the species are sorted by particular values of their measured properties, they are essentially all from the same population.

It is worth considering how large a difference in resonant frequency needs to be to make a "significant difference" in performance for a truly responsive guitar. To minimise over-coupling problems (and hence possible intonation problems) resonances need to be placed as far as possible from scale tones. At main air resonance frequencies a semitone interval is ~6 Hz. To get within 1 Hz of target frequency demands quite a bit of accuracy. Checking against your chart, no more than a dozen of the 32 would pass that test for that particular resonance. For most of the 32 to pass that test, the standard deviation in first resonant frequency would need to be better than ~0.3%.

The proof of this pudding is inevitably in the hearing, and whether people like the sound of V bracing or not, I doubt that the intonation will be any different from previous offerings.
Again for some clarity it is not or my chart .... "your chart".... it is French Brubaker's chart... and the Ovangol bodies appear to be giving results closer to 99 to 103 Hz

http://semimac.org/wp-content/upload...ic-Guitars.pdf

So yes there does appear to be a certain amount of variation in the production techniques used in 2007 with X bracing. And with the amount of testing done at that time including the Helmholtz test accuracy problems noted by French Brubaker

"this data does not satisfy
the requirements of the isoplot method; the test variation is not small compared to the part variation.

Thus, trends suggested by the Helmholtz frequency data should be evaluated carefully (perhaps with more
testing)before being accepted as being real.

Just sayin'
And yes we do agree the pudding is trying it for one's self
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  #213  
Old 03-13-2018, 11:49 AM
MrHooligan73 MrHooligan73 is offline
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Maybe all that dissonance is what makes a non V braced guitar wonderful....
I stopped chasing my tail for perfect pitch years ago. I hear more difference when I change a good setup stock nut with an earvana and can accept it' as the best I want it to get and spend more time plying and getting better.
I wish Taylor luck either way. Bad enough Gibson is so mismanaged. Maybe fender will finally get a consistently good acoustic lone going.
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  #214  
Old 03-13-2018, 11:59 AM
rct rct is offline
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Maybe fender will finally get a consistently good acoustic lone going.
Now that's comedy!*

rct


*I love them. Dearly. I wouldn't live without at least...three or maybe 5 or so of them. 7 I guess.
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  #215  
Old 03-13-2018, 05:07 PM
mattcran mattcran is offline
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Hard to believe this thread hasn't been bumped in over 5 hours.
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  #216  
Old 03-13-2018, 06:35 PM
Seagull S6 Seagull S6 is offline
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As you wish. Ive got the seasoning this thread needs. Mesa Boogie has a designer named Andy Fields on it's design team. It must be a good time in history to be named Andy. Andy and Andy could get together and design V-Class Braising for speaker cabinets and then design cascading pre-amps for the 9000 series Taylors.

(Scroll down) http://www.mesaboogie.com/about/the-design-team.html
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  #217  
Old 03-15-2018, 01:33 AM
B3N B3N is offline
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Originally Posted by Picker2 View Post
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.
Following what you said, I checked the frequency differential between D and G#, you either get more or less B or F :

D being the top note
G# = 415hz
D= 587hz
587-415 = 172, a slightly flat F.

G# being the top note
D= 587hz
G# = 831hz
831-587 = 244hz, slightly flat B.

Maybe that is what's happening?
Interesting stuff...

As a side note, B and F are the fifths of E7 and Bb7 chords , whose guide tones (thirds and sevenths) are g#/ab and d. Maybe another element that could explain why the fifth is often let down in voicings?
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  #218  
Old 03-15-2018, 03:54 AM
Seagull S6 Seagull S6 is offline
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Were does the sub tonic fit in? This is getting way over my understanding of theory. I think maybe what you posted about the 5th has something to do with cadence. Traditional Cadence is 1 - 4 -5. I couldn't find what type of Cadence 5 -1 - (4) is and was wondering about the type of scale. (Type of)
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  #219  
Old 03-15-2018, 04:55 AM
Picker2 Picker2 is offline
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Quote:
Originally Posted by B3N View Post
Following what you said, I checked the frequency differential between D and G#, you either get more or less B or F :

D being the top note
G# = 415hz
D= 587hz
587-415 = 172, a slightly flat F.

G# being the top note
D= 587hz
G# = 831hz
831-587 = 244hz, slightly flat B.

Maybe that is what's happening?
Interesting stuff...

As a side note, B and F are the fifths of E7 and Bb7 chords , whose guide tones (thirds and sevenths) are g#/ab and d. Maybe another element that could explain why the fifth is often let down in voicings?
Exactly. This is what I intended with the 'beats' (probably expressing myself poorly). When tuning stringed instruments using 'two-string methods', you will hear a slow beat when two strings are almost, but not quite, equally tuned. It's basically a volume modulation cause by the continuous phase shift between the two waveforms produced by the two strings.

When the frequencies are further apart, there will still be a beat at the difference frequency, but this frequency will be much higher. Maybe it depends on the person if this rapid volume beat is perceived by the brains as a 'new tone'. In my brains this does not happen.

Whatever the answer, the beat is not a subharmonic according to the formal definition, although its modulation frequency is lower than any of the two tones that cause it.
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  #220  
Old 03-15-2018, 02:26 PM
MrHooligan73 MrHooligan73 is offline
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Originally Posted by mattcran View Post
Hard to believe this thread hasn't been bumped in over 5 hours.
After reading through all this I find my method of walking into a store and playing every guitar I like and finding the best sounding one deeply flawed.
Or it is being way over thought.
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  #221  
Old 05-03-2018, 10:11 AM
bostosh bostosh is offline
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Fascinating thread
has anyone noted this treatise on soundboards ?

INCORPORATING ACOUSTICAL CONSISTENCY
IN THE DESIGN FOR MANUFACTURING OF WOODEN GUITARS

Patrick Dumond
A thesis submitted to the Faculty of Graduate and Postdoctoral Studies
in partial fulfillment of the requirements for the
DOCTORATE IN PHILOSPHY
degree in Mechanical Engineering
Ottawa-Carleton Institute for Mech
anical and Aerospace Engineering
Faculty of Engineering
University of Ottawa

© Patrick Dumond, Ottawa, Canada, 2015
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Been doin this, way too long.....
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