Perfectly round acoustic guitar...

walrus

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So we've had a few threads now about the sound/tone/etc. of a cutaway acoustic guitar vs. a non-cutaway.

Just for the sake of argument, let's assume there is a difference. And let's assume "comfort" is not an issue.

Would it then be true that a perfectly round acoustic guitar would sound the best?? :unsure:

walrus
 

Rayk

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So we've had a few threads now about the sound/tone/etc. of a cutaway acoustic guitar vs. a non-cutaway.

Just for the sake of argument, let's assume there is a difference. And let's assume "comfort" is not an issue.

Would it then be true that a perfectly round acoustic guitar would sound the best?? :unsure:

walrus

Only if you like banjos 😅
 

Nuuska

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Hello

This is a fascinating can of worms.

Assume you do not mean "ball" but "disc" shaped body. In loudspeaker building it is considered good practice to avoid parallel surfaces and equal dimensions as much as reasonably possible. This is to avoid all standing wave resonances to be at same frequency. In a loudspeaker box we can use damping material - in guitar rather not.


So a quick layman conversion to guitar building suggest that there is a good reason for lower bout being both wider and thicker than upper bout.

Also depending where the bridge would be located would make difference.
If body were "disk" - would it be thicker on one end or equal thickness?

My 0,02€
 

JF-30

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If they were why does no one do it. I think the body of an acoustic has to be form and function. A round guitar you would have to rest it between your legs and it might be subject or to neck dive due to the shape as compared to the shape we all know.
 

chazmo

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I could be way off on this, but a perfect disc, cylindrical shape is only suitable for resonating to a certain, limited frequency range. Think loud speakers, although those are mostly cones (varying radius). I imagine (but have no evidence) that a circular guitar would sound thin... restricted to some frequency range. Typical guitar shapes are clearly far more complex and, I suppose, provide an echo box for far more frequencies (with varied resonances).

Anyway, it is a fascinating topic, but as JF-30 said if it really worked well people would already be doing it.

Ray's banjo comment wins the "best answer of the day" award. :)
 

adorshki

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So we've had a few threads now about the sound/tone/etc. of a cutaway acoustic guitar vs. a non-cutaway.

Just for the sake of argument, let's assume there is a difference. And let's assume "comfort" is not an issue.

Would it then be true that a perfectly round acoustic guitar would sound the best?? :unsure:

walrus

Archback or flatback?
 

walrus

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I was thinking of a disc shape, flat back, but you are welcome to take liberties!

walrus
 

JF-30

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Yeah but a banjo makes it sound due to a drum head not a sound hole and a hollow body.
 

adorshki

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Yeah but a banjo makes it sound due to a drum head not a sound hole and a hollow body.

As long as the front and back were not parallel it might work.

Yes and in fact I came across something confirming Chaz and Nuuska's input about shapes when posting in the digression about cutaways, here: http://www.letstalkguild.com/ltg/showthread.php?199132-F30R-New-Hartford-Mint-to-Excellent-Condition ;
describing how air resonances are created and operate, inside an example Martin body:
http://polettipiano.com/Pages/airresengpaul.html

Of particular note is this:
airresonance2.jpg

"A glass Helmholtz Resonator, as illustrated in Ellis' 1885 English version of Helmholtz's "On the Sensation of Tone" (4th German edition, 1877). Helmholtz inserted the small hole (b) into his ear and listened to sounds entering through the large hole (a). The globe accentuated its resonant frequency only if it was present in the overall sound, allowing Helmholtz to determine the component parts of complex sounds".
AND:
"One might think that an enclosed air space would have only one resonant frequency, like a simple Helmholtz resonator, but in reality, the air inside a real musical instrument has many modes of resonance, all occurring simultaneously, all filtering and shaping the final sound we hear. The more the space is divided up into smaller sub-spaces, the more resonant frequencies there are, all interacting with one another to create a complicated and unique mixture."
 

Rayk

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Would you not lose the tones sweet spot being between the bridge and tail block ?
 

walrus

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"The more the space is divided up into smaller sub-spaces, the more resonant frequencies there are, all interacting with one another to create a complicated and unique mixture."

Is this implying a cutaway might be more resonant?!

walrus
 

adorshki

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Would you not lose the tones sweet spot being between the bridge and tail block ?
I was going to go there initially, observing first one needs to determine what string set tension is going to be spec'd, which in turn might dictate neck length/scale length, and fret join location which then would dictate bridge location which would impact bracing pattern and soundhole location although (soundhole) diameter would be variable.
Unless one wanted F-holes and a tailpiece with floating bridge design.
Is it going to be primarily a jazzer or a Havens-type thrasher?
Trying really hard to keep a straight face through all this, btw.
Anything can be cured with the right strings.

Is this implying a cutaway might be more resonant?!

walrus

1jykv7.gif
 
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adorshki

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Would it then be true that a perfectly round acoustic guitar would sound the best?? :unsure:
walrus

Oh you sly...walrus!
I see now this is really a trick question and the answer is that "best" means different things to different people.
I humbly submit this guitar would absolutely deliver the most rounded attack transient, at least.
And probably the most undistorted harmonics at its resonant frequency.
Assuming the scale length allowed such nodes.
A good set of EJ-16s'd probably ensure that.

Yeah but a banjo makes it sound due to a drum head not a sound hole and a hollow body.

And let us not forget the banjitar:
https://www.creamcitymusic.com/used-dean-backwoods-hybrid-banjitar-6-string-banjo-guitar/
Dean-BW6-2.jpg

:glee:
4__02374.1505865266.JPG
 

fronobulax

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DIANAFILLOMREDEBUT-040.jpg


Jack Casady commissioned an acoustic bass from Tom Ribbecke. It is called the Diana Bass, in honer of his late wife, although a Google search on Diana Bass gets way more hits for the author Diana Butler Bass. Money was not really a factor and the design goals were acoustic tone, volume, sustain and the ability to play live. The asymmetry is obvious. Less obvious is the fact that the top and bottom are not parallel. Note the soundhole location and the cutaway. I'm going to use this to add to anecdotal evidence that "round" is not better and a cutaway has low or no sonic significance.
 

Prince of Darkness

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Whilst not perfectly circular, Mandolin family instruments often have a teardrop shape body, as do Portuguese guitars. No idea if there is any sonic benefit to this, most likely just the traditional shape.
 

adorshki

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Whilst not perfectly circular, Mandolin family instruments often have a teardrop shape body, as do Portuguese guitars. No idea if there is any sonic benefit to this, most likely just the traditional shape.
MOST of the original string instruments started off round or close to it, it was simply much easier to build, or a result of using something like a turtle shell or gourd for the back.
32bdc6f2d05940eeb3ce7f09a84abec5.gif

isolated-traditional-indian-instruments-vector-260nw-501329959.jpg

img_813_d20130724103319.jpg

tanbur.jpg

The banjo was invented in Africa, BTW:
CheickHDiabateSammyShelor.jpg

This persisted on up through the early middle ages with the lute ( "l'oud" )
82574-oud_1.jpg

which evolved into the vihuela:
Jaquemart_Andre_vihuela.jpg

When I was introduced to classical guitar I was told the instrument was given its shape to mimic the outline of the female form, but I have a suspicion the ergonomic advantage of being able to hold the instrument at an angle or play on horseback was the real driving factor.
More precisely that, as some mentioned, being able to hold the neck at an ergonomically advantageous angel without having to use the hands to do it, was found to be highly desirable.
In fact my first classical guitar lesson consisted entirely of an analysis of the ergonomics of the instrument, and how to hold it correctly, and why the fretboard was designed the way it is, nothing else.
It was a mind-expanding moment for a 12-year old, no joke.
 
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Nuuska

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effing auto-corrupt.... :glee:
And have you noticed how extremely advantageous it is?
Ergonomically speaking?
(And spelling?)


Just show Walrus THE picture !!!
 
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