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Location: South of most, North of few | Luthier Kevin Ryan in March Acoustic Guitar Magazine:
"An ergonomic thing that we did early on was work with the shape of the back. Most guitars, as far as I know, have a 15 foot radius for the back, and some builders have gone to a 12 foot radius. My radius is seven feet, so the back is very arched. One of the reasons I do that is that the sound is reflected more directly toward the soundhole, not off into the edges which you would have with a flatter back."..."The arched back helps make a deeper guitar more playable and comfortable."
Well Kevin, welcome to our world. :cool: ;) |
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Location: East Tennessee | Jim,
Someday they will all come around. :cool: |
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Location: Scotland | You know, comfort and ergonomics aside, this strikes me as a bullshit (marketing) way to explain very complex acoustic concepts in layman's terms, and anyone who knows anything about the physics of musical instruments will just laugh at it. Guitars just do not work like that. The purpose of the back and sides is not to reflect soundwaves to the soundhole (which itself is a misnomer and should really be called a bass port) but to provide a structure on which a vibrating membrane (the top) can be mounted, and to define the volume of air in the body. The shape, size and materials will all have a bearing on the sound, but "reflected more directly to the soundhole" is a nonsense statement whether it's an Ovation or a Ryan or whatever. |
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Location: Cicero, NY | Interesting, Paul. Not to challenge that in any way at all but, following that logic, is it possible to quantify the differences of a 15, 12 or 7 foot radiused backboard? Given the same material, would those differences in radius produce a noticeable difference in sound or tone? |
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Location: Phoenix AZ | Originally posted by Paul Templeman:
... The shape, size and materials will all have a bearing on the sound, but "reflected more directly to the soundhole" is a nonsense statement whether it's an Ovation or a Ryan or whatever. Agree. If what he (and others, including early Ovation lierature) say was true, about a rounded back reflecting sounds more directly towards the soundhole, then Elite and Adamas guitars should sound like crap with the rounded back reflecting the sound waves right to where there ain't no hole!
Dave |
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Location: Scotland | Absolutely. First of all, you need to understand the concept of soundwave "reflection". The ability of any material to reflect a soundwave is related directly to mass versus wavelength. The low E (82Hz) on a guitar has a wavelength of around 12 feet. Guitar backs and sides(or bowls) are a few thousanths of an inch thick. Whatever frequencies can be reflected by that thickness will be heard mostly by your dog.
This is my theory. The differences in the radius of a guitars back (or bowl) will affect the way standing waves are set up within the air cavity. Parallel or near-parallel surfaces tend to set up a handful of standing waves (related directly to the dimensions of the body) which will either reinforce or cancel the frequencies (and their harmonics) that relate to those dimensions. An arched or bowl back instrument wil set up a much greater number of standing waves, leading to a more random spread of reinforcement/cancellation of a wider range of frequencies. Bear in mind we are talking very high frequencies only here. And that's part of the reason why Ovations sound the way they do....
See, reflecting towards the soundhole may be bullshit, but it's a lot easier to grasp, even if it's wrong. |
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Location: Copenhagen Denmark | So reflectors do not work eh ..?..wonder on what principle , pocket -torches , car lights and the like work , and , it is odd , that a thin piece of wood/material can not stop sound , the whole concept of parabolic reflectors would be a lie , and the whole audio world has no idea what they base their acoustic knowledge on , not to mention the radio industry , radar ofcourse does not rely on parabolic reflectors...or, maybe the aforementioned wisdom has thin bearings , the proverbial " walking on thin ice " , comes to mind...but off course..there is a full understanding of phase -shift being displayed , and therefor I shall not argue , about a subject that has been a part for only but a mere forty yrs. of my existence..I humbly withdraw from this , highly semi -educative " tuition "
..heh heh.. |
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Location: south east Michigan | I probably have no business jumpin into tech talk with Paul, but here I go.
I agree that saying the bowl directs sound out the soundhole is foolish. Even to me.
However, the bowl shape does reflect sound waves... therefore would the top, in some small fractional way, react to the vibrations being directed to it by the bowl?
Here is where I wish Darren could jump in just to clear things up.
edit: Paul posted a great responce while I was hacking out this post. |
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Location: Scotland | Yes, a thin piece of wood cannot stop sound, where (over-simplifying) the wavelength of the sound is significantly greater than it's mass/thickness. End of story. The entire concept of soundproofing/acoustic isolation is simply mass, rigidity and mechanical de-coupling.
Reflection of LIGHT is completely different to reflection of Sound. Try a little research.
Or maybe I was bullshitting my degree students..... |
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Location: Scotland | Brad, the top reacts almost entirely to being torqued by the bridge, which is reacting to string energy, not "reflections from the bowl" which would be tiny by comparison. |
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Location: Copenhagen Denmark | eflection of LIGHT is completely different to reflection of Sound. Try a little research.
----------------------------------------------
Ofcourse..quite right you are..that is why parabolic reflectors on microphones do not work.. |
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Location: Scotland | It's all related to wavelength. Sound reflectors work, but they are NOT full range. The frequencies they can reflect are related directly to their mass, rigidity and thickness. This is basic acoustic physics, and you are way too close to being out of your depth. |
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Location: Copenhagen Denmark | That post is full of contradictions , I have no business being on this thread , therefor I will , seek Fame and Fortune elsewhere , and , Humbly , yet with my head held high , make for a gracious exit.. |
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Location: The Great Pacific Northwest | Originally posted by Paul Templeman:
It's all related to wavelength. Sound reflectors work, but they are NOT full range. The frequencies they can reflect are related directly to their mass, rigidity and thickness. This is basic acoustic physics, and you are way too close to being out of your depth. Ditto on this and everything else posted by you on this thread. Not that you need my approval, but the "conception" or rather popular "misconception" of how a guitar works has become a pet peeve of mine since learning about it a few years back.
The whole "a deep bowl sounds deeper" argument has very VERY little to do with the Bowl and more to do with perception, and other factors such as bracing and sound hole placement and pattern.
I mention perception for physical reasons. A center hole guitar, in general will sound better for the person PLAYING it, than the person LISTENING to it. Several years ago Alpep and I did some comparisons of what essentially the same guitar sounded like, one with a center hole, one with epaulets. Now granted, because of the bracing patterns this wasn't apples vs apples, but it was close enough to realize, beyond any speculation, that most of the sound the LISTENER hears is from the TOP.
Another factor, especially with deep bowl guitars, is the person holding them and how they are held. Those vibrations are being transferred to your body if you are holding the guitar against you.
Anyway, as you can see when dealing with Acoustics there is a lot more than the "top" making the sound, but I agree... the statement about the back reflecting sound to the hole.... Well if strings were capable of those frequencies in the first place.... maybe... but as someone stated, only your dog would care. |
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Location: Chehalis, Washington | In talking with a guy about a custom wood box, he recently told me that in his experience the back and sides of a guitar (shape, type, etc) only makes up about 15% of the overall tone. He claims the scale, top wood, and bracing has much more to do with the tone than the back arch or wood/fiber type.
This seems to keep with what's been said about the acoustics of it...my curiosity is in specifically (at least in simple layman's terms) the body size and shape (OM, dread, etc) affects the projected acoustic sound. Obviously, smaller guitars tend, generally, to have a "smaller," more treble-heavy sound, and vice versa, but is there another factor other than overall cavity volume and displacement that PRIMARILY affects the volume and tonal balance? |
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Location: South of most, North of few | Andrew, I see you changed your sig. ;) |
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Location: Warren,Pa. | One of the pleasures of my life is, when Temp gets involved in a conversation, to just sit back and listen.
John <>{ |
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Location: SoCal | Disclaimer: I am not an engineer although I was a VP of IEEE and Old Crows...my background in Electronic Warfare was a user of the black boxes.
However...
Temp, this is in agreement to what you have said but it brings up a couple of thoughts (dangerous) that I have had.
My observations...
A wood back vibrates more than a bowl. IMHO, difference between the hand layed, standard bowl, shiny bowl, and the contour. In addition, measurement of the tops can show different vibration patterns. As to the early Adamas v. 80's, the bowl transferred the vibration more in the early bowl. Surfaces can be used to dissipate/absorb vibrations as well as accentuate/direct vibrations. Simple analogy is a room with a closed door v. a door ajar v. a door open.
Understand that the composition of the top (type of wood or composite), bridge, bracing, and even how the top is connected to the body can be major factors. It was interesting when I compared my small soundhole shiny bowl 12-string projection/balance with the later slothead models of Custom Legend and Glen Campbell. Prior, I was under the assumption that the smaller soundhole would have less projection-nice surprise.
My understanding of a lower bridge position in a slothead was to create increased vibration (velocity) in the lower bout of the guitar, as well as the upper portion of the guitar.
Questions:
Assuming the volume was the same, does changing the shape of the sides/bottom of a woodie or the shape of the bowl (i.e., contour) make an appreciable difference? Would you be able to tune it to emulate characteristics (velocity) of a wood different than used on the top (i.e., Sitka v. Engleman v. European v. Brazilian Rosewood)?
If we assume that there is the same radius, there seems to be a difference whether the guitar has no pre-amp or is an a/e (i.e., my two Patriots). I have always questioned as to whether wiring secured to the back and a rounded edge v. sharp edges of the box would have any appreciable benefit.
If the lower bridge on a slothead is an advantage, assuming the same scale (i.e., 12-fret), why wouldn't a lower position bridge be an advantage in a standard headstock? |
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Location: Cicero, NY | "Or maybe I was bullshitting my degree students....."
Paul, I cannot tell you how much, as I was sitting here on a Sunday afternoon with a small glass of Cab looking for some education, that one line made me laugh.
With all due respect to your knowledge, your humor is priceless. |
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Location: Phoenix AZ | Paul, Thank you for your wealth of knowledge. Seriously, you should copy/paste every post you've written in the last 5 years and turn it into a book. What a great read it would be.
Dave |
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Location: East Wenatchee, WA | As I read Paul's post, I immediately began to think about my old Ludwig drum set.
Really, not un-similar to how a guitar works, and sure supports what Paul is saying about soundwaves and guitar body/top relationship.
Very fascinating reading. |
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Location: Cicero, NY | Originally posted by Tupperware:
Paul, Thank you for your wealth of knowledge. Seriously, you should copy/paste every post you've written in the last 5 years and turn it into a book. What a great read it would be.
Dave Put me down for three already. |
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Location: Canada | I'm new to Ovations (looking to purchase one shortly) and this thread highlights a couple of questions I've had.
If bowls are somewhat irrelevant to sound (as was said above), wouldn't that mean that top and bracing are more important? Would the LX Scalloped X bracing pattern be better for a sound projection acoustically then the old A pattern (i.e. on the ADII)?
I'm quite puzzled by the bowl issue. Deep, Deep Contour, etc. Does the Deep Contour bowl give "maximum acoustic response" (per Ovations words) due to to its being utilized on Scallop X braced tops, or in and of itself.
Mr. Ovation mentioned the Center soundhole vs. epaulets sound distinction (player vs. audience). Is this an indication that in general, all things being equal, epaulets sound better to the audience? |
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Location: SoCal | All other things being equal, a deep bowl will give a bigger acoustic sound than a shallow or mid depth bowl. A full deep body wood acoustic guitar will give a bigger, deeper sound (again, all other things being equal), than a thin body acoustic guitar.
Contour vs deep bowl? We're talking comfort here.
A bracing vs. scalloped X bracing? Personal opinion (mine being better and more important than anybody else's)...... |
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Location: ms | I have a headache :( |
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Location: Scotland | Going back to basic acoustic physics in relation to body size. A guitar is basically a helmhotz resonator. When Helmholtz theory is applied to guitar design it's about the size of the air-cavity in relation to the size of the soundhole(s). This produces the fundamental frequency of the instrument. There is an optimum soundhole size for a given body size, and changing either will raise or lower the fundamental. This is partialy why single epaulet Adamas/Etlite T's are so highly regarded. It's also how airlocks and feedback bungs work. If you want an example of Helmholtz Theory in practice compare the acoustic sound of your guitar with and without airlocks or a feedback buster. With the bungs in the acoustic output changes only slightly but the bass is reduced because the fundamental frequency has been raised. Those of you with Elites/Adamas play your guitar with the back-plate off and see what happens. Fun with acoustic physics!
Incidentally, Ryan has started making guitars with ports in the rim! So much for "Reflecting towards the soundhole"
Acoustic "flutes" |
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Location: Capital District, NY, USA Minor Outlying Islands | Helmholtz a theory? It's a Helmholtz Fact Jack!
Heir Helmholtz.
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Location: South of most, North of few | Paul, I saw the guitars he makes with the rim ports and have seen similar designs in other makes. I think someone here even drilled an Elite in the upper bout for a sound port. I have played my Adamas and Elites without the rear cover. It sounds like you've lost most of the guitar! Thanks for the insight. |
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| I wish someone would utilize all this new, scientifically proven, information and create a guitar an acoustic guitar that focuses the sound waves toward the top so we can all listen to it and be amazed!
Randy |
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Location: Warren,Pa. | Jim,
I'm the one who drilled the "sound ports" in my Elite. They work nicely, but at present I have the OpPro removed to borrow parts for another guitar. With the added hole where the OpPro was, the sound is pretty thin. It was just "dumb luck" that the holes I drilled didn't ruin the sound. Opening up the preamp hole pushed it over the edge. In tap-tuning a guitar top I believe they call this the "point of dispersion".
John <>{ |
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Location: South of most, North of few | Yeah John, I remember now. (old age) You did a really nice job on it too as I recall, multi hole configuration, like the top. |
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Location: Colorado Rocky Mountains | Doesn't a violin provide further evidence of the theory that the dynamics of a vibrating top are more important to sound volume than the size and shape of the instrument cavity? Isn't this why a violin soloist can soar above a full orchestra without amplification (strings, bridge, bow technique, etc. notwithstanding)? |
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Location: Scotland | Originally posted by Northcountry:
I wish someone would utilize all this new, scientifically proven, information and create a guitar an acoustic guitar that focuses the sound waves toward the top so we can all listen to it and be amazed!
Randy Ok, there are two basic ways to stop a soundwave: either absorb it (as used in acoustic treatment of recording spaces) or put something massive in it's way, which would in effect reflect some or all of the wave back towards it's source and/or diffuse it an random directions. For a surface to reflect a soundwave effectively it's resonant frequency must be lower than the soundwave, or the soundwave sets the surface in motion while passing through it. This is known as the "drumhead effect" and is one of the reasons why sound, especially low frequency, tavels well in internal domestic house construction, which is usually 2 X 4 stud and gyproc. You can't easily make a rigid structure with lots of mass from relatively lightweight flexible materials, and it takes mass and rigidity to stop or reflect LF.
In order to have a theoretical guitar where most or all of it's sound is reflected back to the top, the back and sides would need to be so dense, thick and rigid that you probably wouldn't be able to lift the thing. |
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Location: Jet City | Originally posted by Weaser P:
as I was sitting here on a Sunday afternoon with a small glass of Cab And that's about the only thing I can relate to and understand in this thread.
In layman's terms, can anyone tell me why my Elite LX is so much quieter than other acoustics when I'm playing acoustically? My guitar just doesn't come out in the mix. I find I grab my Washburn just to compete volume wise. I hear myself fine, but others struggle to hear me.
Maybe I need a different O. I was wondering if it was due to not having the round hole. |
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Location: Boise, Idaho | Don't feel all alone, Damon. I've been trying to figure out how the guy who invented the manuever to stop people from choking has anything to do with soundwaves. If you pick the guitar up and squeeze it really hard just above the waste, do you force more sound out the soundhole? |
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| You stand more chance if you spell it waist.
Ignore all the mystical bollocks from The Man Of The Year - he swapped living in England for living in Scotland and plainly cannot be trusted. |
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Location: East Tennessee | Originally posted by schroeder:
You stand more chance if you spell it waist.
He was trying to spell like you Brits spell. :D |
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Location: Boise, Idaho | I was actually concentrating on spelling maneuver and screwed that up too. Don't think Shreodur cought that one, though. |
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Location: South of most, North of few | Good one Mark! :D |
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Location: Boise, Idaho | Those Brits use words like "bollocks" so no one can check on their spelling. My dictionary does have "bullock" though. It's a castrated bull. Is that the same thing, Schroeder? |
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Location: enid, ok | This whole post is bullocks. |
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Location: Cicero, NY | Sandra? That belongs in that other thread... |
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He said it.