alternative body shapes

[kramster]

The Amicus is just plain fun! And looks cool as a bonus.

[Long Jon]

Originally Posted by Song

Sean will sell a new one for 1011.48 pounds, a savings of 37.52! http://emeraldguitars.com/product/am...v=7516fd43adaa

I make it £1352 new (with the pickup). And the eBay fellah is open to offers below a grand.
But the Amicus isn't really for me , if I spot a s/h X20 it'll be mine in a click.

[Johnny5]

My Alpaca not so, ummm, traditional... lol

[Ted @ LA Guitar Sales]

Originally Posted by merlin666

Well that may be the case for you but is certainly not a general truth, as myself and 1000s of other Ovation players find them extremely comfortable, more so than "boxy" guitars.

My comment was based not only on my experience, but also based on the experience of the hundreds of people I discuss guitars with each year. I get that the Ovation has a cult like following, but I have never heard anyone describe the bowl back as ergonomic.

That's one of the points I was making - the box shape is far from optimal and limits the builder. Round backs such as in lutes and Ovations provide better projection, and I am sure this could even be much further enhanced with available technologies.

Interesting, I would love to hear what the builders on the forum have to say about this.

This is unfortunately true, and definitely a function of the lack of supply of alternative body shapes. If more choices were available it is likely that players would notice their various advantages and buy them.

In business supply needs to follow demand, not the other way around. The Alpaca pictured below is actually a great example this. I also own one, and it is by far the most ergonomic guitar I own. The shape is designed to hug the body and position the sound hole in the optimum location for the player. Sadly Alpaca is now out of business.

Originally Posted by Johnny5

My Alpaca not so, ummm, traditional... lol

I ride with Ted on the Ovation. I've had several ovations primarily because of fine necks and great sound. But hanging on to one is a chore. I suspect that if you strap one on you're probably fine, but if you sit to play you need Velcro or glue.

I'd say the same about the Rider--it takes a neck-up or a strap to play comfortably.

This is not a knock against Ovation or the Rider, they are just not for me.

[Ted @ LA Guitar Sales]

Originally Posted by EvanB

I ride with Ted on the Ovation. I've had several ovations primarily because of fine necks and great sound. But hanging on to one is a chore. I suspect that if you strap one on you're probably fine, but if you sit to play you need Velcro or glue.

I'd say the same about the Rider--it takes a neck-up or a strap to play comfortably.

This is not a knock against Ovation or the Rider, they are just not for me.

Thanks, Evan.

BTW, like the Go Guitar, the Backpacker, and the Vagabond, the Rider is a "sub-compact" travel guitar that was not designed to be played without a neck strap. As it turns out, using the Neck-up on these guitars allows them to sit on the leg just fine, making them much more versatile. Joe has thought about a re-design of the Rider that would allow the it to sit on the leg without a Neck-up, but it would add bulk that would take away from the extreme portability, so I'm not a fan of the idea. The Go with it's square lower bout does sit on the leg comfortably, but these sub-compact guitars are just too small. The Neck-up not only helps stabilize them, but it allows you to position the guitar higher up. With the Neck-up, my Rider is actually more comfortable to play than a parlor.

[Earl49]

Originally Posted by Ted @ LA Guitar Sales

....but I have never heard anyone describe the bowl back as ergonomic.....I would love to hear what the builders on the forum have to say about this......

Not a guitar builder, I do acoustical analysis and design for rooms (theaters, auditoria, studios). The acoustic guitar is basically a *really* small room with a funny shape. The shape is largely dictated by what is buildable in woodworking terms, modified by ergonomics -- overall body size and the waist of a OM, for example. The dreadnought gets its louder bass-emphasized sound primarily from a bigger internal volume and larger sound board area, compared to a 000.

Personally I have never believed that the curvature of the back has a significant effect on tone or projection. Guitar tone has so much more to do with the top bracing and thickness and how that surface vibrates than it likely does from the "room acoustics" of the body. Aren't there stories about a Spanish builder (Torres or Ramirez) making a guitar with paper mache body, that still sounded quite good?

This is especially true of the minimal curvature on something like a Taylor GS Mini, which has to be something like a 60 foot radius minimum. (Taylor used that curved back to avoid the need for back bracing to keep costs down, not for some acoustic reason). People often attribute its sound to that slightly curved back, but I'm not buying that. The curvature might reduce some standing wave modes inside the body, but do those particular modes cancel certain sounds or emphasize it? It would take a PhD dissertation in physics to adequately study that and maybe come to some conclusion. Guitar design is not based on analysis and modeling. It is based on empirical trial-and-error over centuries. Now we have the chance with composites to try different shapes that were not easily constructed in wood. Still most of those shapes are targeted at ergonomics, not acoustics.

I've occasionally thought about getting a beat up old Ovation Applause and cutting out the bowl, replacing it with a flat laminated back, just to see if there was any perceptible difference. But with such a cheap guitar to cannibalize, the quality and bracing of the top still has to dominate the tone. JMO.

[Ted @ LA Guitar Sales]

Thanks for the post, Earl.

I've been collecting guitars for about thirty years, and have read all the opinions, including the one about how the Guild D15 sounds so good because of it's cheap to produce curved laminated back. Thirty years later we hear the same thing about the cheap to produce curved back on the GS Mini. As you point out, most of the tone, and projection of an acoustic comes from the soundboard, something I've discussed with many builders, and it's something I discussed with Charles Kaman as well. (For those who don't know, Charles Kaman was the founder of Ovation Guitars, and was responsible for developing the bowl back guitar in 1964) Like many others in the industry, Chuck felt that what you use for the back and sides of an acoustic is not that important, so why not use an easily constructed bowl, using the same material he was using for military helicopter rotors. He had tons of the stuff on hand, his team was comfortable working it, and the rest is history.

[merlin666]

Originally Posted by Earl49

Personally I have never believed that the curvature of the back has a significant effect on tone or projection. Guitar tone has so much more to do with the top bracing and thickness and how that surface vibrates than it likely does from the "room acoustics" of the body.

Over on the General discussion forum there are many who are convinced they can hear systematic differences between different wood types and are willing to pay big premiums for this or that wood. Anyway, with the few Ovations I have played I always hear comments about how relatively loud they are, even the mid-sized bowl ones. Now this may also be due to bracing, as Ovation also did a lot of experimenting in order to optimize bracing patterns and of course they were the first to produce carbon fiber topped guitars.

Regarding bracing - I thought that most carbon fiber guitars don't have bracing, or don't need it for stability. Or are the tops varied in thickness for some of the models in order to accomplish a specific tone?

[Ted @ LA Guitar Sales]

Originally Posted by merlin666

Over on the General discussion forum there are many who are convinced they can hear systematic differences between different wood types and are willing to pay big premiums for this or that wood..

They can, but it has nothing to do with the shape of the back, it has to do with how different tonewoods "color" the tone of the soundboard.

Regarding bracing - I thought that most carbon fiber guitars don't have bracing, or don't need it for stability. Or are the tops varied in thickness for some of the models in order to accomplish a specific tone?

Most CF builders use either braces, or in the case of Rainsong, a patented layering of the soundboard to achieve stability and more importantly, the desired tone. Emerald does not, they rely instead on arching the back, and soundboard for stability. Not sure how they voice them.

[Earl49]

Originally Posted by merlin666

Regarding bracing - I thought that most carbon fiber guitars don't have bracing, or don't need it for stability. Or are the tops varied in thickness for some of the models in order to accomplish a specific tone?

Many composite guitars do not have any bracing, because it is not needed structurally. Certain CF guitars have SOME bracing, and in those cases the bracing serves more to modify tone to approximate the "wood sound" in the way that the top vibrates, and is not really needed for strength.

As for the loudness of Ovations, there may be some internal sound reflections that help. It seems easy for sound to get "trapped" reflecting back and forth between the back and top inside a "box" -- which would not occur as easily with a pronounced rounded back. When I design a recording studio, the goal is to avoid large parallel surfaces in the X, Y and Z axes that support lateral reflections. Many of the surfaces are sloped slightly to prevent those standing waves and room modes that can be audible, coloring the sound. It could be that the round back helps in a similar way.

Early;

I like the notion of "trapped" sound. I'm not sure where I first got the idea, but my understanding is that one goal of instrument making is to have as little parallel surface as possible. I presume that would be to avoid trapped and muddy sound??

[Earl49]

Yes, Evan. And some of those trapped sounds -- actually standing waves where the wavelength coincides with the dimension of the "box" -- could either reinforce or strengthen certain top frequencies (wolf tones) or cancel them out (aka dead spots). And everything changes when you move to the next note / frequency. See how complicated this gets if you dig in?

If room geometry is working for you, you don't need a lot of acoustical treatment. The room analogy to trapped sounds might be using bass traps in the corners to absorb away the natural build-up of sound when surfaces meet. [When you get one reflecting surface (getting close to a wall) the sound level increases by 3 dB. Two reflecting surfaces (intersecting walls) increases SPL by 6 dB. A corner with three reflecting surfaces adds 9 dB compared to the center of room sound level]. Plus there is a likelihood of sound waves bouncing back and forth between the parallel top and back. Kinda like standing between two parallel mirrors, where multiple images reflect back and forth extending out to infinity.

Back to curvature. Take 1000 Hz for an example, which has a wavelength of about 13 inches. If the depth of your guitar is half that, it will reinforce the waveform maxima corresponding with 6.5". Most of our guitar bodies are about 4" deep give or take, so they would tend to reinforce 377 Hz. That is part way between third harmonic of the low F# and G, and right where some primary vibration modes occur on a typical acoustic guitar top.

Earl;

Wow! This is great stuff. You and Tom2 have really added to the content of this forum.

Your current contribution reminds of a Kirk Sand discussion many years ago regarding the production of the a hollow, thin bodied electric guitar. He ended up having to place a block in the guitar in order to get a clean sound.

I've often wondered if violin tone posts were not designed to clarify sound? I've also thought that thin bodied guitars might use tone posts rather than bracing??

There's a lot of wonderment in the creation of musical instruments.