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Hi,
What do you think is the largest contributor to the volume/projection of an acoustic guitar?
I ask because I am planning a thin bodied acoustic guitar, and want to maximize volume, but not at the expense of what little low end I can get out of the instrument.
I have built a sort of hybrid acoustic/electric, with a hollowed out electric slab body and a braced and thicknessed sitka top. Believe it or not, that guitar acoustically, at 1 and 3/4" depth, is very loud, although seriously lacking in tone acoustically, particularly in the low end(not surprisingly).



Understanding that this is one guitar, and not definitive in any way, I suspect the volume of that guitar has a lot to do with the stiffness of the back, but if true, how and why, and particularly, the nuances of that relationship is beyond my understanding at this time.
I've touched on the idea of a thin body before, and got the usual suggestions to pursue things like a body wedge instead, but I have decided to go with a thinline instead. I would appreciate any insights the builders on this forum might have.
Note that I am talking about a true acoustic this time, not the hybrid instrument above.
I intend to chase this rabbit until I get what I'm looking for. I'm talking consecutive builds on this theme. I think that's probably the best way to actually finally get what i'm after, or at least an understanding of why I cannot.
Thanks.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

A pick up. Sorry, I just wanted to be first.

LOL, Danny.
Yeah, it's got one. Sounds pretty good plugged in. But I don't plan to build another hybrid at this time.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

I'd say midrange will deliver the strongest projection of sound with fidelity.
Bass tones go farther, but are usually less distinct.

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"Act your age, not your shoe size" - Prince

I am not an expert but I have played a lot of guitars so I would say the 2 things are:

The largest body you can make with the the heaviest strings you can get. Large body guitars are always louder and have more base and heavier strings will produce the most volume.

If you are talking the type of wood or construction methods then someone else more enlightened can handle that one. I am just working on my first build so I am still learning.

Cheers,
Bob

To maximize bass there are lots of little things you can do - like loosening up the rim of the top for example - but IMO there is really no substitute for air volume inside the box...

Thanks for all the responses. About the bass, I'm not looking for the boom of a dread, but definitely a full, balanced tone. I just don't want the bass to be lacking, and I don't want the midrange "honk" or "boxy" kind of tone that many small bodies get. More smooth and warm sounding, if that makes sense.
But I also want to maximize volume for size(L-00). I just don't want to give up tonal balance in exchange. A loud but overly bright guitar is not what I'm looking for. In the end, if I had to, I'd give up a bit of volume for balanced tone. But I hope I don't have to.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

Wood choice would also be a consideration to look at.

I know Mahogany and Saple would give you a warmer tone. And if you have deep pockets Brazilian Rosewood (old growth) would be a good choice. Those are the ones I know of but I am sure some of the guys that have built more would be able to give you more options.

The other thing to consider would be using lighter bracing or thinner soundboard. I recently rebuilt a Gibson J-40 for myself. It came to me in pieces so it was a complete rebuild. The J-40 is a less expensive version of the J-45 but it has double X bracing. When I redid it I scalloped the braces considerably and thinned the top. Normally the J40 sounds boxy and much thinner than the 45 but after it was done it now has a bigger voice than the 45. I have had a couple J45 owners ask to buy it because they think it sound better than their 45s. but I am not ready to part with it yet.

So bracing, wood choice and top thickness are some of the things to think about.

Cheers,
Bob

It can be a lot easier to build a loud little guitar than it is to build a loud big guitar. The smaller the guitar, the lighter it can be built. The larger the span, the thicker the braces and the top have to be to support the string tension. There's a reason that the OOO-size guitar is so popular. It lands at a nice compromise between volume and bass end. But, it is possible to build a smaller guitar with more volume and pretty decent bass. Sometimes, I make a heavier bridge to damp some of the treble and make the guitar sound bassier when I know the design is going to be loud and bright.

"volume" and "bass response/low end" are one and the same thing- it takes much more energy to make, for example, a 75dB tone at 60hZ than it does to make a 75dB tone at 2500hZ....same reason why a bass player needs an 800 watt bass amp to keep pace with a guitar player's 60 watt amp- gotta push bigger speakers mounted in bigger cabinets to make the same sound pressure level(volume) as the higher pitched 6 string.

I would tend to agree with James... no substitute for air volume. What is your reason for wanting the thin body? Shoulder comfort, or something else?

I have a factory made nylon string thinline guitar that I like a lot, so if you're not set on steel, I'd recommend that. You'll never get the deep, rich bass or a normal guitar, but nylons naturally lack in the high range, so the balance isn't thrown off as much as it would be with steels. The one used in this song sounds pretty similar (which is what I was trying to emulate at the time I bought it)


That said, I have been curious to try building a thin steel string just to see how it would sound. I'd most likely do a Gibson J200 type shape (17" lower bout, 21" length). Seems like the additional soundboard area would help with the lows, as well as the added air volume without increasing depth. But it would negate the comfort aspect to some extent. I have a hard time picturing a 00 thinline ever sounding "right" with steels at standard tuning... just too small. But if you think it can be done, I'd love to be proven wrong

Thanks for all the responses.
Dennis, yes, not only shoulder issues, but nerve damage in my arms and hands which are inescapable.
As to making a thinner body sound good, I'm gonna give it the old college try(though I've never been to college). I intend to build this model a few times, and try to tweak until I get what I'm looking for, or until I come to the conclusion that it's not possible. I know it won't sound like a larger guitar, and I'm not after that. But if I can balance the tone and smooth out the response, move away from that boxy tone, and not get overly bright, I'll consider that a success.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

Hmm, nerve damage sounds like even more reason to go nylon. Easier on the fretting hand too. Especially if you go for low action with a highly responsive soundboard.

But for a steel string 00... what about trying a higher damping soundboard wood? Mahogany, koa, monkeypod, walnut, butternut, redgum. Maybe a softer saddle material as well, to kill some of the janglyness. I do think a rigid back is a good idea to avoid the boxy sound of a lively but high frequency air resonance. But probably need a really loose soundboard, to avoid the whole thing sounding like a hard wooden box.

What I'd do is make a quick and dirty testing body and try lots of different soundboard woods at different thicknesses and bracing patterns and stiffness distributions. Maybe sitka, cedar, and mahogany. Start thick, like .120" on the sitka, and with very minimal bracing. Then either try one of the other woods at similar stiffness to the .120" sitka, or thin the sitka further and rebrace and try it again. Get a feel for the effect of different things.

Heck, maybe even try a rosewood top. The 3 properties that determine resonant frequency are size, stiffness, and mass. So if you can't make it bigger, and it's already as loose as possible, more mass could actually improve the lows. Probably .070" or thinner on that one.

Thanks. I like a lot of what you mentioned, it makes sense. Nut and saddle material will be corian, which is softer than bone, I think. I have some of that around, and it doesn't cost me anything.
For the woods, right now I'm leaning to walnut back and sides with a Sitka top, but mahogany or even walnut for the top is something I hadn't thought of.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

You may want to check out a good archtop guitar. A good one can be as loud or louder than any flat top. Jazz players like them for the even tone they produce.

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http://www.cushmanguitars.com/.

A man who carries a cat by the tail learns something he can learn in no other way.
Mark Twain

Interesting. I would expect that a rigid back would raise the resonance frequency of the first air cavity mode, and a compliant back would lower it. You seem to be suggesting the opposite. But I am just going on intuition, so maybe I'm wrong.

No, I think you're right. It's just that the live back style also makes the air resonance more prominent, and it will never be low enough, so in this case, you'd probably be better off suppressing it.

But I'm going on intuition for the most part as well. Just seems like a lively and high air resonance would make a honky/boxy/wah-wah type tone with steel strings. Nylon, I would go live back.


That reminds me, the Padma makes tiny archtop travel guitars. Might check with him for some advice.

Hi Mike,
I wonder if you wouldn't get a bit more base if the bridge was positioned lower, a little more on the large lower bout. I'm curious how the bridge pictured sits in relation to the bracing.
Gerry

I've wondered that also, and was considering a 13 fret.
But in all the research I've done, the consensus I get is that it "sweetens" the tone more than increases the low end. If by sweetening it is meant that the instrument sounds soother then I might try that out as well.

_________________
Mike

The only thing nescessary for evil to thrive is for good men to do nothing.