Official Luthiers Forum!

Hello Everyone,

I recently ran accross an article that stated that increased guitar size, does not equal increased volume, but just increased bass response. I found that an interesting statement that a smaller guitar can be as loud as a larger one, and that bass would be the only thing gained.

Is this true in your experience?

Thank you!

Jeff

Jeff,

From what I understand, you want to build lighter for more volume, however there is a limit to the point where building too light affects tone. Also, there is some truth to building bigger for more volume. With a longer scale, you will have increased string length, and therefore be able to use a higher tension string which will give you more volume. There are trade-offs everywhere so I don't think it's a single solution for all. I guess it depends on each guitar and the things you can do to each instrument to make it louder. Every design and plan is a little different.

Cheers!

John

Hi Jeff,

It's certainly true with speaker cabinets. I've read of many luthiers comparing the action of a guitar top with that of a speaker cone - sort of. So it does make sense that more internal volume (with the correct size soundhole) gives deeper, not necessarily louder, bass response. Of course like anything, you soon reach the point of diminishing returns.

It's amazing that with all the scientists and physics students who play guitar (my assumption), that so little acoustics research has been done as to what is really going on with string instruments. I know of some violin / guitar research out there but not what one would expect.

Skip

Thanks John and Skip.

Volume seems to be one of the variables that gets a lot of attention in the classical world. More so it seems than with steel string players. I am of the belief that the acoustic guitar was designed to be played in a small, intimate setting, not a concert hall, so volume was not an issue then as it is today.

If the statement that larger equates to more bass response is true, I wonder if there is any benefits to a wider body, as opposed to a larger body size?

Jeff

Jeff,
If you realy want to learn more about volume, bass, etc. try to find something about the the three "major poles" ...the Polock...the pole-bearer...just kidding! Find out about the Mono-pole, The Long-dipole and the Cross-dipole. Somogyi explained it to me but reading about it what you need. It's too complicated to fully explain here. I think LMI's old catalogue or perhaps one of their red-books addresses these "poles". It realy helped me.

_________________
Dave Bland

remember...

"If it doesn't play in tune...it's just pretty wood"

That assertion is probably based on a PhD thesis done by Howard Wright at UWales/Cardiff in '96, in which he used a computer model to generate guitar sounds and asked people if they could hear the differences when he made various changes. The thing that had the most effect on the tone was the ratio of vibrating area to mass of the top resonance modes, and particularly the 'main top' mode, which is the one that acts like a loudspeaker. Wright's thesis advisor, Bernard Richardson, later used those results, and some other data, to argue (in an article in the Catgut 'Journal' entitled 'Simple Models of Guitar Design') that small guitars can, indeed, be as loud as bigger ones.

There's one absolute requirement that every guitar top has to meet: it has to be stiff enough to not fold up too fast. Anybody who's worked on a house knows that as you increase the span of the floor you have to use heavier joists to keep it from being too bouncy. Richardson showed that, for a given top structure, increasing the span beyond a certain point increases the weight faster than the area: the A/m ratio goes down and the power suffers.

Of course, you can't always lighten up a smaller instrument all that much either. There are absolute minimum limits to the thickness of the top, below which you'll be putting your finger through it.

So, if you start with that minimum thickness, which gives you _some_ stiffness automatically, you can increase the size for a while without having to make the structure heavier. But, at some point, you will have to start beefing things up, and shortly after that the weight will be rising faster than the area, so you're losing ground. For any structure there seems to be an optimum size.

It's interesting to look at a book that has lots of pictures of old guitars with this in mind. The early, ladder braced ones were small and narrow. As soon as the more efficient fan bracing came along they started making the lower bouts wider, until you get up to Torres and the 'modern' designs, and the growth pretty well stops. Meanwhile, on this side of the pond, when X bracing came into use, the guitars grew again until the Dread and Jumbo, and stopped pretty much. You see an occasional bigger one, but they are not common. Archtops were built that were wider than Dreads and Jumbos, but there is a limit to what you can tuck under your arm, too.

Anyway, a larger box will tend to give off low frequency sound more effectively, so that effects the bass balance of the tone. In terms of tone production it seems to me that length is far more important than width. This may have to do with the way the lower air resonance modes couple with the top, or it could be more related to precession of the equinoxes....

Hey Dave and Alan,

Thanks! I really appreciate the help.

Dave I will check on the poles.

Alan, it will take many readings to digest your comments, as I am just starting to delve into this material. But, I am happy you are speaking at a level above my knowlede, it inspires me to continue to learn. The great ones must have known these things intuitively after gaining experience building.

Jeff

Al said "but there is a limit to what you can tuck under your arm, too"

Some guys are more talented at holding them than others, ha!



Gerald

Even though he can fit that "boat" under his arm, you can see the other aspect of increased size is that as the scale length increases with it, the less playing range he has...from the picture it looks like he only has 6-8 frets to work with...the bridge has to be about the size of a 12" ruler and 4 times as think.

I didn't hardly recognize you in the picture with that big sombrerro on Gerald.

_________________
tim...
http://www.mcknightguitars.com

One of the great variables to volume is, of course, how you play it. On any one guitar a flat pick is going to be louder than fingers. Are those just the finger pads, pads and nails. Are the nails bare or acrylic or fibre glass and CA (I could write a whole book on nail care!).

I can make a finger picked 00 sound like a flat picked Dreadnought if I relly dig in, but why would I want to? Music is all about tone and dynamic variation. If you want it loud stand in front of a mic.

Colin

_________________
I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Ha. I know a Classical guitar player who can blow most flatpicking steel string guys out of the water with just his fingers, ad on nylon strings. His wife sings along with him, and she's a powerhouse, so he's had to learn to produce beaucoupe power to keep up. And the cool thing is, his _tone_ is wonderful too.

beaucoupe

Alan, I've heard this term before, where does it come from, looks French. thanks.

[QUOTE=Dickey] beaucoupe

Alan, I've heard this term before, where does it come from, looks French. thanks.[/QUOTE]

It's mispelling of 'Beacoup', pronounced 'bow koo', means 'lots' or 'a lot' in French.

I heard it from a redneck VW mechanic that liked to hang out with hippies. He had a lot of cool terms. Most of which I can't share....

[QUOTE=Dickey] I heard it from a redneck VW mechanic that liked to hang out with hippies. He had a lot of cool terms. Most of which I can't share....[/QUOTE]

So maybe the spelling is OK. Maybe we are referring to a good looking VW or whatever. Beau Coupe

And to think, I used to take French! Oh, the embarassment.

Al I wouldn't give it a second thought. We all took English classes and have you noticed the spelling around heare?