Geometry of a guitar

[Bizman62]

I've often times wondered if there's some professional wisdom about the shape of a guitar, more specifically a consensus about the proportions between the upper and lower bouts, the width of the waist, the angle of an offset body, the depth of a carved top...

There's guitars that please my eye more than some others don't but why is that? Is there a golden ratio hidden somewhere?

The big question is, is there a formula, a universal model for shaping a guitar that "looks right"?

[MiKro]

1 hour ago, Bizman62 said:

I've often times wondered if there's some professional wisdom about the shape of a guitar, more specifically a consensus about the proportions between the upper and lower bouts, the width of the waist, the angle of an offset body, the depth of a carved top...

There's guitars that please my eye more than some others don't but why is that? Is there a golden ratio hidden somewhere?

The big question is, is there a formula, a universal model for shaping a guitar that "looks right"?

It all started with a stick.

[henrim]

9 minutes ago, MiKro said:

It all started with a stick

Then came lower and upper bouts to make it playable while sitting. Then the player wanted to have access to the upper frets he had paid for. And he got the cutaway.

That’s pretty much the essentials. Rest is about balancing. Physically and visually. And they of course affect each other. But the visual balance is more of a universal thing than guitar related. Not all curves and shapes go together, be it a guitar, car or toaster.

Golden ratio is one rule that can be applied in design. In my opinion it shouldn’t be used too strictly though. But it’s a great guideline for pleasing proportions.

But personally I don’t think it is just about the shape. Especially electric guitars are very complex objects with all the hardware, knobs and bolts. Getting all the conflicting parts to work together as one requires more than just getting the body shape perfect. And of course the hardware also affects the shape and balance.

[Bizman62]

10 hours ago, MiKro said:

It all started with a stick.

That's true. I should have been more precise. @henrim said one key word: balancing.

I mean, the upper and lower bouts of early acoustic guitars were more symmetric than they are today and also slimmer. They look like prototypes to me, some ergonomics already but not capable of reproducing all frequencies. The development to the rich sounding acoustic guitars took centuries to get where we are now, ringing trebles and booming basses, the shape serving both balanced sound reproduction and ergonomics - aesthetics through functionality.

In electric guitars the shape doesn't matter when speaking about sound, a solid body has the same electric sound be it square or round or pointy. Thus it's more about ergonomics and aesthetics. Hardware and other decoration aside, the silhouette is what I'm after. Is there a "box" where you could drop your design? Some diagonals going through the entire instrument? Sorry, it's hard to explain...

[henrim]

1 hour ago, Bizman62 said:

Hardware and other decoration aside

I don’t think you can put them aside even when discussing the overall shape.

Anyway, the box we are in is horizontally close to golden ratio. Vertical dimensions are more symmetric (more or less mirrored) and are mostly determined by ergonomics. Those are the rudimentary dimensions. Now, how the curves are connected then either makes it or breaks it. Very slight differences can lead to a very different look and feel.

E.g. Stratocaster has a diagonal inside the box and it makes the design more dynamic compared to stationary Les Paul. Also Stratocaster shows a fine example what I mean with the connection with hardware and body shape. The angle of the bridge pickup follows the diagonal in the body making the body shape more aggressive than it would be with a straight pickup. Of course a strat can hardly be described as aggressive today but it was when it was designed about 500 years ago.