Digital pianos are soulless and plastic, real pianos are too heavy (and I don't love them). While I love harpsichords, my wife hates them. So I want to build something like this: https://www.youtube.com/watch?v=k2FGcggM4Ro
That sounds fantastic, like a cross between a harpsichord and a classical guitar or lute. I also have no need for it to be any louder than a classical guitar.
I have the basics of woodworking down (and I intend to make money building things), and the design looks fairly simple.
There are some fundamental things about acoustic instruments I don't fully understand though, so perhaps someone could explain some things or point me towards some reading?
Are the curves of guitars and lutes and such there for ergonomics? Or do they improve the sound, compared to a rectangle-shaped soundboard? Is there a reason for two bouts on many string instruments besides ergonomics? Is a bigger soundboard generally going to be better, and is there a limit to this?
Why is the bridge slanted on the instrument I linked to? Why is it curved on some others? How do you predict a good bridge location?
How do you predict a good soundhole location?
I've heard that the sides and back of guitars don't contribute much or even interfere with the sound. Would it be a good idea then to have a thick, rigid box with a light flexible soundboard glued on top?
Is it better to have the boards on the soundboard be long, or greater number of shorter boards? The pictures in the video seem to show it done the second way, which sounds wrong to me since it would result in more expansion and more glue.
There's also wood choice. I'd be very happy if I could use inexpensive lumber local to the Arkansas. Certainly I won't be satisfied until I try.
It makes sense that the soundboard should be as light as possible. On the other hand, I have a mahogany steel string guitar that sounds wonderful. And while mahogany can apparently refer to a number of different types of wood, none of them appear to be that light. And it's not that much stronger than say, spruce. I imagine that flexiblity might be a factor, but I'm not sure. Spruce is apparently also unremarkable in that regard. I can imagine board width to be important since glue is stiff, so maybe I should just go with something available in large widths?
Eastern red cedar is both extremely light and flexible, so it's tempting in that regard. Hardwoods tend to look better, so I'm tempted to try something like cherry or soft maple, which on paper sound very similar to mahogany.
Lastly, is there any recommendation for strings? I'm thinking of just doing classical guitar strings. That would limit the length of the lowest strings, but I'm not sure that matters since guitars seem to do just fine with that. Or maybe that would end up with too much tension on the soundboard?
Edit: Another obvious choice for strings occurred to me: nylon harp strings.