"Know-nothing" probing questions

[abarson]

I played cello as a child, and have been playing electric bass for some time. Lately, I've started building my own instruments. The design I'd like to try most is an acoustic bass guitar that incorporates some characteristics of an upright. I'd like more volume than existing ABG's, but don't want to get into the upright's size and fingerboard scale.

At a recent music festival, an upright player allowed me to check out his instrument. First find: the sound post. Obviously, it's role is to help physically transmit frequencies to the back as a second "diaphragm". Does the size/mass/material/location of the sound post have any bearing on what gets transmitted to the back?

While playing open strings, I noticed frequency "hot spots" on both the back and front. Lower frequencies were more present on the back in the lower bout and higher frequencies were more pronounced on the front and upper bout. Higher frequencies seemed to produce multiple "hot spots", while lower frequencies were very broad. How much does the shape of the front and back contribute to the tone and volume? I've seen pictures of Savart style basses and wondered about how the shape influences both.

Is anyone familiar with attempts to make some kind of folded horn body design?

Laminate vs. solid wood. Are laminate backs and fronts typically thicker? How are laminates given their convex shape?

I appreciate any and all replies about this, and if this is all covered in different threads or on different websites, please let me know.

[Marcus Johnson]

Originally Posted by abarson

The design I'd like to try most is an acoustic bass guitar that incorporates some characteristics of an upright. I'd like more volume than existing ABG's, but don't want to get into the upright's size and fingerboard scale.

There are some great DB luthiers here that can address your other questions, I'm just a lowly jazz bassist. But your post reminded me of a UK luthier named Toby Chennell, who builds an instrument that comes close to what you're talking about. Maybe it's of interest to you.Toby also builds traditional double basses that look very nice. If it's of interest, go ahead and contact him. I did so a few years ago, and he's a really nice guy.http://members.aol.com/arcouk/arco_a...ass_guitar.htm

[drurb]

Originally Posted by abarson

Obviously, it's role is to help physically transmit frequencies to the back as a second "diaphragm".

Obviously? Well it's far more complicated than that. For example, the sound post creates a nodal point on the top plate. There are decades of research and publications available about all of this. Digging into them a bit would net you rewards far beyond trying to intuit the physics. Here's one of many places to start.

Folded horn design? Well that applies to loudspeakers that have compression drivers at a point. I don't think it applies very well in creating the desired characteristics of a stringed instrument.

[mattfong]

It's going to be hard to make an ABG that's louder than current ones, because lower frequencies need larger spaces to resonate in. What if you made an ABG with an arched top and back, along with a soundpost, etc? It would create more space in the body, and you could keep the actual size fairly normal for an ABG.

Oh and I'm pretty sure laminated wood is arched with a mold.

[shadygrove]

What if you made an ABG with an arched top and back, along with a soundpost, etc? It would create more space in the body, and you could keep the actual size fairly normal for an ABG.

What you've described sounds alot like the Takamine B-10 archtop ABG, although I think the B-10 body is constructed with no soundpost more like an archtop guitar than a UB. The B-10 is a 34" scale fretless and has an endpin so it can be played in the upright position.

[mattfong]

Oh actually I've seen that before. Maybe the OP should check it out?