Replies to This Discussion

Permalink Reply by Ron "Oily" Sprague on November 9, 2011 at 7:14am

David,

I understand your desire to optimize, due to limited time and equipment.

I build my own boxes from 3/16" lauan plywood, top, back and sides. I strengthen them by an internal frame of 1/2" pine, with upright posts of same in the corners, and stretchers of same along the top and bottom sides all the way around. All are both glued and screwed together. I do this because good cigar boxes are hard to come by where I live.

I have found that thin walls attached to such a framework, which stiffens the plywood, creates amazingly light but resonant bodies. Also, my boxes are larger than standard, 12" x 10 1/4" x 3 1/2 - 3 3/4". This last measurement is nearly the same depth as a standard commercial acoustic. They sound really warm, with good sustain. This is somewhat similar, in a crude way, to how violins are constructed.

I have also seen thick walled boxes here at CBN. In one instance, the guy used 1/2" thick birch, then drilled a multitude of "tone holes" vertically into the sides of the box. He also used a pretty thin soundboard. He reported great tone and sustain from this box. Thin stiff-yet-flexible soundboards are virtually required for good acoustic tone, but aren't really necessary if adding any sort of magnetic pickup. There are examples here of boxes mades from thick wooden ammo cases, that are great electric CBGs.

The reason you get lots of "build it and see" hereabouts is because each box is different. Also, for most builders who are just cranking them out, it's cheap and quick to build 10 variations to test design ideas. I have been playing guitar for 35 years, and can assure you that no two guitars from the same assembly line, made from the same materials with the same specs, sound exactly the same. When expert craftsmen hand build instruments, they also know this to be true.

Another thing to consider, is how acoustic stringed instruments have been built over the centuries ( ouds, lutes, guitars, mandolins, violas, violins, cellos, etc.). In nearly every case, they have been built with the lightest, straightest grained tonewoods available. This is because, as you know as an engineer, all parts of the instrument resonate together, not just the soundboard, though this the bit where the greatest energy transfer from the strings occurs, followed by the neck.

Using birch is a great choice. The best amplifier cabinets are made from it, and some of the most affordable yet collectible guitars, Harmony / Stella / and variants, we're made almost entirely of birch.

Hope this helps you decide, when Craft Day rolls around again ;-)

Permalink Reply by Rand Moore on November 9, 2011 at 8:44pm

Hi David,

Your box made of thin wood should make for a nice sounding sound box, especially if you use something like 2mm plywood veneer for the soundboard. The various instrument I have built using cherry trim wood for the neck, headstock and the walls of the sound box, coupled with the the 2mm plywood veneer I use for the sound board and the back board have resulted in instruments that consistently sound richer with longer resonance as compared to the other cigar box based instruments that I have built. I feel that ruggedly constructed boxes are less likely to sound good without pickups, amplifiers and sound-effect boxes. Most of the rugged-ized box instruments I've seen had either piezo- or magnetic pickups (pups).

-Rand.