Because an acoustic bass guitar is an octave lower than a standard guitar, it only makes sense that it needs to be a different shape if it is going to perform well. The basses (4 & 5 string, fretless or fretted) that I build are about 18 inches wide in the lower bout and 5 inches deep at the end block; yes a large guitar, but not a large instrument considering its range.

To a considerable degree my instrument develops its volume by being constructed very lightly. I believe I am applying the knowledge obtained constructing fine flamenco guitars.... to another instrument. My basses have an adequate volume for the living room (even in the company of banjos), and on board electronics are optional for the stage. Also I've got a new version that came out early this year, and it is even louder than my previous basses. Sorry I don't have time to put up some pix of it right now. It is the same basic body shape but it is braced entirely differently and has a floating bridge and tailpiece like an arch top guitar....and it is MUCH louder!