I have noticed that sandwich-type bodies are becoming more popular on basses (and guitars), with a popular tone-wood for the middle of the bass, and then a figured hardwood top and back. It seems more obvious how a hardwood top would affect the tone of an instrument since the top is right under the strings. What I am wondering is...
On a solid-body electric bass, does a hardwood back make much of a tonal difference, or is this done more for cosmetic reasons?

Thanks in advance for any insightful replies :) .

On solid instruments, the back wood will play just as much a role in the resonance of the body as the top.

This, of course, is different on hollow bodied instruments.

I would think it has more of a role on a hollowbody. Some classical/acoustic luthiers use "tone" wood (spruce,cedar,etc.) on the top and back. They claim it helps out quite a bit.

Darrin

I hadn't heard about acoustic builders using spruce on the back of an instrument. I'll have to pick the brains of the classical/acoustic builders next door for their opinion. These guys are pretty traditional, so I may be asking for trouble.....

It is used on Kasha/Schneider designed guitars.