So I did a search on this, and didn't find much. There is a post about it in the "Newbie Links" Sticky, but it doesn't say a whole lot. I deeply value and encourage people to share their personal experiences, and I am also hoping that some of our luthier friends here will chime in with some knowledge from the bench. What I do know about construction: Roundbacks are more expensive to make. You need significantly more wood to allow for the arching, and you need significantly more time to carve the wood to create that arch. Flatbacks come from the Viol family. In a lot of ways, the double bass is much more a member of the viol family than the violin family. Violin shaped outlines and corners are fairly common, but from what I know (very little) about bass construction, they are structurally closer to big viols than big violins. What I would like to know about construction: What are the pros and cons of both construction methods? Are flatbacks really more prone to cracks than roundbacks What do people do from a construction point of view to reduce that risk? Although the back is one of many choices you make when making a bass, other than customer requests, what makes you pick one construction method over another? Does one result in significantly different characteristics than the other? What I know as a player: Each individual bass is different. This comes up when anything related to construction is mentioned, and is extremely valid. How a bass feels and sounds is dependant on a lot of factors, the back just being one of them. Some players have preferences. Some love roundbacks, some love flatbacks. Some really don't have a particular allegiance and just look for "the best" bass when shopping. Some feel that flatbacks are more comfortable to play, etc. What I'd like to know: If everything else was the same, (let's say you took the back off of a flatback and put a roundback on it) what would the differences be? Why do you prefer one over the other? Do flatbacks really "project" more/further? Do roundbacks really have a "fuller/rounder" sound? What characteristics can (even partially) be attributed to the differences in back construction? I know there are a lot of questions here. There are probably a lot more I am forgetting to ask as well. Although I am not currently in the market for a new instrument, I am considering commissioning a modern instrument for my next instrument, and this is one of the many choices I will eventually have to make. Thoughts?