simple vocalbooth construction

hallo to everybody in this great forum from a newbe... i need to build a bedroom vocalbooth to bring my recordings to a new level. this 2 drawings show my fist layout. the goal is to get a preferably dry sound in a small space. anny coment on this is welcome. my main question is if the inner construction with angled surfaces is the right way or dispensable. its not so important to make it soundproof. THX!

Should work OK; but I'd make that wall at the top of the drawing absorptive if you want a dry, non-phasey sound - even cardioid mics pick up from the rear if too close to a boundary... Steve