And to Rhinowing, 9v's should last a long, long time in batt boxes. You may have a faulty box.
Unless you don't read directions and leave the mics plugged in when not in use. I know that's not the likely cause, but its always possible.
my box actually takes a 12V (energizer sells them branded as "M21/23", same kind ethat goes in a car remot). I dunno. Any way I can check out how well the box is working?
also, I very rarely use roll-off. Only if I can really see the bass peaking above everything else
I use the SPSB-10 box as well. I changed the battery once this year after probably doing over 100hrs of shows. Those batteries seem to last pretty well.
Funny that more people here don't use this box. Although finding those mini batteries is a bit of a pain, the design is fantastic - mostly plastic, but solid (i.e., lightweight, stealthable, portable) and a bit more secure than the Church BB where the battery remains exposed. I love this thing. Far superior to the larger SoundPros boxes too; obviously not as secure as the locking Coresound 3-wire box or other mini-XLR boxes, but I've never had a problem.