I have made a blower ( and cyclone) using Bill Pentz design and using a Clearvue impeller. made entirely from thick mild steel sheet. using a 3 phase motor. 50 hz. (not looking at using a speed drive at the moment- just straight on 3 phase eg: approx 2880 rpm) the impeller is sized right. according to Bill Pentz.

I would like to know if anyone has had any experience with reducing the blower noise by adding another 'gore point' inside the blower casing OR altering the outlet or inlet etc?
I would very much appreciate any info, before I start testing. I would like to reduce the blower noise as much as reasonably possible.