Bert,
I am unaware of any modifications to the blower impeller (I agree that would be a potential hazard), but as you will find in John Samuel's post in this thread and on Bill Pentz' website, most of the noise emanates from the exhaust side of the blower. One modification that has proven effective is to add a small block of wood inside the blower exhaust mouth as shown in the attached picture (repportedly, this drops the sound output by 10 dB). A second method is to use a 10 foot length of 10" insulated HVAC duct (the type used for residential heating distribution from mains to registers) between the blower mouth and your filters or to the outside if you discharge directly outdoors.
Hope this helps.
I am unaware of any modifications to the blower impeller (I agree that would be a potential hazard), but as you will find in John Samuel's post in this thread and on Bill Pentz' website, most of the noise emanates from the exhaust side of the blower. One modification that has proven effective is to add a small block of wood inside the blower exhaust mouth as shown in the attached picture (repportedly, this drops the sound output by 10 dB). A second method is to use a 10 foot length of 10" insulated HVAC duct (the type used for residential heating distribution from mains to registers) between the blower mouth and your filters or to the outside if you discharge directly outdoors.
Hope this helps.