I recently purchased an older spa, and added a new controller/heater and it works great, but I'm not happy with the noise of the air blower and the way it injects cold air into the tub.
After a lot of research, I see that newer manufactures have dropped the idea of the blower altogether for these two reasons.
I like the way the blower churns up the water, so I'd like to keep using it if I can find a way to insulate it to make it both quiet and a bit warmer.
Was thinking about making a box around it with 2" rigid styrofoam, leave a few air holes in the top to let it breathe. I'm hoping that the heat the electric motor produces will warm the air in the box up a little.
Sound crazy? Has anybody else tried an upgrade or modification of this sort?
I'd love to hear your ideas and comments.

you won't gain any noticable heat from the blower's own motor. If the blower is located inside the spa cabinet already, it's going to draw in the heated air from inside the cabinet. To further heat the air, you would need to physically heat the air, either before or after the blower. If you insulate the blower in a box, you run the risk of starving your blower of the air it needs, and will actually create more noise... put your hand on the wand of a vacuum cleaner, it gets louder. Blowers are just a glorified vacuum cleaner motor, seriously.

So why don't you build a box big enough for the blower and a small space heater? You can put holes in the end of the box where the heater is, so that way air comes into the holes, get warmed up by the space heater and then goes into the blower.

Dan