booster fan noise

[avant gardener]

my room was getting a little warm, so i put a booster at the end of the line to help pull the air that the can fan at the front is pushing.
the damn thing is deafeningly noisy.

it's definitely not a function of the big fan pushing air into it.
the noise is awful whether the can fan is running or not.

1. is this normal for booster fans?
2. if not, what's the fix?

will trade my electrical know-how for your hvac expertise.

thanks.

 

[PuReKnOwLeDgE]

In my experience my booster fans were not loud.

 

[avant gardener]

did you just slide them into the duct or did you do something special to mount them?