Noticed a few threads on the forum about reducing the whoosh noise, i have been thinking about giving this idea a bash!

Righty'o, from the output of the extraction fan (in my case the rvk 6") clamp a duct reducer and then connect 8" ducting instead of the usual 6"!

Surely that would reduce the air velocity and in theory should reduce noise.

What do you think?

increasing the duct bore will slow the air down yes.... got to be worth a go if you have a problem.... venting out through the filter eliminates the exhaust noise for me

Reducing velocity is the moat important factor. Foam fittings on the end of compressed air exhausts reduce noise significantly. I think the best thing for home made noise reducer would be to make a mesh section of the pipe diamiter u have, line it with foam and cap the end with foam. for a 6" duct make a 12" long section of mesh with a mesh end n line wit foam.

Hope that makes sense

peace
Johna

Bigger the better