duct muffler ...cheap, easy, & effective

  • Thread starter gudkarma
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having tried a fan speed control & getting poor results regarding noise at my fresh air intake, i came up with this solution on the fly.

as you can see the "duct muffler" is super simple yet, and i assure you having tested it completely, works bomb diggity.

in the pic, you can see the 4.25" fresh air intake at my roof peak with flexible duct going to the top corner of an 18 gallon tote.

what you dont see is another 4.25" collar at the bottom (opposite end from intake) of the tote & about 8' of flexible duct which continues the fresh air intake to my grow room.

you also dont see the 4" 200 cfm fan (which i'm in the process of upgrading to a 6") that does all the work.

nevertheless, we have a simple box (acting like a plenum) with an in & out.

no insulation. no padding. nothing inside.

i cut the necessary holes with a 4.25" hole saw, installed starter collars (found in duct work section of home store), and carefully foil taped both sides of each collar.

with some creative foil tape skills, one could easily make a filter rig on the inside of the tote & accessable via the lid to accept a furnace filter over the intake or exhaust collar.

this simple tote set up cuts down on the "wooshing" noise of air being pulled into my intake 100% .

you hear nothing (zero, zip, nada) at full bore fan speed on the outside of my garage.
Duct mufflr
Duct muffler cheap easy  effective 2


good stff man thanks.next time i have sound issues i will give this a shot before buying mufflers


Very nice work sir!

If you look at the intake of all modern cars you see something very similar. I just made a silencing device for my 45W "econo" air pump that I had hanging from the ceiling with a bungee, the pressure pulses were still vibrating the floor and probably going to disintigrate my air stones in a matter of days! It's basically the same thing you've made but much smaller, and I had to wrap the sides up in some cardboard and tape to stop the bottle from vibrating. It has really worked worders. 100%-0% exactly as you say.

I'm glad you posted this, I would like to shut up my fan a bit more. I'm going to put an accumulator/silencer on it's intake now!


if you have the space for a muffler set up like this, it works nicely.

i've been using it for three months... no issues only pure quiet.


dude easy way to replicate the PHRESH filter silencer. Line a duct tube with the egg crate stuff u use in a sound room or studio. line the walls and glue it in place. it will maintain 90 percent air flow with 90 percent sound reduction and it runs in line


I like that gudkarma.. thanks! I've used light dimmers on muffin fans in a cabinet I used to have, but I also doubled up on the fans when doing so.. ie: 2 fans at 1/2 speed in place of 1 fan at full speed. .. But in a cabinet, you don't have much real estate to play with. Something like this, in a smaller package, could still fit within a cabinet. :)



never did any math as it would relate to scale of my tupperware box/muffler.

i do believe you could scale up or down maintaining similar effectiveness.

try it & let us know!


gudkarma, What size (cfm) exhaust fan do you use?

.... I just made a silencing device for my 45W "econo" air pump...

Any chance you can post a pic or some more details? I'm about ready to pitch my air pump due to noise and vibration.


4" : 190 cfm

this muffler was built for the intake side... to stop the "whooshing" sound of air rushing/moving into the vent ...in route to the grow room.

on the intake i have a 6" @ 400 cfm (i was using the 190 in this spot).

no noise from either fan set up.

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