DIY extractor fan noise reduction

"Step one: cut a hole in the box ..." LOL

Hey guys, if you're like me - doing what u gotta do - growing in a tent in your bedroom/apt and you want to cut down that damn fan noise a bit, here's something you can try. Now I'm not gonna lie and tell you it's going to be silent or super-quiet even, but it does help. I'd say it cuts the noise level around 20-25% and costs only $30. I run a fan speed controller with a 4" extractor and this makes it easy to sleep next to. No complaints from wifey who supports my hobby.

Pretty self-explanatory. Captions beneath each photo.


Pick up a 4 sq ft kit of Extreme Dynamax at Best Buy for $30. One kit is enough for a standard 6" extractor fan. This is the same stuff car stereo installers use to soundproof cars and keep trunks from rattling.


Cover the entire surface area of the fan. It's pretty easy to figure this out for yourself. All you need is a box cutter.


Alternate view. Really mash it down good.


Parts needed: a box, roll of duct tape, box cutter, pen, screwdriver, hose clamp, length of flexible ducting.


Trace 2 holes on opposite sides of the box. Half a roll of duct tape worked perfectly for 4" ducting.


Cut a hole in the box (It's my dick in a box - LOL). Actually you probably need two holes.
Work one end of the ducting by hand thru the hole and connect the other end to the fan (input/sucking side).

Stuff sound-deadening material inside the box all around the fan. Shipping/packing foam/material works well. Don't forget to run the power cord out.

Now do the output end the same way & tape up the box nicely with duct tape.

I set the box on top of my tent, using the ceiling port, and connect to the scrubber inside the tent.

I cover the box and exhaust ducting (except the very end) with a blanket for further noise reduction.

+rep me if you like it!

All recommendations for improvement are gladly accepted.

The main drawback is if I decide to try to incorporate CO2, I will be venting out, as opposed to keeping the scrubber exhaust inside the tent.

high bro! good work, insulating the vent is always a good idea

if you want to go hardcore, insulate your tubing as well, and put a silencer on the exhaust end of the tubing, cause if you don't silence the tubing, the passing air will create a big amount of noise... but to be honest, even when all is insulated and silenced to the maximum, the normal air circulation fan will be louder than the intake vent lool

blessss

Looks interesting, but honestly, with most well-lubricated centrifugal fans (all bearings intact), most of the noise created comes from the vibrations of the air passing through the ductwork the fan is connected to.

yea

purple_man said:

high bro! good work, insulating the vent is always a good idea

if you want to go hardcore, insulate your tubing as well, and put a silencer on the exhaust end of the tubing, cause if you don't silence the tubing, the passing air will create a big amount of noise... but to be honest, even when all is insulated and silenced to the maximum, the normal air circulation fan will be louder than the intake vent lool
blessss

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Thx bro. Yeah, I'm at the point where the circulation fan noise is overtaking the noise from the extractor fan. Silencer on the exhaust? Sounds interesting ... but I'm not sure what you mean by "silencer". Got any links?

supaleeb said:

Looks interesting, but honestly, with most well-lubricated centrifugal fans (all bearings intact), most of the noise created comes from the vibrations of the air passing through the ductwork the fan is connected to.

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Not sure if there's anyway around it. To me, I can still hear the fan coming out of the ducting and some "wooosh" from the ducting itself, but I've kept the ducting length short (4-5') enough to where it seem balanced. Any suggestions on cutting down noise even more?

Using straight ductwork instead of flexible ductwork will help, and avoid as many bends/turns as possible. You can also get a commercial duct muffler..

Darth Fader said:

Thx bro. Yeah, I'm at the point where the circulation fan noise is overtaking the noise from the extractor fan. Silencer on the exhaust? Sounds interesting ... but I'm not sure what you mean by "silencer". Got any links?

Click to expand...

Check out the adjustable grill these can quiet down the air noise a bunch
http://www.continentalfan.com/docs/AXC-C_Hydro_Brochure_16387.pdf

nice, also instead of using expensive dynamat, peel and seal is foiled roll of roof sealant sold at lowes for a lot cheaper that can serve the same purpose

K+ but what about adding acoustic ducting instead of regular ducting it cuts the noise down by 50% easy as alot of the noise is comeing from air rushing through the ducting and not the actual fan itself
the fan does make noise aswell but and this will make a big differance i is a paranoid though and when i do this might wrap the box thingy where the lead comes out with a fibreglass fire blanket

roseta_stoned said:

K+ but what about adding acoustic ducting instead of regular ducting it cuts the noise down by 50% easy as alot of the noise is comeing from air rushing through the ducting and not the actual fan itself
the fan does make noise aswell but and this will make a big differance i is a paranoid though and when i do this might wrap the box thingy where the lead comes out with a fibreglass fire blanket

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Thx man! I didn't know about that - never heard of it. Had to to google it. Did you mean something like this: Phresh Carbonarie duct silencer or this: Insulated acoustical duct (only available in 6" diameter)?

Yeah, here's another one that I've heard good things about:

http://www.horticulturesource.com/c-a-p-custom-automated-products-duct-muffler-6--p5110/

15dB is likely only 15-25% of total sound output on most systems, but every little bit can help.

supaleeb said:

Yeah, here's another one that I've heard good things about:

http://www.horticulturesource.com/c-a-p-custom-automated-products-duct-muffler-6--p5110/

15dB is likely only 15-25% of total sound output on most systems, but every little bit can help.

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15db is a very large reduction of noise. Every 3db of reduction is cutting noise by one half

Eeep, my bad. Didn't know dB was a logarithmic unit.