how to make a fan quieter?

the stealthy chest of drawers-turned-growbox is almost underway! growing is imminent i've been wiring CFLs and plugs, mounting a thermometer and setting up the exhaust this afternoon, and the wagons are about to roll. i'm so excited

however, on a test run just now, i discovered my fan is a bit loud... i have a pc fan as the grow cab is pretty small. (see here: http://www.pcworld.co.uk/gbuk/ak-183-l2b-120mm-amber-series-case-fan-00772801-pdt.html)
it could probably be disguised when my computer is on but otherwise might raise suspicions. hopefully the carbon filter will muffle it a bit? so i have two questions:

1) any suggestions on how to make a fan quieter?

2) does an exhaust have to be on all the time? could i put it on a timer? bearing in mind i'm using a false floor labryinth to harness the power of negative pressure and passive intake for my airflow, if i stopped the fan the air would all just leak out right? my false floor is pretty easily converted into an air and light tight floor, so if i just did this when i turned the fan off during certain hours?

any suggestions and advice would be greaaatly appreciated.

anyone? .___.

Thats a tough one, mate. I tried so hard to make my closet stealth, but there was still a faint hum. It wasn't too loud but you could still hear the fan. I guess you could try to put foam rubber around the exterior of the fan, like the kind they sell for air conditioners and doors. That might help, but there's nothing to mask the sound of moving air.

Hooking a 4 inch duct both ways on the fan will act as a muffler. If there are bends, it will cut the flow though.

they sell soundboard at lowes with the insulation. Also a slightly easier material to work with are thermal curtains from a dept store like penneys for 19 bucks. Blackout and soundproof they muffle well and I drape all over my tents.

Also insualted ducting. Ducting attached is a must for sound.

I have a similar closet under construction and am using a12v speed control combination -transformer from silenz fans to dial down the rpms to a minimum.

tea tree said:

they sell soundboard at lowes with the insulation. Also a slightly easier material to work with are thermal curtains from a dept store like penneys for 19 bucks. Blackout and soundproof they muffle well and I drape all over my tents.

Also insualted ducting. Ducting attached is a must for sound.

Click to expand...

You can use shrink tubing over the screws to tighten it up and muffle the sound the contact make.
With that you should use cardboard in any place that touches another surface.

And the good old WD40 to help noise from the motor itself.

carbon filter restrict air flow, they help reducing the noise of the air flow but they can cause the fan to put more energy and thus creating more noise.

that is a quiet fan. The mounting could be acting as a sound board - place something soft between the fan and what it is mounted too. A masking sound can help. A fan in the room so noise is attributed to it, back ground noise like a radio or a fountain.