Need help with silencer

Hey everyone, Im new here and hoping to get some help.

I built these up yesterday to silence a 80cfm fan. I built a CS(carbon scrubber) Style Silencer that is 4" x 2' for the exhaust. It uses a mattress topper as the liner. It really cuts back on the sound but it is not silent. It uses 6" as the outer tube, do you think using 8" and lining with more foam might reduce the sound more or do I need to go longer?


This is what I rigged up for the intake. It cuts back on the sound a lot but still not silent and Im kinda worried about the foam getting too hot since it will be next to several 42W cfl's. The foam says to not place on lit bulbs due to fire hazard. I think I want to make another CS Silencer for the intake as well to give it some more length, currently 14" of foam. I also covered the fan with foam but I think I need to wrap it again for more sound reduction.


Any ideas on how I could silence these further? Would quilt batting or pillow stuffing be able to withstand more heat than this foam and/or would it reduce the sound more than this foam? Do you think acoustic foam or roxul(rockwool?) might be better? I really dont want to use fiberglas due to the particles being blown around the room.

Hi!
Nice silencers,man!
I wouldn't worry about the foam catching file, you could put a digital thermostat(thous with in/out,and the out thermostat on the end of a wire)inside the silencer just to be safe.
Making them better,I'd say go longer,not thinker. Have you thought about sono-dec tubing?
http://hanfburg.de/store/product_info.php?cPath=7_29&products_id=354
And I would use something something softer as sound dampener,at least on the inner side.
Don't know what mattress topper is...
I wouldn't use rockwool, I've heard its not good to be breathing that shit.
There's some treads on silencers on the forum,try to search if you haven't read them jet.
Do have to say,I like the box idea your using on your intake,how simple !

soundboard my friend you cant hear shit through it
here you go
http://www.soundstop.co.uk/solutions/wall_solutions/wall_solution_1.php

samba said:

Hi!
Nice silencers,man!
I wouldn't worry about the foam catching file, you could put a digital thermostat(thous with in/out,and the out thermostat on the end of a wire)inside the silencer just to be safe.
Making them better,I'd say go longer,not thinker. Have you thought about sono-dec tubing?
http://hanfburg.de/store/product_info.php?cPath=7_29&products_id=354
And I would use something something softer as sound dampener,at least on the inner side.
Don't know what mattress topper is...
I wouldn't use rockwool, I've heard its not good to be breathing that shit.
There's some treads on silencers on the forum,try to search if you haven't read them jet.
Do have to say,I like the box idea your using on your intake,how simple !

Click to expand...

I plan to fire it all up soon and watch the temps all around but if I can find something thats more fire resistant and reduces the sound more, Im all for it.

I think the sono-dec tubing is like insulated flex ducting, if so, yes I tried that before. I used 10'+ and noticed very little reduction in the rushing air noise.

Mattress topper is just like memory foam that you put on top of a mattress to give a little more cushion. They sell them at target/walmart, etc...

I got the box/foam idea from another member on here and figured I'd try it out since my fan fit perfectly inside the box I had.

brainthor said:

soundboard my friend you cant hear shit through it
here you go
http://www.soundstop.co.uk/solutions/wall_solutions/wall_solution_1.php

Click to expand...

This stuff looks cool but is it flexible like foam? Im not sure where I could find this in the US either, I'd rather not order online. Anyone seen similar stuff at Home Depot or Walmart?

they use it to sound proof home theaters...no its not flexible

rock wool these days is alot better than in the past but would still use a mask if tearing it or cutting it to shape..

yep nice silencer i cheated bought an $100 can fan silencer, for silencing my fan and filter i used compressed rubber (fkn heavy) the stuff made from recycled car tyres used in kids play centres and then boxed in MDF followed by a thick wrapping of doona stuffing...

there are cheeper insulators green and blue stuff its called ones a heat and the other a sound insulator but R6 was the thickest i could find..

My silencer> fan> filter before wraped in thick doonas.


Ps insulated duct comes in varied amounts of sound proofing the stuff i used from a grow shop has very little insulation maby 2inch($60 3meter) but you can get with a thicker insulation for more $$ found at a good air con installer.

I went back out and got a 7" x 3' outer tube, skipped the interior hardware cloth and just cut a piece of foam to line the new tube. This works so much better than the 2'er and is very close to silent. I took a pic but my usb port if ****ed so I cant get it off my camera. My fan is still a little noisy so thats next to silence.

thc43 said:

for silencing my fan and filter i used compressed rubber (fkn heavy) the stuff made from recycled car tyres used in kids play centres and then boxed in MDF followed by a thick wrapping of doona stuffing...

there are cheeper insulators green and blue stuff its called ones a heat and the other a sound insulator but R6 was the thickest i could find..[/QUOTE=thc43]

Can you please explain this a little more? what is mdf, some type of foam I take it? whats doona? did this box really silence the fan noise?

Click to expand...

I ended up upgrading my fan to a Fantech 167cfm inline model due to strain on the smaller fan. The silencer I built (3' x 7" round) works pretty well with the fan running at 100% but I still need to quiet the sound considerably. I wish I had room for the 5' x 7" round but it is just too long so I picked up 3-10" adjustable elbows. I plan on taping them together then lining the tube it forms with the mattress topper, memory foam. I am hoping the increased diameter, should be about 8.5" for a 4" fan, will decrease the rushing air sound significantly. If it doesnt get the sound where it needs to be, I guess I can try putting 2 layers of the foam lining inside the tube but Im not sure if that will do much if anything. Has anyone tried that before?