Cyclone noise reduction

[Dick Sylvan]

There have been several threads recently that have been discussing ways to reduce noise from a cyclone DC. Several have suggested putting the entire DC or , at least, the filter unit in a "noise reduction closet" with various types of lining to muffle the noise. Where I am still confused is how to handle the return air going back to the shop. If there are vents large enough to handle this amount of air going back in to the shop, doesn't this large return result in the noise also going back to the shop. There is something that I am missing here. Thanks.

[Randy Denby]

Build the return air chamber similiar to an anechoic design,,,with baffles or offsets, so that the air can make its way back, but you cant see into the room. ALso helps if you use some kind of sound absorbing material in the baffles.

[Dick Sylvan]

Build the return air chamber similiar to an anechoic design,,,with baffles or offsets,

Maybe if you could answer me in ancient Swahili, I might be able to understand, so I guess the heart of my confusion is, "what the heck are baffles and offsets?" These are not terms that I find in general use, so I remain confused.

[Hank Knight]

Maybe if you could answer me in ancient Swahili, I might be able to understand ....

This might help: http://en.wikipedia.org/wiki/Anechoic_chamber

[Randy Denby]

Maybe if you could answer me in ancient Swahili, I might be able to understand, so I guess the heart of my confusion is, "what the heck are baffles and offsets?" These are not terms that I find in general use, so I remain confused.

Sorry Dick.....main thing is to allow the air back thru without going straight back thru the wall. For instance, cut an opening in the top of the inner wall and then an opening in the bottom of the outer wall....so that the air has to travel inside the wall for a bit. For best effect, line the inner wall with sound absorbing material.(such as acoustical tile or even foam rubber) Anything along this line will do the trick. Just so the air doesnt have a clear line of site back to your shop. If you can picture a car muffler, where the airflow makes several turns before exiting the tailpipe, this is kind of the same theory.

[Ken Fitzgerald]

Dick......If you look up Jim Becker in the membership list and check some of his posts form a couple of years ago....he found a remedy. He basically built a return air duct that when viewed from the side was "Z" shaped and lined it with a soft insulating material. I can tell you that I will be doing that later this fall. I hope to be ordering my Oneida DC and enclosing it in a closet in a few weeks. The "Z" shape prevents direct line of sight travel of noise and the insulating material helps absorb the sound that strikes it.

[Dick Sylvan]

OK, that makes sense, but does the insulating material impede the airflow, so that it increases the back pressure on the whole system?

[Eric Gustafson]

OK, that makes sense, but does the insulating material impede the airflow, so that it increases the back pressure on the whole system?

My guess in this is that insulation material will no doubt impede airflow as it restricts the available cross section of the return duct. Therefore it makes sense to enlarge the return duct from the noise damping closet. How large to make the duct is the question!

The duct feeding the cyclone will only have a cross section of 6" diameter or so. I would think almost any reasonable sized furnace duct would be sufficient to avoid adverse back pressure.

[Doug Shepard]

I got a 8x24x4 filter for the return
http://gallery.clearvuecyclones.com/...00/ClosetVent2
http://gallery.clearvuecyclones.com/.../ClosetFilter1
Most of the ambient noise coming off the DC isn't so much on the filter side as the motor end anyway, and the return is about as far from that in my closet as you can get so really trying to soundproof that return (at the risk of airflow) seemed like something with a minimal payoff anyway.

[Roland Chung]

These cyclones are just noisy. How much noise reduction you acheive will depend on how much work and money you want to put into the effort and/or how much performance you are willing to compromise.

I built a closet - two stud walls and drywall around an inside corner location. I installed a solid core door. I tried a hole in the bottom of one stud bay on the inside and another at the top of the same bay on the outside. I still got plenty of noise - but less than before.

There's even plenty of noise being transmitted through the wall that the cyclone is hanging on. The biggest noise reduction came when I installed a bunch of hooks and shelves and started storing hoses and cords on the two new walls. I think that the assortment of shapes sort of break up the sound waves, like primitive anechoic tiles. Oh yeah, you could line the inside of your closet with acoustic tiles.

Until I am ready to sink a lot more time into this science project, I am resigned to leaving the door slightly ajar when the cyclone is running. It's like a volume adjustment, the wider I leave the door, the louder it is. Wide open = best performance.

P.S. When considering anyone's suggestions, remember that there is a potential fire hazard with the cyclone. If you were to have a fire start inside of your closet, the cyclone could act as a 2 or 3 hp bellows pumping fire through your wall if you do the offset hole stuff.

[Eric Gustafson]

I got a 8x24x4 filter for the return
http://gallery.clearvuecyclones.com/...00/ClosetVent2
http://gallery.clearvuecyclones.com/.../ClosetFilter1
Most of the ambient noise coming off the DC isn't so much on the filter side as the motor end anyway, and the return is about as far from that in my closet as you can get so really trying to soundproof that return (at the risk of airflow) seemed like something with a minimal payoff anyway.

Nice install, Doug. I have my clearvue on order and will take delivery as soon as I have space! I plan on doing something just like your setup.

[Jim O'Dell]

Jim Becker used to have a nice tutorial on his web site on how he built his. It is best to make the air go in a double "u" shape. Or the air go out, turn and come back to you, then turn to go out again. This is how most mufflers on cars work. What you want is for the sound waves to bounce around and thus cancel themselves out. If you could do that without redirecting the air flow, it would still cancel the noise. If you had the bucks, you could go with an electronic noise cancelling system, and tune it to the offending frequencies. Jim.

[Bill Wyko]

I own a Mobile Electronics business and we sell various sound dampeners which will do anything from deadening noise to reflecting it and to absorbing it. You might check into a product called Road Kill. There's another called Dynamat but I haven't had much luck with there adhesive choice in our desert heat. Road Kill will stick to WD-40. You can get about 35 to 50 square foot boxes of these products as bulk packs. It may help many of you.

[Doug Shepard]

...If you had the bucks, you could go with an electronic noise cancelling system, and tune it to the offending frequencies. Jim.

If that's anything like running AC/DC on the stereo loud enough to hear it over the cyclone and TS running, I already have one of those

[Jim O'Dell]

If that's anything like running AC/DC on the stereo loud enough to hear it over the cyclone and TS running, I already have one of those

NO NO NO!!! I said noise cancelling devices! Jim.