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! :rolleyes:

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/Dougs-Mini-CV1400/ClosetVent2
http://gallery.clearvuecyclones.com/Dougs-Mini-CV1400/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/Dougs-Mini-CV1400/ClosetVent2
http://gallery.clearvuecyclones.com/Dougs-Mini-CV1400/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. :D 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. :D 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:D

[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:D


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

[Susan McMillan]

Hi, Dick---I have a 5hp ClearVue cyclone that I put in a closet lined with acoustic insulation (from Acoustical Surfaces). The closet's air return is on the wall opposite the cyclone covered by a 3 ft high L-shaped box made of plywood, lined with more insulation. The opening of the L faces away from the cyclone toward another wall lined with insulation. Works fine. As others have noted, most of the noise doesn't come through the return in any case, but I have to say that there was a noticeable difference when I put that simple baffle in place. Now, I just have to finish putting Dynamat on the ducting----which is now noisier than the closet. Sigh. Hope that helps, Susan

[Eric Gustafson]

Hi, Dick---I have a 5hp ClearVue cyclone that I put in a closet lined with acoustic insulation (from Acoustical Surfaces). The closet's air return is on the wall opposite the cyclone covered by a 3 ft high L-shaped box made of plywood, lined with more insulation. The opening of the L faces away from the cyclone toward another wall lined with insulation. Works fine. As others have noted, most of the noise doesn't come through the return in any case, but I have to say that there was a noticeable difference when I put that simple baffle in place. Now, I just have to finish putting Dynamat on the ducting----which is now noisier than the closet. Sigh. Hope that helps, Susan

PICS! We want PICS!

I am doing a clearvue, too, Susan. If you can include pics of your install that would be great.

[Dick Sylvan]

What about this idea? Erect the cyclone in a corner; build a closet around it with insulation, sound boards, etc. on the inside. Then, vent the exhaust air out of the closet into 10-15 feet of flex HVAC duct into the attic and then back into the shop after several "snaky" turns.

[Dick Sylvan]

PICS! We want PICS!

I am doing a clearvue, too, Susan. If you can include pics of your install that would be great.

Yes, PICS would be great. While you were posting this I came up with this variation. Build a closet as Susan has outlined, but vent the exhaust air out into the attic into 10-15 ft of flex HVAC duct which is "snaked" around the attic and then returned into the workshop. Seems like the sound rattling around in the flex duct would result in, at least, some level reduction.

[glenn bradley]

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! :rolleyes:

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.

Right, as long as your exit path is more than adequate to allow the airflow through, the fact that the sides are soft should be of little impact. For example, if I know that an 8" square (this is an example, do not take 8" as a recommendation) tunnel 24" long will allow adequate airflow without adverse back-pressure and I baffle a 24" square tunnel with a 12" total travel path . . . I'm probably OK.

Beware the tendency to go sci-fi-freaky over your DC specs, you'll never start and every day you don't have it, you're breathing bad stuff. Do your research and if you like; determine the ideal setup. Now get as close as you can within reason. *** This is definitely, just my humble opinion *** ;-)

[Bill Wyko]

I just went to www.clearviewcyclones.com (http://www.clearviewcyclones.com) then went to testimonies, then gallery. They have some great pics of this system.

[Bill Wyko]

I just rembered another good sound absorbtion material. carpet jute. This is the geround up upholstery that is used to insulate automotive carpet. 40oz per sq ft runs around 6 bucks a yard and is 40 inches wide. What I have typically done with this is spray contact adhesive on it and the surface it will be going on. put down as many layers on as you want and you can leave it like that, or you can glue a layer of 1/4 mdf over it. It is a great material for this and will absorb vibration and sound very well. If you were to make a duct with a layer of wood outside, then a couple of layers in the middle of this stuff, then a layer of mdf in the center, you would cancel the noise and still maintain air flow to your room.

[Doug Shepard]

I forgot to mention FWIW that I took decibel measurements before and after the closet build that are on this thread
http://www.sawmillcreek.org/showthread.php?t=64272
I think you could do even better with some of the sound deadening insulation and the baffle setup on the return. But the unit is nowhere near the volume problem I thought it would be when first I first powered it up and took measurements without the closet, and no filters/ducting installed.

[Jim O'Dell]

What about this idea? Erect the cyclone in a corner; build a closet around it with insulation, sound boards, etc. on the inside. Then, vent the exhaust air out of the closet into 10-15 feet of flex HVAC duct into the attic and then back into the shop after several "snaky" turns.

Dick, I think that would be a great solution. Might want to use 2 runs of 10 or 12" to do it. Otherwise, you might get some back pressure, or noise from rushing air as it exits back into the shop. If you use the insulated flex, that should help cut down that much more noise, and keep from losing as much heated/cooled air if your shop is climate controlled. Also would help with condensation problems of cold air in a hot attic. Jim.

[Bruce Wrenn]

If your blower has a steel impellor, check and see if Onedia still sells a cast aluminum impellor that will fit your machine. I have a Cinncinatti Fan, 10" cast aluminum, 1 HP unit mounted on top of my homemade cyclone. A fifty tooth combo blade on the saw is louder than the cyclone. My cyclone is one of the Wood Magazine ones with seven of the 6" X 65" socks on it. It seems that the sharp corners on a steel impellor contribute to the noise.

[Eric Brenneman]

In a previous life I was an Insulator. We had to insulate for heat. cold and sometimes sound. When insulating for sound we used 1" sheet rubber and then lead or potmetal backed aluminum. Really knocked the sound down. We once had a project that we had to wear earplugs AND ear muffs. When we were done you could stand next to it and carry on a conversation with no hearing protection. None of this is inexpensive but talk to an industrial insulation contractor and they could price out the materials.

[John Browne]

Try having a diesel engine in your living room--this is basically what boats have. So get yourself some engine room insulation and screw it to the inside walls of your closet--it will kill the sound. You can also buy sound-deadening paint. Buy from most reasonable marine chandlers (which means probably not West Marine:D).