Any "sound guys" or gals here?

[HMH]

Good afternoon all,

Long story short - I was recently burned on a DC deal wherein I sold off my "decent" DC in favor of an upgraded unit, that was subsequently removed for sale after I sold mine - it happens. That said, given the market and relative scarcity of used equipment right now, I've decided to just bite the bullet and step up to a dedicated cyclone. Not to steer this thread down that path, as I know it can get polarizing, but as a general question, one of my primary concerns is "noise". Not that any of these things are quiet, but a 5HP DC is a good sized step-up from a 2HP for sure.

I understand that the best possible solution would be to build a closet - and eventually I will, (in a future free-standing shop, that'll happen sometime down the road, once my kids are grown and my businesses slow down, but no plans in the immediate future), though in the meantime, I'm building out a dedicated bay of our oversized garage.

That said, I've got my layout and duct runs sorted out, and that will put the DC right in a corner, (the farthest corner from the common walls of the house), w/ the filter stack rotated such that it is right in front of a (extra tall) garage roll-up-door). For the particular model I'm somewhat set on, a free-standing stand isn't an option, and I will be connecting directly to the wall.

I'm not an audiophile by any means, but I do understand that to get the best output from say a home audio subwoofer, would be to place it in the corner, though in this case, I'm looking to DOWNPLAY the increase in output here.

That said, my thoughts on a possible "help" to the sound reverberation in the corner would be to frame out some acoustic panels, immediately behind the DC. For those that know about this sort of thing - would that do anything at all, or just a waste of time?

Obviously, I wouldn't be expecting miracles here, as all DC's are loud, but if I can eek out a few Db's, for the minimal cost and time involved, I'd consider that a win.

Thanks!

HMH

 

[tvrgeek]

The frequency a panel absorbs is directly related to it's thickness. For low frequencies, this can mean FEET, not inches.
Yea, my ClearView makes some noise. You are welcome to come hear it. I have it in a corner in another room. Putting it in a cabinet you need to remember airflow. Sound is moving air. Kind of a catch-22.

So, what to do? Well, some analysis of where the majority of the noise comes from and knowing what frequencies may help to design a solution. Just enclosing the cyclone for instance, leaving the canisters out may help quite a bit. I expect long radius elbows make less noise than short.

And FWIW, the 5 HP Clearview REALLY sucks. I am very impressed.

 

[Pop Golden]

Having designed and built 3 TV studios and 1 audio studio I have a little experience on this subject. My audio area had 2 straight walls and 2 undulating walls Because the City of Charlotte was footing I could have what I wanted. All my walls except the glass for the control to see what was going on in there were covered with 3 in. Sonex. The room didn't touch the building. Sonex is expensive, but works very well. Back in the day I was taking classes in audio engineering the cost of good audio recorders dropped. Now every musician wanted his own studio. When they wanted audio absorbing panels they got a good dose of sticker shock. What they came up with was the egg trays that restaurants got their large quantities of eggs in. These things are 18 in. or so square, and their free. They are a fire hazard. They're other options plain old Styrofoam will work. put it on all walls. Last but not least get on Goggle and see what's out there. New products are popping up all the time. It's been many years ago when I was in this business. Now there may be a low cost version of acoustic foam.

Pop

 

[Rushton]

Heath, two things you can do without resorting to a closet:

1. Place a muffler between the cyclone output and the filter stack. A lot of the noise comes right at the output from the impeller. Look at the Australian Woodwork Forum for designs. A common solution is a wire mesh cylinder with rockwool or fiberglass wrap, 6'-8' long.
   
   
2. Place some 3" or greater Owens Corning 703 rigid fiberglass panels on the walls near the cyclone for sound absorption. Thicker will get the midrange frequencies. Nothing reasonable will get the low frequencies. (For that you need mass and distance.) The Owens Corning 703 has pretty good sound absorption and transmission reduction figures.

 

[McRabbet]

Heath,

It sounds (no pun intended) that you are in a garage. One method of reducing sound transmission is to mount your DC on a floor mounted stand/frame rather than mounting it on a wall of the structure. I poured a separate concrete pad (in the crawl space below my shop which is nearly 9' high) and built a standalone 2x4/2/6 frame to mount my ClearVue CV1800 onto rather than mounting the cyclone on an adjacent concrete block wall. By doing so, any low frequency vibration is isolated from the house itself. If you must mount on a wall, use vibration isolators. Later, you can add insulation inside the frame, add a door and then add cladding to the outside to make it a closet.

 

[Oka]

Sound pressure waves transmit through material at different rates. Without all the science and techie jargon, the easiest way to isolate sound is to isolate the machine. If you have. There are many things you can use, as Golden pop referred to Sonex foam is one. There is a similar foam used in packing that is almost as good and 20% the cost. If you want to reduce lower frequencies you can use bithuthene (Dynomat). I would use that under the platform the unit is resting on. Have that stand isolated on rubber standoffs. Then box out the entire unit with plywood/sheetrock add the foam on that for the inside lining. This will provide a simple cheap sound deadening system for the Dust collection. If you want to isolate sound passing through the pipe, there is a HVAC piece that is a sound dampening fitting. We use them in consulting rooms in the hospitals. Finally, if you want to really go more OCD, there is a vinyl flooring that absorbs sound. They use it in Hospital hallways. Cool stuff works great..... NOT CHEAP. Another way to really cut through wall sound is to build another wall against the wall you want to prevent sound passing through. THE trick with this is to use J Channel and the Fiber board and sheetrock are attached to that . This way the fasteners will not transfer the sound through the wall. This is one way we do it in hotels. The other way is just building 2 walls against each other that do not touch.

You really can get into the weeds on this, but common sense is the key. Not rocket science.

 

[chris_goris]

Iv got mine in the next room over, 2x4 wall with R13 insulation. wall is covered with OSB both sides and I can barely hear it running. Mine is floor standing.

 

[Pop Golden]

The true name for acoustic foam is finger foam. That means that there are peaks and valleys across the sound absorbing face. I forgot about the foam used in packing. It is very close to the Sonex design, and seems to work just as well.

Pop

 

[HMH]

Thanks guys - lots of good info here, and great food for thought! I do quite a bit of sound isolation in hotels, etc via my role as a commercial structural engineer/ GC, but in this case, am just shooting for the simple approach before I set the unit. I am going w/ the clearvue cv1800, as it specs out great, but a 5HP “air mover” is certainly going to be loud - no way around it, and not necessarily a deal breaker by any means. That said, the CV is absolute overkill for my current setup, but my intentions here is just to go big now, and not worry about outgrowing it if/when I build a standalone shop down the road, at which point, I’ll certainly be building a MECH closet on the exterior to keep it isolated. Great tips in the meantime - thanks!

 

[tvrgeek]

The true name for acoustic foam is finger foam. That means that there are peaks and valleys across the sound absorbing face. I forgot about the foam used in packing. It is very close to the Sonex design, and seems to work just as well.

Pop

Actually the fingers are just to reduce the cost of the foam. It is the depth of the foam that matters for transmission. Texture only a little for reflection.
You need 11 feet of foam to absorb 100 Hz. Just physics. Foam works for high frequencies much better. Above 1000 for instance can easily be helped by 2 inches of foam, fiberglass, ( I am a big fan of Owens Corning compressed fiberglass boards, 409 etc). It works best when a small air gap behind it effectively doubling it's depth. You can cover it with cloth to keep it from gathering dust and to keep any FG from the air. It was the primary material I used for sound CONTROL panels I have built.

You can absorb by converting sound into heat, reflect and the energy heads elsewhere, and you can block. That's all.

Adding a muffler will greatly reduce the air flow. Some units even have them, but kind of defeats the function. Mufflers work by adding restriction to the flow. Some units ( Laguna) for instance, have partial enclosures that may help some.

Dynamat and the like does not absorb or block sound. It adds mass. This causes thin flexible panels to resonate at lower frequencies. It is the panel vibrating that is absorbing the sound. Using it to reduce in-contact transmission is slightly effective as sound does not like crossing barriers.

What is not done, and really should be, is to have notches in the fan blades that break up the frequencies by distributing the trailing edge vortices. A lot of the muffin fans we used in office equipment had these. You can't DIY it unfortunately.

Many materials like foam will build up dust. Not what you want in a woodshop. Most are highly inflammable. Again, not what you want in a woodshop.

Notice Pop mentioned the control room did not touch the building. In other words he BLOCKED the sound.

My CV1800 hangs on the wall, but the motor plate is suspended on rubber isolators as provided in their kit. You can come and hear if you think it is transmitting vibration to the wall or if the predominant noise is from airflow and motor directly. As far as a closet, you have to have all that air return to the room, which means it can't be completely isolated. A fair bit of noise comes from the ductwork. You can block by reflection with just a bit of sheet-rock so you are not in direct line. FWIW, I think it is quieter than the Jet 1100 it replaced.

 

[tvrgeek]

Now if you want to get exotic. If you have just a couple of frequencies that are predominant, you can build Helmholtz resonators tuned to those frequencies.

 

[Pop Golden]

actually the fingers are just to reduce the cost of the foam. It is the depth of the foam that matters for transmission. Texture only a little for reflection.

No Scott. The irregular surface enhances the absorbing effects. It is not there to lower the cost. I base my experience on the design and construction of the City of Charlotte's million dollar facility. I was assisted by a acoustic engineering company hired by the architects, and my staff audio/video engineer. This included tuning the room. We had a removable carpet on the floor witch was wood to control some frequencies.

Pop

 

[Rushton]

Heath, I mentioned using a straight muffler between the impeller and the filter stack to reduce noise levels. This is what BobL at Australian Woodworker Forum suggests (he's the dust collection guru there). Note that he says the fingers can be much shorter/stubbier than shown, as little as about 2":

https://www.woodworkforums.com/f200/baffle-box-muffler-dc-enclosures-193797

Another variation is simply a tube of chicken wire wrapped in insulation and some sort of outer sleeve, like this (dashed lines represent chicken wire tube):

And a picture looking down the interior of the straight tube:

I plan to use a variation on the first design for the exhaust from our sound insulating closet, but no reason not to use it as a muffler between impeller and filters, as BobL describes in his post.

 

[tvrgeek]

We wil lhave

actually the fingers are just to reduce the cost of the foam. It is the depth of the foam that matters for transmission. Texture only a little for reflection.

No Scott. The irregular surface enhances the absorbing effects. It is not there to lower the cost. I base my experience on the design and construction of the City of Charlotte's million dollar facility. I was assisted by a acoustic engineering company hired by the architects, and my staff audio/video engineer. This included tuning the room. We had a removable carpet on the floor witch was wood to control some frequencies.

Pop

We will have to disagree. I know what the sales brochures says, and I understand the physics.

 

[tvrgeek]

Heath, I mentioned using a straight muffler between the impeller and the filter stack to reduce noise levels. This is what BobL at Australian Woodworker Forum suggests (he's the dust collection guru there). Note that he says the fingers can be much shorter/stubbier than shown, as little as about 2":

View attachment 201924

https://www.woodworkforums.com/f200/baffle-box-muffler-dc-enclosures-193797

Another variation is simply a tube of chicken wire wrapped in insulation and some sort of outer sleeve, like this (dashed lines represent chicken wire tube):

View attachment 201925

And a picture looking down the interior of the straight tube:

View attachment 201926

I plan to use a variation on the first design for the exhaust from our sound insulating closet, but no reason not to use it as a muffler between impeller and filters, as BobL describes in his post.

Reason is restriction. Yes even what looks like a strait shot turns out to cause quite a drop. This has been well documented from the original works by Smith and Morrison. Now, do you have enough to handle those losses and still perform as the system intends? Only testing will tell. Physics, not wishful thinking.

Second reason is that airflow is full of dust, so it will load up the muffler with dust.

 

[Rushton]

Scott, those are not reasons not to use a muffler. They are simply considerations for implementing the design. Clearly, you have to increase the area of the exhaust from 2x to 4x the area of the intake to account for the restriction caused by friction, etc. The point is that the muffler is reported by the Aussies to be effective for noise control and it is a reasonable addition for Heath's needs without a closet. And the exhaust airflow from a CV1800, which he plans to use, is relatively very clean.

 

[tvrgeek]

Scott, those are not reasons not to use a muffler. They are simply considerations for implementing the design. Clearly, you have to increase the area of the exhaust from 2x to 4x the area of the intake to account for the restriction caused by friction, etc. The point is that the muffler is reported by the Aussies to be effective for noise control and it is a reasonable addition for Heath's needs without a closet. And the exhaust airflow from a CV1800, which he plans to use, is relatively very clean.

Again, we will just disagree. Yes it is "relatively" clean. I know, I have one, but not that clean and what does get through the cyclone is very small, exactly what will load up any batting used in the muffler. Actually the function of absorbing the sound means the dust will be driven deep into the batting. If it was as clean as you suggest, we would not need the filter cans.

There other muffler designs that may be less susceptible to dust build up. But, by the very physics of why any muffler works, it must restrict the air flow. For a DC, airflow is everything.

There are other sources of the sound radiated. It may be better engineering to look at how to block, redirect, absorb other sources. A large portion of the sound is generated by the vortices at the blade edges. How much of that is radiated though the housing might be worth investigating. Ever tiny edge, transition turn in the ductwork, in and out, causes disruptions that generate noise. I think PVC ducting will be quieter than metal.

 

[Fingerpicker]

There is clearly a lot of good information here. I al also quite pleased that many of you have ClearVue cyclone systems. As you chose these, I assume that you are familiar with Bill Pentz and his website. The ClearVue systems are based on his design criteria.

Pretty much everyone who installs a cyclone system in a residence has concerns about noise and as a result, there are a lot of suggestions and lessons learned available about this topic. I highly recommend that you check out the ClearVue Cyclones forum as there are quite a few very helpful discussions, photos and actual test results of different installation strategies that different owners have posted over the years.

I located my system in a new closet I built and insulated with rock wool in the walls and two layers of 6" cotton batt insulation in the ceiling. walls and ceiling are sheet rocked. I did allow a 1 1/2" gap under the door to provide some air flow and even during extended run times while using the surface planer, the temperature in the closet only increases by about 10 degrees.

Heath is right though, a 5hp cyclone is not quiet but man it does really make a difference compared to 1 1/2 or 2 hp systems. As others have said, this system sucks!