Adding The Sound of Silence to My Dust Collection System
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- čas přidán 3. 06. 2024
- I find out just what it takes to make my dust collector quieter one way or another.
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Hey Brad, acoustical engineer here. I have one plausible reason why that meter may show more noise with dampening on the metal parts.
That meter has "weighted" scales for measuring sound pressure levels. "A weighted, "B weighted and C weighted" scales change which frequencies are favored. These scales "weight" the frequency range for different applications. Some are for environmental noise outside; Others for industrial noise inside. Some are for music as measured from loudspeakers or a band.
Basically, the weighted scales change which frequencies and TYPE of sounds are more important. These weighted acoustical scales differentiate between impulse sounds ( jack-hammer, banging etc.) and continuous background noise.
Check which scale you used, or which scale is the default setting for that meter.
It MAY be that, by dampening some frequencies on metal parts, other frequencies in the ROOM were accentuated.
Also, 3dB is actually TWICE as loud in acoustical measurements, so that is a significant difference. Some people confuse acoustical measurements with electrical ( voltage ) measurements.
In audio equipment, 6vU (voltage Units) is twice as loud.
But in acoustical measurements, 3dB is twice as loud.
Those scales are different because electronic equipment has a much lower dynamic range than human hearing.
One other related cause for those mysterious readings: The microphone of most volume meters is OMNI- directional. So even though you used the same location for all measurements, dampening sound in one area ( metal parts ), that could cause the room to resonate at different modes, thereby tricking the mic into hearing those accentuated frequencies.
I know you enjoy problem solving and analytical thinking. That's one reason I really enjoy your videos.
So this is one of those rare occasions when I'll spout off in hopes of helping you.
Try changing the scale on your meter if that is possible, then take measurements again from the same location. Perhaps that will give different readings and solve this interesting puzzle.
Also, there are a number of "apps" for phones that do a decent job of measuring sound. Try comparing those with your meter.
I am keen to discover the cause, so I hope that helps!
Kind Regards! ~g
People like you is why I still stick around on CZcams. This is what it used to be. Strangers forming a community and helping each other.
Thank you!
So 6dB is twice as loud as 3dB, 9dB is twice as loud as 6, 4 times as loud as 3dB.
@@jeffcarr392 In acoustical measurements, every 3dB is twice as loud. It's a logarithmic scale because humans can hear over a tremendous dynamic range. From the threshold of audibility to maximum volume before pain would be a range of over 240 million times. That's why Decibels are logarithmic. It makes the numbers easier to parse and calculations easier.
Mathematically, we factor each 3dB by a power. I can't write scientific notation here in comments, but this link will provide you all the math clearly. It's basic high-school level stuff. www.dsprelated.com/freebooks/mdft/Logarithms_Decibels.html
@@user-sb3wh3dd4v does the dampening material changes only it's frequencies not noise level?
Great info. Can you give a recommendation for a sound meter, or do you think a smartphone app is (on average ) better?
When you installed the deadening you've changed properties of the thing that's vibrating to make noise.
It's probebly changed the frequency of resonance which reads as being louder.
After reading all these “expert” comments, I figured it out. I pressed the ‘mute’ button on my remote and all the noise went away. Sometimes it’s the most obvious that we overlook. You’re welcome! 😉 😂
In case it has not already been mentioned, put the meter close to the components of the system to see where the most noise is originating from. I suspect that most of the noise is coming from the motor/impeller. Building a panel around it but leaving room for air flow would probably give you the best results.
I too think this is the best case of action
That would of been my first step. If you ever listened to a shop vac it’s not the hose it’s the motor that creating 90% of the sound. For example if you were able to move the dust collector to the others side of the wall and plumbed the two pipes through it would be so quiet you would be wondering if it was on or off ok maybe not that good but pretty quiet.
Seriously awesome that you built your own dust collection system. Thanks for sharing your noise results Brad! 😀👍
I had a ClearVue system setup for years very similiar to your setup and had some pretty good succes at limiting the noise. One simple trick is to use a small flexible hose in between your fan's output and the rest of the exhaust, and on input as well. I ended up putting the whole cyclone in a cabinet of MDF with insulation stuffed in between - a ton of work and tricky but it made a huge difference. Lastly I took a different approach on the exhaust. First I used standard HVAC insulated flexible piping to connect to the filter housing (no need for stiff metal piping on the exhaust, it's exhaust not a vacuum) big, big difference there. Fast air moving through metal pipes is really loud especially at turns. Additionally I actually housed the filters in a box in the attic with a pass through back to the shop via more HVAC ducting to a return vent. All of these changes resulted in a nice low hum, could still have a normal conversation without raising your voice. The one big down side was the air ran through the attic which was hot, so that tended to heat the shop up pretty quick - I live in FL and that's a big downer. Additionally if I ever forgot to empty the main dust bin and overflowed the system I'd have to climb into the attic and clean out the fitler box. If I'd only spent a bit more on one of those monitoring systems I could have saved myself trouble there. I've since dismanteled the whole system as I'm doing a total refresh of the shop and in the meantime have gone back to push broom, shop vac, mask and ear muffs. Got to admit, the simple approach is so much cheaper and adaptable, I've been hesitant to reconstitue the whole system as I'm not longer sure if it is worth all of the hassle. Anyway, hope the info is useful to some.
I use the same unit with the top and bottom bags. I found that fan vibration enters via ducting and is amplified. I placed motor/fan unit on engine mounts and that caused less noice. Not total silence, but made things beter. Found that sound enters building were ever there is bracket mounted. Hope this helps. 👍
Oh and also spent alota time trying to balance fan, not easy🙈
It appears that the sound deadening panels did a better job in reduction of noise level. Just curious if you checked the CFM readings (at any given port) to see if those panels restricted the airflow in an appreciable way.
it's to do with acoustics vibration. you removed a lot of the resonance by adding the chrome damping material that was probably resonating at the same frequency as some of the noise from the system, stopping the vibration that stopped the harmonic that was very crudely cancelling some of the sound, hence the sound increased slightly.
Totally agree. The sound was resonating out all over before, and the sound deadening material kept it in and focused it.
Like playing the trumpet... you make a raspberry sound with just your lips, and it isn't that loud, but you put restrictions on where the sound can go (brass tubing) and you can deafen everyone!
I bet it would be quieter if you removed the sticky stuff and made a baffle out of the sheet in front of the cyclone.
Daftman!! I watched your videos years ago and was a huge fan... glad to see you are still kicking....
I would suggest dampening the vibration between your motor and the wall, floor mats between the surfaces maybe. I suspect a foam diffuser cap (cheap cooler) over the motor may help. Cheap moving blankets from Harbor Freight do a good job dampening sound when draped over doors and windows. Consider putting the box around the motor/impeller instead of the filter...
Should have had this discussion before beginning, but... "g" (below) is spot on. Picking a scale might be as easy as standing between the microphone and the source and just holding up a blanket to see which scale reflects that change most efficiently. This doesn't give any absolute benefit, but would illustrate the relative improvement better. Some other things you might consider: If you couple your damper to the source, it acts like a speaker cone - vibrating with the source. In order to deaden the vibration you'll need to separate the two - as you did on the filter, or significantly increase the mass of the damper, so that there is not energy enough in the noise/ vibration to affect it. In other words, wrap the device in lead and/or hang any (massless) damper an inch away. Lead may be more effective on the pipes near the dust collector body.
Also, measure much closer to the source. As "g" mentioned, the mics are omni-directional (you could use a something as simple as a toilet paper tube to change this somewhat); at distance you are measuring the resonance of the room rather than the noise at the source.
As I consider dust collection in my shop, I'm much interested; I hope you'll revisit this topic.
The Ridgid shop vacs line the inside of the blower housing with open cell foam. It makes a huge difference in sound levels. Dust collectors have a much lower frequency so it may not help much but it's cheap and easy to try.
Using a larger blower exit pipe lined with foam would help too.
the increase in sound that you experienced at the decibalometer (thats the sciencey name for that device) is a direct result of the sound deadening material that you applied to the system. you forgot to turn on the sound deadening material (the switch is located in the dinglehoffer relay junction box on the south side of each section) and once the material is turned on (dance a little jig near each piece) you should notice a definite difference in the decibalometer. If for some reason this does not solve the problem, dance the jig again and keep repeating that until the device is sufficiently turned on. I don't think I need to mention that all of this should be done in a new video so that your viewers can observe the sciencey parts of this procedure.
Lol
Your instinct to not restrict the air is appropriate. I would submit that you require a larger gap around the air filter otherwise you are back pressuring the system and limiting its suction. I also have SonoPan around the blower motor.
I'm an old car/home audio guy with about 30ish years playing lol... All metal parts including the impeller housing needs to be cover with an asphalt based or similar sound deadening material since the it is the source.
I use to use a roofing product back in the day called ice & water barrier. It's a little stiff but with a heat gun and J-roller it can be manipulated pretty easy.
After all metal is covered you should see a huge result. Then wrap the PVC & I bet you could get well under 70ish db mark.
my dust collector is mounted under a staircase in my garage. I mounted some moving blankets under the stairs and on the garage side of the staircase and the noise level in my shop is around 66 decibels with only the DC running.
Thanks Jim. This is so helpful. And all these short tip videos you're doing are invaluable. Thanks for the great work.
Who is Jim?
You probably want a baffle box around the dust collector motor/fan assembly, which I would think is where the most noise is coming from. Or replace the motor/fan. I don't hate Harbor Freight, but I also don't expect them to use good bearings.
The sound is not bearings it's the howling wind.
It sounds like your adhesive foam was concentrating/focusing the sound toward the "outlet", the filter. I'll have to consider what you've done here in the design of my shop filtration system... I like that you're recycling your conditioned air.
The sticky back sound deadener simply reduced the surface resonance of the parts wrapped by reflecting some of the energy back inwards - that focused the energy which simply made it's way to the outlet and entered your space there. That could be louder, or it could be simply increasing a resonant node where you have your meter placed. Surrounding the outlet and finding a reduction in SPL gives a clue that a significant amount of energy is coming from that exact location. Before you insulated that last bit it would have been interesting to place a piece of acoustically absorbent material behind your SPL meter, just to collapse some resonant reinforcement if that was in fact the reason the meter was reading high like that.
This is great info. I really appreciate the test. I have a similar setup and am wondering how to reduce the noise. I think maybe the panels around the fan/motor may be a good test also. My fan exhausts out the window so I feel comfortable saying that most of my noise is the fan & motor. There is also the chance that dust container under the cyclone could be an amplifier.
I think this is the right ‘next step’. Create a baffle around the motor and fan…AND…put some egg carton (or similar) on the flat surfaces behind the motor because the sound is projecting off those surfaces as well.
I have nothing to say really, but I appreciate your content, and wish to help with the yt-algorithms.
So, unfortunately the material added to the cyclone is a thermal insulator, not an acoustics related product. It appears to be some sort of open or closed cell foam with a super thin aluminum layer. To get some sort of reduction in structure borne noise, you would need a constrained layer damper. Most of these use a butyl formula with a much thicker aluminum constraining layer, but not all products are equal. In fact, in testing, the best performing product I’ve tested performs better than using 10 times as much as one of the most recommended budget products on Amazon.
very informative video, good stuff
My general understanding is that the resonance does not increase through the materials(pipes and cyclone) enough for dampening the outside to matter. If the sound absorption was eating the sound inside the enclosures would be more effective but that isn’t reasonable because dust collection. I don’t think any isolation related to the equipment matters and instead it isolating the air exits. Maybe a sound curtain around the air filter would net a few. Like what is marketed for home theaters. Or .. live with machines singing the song of production.
I had a good chuckle with this one. Very strange results in the beginning. That sound deadening material is neat stuff though, would be interesting to build a box for an air compressor and see how much it quiets that.
As I learned all my years in broadcasting and voice-overs, the more density you put between the source and your work environment, the more unwanted noise will be reduced. Building a thick concrete wall between your extraction system would be most impractical, but that goes in the direction that might give you an idea. There is a difference between soundproofing and acoustic treatment. Proofing required some degree of density. Jon Peters solved this by having his dust collection motor and cyclone in a separate room, also impractical for my shop and many others I suppose..
I'd imagine putting the panel material around the motor assembly would help some too. I might have to check that stuff out, seems like it'd help with my air compressor noise!
For sure it would I just didn't get to that / figured out a good way to do it.
Put some sounds proofing material around the motor and propeller/fan. I'd seriously expect most of the noise coming from there. You probably would need to leave significant air gaps so the motor doesn't overheat.
Hey Brad, I think if you had installed a shield around the motor as well as the canister you would notice an improvement. The main source of noise is the motor itself. Although the passage of air through the system creates some noise, it's the high frequency motor that would be the main concern. The panel in front of the canister helped because air under pressure is being forced through all the openings in the canister. That creates a higher frequency hiss.
Watch my follow up video to this for those results ;)
just to clarify, there was nothing wrong with the previous setup where the fine dust was exhausted outside. It worked well? And the only reason you brought it all inside was so that you didn't lose conditioned air from the shop? Let me know, thanks!
Yup
I wish we could get sonopan here in the states, Jeff at home renovision raves about the stuff
When I saw you wrapping the cyclone with tinfoil, I knew there was going to be a conspiracy!
Very, very interesting. I would have thought the noise level would have gone down with the silver insulation. Thanks for the very interesting video experiment. Keep up those great videos. Say, you don't sound Canadian, ya know!
By adding the silver deadening material you "moved" the vibration or resonance to a different spot, probably the impeller. Sound is vibration. Adding a baffle around the motor would be the first step(w/o restricted airflow of course).
I would think much like a fan most of the noise produced is from the volume of air moved rather than the machine itself. However reducing that for dust collection would be dumb. Building an enclosure for the blower motor/impeller and filter would reduce this noise. Yes air flow for cooling the motor as well as venting air from filter are needed. You can build the enclosure as a single unit, a large upper cabinet in that corner of the shop. Line it with sound deadening/reducing material. place vents like your HVAC system would use at both ends. This will allow for air exchange with the rest of the shop while greatly reducing sound.
That blew my mind that the Db went up with that insulation.
Pretty curious results indeed, dude! But thanks for the info! 😃
BTW, you should put some of the green material around the motor as well, since it should be the noisier of them all.
Anyway, stay safe there with your family! 🖖😊
Is there a reason you didn't fit any sound deadening around your vacuum motor. I know it needs to be cool, but.... and I can't help how you overcome that problem, sorry
Might be that the first material acts more as a sound reflector (better placed with silver side facing the source of the sound waves and not attached to sound source).
Without detailed measurements of what is going on we can only guess (but you did measure a significant increase, so something happened). I figure out how to predict equipment noise in my day job, so I'm going to guess that the treatment that you put on the structure added mass to the sheet metal and it didn't vibrate as much.The acoustic energy in the air didn't inject as much power into causing vibrations and you ended up with more acoustical power flowing out through the air and out the filter. So you funneled the acoustic energy down the pipe.
Vibration and acoustics are always interesting and often not intuitive.
Maybe you should have created a cage around the piping so the sound detoning can contain the noise within and vibrant with the piping.
Sound deadening is based on the frequency, the lower pitch the thicker the insulation need to be as it needs to stop the longer waves.
It's the motor that's making the noise. You need a muffler box over it with sound deadening inside the box
3 dB sound reduction is normally quite noticeable in a side by side comparison. You could probsbly just use a sound meter app on your phone instead of the dedicated meter. Try finding the noise source by moving the meter closer to the suspected noise source to isolate it. You might find that the blower/motor mounting to the wall is a source of noise and that isolating it or making it more stiff would make a difference.
Also, the more annoying noise is the air compressor in the shop! How about a video on that one?
Lol thanks. No my air compressor is a quiet modle I treated myself to last birthday.
I would expect that the motor makes the majority of the noise, create a sound insulated enclosure for it (maintain air flow to stop overheating).
Do you take fin
I first thought it would make more of a difference if you created a little box over the actual motor of the dust extractor, not the piping.
I wonder if covering the filter will reduce efficiency of dust collection.
It's not covered
Can't wait to see the "expert" comments on this one. I personally have no clue why it got louder (as I usually have no clue about anything ) Cheers!
dBA? I know you are Canadian but isn't there a nice, intuitive freedom unit for noise? 😛
I am a slave to the cheap device I regret.
Oh, I didn't know this guy was Canadian...now that explains everything!
That sticky back material you're using is not soundproofing material it is for minimizing resonance and vibrations.
You missed the most important parts: the motor and the impeller, That’s what generates most of your noise.
A lot of your noise I think is coming from your motor and fan rotor. If you did the same as you did around the filter it should quite it down even more
"How to improve your dust collection sound"... I think u should build a plywood box around the motor and impeller.
Don't have an answer on the first two tests, weird. What about the motor? Sound proofing box around it.
That's next lol
The problem is that you have added noise-absorbing material when what you need is noise-insulating material. It's a common mistake. If I had used multiple layers of gypsum board, I would have gotten a lot of noise reduction.
A 3/4 plywood is a better noise-insulation material than those noise-absorbing material that you added.
Maybe an obvious question but in practical applications what is the difference?
@@markevans2236 The noise-absorbing is used to reduce reverberation, noise-insulating is used to encapsulate the noise in a limited space. In a workshop the idea is that the noise doesn't fill all the workshop. If you build a cabinet around your dust collection system, you will find that the noise reduction is as big as how many layers you add to the walls of the cabinet. Drywall is a cheap and excellent noise-insulation material. With five layers of Drywall, you probably won't be able to hear the dust extraction system.
@@JosePedroEspinosa Have not measured it, but I have converted my Grizzly dust collector into a cyclone. I always wear hearing protection but I would like to have an overall quieter shop if I can manage it.
The sound is disturbing itself throughout the whole run. Now you have constanted it to the filter.
The word "anyway" is an adverb. Grammatical rules dictate that adverbs cannot be made plural. Therefore, "anyways" is incorrect. It's just ANYWAY without an S on the end.
Shhhhh
....Anyways....