This Generator Quiet Box has a SECRET!

This is no ordinary quiet box, specially built for a fairly large 7kW petrol generator. The inside features Helmholtz Absorber Panels to help reduce the noise and specific frequencies that the generator produces. The result is very effective at damping the noise, and I can stand right next to it and have a normal conversation with someone without shouting or even raising my voice even slightly.
I asked my neighbours if they could hear it, and they said they did not even know that I had a generator!
Writeup on the installation at the Cape Town International Airport: www.machoyrsa....
Parts used:
24mm/0.94" 316 Stainless Steel Thru Hull Exhaust Outlet - amzn.to/45DdU1a
24mm Inner Stainless Steel Exhaust Pipe with Clamps - amzn.to/3qh7eWj
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[@marksmith4539]

The best DIY Generator enclosure on You Tube. Great build. Thank you for sharing all of your research and the build process.

[@SoundBlab]

Glad you liked it! Thanks

[@brentmchenry9273]

This is one of the most creative and practical uses of acoustic research and development I have seen in a while! Great video and looking forward to the new content

[@SoundBlab]

Thanks man!

[@kreasenchetty]

Wow. Blown away by the sound engineering knowledge and technical specifications for an everyday problem. I had to look twice because this brilliant man is from my own country! So proud of you Man! ... and thank you!

[@ubacow7109]

I wish you did a measuments with a measurement mic to compare before and after to see what frequencies were tamed

[@superspeeder]

Awesome project! I was thinking of ways to keep generators quiet recently so the timing is perfect. I love the scientific approach you took!

[@SoundBlab]

Thanks

[@JakesMusicPalace]

Excellent video and use of ancient technology. I’m an audio engineer with 40 years experience in designing systems. The Helmholtz resonators were used in the grand gallery in the great pyramid of Egypt tuned to the resonant frequency of hydrogen. Chris Dunn, get his books they are fabulous, and some acoustic engineer friends of mine went there and did some extensive research on this subject. You could certainly target some of the major frequencies via phase cancellation. Using them to quiet generators is genius👍👍 thanks for sharing, nice work. Now about those calculations to determine the size and cavity dimensions of the resonators….

[@dougcorea6508]

What about the calculations? Please elaborate more I appreciate your detailed comment

[@woowooNeedsFaith]

WTF "resonant frequency of hydrogen" is supposed to mean?

[@akbychoice]

@@woowooNeedsFaithit’s above your pay grade.

[@Tiersmoke92555]

I'm loving your venting

[@Paunguliaq]

Thank you for your technical expertise. It's quite impressive. Thank you.

[@SoundBlab]

Many thanks!

[@jonfranklin9361]

This is super cool! I used to build speaker boxes for car stereos. Me and my buddy build some wild stuff.

[@danielfarrera2396]

@SoundBlab This video is great. It’s the first one I’ve seen that provides a detailed technical analysis on noise reduction. I’d love to see the final assembly and know if there are plans or a materials list to build something similar. A follow-up video on its performance over the years would be fantastic. I believe you could generate a lot of content on this project alone. Also it looks like you used independent panels, and I’d like to see how they are fastened, how to disassemble them for maintenance, and the overall mechanical aspects of the assembly. All aside thanks a lot for the video and the rest of your content. 😁

[@SoundBlab]

Thanks. Yes, I should do a follow-up. I have been aiming to draw up build plans, but time always seem to catch up to me...

[@DanielLopez-jv6zk]

⁠@@SoundBlabthank you! I’m glad you mentioned I will wait for the plants.

[@danielfarrera2396]

@@SoundBlab thanks a lot!

[@lapinfurax615]

Excellent ! I saw recently a lot of videos about this subject ! and it s the best off all ! Thanx a lot for this video

[@SoundBlab]

Thanks!

[@RayleneCawood]

Mooi man! :) There is plenty of info on using a Helmholtz and/or a quarter wave resonator in the exhaust itself. You also see them on the intake systems of various motorcars. As this is a fixed rpm engine; I look forward to part 2 where we can hear yoiu breathing next to the genset. Another idea: A French Drain is basically a anaerobic 'digester' that produces methane that could be piped to the intake very easily with a thin tube to help with fuel. Perhaps add a tethered weather balloon for gas storage. Not a necessity yet but we all know sewerage will follow power into obscurity here, just as it has in rest of africa.

[@djl8841]

Great work. Thus is the best quiet box I have ever seen.

[@mickwolf1077]

Your approach was great, measure the problem sound frequencies and suppress them accordingly. I'm going to work on one too but for a single cylinder diesel generator. It sounds like a distant helicopter and makes everything rattle. I was even thinking of using concrete too as it will be permanent for occasional battery charging in a residential area.

[@adca540]

This is by far the best video i have seen, however, do you supply a build breakdown (plus parts) for those of us who want to build one?

[@diegodm4844]

Buen vídeo, no me termina de quedar claro y el aire fluye a través de la lana de vidrio ? O los agujeros agujeros que conectan con el exterior atraviesan la lana de vidrio ? Hiciste alguna proba de temperatura dentro de la caja ? …..Saludos desde Argentina 🇦🇷

[@yogaforsuccess]

Thank you for sharing. Learnt something new today

[@diepieche]

Amazing. Thank you for giving some insights and enlightenment.

[@SoundBlab]

Glad it was helpful!

[@tristanschaper281]

Very well done!

[@SoundBlab]

Thank you very much!

[@jtmg11]

Alright you take the top spot in this niche category! (by far)

[@SoundBlab]

Thanks!

[@larryadams4358]

Very creative and outside-the-box thinking.

[@pmarreck]

Pun intended

[@AndinKansas]

That was amazing! Thank you

[@SoundBlab]

Glad you enjoyed it!

[@orical2832]

Great job! 👍

[@cyclonetcracer]

Can you provide some approximate dimensions? Impressive build. Thanks for sharing.

[@wazza33racer]

Thanks for sharing your experience! What was the before and after db?

[@spongebob1712]

Dig a shallow hole in the dirt and run the exhaust pointing down in it. The dense ground will absorb most of the noise.

[@jackd2083]

If you’re handy you can extend the exhaust into a container of water to quiet down the exhaust. Same as most inboard boats. If you enclose the generator, have the water container in a “chimney of sorts” that vents to the outside. In the winter you should replace the water with RV antifreeze or even windshield washer fluid.

[@adrianwilliams763]

Elegant solution

[@SoundBlab]

Thanks

[@markwilliford5319]

Dear South African Government: Please hire this man to run your electric grid.

[@PefleyD]

@SoundBlab You make reference to plans here and that is not right. It takes you to all your other speaker plans. Many have asked and would pay for plans of the gen quiet box. Please take the time to draw this up. Perhaps you have some Christmas time off and could draw the plans up then? I am about ready to fire up my new generator and the noise has me worried as I would like to keep my pals next door, pals and not become enemies! Thanks so much! LB

[@CarlosRamirez-col]

Great work man. Thanks for sharing. What is the name of the software you use? Do you have any plans?

[@sharkbite1686]

It looks like you only made panels on 3 sides for the resonators? Looks to me like the rear top is the 60hz, rear bottom is the 240hz, and at least one partial side is the 480hz (both sides?)? Are the front and tops just simple flat panels with damping? Really would have loved a slightly longer build montage showing more of the assembly. Really an epic box and I’m planning on making a smaller version for a portable generator

[@SoundBlab]

Thanks. Yes, that is more or less correct. I was hoping to do a more detailed video, but I needed this up and running, so unfortunately the video is rather quick and to the point.

[@sharkbite1686]

@@SoundBlab no worries I understand. Does the size or dimension ratios of the box matter? Not sure if room modes matter for this application.

[@Luis-Tesla]

Excelente canal!!

[@SoundBlab]

Thanks

[@maxjerin]

Will there be a need to combat mold and mildew?

[@SoundBlab]

I have not encountered this at all so far, so no need. Enough ventilation through the enclosure.

[@Aggielandtutoring]

Awsome video! I'm ready to start building mine, but I would love to "cheat" off your design. I think I can figure out the number and size of holes to match my generator's acoustics but "reinventing the wheel" is never fun. So if you had some rough measurements to provide that would be fantastic!

[@Aggielandtutoring]

I'm sure you know this, but you really could make some money by selling the plans with referral links to everything you are using to do this project (from the sound measurement app, to the hardware, and everything in between). The plans don't even need to be that detailed. You have a lot of subscribers and this video is starting to get some traction in the DIY market in the US. Really looking forward to hearing back from you and crossing my fingers that you will pass along some dimensions.

[@SoundBlab]

Thanks for the feedback, Very helpful! Hopefully I can get some time in the new year to put something together.

[@ibnuhajarulinnuha6288]

marvelous!

[@herewegoagain4041]

Could u tellme the size of the holes u cut out?

[@KariSteed]

Gosh I wish you had a detailed build plan. I would buy it so I could build my own

[@jamespineda5693]

I would, too. But if that's not possible, then a video tour of the box components and assembly. Nothing elaborate, just show each major component and discuss materials, basic measurements and assembly tips or challenges. Show component assemblies as they are being assembled into the working quiet box so we can see how everything works together with the generator in place: airflow, getting fuel to the generator, power out, lessons learned over time. Thanks again, Soundblab!!!

[@pmarreck]

You could probably make a business out of making these for various generators, because one of the biggest (ok THE biggest) argument raised against them is the noise problem. You could custom build them in parts and then ship them with assembly instructions. Great to see that doing a little homework (it's interesting that these have to be custom-built based on the specific frequencies you're trying to neutralize) paid off. I'm currently researching the tradeoffs of a 22kW generator as my power needs are a little higher...

[@Lastcallrepent]

Running hot 🔥

[@MD.ImNoScientician]

@SoundBlab Thanks for the video ! How did you mount your axles onto your generator?

[@TiredOfApathy]

Given the inside heat, I see a lot of people using materials to withstand 250 degree etc. Is that one fan enough to keep the generator's heat from creating a fire risk in the enclosure?

[@SoundBlab]

It's a year later and so far it has been working great. It does get hot inside, but that is to be expected. The one fan has enough CFM to get rid of the hot air though.

[@davidschipsi1316]

@@SoundBlabit is highly preferable to have duct directly to the engine cooling air intake, alternator, and carb. This way the equipment sees the coolest air possible instead of air that gets recirculated heated up in the cabinet. I understand you have the fan. Almost all home made boxes have heat problems. It would take some creative fabrication.

[@dhenn135]

Do you have plans available for the generator box?

[@SoundBlab]

Currently no, but if I get time next year I might consider it.

[@ddc2343d]

Growing up my dad would get so made at us if we used the pull cord on lawn mower like you are doing here. He'd always yell, make sure its has resistance before you pull or you are going to break it.

[@ckwicko]

You should have made the outer case out of HDPE aluminium sandwich panel, the stuff they make enclosed trailers and caravans out of. From experience in doing ultrasonic testing, nothing gobbles up sound frequencies like HDPE, it’s an excellent sound deadening material.

[@Shaddow-r3f]

Hi, what is the specification of the fan that you have been using? what its size? Is it pushing air out or pulling air in? [there are two types] What is the heat that it is build up in the chamber during hot wether? thanks for your response.

[@SoundBlab]

The fan is 10inches or 250mm in diameter, and it pulls air out of the enclosure at 1100 cubic metres per hour. The generator does get hot inside, but so far I have not had any problems with overheating and the temp stays constant. The box is mostly in the shade though, this helps. I have run it between 2 and 4 hours at a time, and it is still going strong.

[@Shaddow-r3f]

Very nice work you have inspired me@@SoundBlab

[@privateuser-xp4nz]

How will you protect the box from weather It will need a roof

[@SoundBlab]

All panel joins are sealed with weather strip. The box is made from weatherproof ply, and further sealed with a good quality roof paint. So far, it is holding up very good with no leaks.

[@1997LT1Camaro]

Most effective sound cancellation I have seen in these generator enclosures. What do you think the build cost you?

[@SoundBlab]

Thanks. Approximately US$500

[@pixelpearlproduction538]

Can u by any chance make and sell these ? I have the exact same generator and would love to have this quiet box

[@SoundBlab]

Won't have capacity to build. But I'm hoping to get some time to draw up build plans. Not sure how soon that will be though...

[@mrjackharbour]

@@SoundBlab Love to purchase them if you do.

[@MacStoker]

would q acoustics Gelcore® improve it? i know they utilise the helmholtz technology as well...

[@SoundBlab]

The Gelcore will work well to help dampen panels and prevent resonances.

[@adrianbennett9322]

Soundblab, where can one get that same "egg crate" foam from? I am battling to source it from car audio places, for car door quietening.

[@SoundBlab]

This foam is rather dense and heavy. Its not the typical cheap low density foam often found. I got mine locally, not sure where you can find it, but try a search online.

[@felixschneider8888]

Where did you buy the Fan? Could you post a link, Thanks

[@ericallen7200]

I had to fire up my 11kw generator 3 times in the last couple weeks... about 20 hours each time. I was unable to get a nights rest when it was running, and neighbors as far as 5 homes away were put in that situation thanks to me having AC during a power outtage. I'm trying to come up with something to make it quiet. I was thinking about another neighbor who bought a generac that was set up in a cabinet. NOPE. Not quieter than mine at all. So I'm really really interested in a quiet cabinet, but so far, it's all short video with no real proof on how quiet they are, or short videos that don't actually give you a full build list and show the cost.

[@russgenders7550]

brilliant

[@SoundBlab]

Thanks

[@cayrick]

Very well done! Too bad you did not take sound level readings. Wish I had a neighbor like you instead of the guy next door with an elevated open generator that faces directly towards my bedroom window.

[@SoundBlab]

Thanks. Sound level meter readings can be very misleading, and cannot tell you what it really sounds like, thus I don't like using them for this type of experiment.

[@gil6995]

@@SoundBlabexcept you can compare the frequency dampening effect before and after to see how much difference it made.

[@dragonlotion1789]

Please give us a general list of materials list needed. I’m a carpenter so I don’t need dimensions but I’m not too familiar with acoustics materials and sealants. I have a Generac and I’d rather sit without power than bother my neighbors with this god awful noise, so this would be very helpful, if you find time. Thanks

[@susansnow4894]

You won’t care after 2 days! Your neighbors need one too

[@jwm6314]

Now THIS is what I wanted to build. Not a plywood box with insulation slapped in. ...also a great warning against DEI lol.

[@fredasiong]

do you have a plan for sale?

[@SoundBlab]

Not yet, but hopefully i will get a chance soon to make plans available and do a follow-up video perhaps.

[@skanderchida9174]

Can you do a before and after video?

[@AlainBoisclaircoaching]

Really interesting. I've built a generator box already but i will be looking to improve it. What application do you use on your phone?

[@SoundBlab]

Thanks. The app is RTA Audio (iPhone).

[@-iIIiiiiiIiiiiIIIiiIi-]

Those walls are pretty low. 12 ft seems be a good height.

[@busterhyman6633]

I suspect this is going to get very hot inside. Gas flashpoint can be a low as 140 degrees good luck.

[@nyteification8801]

I'm very curious about this too. I'm looking to build a quiet box, but am very concerned about heat and how to properly dissipate it. Have you noticed any issues with heat? Do you have something built in to manage it?

[@elcouz]

Did you mean autoignition temperature?

[@JazerMartinez]

Most detailed explanation of dampening a generator by talking about frequency and research source of their approach.

[@SoundBlab]

Thanks

[@scott1063]

The acoustic foam was a waste of your money & time. 4” Rockwool would work much better and at lower frequencies. Otherwise, brilliant!

[@SoundBlab]

The acoustic foam is very heavy and dense, which helps to dampen the panels. Rock wool is an absorbent material, not heavy and dense enough for the purpose of dampening.

[@DonFarmer-hq5sw]

Why did you choose such a bloody loud generator to begin with. Surely a Honda would have been a far quieter choice.

[@SoundBlab]

This is not louder than a Honda, and a Honda is twice the price.

[@DonFarmer-hq5sw]

@@SoundBlab surely you jest ? 🌬️🌚🎪

[@MudflyWatersman]

Cheap loud generators are never good choice ....even for construction

[@dml2205]

the box cost more than the generator

[@TAGUPNBLUE]

Generator way too big 5,500 W is more than enough you need longer run times f o r fuel consumption