Generator Soundproofing boxes: '04 Project

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Kinetic II

Generator Soundproofing boxes: '04 Project

Postby Kinetic II » Sun Nov 30, 2003 11:39 pm

Help! I am looking for a soundproofing box that would muffle the roar of a portable generator for BM 04. The small Coleman Powermate I used this last year was way too loud and a royal pain in the arse to deal with. Anyway I saw several power boxes as I call them that you could sit a genny inside and close up. They used PC case fans to ventilate the case yet they did a very good job of muffling the sound. My problem is after 3 months now of scouring the net and looking all over the place I can't find any plans, hell even pictures of the boxes. I regret not taking pics of them...hell one guy had one on his art car!

Would anyone have plans for such a box or could tell me if they built one and how they did it? If I can build a box I'll bring the powermate back for 04, otherwise it's off to Southwest Fastener Supply in Reno for a Yamaha Generator/Inverter combo.

I also want the box for when I take my camper out for trout fishing weekends and spiritual retreats in the Ozarks. It's kind of hard to perform a ceremony or ritual with the braaap of a genny cranking along in the background. Anyway if there is someone out here who could help, please PM me or post it here.

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Loads Of Information From Someone Who's Never Tried This

Postby robotland » Mon Dec 01, 2003 5:50 am

I have never specifically tried to soundproof a generator, but from acoustical experiments that I have done in the past with audio recording and sound installations I have found that materials with deeply convoluted "acoustic valleys" can be very effective....(know any garage band kids that have lined the basement or garage walls and ceiling with egg cartons?) There are lots of post-consumer materials that could be used for sound deadening, such as egg cartons, cardboard, packing foam etc.....A Big Baffle could be made for BRC that was not only Burnable but An Art Installation as well! Obviously you wouldn't burn foam, and what works on the Playa probably ends up being difficult to reuse elsewhere. The foam wall material that is used in professional recording studios is grotesquesly expensive, but you can create a reasonable facsimile with whatever scrap foam you can lay hands on (try surplus stores for roll ends and scraps, and furniture store dumpsters for big chunks and slabs) by cutting the foam into long, thin "daggers", as long as you can make them and still cover the inner surface of your gennybox (sounds dirty!). Crowd these foam spikes together and anchor with Goop (best adhesive on Earth, says I!) or hot glue. You're done! The specs on the box depend on generator size, of course, and you want as much extra room for heat dissipation as you can manage, so maybe you should make it knockdown-style by using openended hinges or latches to connect the plywood-or-whatever panels- that should travel better-And the whole thing could be made To Burn by making the acoustic valleys with folded cardboard affixed to more cardboard or wood.
I've achieved some disturbingly effective results in art installations where I've created little egglike or nestlike spaces soundproofed with scrap foam- If you can manage to incorporate a nautilus-shell spiral to the shape, or even just a sharp bend, then the structure can be left open for exhaust and ventilation as long as the structure is covered with soundproofing so the noise doesn't just bounce out the opening.....You could use your gbox as a sensory deprivation chamber when the gen's not running, although you'd want to air it out and burn some incense in there first......

Happy Experimenting!

Planet "Happy Too Much Information Monday" Steve
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Postby DangerMouse » Mon Dec 01, 2003 10:13 am

Easiest thing to do would be to build a box, say 4' x 4' square with no roof or floor.

The box will deflect most of the sound up where it has little to bounce off of and will significantly reduce the noise that you perceive.

You may further be able to line this with egg crate style sound foam (Things like Dynamat tend to be too expensive and too heavy to lug around.) Though you may want to take care that the generator doesn't 'walk' inside the box and touch the foam in ways it shouldn't lest you get a rock concert effect going on the playa.

You can put hinges on the box to be able to fold it flat when you're done. In my experience MDF (Like they use on speaker boxes) dampens sound pretty well, but isn't as durable as plywood.

I think there used to be an FAQ on this on the BM newbie guide... ... ofing.html

Ah, there it is.

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Postby nodule » Mon Dec 01, 2003 1:00 pm

I also have no direct experience, but someone said the best thing to quit a generator is to put an old car muffler on it.

I'll be experimenting with that, and these other ideas, before August.


Kinetic II

Postby Kinetic II » Mon Dec 01, 2003 6:39 pm

Thanks for the inspiration...I've got access to foam and I'm going to give that a try, I also have old mufflers that I could use if I weld in some adapters and brackets.

The key is going to be weight...I am trying to lighten my load so I can pull my trailer and keep up with traffic when I take I-70 up to the Eisenhower tunnel in Colorado.

Again thanks for the replies as I was having a bad case of brain freeze and the posts helped spark some more ideas.

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Postby unjonharley » Tue Dec 02, 2003 6:30 pm

Putting a car muffler on a small engine my create to much back pressure. We plan to use the neck of the old muffler to weld a flex pipe to it and use a small motor cycle muffler.

The flex pipe for a gas stove or a water heater supplie line

Still the box is a good idea. I saw one this last BM. Just four sides of plywood with some old sofa cushion. It seem to work great.
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Postby Bob » Thu Jan 01, 2004 9:18 pm

Possibility -- Search loading docks behind appliance stores or plumbing/HVAC outlets, which sell large appliances or other smallish-crate-packed equipment, for largish cardboard box material (eg refrigerator boxes), which can be folded flat for transport, and maybe add a coating of papier mache gloop for extra deadening. Burn when done.
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Postby Skyhawk » Tue Jan 13, 2004 1:25 pm

speaking from my own experiences, a great way to get cardboard is to get to know the guys using it. most of those big box stores (home despot and that type, as well as sears and walmart) use compactors to crush and bale their cardboard boxes and waste into large cubes which are usuall sold to a recycling company) try to get to know those guys in the back. ask associates to check for cardboard and explain what you doing with this. a good time to try is late evening, appx an hour before closing times, when stuff might be stacking up. keep trying. get to know those guys. Im speaking from my own experience working at home depot. we go through a Lot of cardboard packing things, and would just as well like to see someone doing stuff with it. also, talk to the "lot/loader" (home depot) because in most cases, they will be willing to help collect And drag this stuff out to your vehicle. try to stay away from most managers. company policies are againts this practice for vague or meaningless reasons in some stores

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Postby unjonharley » Tue Jan 13, 2004 6:41 pm

Just go down to your little applince store and tell the man what you need. Those big outfits are just going to shine you on.
I have one already. Will see if i can get hold of another to share.
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sound deflection vs sound absorption

Postby RouseMouse » Sun Apr 11, 2004 1:58 pm

there are 3 ways to deal with sound.

1) Deflect it
This helps the sound go somewhere else but not actually go away

2) Absorb it
This works easily for high frequency sounds that have little wave energy but not so easily for low frequency sound which can have a large amount of energy that can travel long distances and through denser materials.

3) Cancel it out using Reverse phase sound wave cancellation
The sound you hear is the sum of the waves being created


1) Deflect it
Last year we took 2 4x8 sheets of sound board to help keep our quiet peace in the midst of our neighbors generators.
1 sheet we wired to a fence post as a short wall between us and our neighbors across the street who were kind enough to place their very loud generator on our side of their motor home camp, and the second sheet was given to our back door neighbors who had a newer quiet one. just by placing the sheet on the camp side of the newer generator the sound was almost totally dealt with.
The sound from the older one across the street was cut significantly , but was still reflected to us by the motor home wall behind it, but it was still much better , ,, from our side.

2) Absorb it
Sound board is a dense fiber board basically like the bulletin board from school days, it's about $7-18 a sheet and about 20-30lb per sheet, if you have room take an extra sheet for the ditz who sets up next to ya, it was well worth the cost ( we sent one sheet home with the back neighbors so he could make a screen with it.
Sound board deals with higher frequencies quite well, but sound board by it's self will only help cut down , but not stop low frequencies.
The best way to deal with low cycles is a concrete wall or a double 2x6 wall or a 2x 12 wall with split 2 x12s faced with rubber coated 3/4" plywood and filled with road base gravel mix, with your high frequency absorbers on the inner face of the wall.
This should only weigh a couple tons.
Particle board is very dense and heavy like the gravel and rubber, so it is used to contain the sound in speakers, but will reflect , not absorb the soundwaves.

3) Reverse phase sound wave cancellation
If you have 2 waves in sync you have twice the power , if you take 1 wave and phase it so it perfectly Mirrors the original, they cancel each other out and sum of the 2 is "0". this is how directional mics work.
I'm not writing a book , but they have worked on using this technique and if you have the desire and money it is possible to cut down the ambient noise with more noise.
This is actually how some mufflers work using baffles to break up and reflect the waves to cancel each other. they are often "tuned" to the motor they are designed for.

A box tapered like a popcorn box made from a layer of sound board inside dense particle board, preferably spaced so the layers are not touching, with a layer of those foam hospital mattress cushions glued to the inside of the sound board will do the best to absorb the high frequencies while deflecting the lower frequencies out to space ,, or up away from people.
The particle board is about 80lb a sheet so for a 4 x 4 box you are still talking 200 -300 lbs.
Be careful about igniting the foam or fiber with the exhaust.

If you add a muffler to your generator be sure you don't cut the air flow by sizing it too small or you could cause heat build up on the exhaust valves and have a mild melt down. Larger is better , not smaller and constricting.

Oh , our generator?
We had a 2x3' 80w solar voltaic panel that charged our batteries during the day and kept quiet at night.
no gas , no noise , and probably costs about as much as the generator, if you aren't planning on lighting the city by yourself.

Rouse, the long winded Mouse
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Postby unjonharley » Sun Apr 11, 2004 2:48 pm

Damn your complicated, Sounds like your killing a knat with a sledge hammer. I like the washer/dryer box idea. Them throw in a couple a old sofe cushions...Done. Folds almost flat too.
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Postby Captain Goddammit » Sat May 01, 2004 11:05 pm

Ive done a lot of experimenting with trying to quiet those god damn cheap shitty lawnmower engined generators.
You can try messing with the exhaust, but it isn't gonna help much if any. I've welded on car mufflers, motorcycle mufflers, even tried running the pipe into a garbage can full of water. The motor itself just radiates lots of noise, a muffler isn't going to make it quiet.
Boxes will help, but it will still be annoying.
The best solution is to ante up for a Honda EU-series inverter generator, or the Yamaha equivalent (not really equivalent because they lack the Honda's extremely cool ability to be linked together for greater output).
I've been very happy the last 2 or 3 years to see so many burners doing this. The roar of crappy generators has diminished greatly.
I don't mean to come off as elitist, I'm not a rich guy... but these things are worth at least every cent. (They are more expensive than the noise monsters.)
Nothing you're gonna do with one of those lawnmower-powered sets is going to be as peaceful and quiet. There's the ugly truth.
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Postby dman » Sun May 02, 2004 5:11 am

Yeah, I'll second that on the EU series. We were talking generators the other day in preparation for our registration and one of the co-leaders says, "What, we had a genarator last year?"

Specs say 49 db at 1/4 load; a 50 amp charger at 12 volts is 600 watts, or about 20% power on an EU3000
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