Generator Quiet Boxes

A place to discuss all things involving power and technology (including cameras). Generator tips, alternative energy, lighting your camp/bike/art/self, sound systems and more.
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Jay Johnstone
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Generator Quiet Boxes

Postby Jay Johnstone » Tue Jul 26, 2016 1:22 pm

Hey there fellow burners. We need to create a generator box to help quiet down our loud ass gen. Do any of you do this with your gens? If so what material are you using to make the boxes out of? I think I have an idea of a few different mediums to create the box with, but I feel this has already been figured out, and it would save me a lot of time if someone could point me in the right direction.

As of right now I'm looking at 2in Thermasheath insulation board (yeah my gen is loud as FUCK), and putting in a 6in 450cfm fan for ventilation on one end, and cutting a vent hole in the roof to let hot air escape. I will be venting the exhaust out of the same hole, but directing it with a flexible metal hose. Going to use duct tape to hold it all together, and then use a ratchet strap to hold it down to 2 pieces of re-bar, sunk in to the playa. I will also add some coarse foam at the inlet of the fan to help keep some of the playa out of the box.

This generator will not be on all the time, but for a few hours each day to charge items.

Do I need to use 2in insulation board? will 1in get me by?

Thanks in advance for any and all help!

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EGAZ
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Re: Generator Quiet Boxes

Postby EGAZ » Tue Jul 26, 2016 3:51 pm

That should work, though hard(er) surfaces reflect sound, soft(er), or porous surfaces absorb sound to varying degrees. And some sound is reduced by removing vibration, (automotive and sound booths) You would be better off lining plywood with actual sound deadening material. Can be Pricey. or Fiberglass or other dense fiber board. But not hard foam board. Hard Foam does deaden a little but soft material works better. Various materials and prices here. If it comes with a backing, apply that side to the plywood, fiber side towards Genny.

The wood box allows for more solid anchoring too.

To really quiet it down one needs a box, in a box, with fans. Works like a light box. Too many 'lined' channels & turns to make before exiting the box, thus quieter DBs.

More reading here.

FWIW, YMMV
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Jay Johnstone
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Re: Generator Quiet Boxes

Postby Jay Johnstone » Tue Jul 26, 2016 4:14 pm

Alright, what do we think about 1/2 in MDF, lined with a layer (or 2 if there is enough) of this UltraTouch denim insulation? ( http://www.homedepot.com/p/UltraTouch-1 ... /202710055 )
I'm trying to keep this build as small as possible. I'm not looking to completely kill the sound, just muffle it decently.

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Popeye
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Re: Generator Quiet Boxes

Postby Popeye » Tue Jul 26, 2016 5:38 pm

With all the hassle of building and transporting a sound box it might be easier to just buy -either new or used- a Honda generator. However if you can't afford one then this might give you some ideas:
Hard objects like plywood, MDF etc. transmit sound by conductance. There is not much attenuation. Softer items like Thermosheath, styrofoam and fiberglass attenuate and do a much better job. If you wanted to deaden sound in a building standard practice is to install fiberglass in the walls and ceiling, run hat channels horizontally screwed to the studs and joists then screw 5/8 sheetrock to the hat channels, making sure that you don't screw through the channels into the studs (this makes a BIG difference). The dense. soft sheetrock absorbs sound without much conductance. The airspace between the rock and the fiberglass and studs stops conductance and the fiberglass further attenuates vibrations.
You won't do all this and if you did you would have to have an opening for ventilation which would let noise through.
Best advice is to buy a Honda.
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Re: Generator Quiet Boxes

Postby FIGJAM » Tue Jul 26, 2016 7:03 pm

Lining any box with some use deep pile carpet works for most gennies.
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GreyCoyote
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Re: Generator Quiet Boxes

Postby GreyCoyote » Tue Jul 26, 2016 7:40 pm

Lots of good suggestions herein. Heed them. But also do a little research on acoustics.

The first line of defense is simple blocking. This requires mass, plain and simple. You want a physical divider between ears and source. Of course, this means all that noise just goes elsewhere.

The second line of defense is deflection. If you can channel the noise in some harmless direction (ie, upwards?), then the measured db at the ear drops.

The third line of defense is absorption. The noise gets turned into heat (basic thermodynamics). For this you need something that the waves can "work" against. Foam and batting fit this function.

A successful enclosure does all of this while still allowing the genny to breathe. And make no mistake about it, balancing these factors is NOT a trivial endeavor.

The best advice on this entire thread so far has been to start out with a quiet genny. Good engineering at the source is absolutely key. Anything that comes after is a compromise.

There is a reason quiet gensets demand a premium. For a real eye-opener, google the price on some of the "silent" gensets used for hospital backup and on-site movie power. The prices will shock you... until you understand just how hard it is to quiet a generator!

Good luck with your acoustic endeavors, and THANK YOU for caring about your neighbors ears! Too many camps simply dont care. For this you are to be commended.
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Jay Johnstone
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Re: Generator Quiet Boxes

Postby Jay Johnstone » Tue Jul 26, 2016 10:21 pm

Alright, well a new Honda gen would be a better way to go, but not all of us are able to just simply go out and pick up a new gen like that. So I'm going to have to build a box for the one I have. I'm going to go with a high R factor foamboard, lined with denim insulation. I'll put either a top piece of foam, with a decent amount of 1 or 2 inch holes drilled in to it, or just cover it with some kind of a mesh. Mainly trying to keep the sun from beating on it. If I do the top with the holes cut it in, I'll also cut, on the short ends, at the bottom of the box, a couple of vents. I'll again vent the exhaust out the top, via metal flex pipe. That should deaden the sound from traveling laterally, and allow it to vent mainly up. That should be mainly effective.

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Captain Goddammit
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Re: Generator Quiet Boxes

Postby Captain Goddammit » Tue Jul 26, 2016 10:45 pm

When the cost of a Honda comes up, I gotta chip in with my experience with portable generators which spans almost two decades and countless sets.
In the long run, buying a Honda EU quiet set is the cheapest option and here's a few reasons why.
When you measure watts-per-dollar, those 4000 - 7000 watt lawnmower-engine gennys lose because they put out exactly ZERO watts when you can't stand to listen to them running. So there's that.
You'll eventually get rid of the loud one and get a quiet one. I went through several, even a few regular non-super-quiet model Hondas. It would have been cheaper to get a quiet one in the first place and not go through all those others.

Early last year, I decided to put my 12-year-old pair of EU2000s up for sale just to buy myself a fresh pair. I didn't need to; they still worked perfectly, but I got $1400 for them, then ordered two new ones for $1800! I lost $400 on a pair of them over 12 years. That means they only cost me $17 a year each. They went to the playa many times, often running 24/7 while there.
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Re: Generator Quiet Boxes

Postby Popeye » Tue Jul 26, 2016 11:26 pm

Jay Johnstone wrote: I'm going to go with a high R factor foamboard, lined with denim insulation.

OK, let us know how well it works for you and your neighbors :D
Remember that foam board is moopy and tape the ends like a hexayurt.
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Re: Generator Quiet Boxes

Postby EGAZ » Wed Jul 27, 2016 12:59 pm

I'll add my Two Cents to echo CGD. I bought my Quiet Honda when I completed my car hauler conversion. I have the 3000 so it was $2k. Wasn't really happey to write the check but I'm glad I did. But after 8 years of use. ( at least ten trips a year, 3-day being norm, running 24/7) Doing proper maintenance it has paid for itself many times over. One thing many forget is you can, and will, find uses for it away from BM. Especially the 2000, it being so small. When you don't want to run a long ass cord, just grab the 2000, fire it up, plug in your device, do the job, put it back on the shelf.

I realize Quiet Genny owners sound like ex-smokers the way we preach. But there is a reason.
Pricey? True! Worth every Penny? Yes, Yes it is. :coffee:
2nd time better than the first. And the first was pretty Freakin' Great!
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Re: Generator Quiet Boxes

Postby maladroit » Wed Jul 27, 2016 2:01 pm

Thermasheath or any other kind of foam DOESN'T INSULATE SOUND. They're just a heat barrier. They're basically transparent to sound no matter how thick the insulation is. Ask anyone who sleeps in a hexayurt. It's not much quieter than a tent in there.

To get rid of sound you either have to reflect it or absorb it. Hard plywood angled toward the sky works OK. Sheetrock, brick, and clay will insulate well against sound.

Last year our neighbors had this "attempt" at a baffle box:
Image

It didn't work and they ran their loud-ass generator ALL the time. My hexayurt walls are 2" thick, their generator door and insulation contraption was 2" thick, and I moved my car in between the generator and my hexayurt. None of that reduced the sound enough to make me stop prejudging their entire camp as a pile of assholes. I felt bad about it because the only thing I knew about them was the generator, but no one even wanted to go over and say hi to them all week. Eventually one of them tried to fill the gas tank while it was running, started a fire, and since we actually had fire extinguishers around we put it out for them.

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Token
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Re: Generator Quiet Boxes

Postby Token » Wed Jul 27, 2016 4:19 pm

You know how they have this kind of stuff at airport runways, both ends.

Image

They work reasonably well.

At airports they deflect noise and the actual jet blast but same principle works fine for noisy generators.

Use it as inspiration, design something fabulous, then build it!

Plywood in 3/4 inch is fine. Tilt it ~ 60 degrees to get most of the noise skyward. Must do all 4 sides.

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Re: Generator Quiet Boxes

Postby dustyfux » Wed Jul 27, 2016 5:10 pm

Another Honda 2000 owner with an opinion. I appreciate your dedication to reducing the clackity clack noise that can drive part of the community bonkers. I get it, $ can be tight and c'mon we're like what - 4 weekends away to get our shit dialed in? Now's the time to go with what you got.

Problem is we all have bad generator stories. I've had some pure evil fuckwags slip their generator next to my camp in the middle of the night. One assdouche actually ran a 50 foot cord back to his trailer.

Personally, I haven't experienced a well built baffle box. So that either means all of them are shit or the ones that work are near invisible. I built one and it failed in test mode, so I sold that loud as fuck and bought another Honda.

So if you have options and maybe can be swayed from your loyalty for that loud as fuck, let me tell you why I chose a second Honda 2000:

Size - its light and tiny compared to other generators. More room to pack beer.

You don't need an accompanying box to muffle it. More room to pack beer.

I've seen them run during the worst dust storms and out in the direct sun. They. don't. die.

Gas consumption - They use less gas. Less to pack, more room for beer.

Well maintained they last forever. After each burn it gets serviced and I'm bringing the old one for its 12th year.

You don't really need 4K watts. OK, maybe sometimes you do but not always. If you do, run 2. When you don't, put one away and save 50% of the gas.

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Re: Generator Quiet Boxes

Postby BBadger » Wed Jul 27, 2016 5:49 pm

Yeah, I agree with maladroit: foam board will do jack shit for sound. The waves will pass right through them because there's no mass to impede them.

If you want sound blocking, you could get some cement board and position them such that sound is blocked around the lower area of your genset. It's pretty cheap and has the mass to reflect most sound waves, but you'll need to make sure that there aren't gaps.

You'll still need some means to absorb sound. Perhaps get some soundproofing drywall. It's designed to reduce the amount of transmitted sound. Then aim the sheets upwards so that the reflected sound has somewhere else to go. This may all cost you a bit of money and time. Stuff like soundproofing drywall is $50/sheet. Acoustic blankets cost $100/blanket (4'x8'). It adds up, and doesn't include the cost of the structure to mount it all on.

I hope you're dedicated to making something good and tested. Might be fun to decorate too.

I've never tested any of the above materials as we've traditionally had Hondas. Please report back if you build something decent.
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Jay Johnstone
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Re: Generator Quiet Boxes

Postby Jay Johnstone » Fri Aug 12, 2016 11:58 pm

Okay, so after much research and taking in account the hepful comments about generator sound theory, and the sound dampening properties of various materials, I have decided to build a box in a box. Going to line the inner side of each box with 2in denim insulation. I will be installing a 6in inline duct fan for fresh air intake, and cut 2-3in holes in the oppiset side from the intake wall, and top pieces so the hot air can escape. Also going to plum the exaust out the top via metal flex pipe. I will mount the boxes to each other so I can just lift one side and get to the generator easily for service/starting/stopping. I'll be mindful to put the exaust in the box correctly when I move it.

I should have 4in of space from the insulation on the sides, and 6in on the top for the forced air injection to help cool the gen down while running.

This will also be under a tarp being suspended 5 feet in the air. No direct sunlight will be on the box at any time.

Gen will only be running a few hours a day, a couple times a day.

I think this is going to work very well, and will cost about $120-$140, far less then "just buying a Honda",that I can't afford to start with. Even with the cost of the gen, I'm still under $500 for a strong 2200watt 16.4amp dual socket 4 stroke gen with great fuel consumption, and sound box. Works for me!! (I hope!)

I'll be building this tomorrow! And then testing it. I'll report back with my findings.
Video to come soon!

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Re: Generator Quiet Boxes

Postby BBadger » Sat Aug 13, 2016 12:06 am

Yes, please report back with findings! It'll be good to see how different baffle boxes improve the noise.
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Re: Generator Quiet Boxes

Postby GreyCoyote » Sat Aug 13, 2016 12:21 am

My gut tells me you may need more airflow, but maybe not.

Remember to load the genny up and let it run under load for an hour or so before blessing your design. Also remember a stiff wind in the wrong direction can completely nullify the effects of a fan. If the interior gets much above 115-ish degrees, your genny is living on borrowed time, especially when you load it up.

Sounds like an interesting design. Can you post some pictures when its all together?
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Re: Generator Quiet Boxes

Postby Luigi » Sat Aug 13, 2016 8:52 am

I am with the Cap't - ditch the loud gen set. But if not possible, use soft material in the box like fig jam said - old shag carpet! I also have had luck with changing the exhaust muffler, but not all gens allow that.
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Re: Generator Quiet Boxes

Postby dustyfux » Mon Aug 15, 2016 8:42 am

with that double box setup, once all the potential heat issues are figured out, might want to think about an external fuel source. It would make the refueling process a lot easier.

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Re: Generator Quiet Boxes

Postby Canoe » Sat Aug 20, 2016 8:05 pm

I'm coming in very late on this, but my vote would be with Figjam's used deep pile carpet.
Best bang for the buck, especially as it can often be had free. Who cares if it rains.

  • Plywood box open to the sky, meaningfully taller than the gennie.
    • This blocks the direct line-of-sight path of gennie sounds through the air to our ears.
    • Better if the box is higher than the average person's ears, so reflections on the inside near the top of the box don't have a direct line-of-sight to ears.
  • Carpet on both the inside and outside of the box:
    • inside, the carpet absorbs direct and reflected gennie sounds, minimizes how much sound manages to modulate the plywood to vibrate, dampens the vibration that gets into the plywood, limits the vibrating plywood from re-modulating the air inside the box, and softens the hard edge of the sound that it reflects, and
    • outside, the carpet dampens the vibration in the plywood, inhibits the ability of the vibration in the plywood from modulating the air to transmit sound outwards, with a softer edge to what sound manages to radiate outwards.
  • Sound that goes up, goes up and largely away.
  • Sounds that manage to reflect instead of being absorbed and damped, if the walls are tall enough, will largely be angled upwards from the horizon as it gets out of the top of the box.
  • With carpet on both sides of the plywood box, it works to absorb sound, dampen sound and limit the transmission of sound through the box sides, while softening the signature of that sound.
  • Box is open to the top, so minimal heat risk.
Enhancements:
  • If the box had a large lip (carpet both sides) at its top that extended upwards and inwards at 45 degrees, it would seriously inhibit sound reflections off the side of the box getting out of the box, as reflections near the top of the box would be:
    • exiting at a higher angle (more up and away),
    • absorbed, or
    • reflected back into the box to be further reflected/absorbed/damped.
    There would be an optimum lip width and angle combination to maximize the upward angle of escaping sound. Need to leave ample opening for air flow.
  • A sheet of dampening rubber on the plywood before mounting the carpet would be a great improvement, but costly unless you got an amazing deal or find somewhere.
    .
  • If you had the space or inclination, then a larger box as above, but with a carpet-both-sides panel, angled at 45 degrees, low towards the generator, high on the box wall (as high as the height of the generator?), to reflect as much of the generator sound (that it didn't absorb or dampen) upwards as possible. This box would be rather larger than the gennie; benefit may not be worth the effort

Anyone who has already built a gennie damping box out of MDF or plywood and doesn't have anything on the outside, can improve it's performance by adding used deep pile carpet to its outside.

Harmonic vibration can be a bitch. Be prepared to modify your dimensions on the playa.
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Re: Generator Quiet Boxes

Postby maladroit » Thu Sep 08, 2016 12:42 pm

Our camp used a lot of generators this year. In my section of the camp, we had an EU2000i and a Champion inverter running next to each other. The Honda was running non-eco because it couldn't handle the startup load of a small AC unit for a campmate's RV. My generator was hacked to run in eco mode most of the time, then receive a signal from our AC unit to go off eco mode for a few seconds during compressor startup. After startup, it was happy to run back down in eco mode with the compressor running.

Anyway, a couple simple pieces of plywood as temporary baffle boxes helped a lot even with the quiet generators. We had both generators about 15 feet from our yurt and they were not annoyingly loud.

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Re: Generator Quiet Boxes

Postby JakeAndBake » Wed Nov 22, 2017 7:39 pm

Jay Johnstone wrote:Okay, so after much research and taking in account the hepful comments about generator sound theory, and the sound dampening properties of various materials, I have decided to build a box in a box. Going to line the inner side of each box with 2in denim insulation. I will be installing a 6in inline duct fan for fresh air intake, and cut 2-3in holes in the oppiset side from the intake wall, and top pieces so the hot air can escape. Also going to plum the exaust out the top via metal flex pipe. I will mount the boxes to each other so I can just lift one side and get to the generator easily for service/starting/stopping. I'll be mindful to put the exaust in the box correctly when I move it.

I should have 4in of space from the insulation on the sides, and 6in on the top for the forced air injection to help cool the gen down while running.

This will also be under a tarp being suspended 5 feet in the air. No direct sunlight will be on the box at any time.

Gen will only be running a few hours a day, a couple times a day.

I think this is going to work very well, and will cost about $120-$140, far less then "just buying a Honda",that I can't afford to start with. Even with the cost of the gen, I'm still under $500 for a strong 2200watt 16.4amp dual socket 4 stroke gen with great fuel consumption, and sound box. Works for me!! (I hope!)

I'll be building this tomorrow! And then testing it. I'll report back with my findings.
Video to come soon!



So did you ever make this??


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