Good sound buffer for generators?

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RemingtonRand
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Good sound buffer for generators?

Post by RemingtonRand » Sat Jul 05, 2014 3:23 pm

I'll be bringing two Honda eu2000i generators paired together so that I can run the AC in my travel trailer. Most of the time I will only need one for fans and such. But, I'm aware that even "quiet" generators are noisy when they are in full mode, like when running a little rooftop AC. I've seen some discussion of creating something to deal with the noise. I'm wondering if my plan is a good one or not:

- plywood for generators and extra-supply fuel tank to sit on (hopefully with a protector for leaks under the equipment)
- four walls of plywood that I can assemble on the playa, carpet on the inside to deal with noise
- open on top for venting, hopefully positioned in shade, otherwise with some shade material draped across
- my partner insists that it needs a hard top, but I'm afraid of air flow and overheating. He says just have a few openings in the side for air flow. I'm afraid it's not enough.

Any suggestions about the actual construction: including a hard top or not?

Thank you.

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BBadger
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Re: Good sound buffer for generators?

Post by BBadger » Sat Jul 05, 2014 3:50 pm

Hey if you're going to build one, I had this idea for a vertical parabolic baffle:

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Re: Good sound buffer for generators?

Post by tamarakay » Sat Jul 05, 2014 3:57 pm

We leave ours open. Same generators. Generators sound louder at home than they do on playa as the ambient noise is constant out there. Cut two pieces of plywood in half, glued carpet to the four pieces of plywood, drilled holes down sides. Stacks flat for transport. then use tie wire to tie them into a box on playa. Do all the glueing and drilling at home. No moop.

Bbadger is way more techie than me lol.

We have come prepared to run an air conditioner every year but have not found it necessary. Figjams cooler and a good shade structure is really all you need.
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Re: Good sound buffer for generators?

Post by motskyroonmatick » Sat Jul 05, 2014 8:29 pm

Definitely do not put a top on the box unless you want to waste valuable power providing lots of forced air ventilation for the box. Also the sound needs to go somewhere and the best somewhere is up. I would build a 4 side baffle out of plywood lined with the thickest shaggiest carpet you can find. Make one side easy to open so you can get in to start and mess with the generators. Do not allow the generators to rest against the side and make sure there is good space between them so they breathe well. A generator that is trapped in a hot space will suffer from much lower output, frequent breaker tripping, stalling and possibly engine failure. To that end elevate the box off of the playa 3/4 to 1 inch to allow air flow in the bottom so that the generators can pull in fresh air and so heated air and exhaust does not get trapped in the box. I would run the generators in full power mode when starting the AC and then switch them to eco mode after a minute or so. Installing a Hard start capacitor or soft start capacitor(same thing but different names- Google supco SPP5) along with the run capacitor on the AC pump motor could dramatically change how hard the generators have to work to get the AC going. At altitude that can be an issue depending on the size of AC one is trying to run. There is much info on RVing forums about hard start capacitors so look around there if you are curious about it.

Good luck with the project!
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RemingtonRand
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Re: Good sound buffer for generators?

Post by RemingtonRand » Mon Jul 07, 2014 11:17 pm

Thanks folks. Lots to think about. And Bbadger, you rock!

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Re: Good sound buffer for generators?

Post by nixiebunny » Thu Jul 17, 2014 8:10 am

As long as you keep the generators inside your camp, they won't bother your neighbors. The best place is between two vehicles. Then you don't have to build anything to quiet them.

I still can't believe that some people think that their generator should live on the street side or the neighbor side of their RV. The next time that happens, I'm coming over with an extension cord.
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Re: Good sound buffer for generators?

Post by chuckularone » Thu Jul 17, 2014 9:17 am

nixiebunny wrote:The next time that happens, I'm coming over with an extension cord.
Just added "Extension Cord" to my list! :-)
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Re: Good sound buffer for generators?

Post by Fan C » Thu Jul 17, 2014 10:48 am

I had a Honda eu200i about 2 feet from my head with 1" of yurt between us. I couldn't tell if it was off or on most of the time.

For that gennie the simple carpet lined box will do fine.

As was said it'll likely get buried in the ambient sound of brc.

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Re: Good sound buffer for generators?

Post by Elderberry » Thu Jul 17, 2014 10:58 pm

tamarakay wrote:We leave ours open. Same generators. Generators sound louder at home than they do on playa as the ambient noise is constant out there. Cut two pieces of plywood in half, glued carpet to the four pieces of plywood, drilled holes down sides. Stacks flat for transport. then use tie wire to tie them into a box on playa. Do all the glueing and drilling at home. No moop.

Bbadger is way more techie than me lol.

We have come prepared to run an air conditioner every year but have not found it necessary. Figjams cooler and a good shade structure is really all you need.
Yup, I second this. That's we do. It's easy to transport, easy to setup, easy to open to get to the generator for refueling, etc. This year we will be raising the geni a bit off the playa on a pallet or something, and also adding some shade cloth on top.
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Re: Good sound buffer for generators?

Post by maladroit » Thu Jul 17, 2014 11:47 pm

The best generator sound buffer is the one built into a quiet generator...

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Re: Good sound buffer for generators?

Post by Elderberry » Fri Jul 18, 2014 11:02 am

maladroit wrote:The best generator sound buffer is the one built into a quiet generator...
The lower decibels are not worth the cost. IMHO I'd rather have more watts and a baffle and save some money to spend on something else for burning man. It's not like BM is a bastion of quietude.
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Re: Good sound buffer for generators?

Post by JayBobBoy » Fri Jul 18, 2014 12:37 pm

I have a loud generator and I'm not afraid to use it!

For that reason, I have built a generator baffle each of the last two years using recycled materials, and I'll be doing it again this year too. My neighbors have always appreciated the effort, and it really works too!

The best advice is to deflect the sound waves upward as best you can. I have an opening on top of my baffle box that's covered by an old floor fan, blowing upward. It turns on as you start the generator and really helps with the airflow.

Make sure to plan for exhaust (it will melt or burn stuff that's too close). Make sure you have a plan to lock or secure your generator. Although your box will hide it well, don't leave it to chance. Give yourself easy access for starting/maintenance. And if you have time...make it look cool!
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Re: Good sound buffer for generators?

Post by Captain Goddammit » Fri Jul 18, 2014 12:46 pm

Your neighbors appreciate the effort to try to lessen the annoying racket those shitty generators make, because it's annoying the shit out of them!

But hey, fuck them, right?
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Re: Good sound buffer for generators?

Post by maladroit » Sat Jul 19, 2014 1:16 pm

jkisha wrote:The lower decibels are not worth the cost. IMHO I'd rather have more watts and a baffle and save some money to spend on something else for burning man. It's not like BM is a bastion of quietude.
I like all the loud sounds at Burning Man that DON'T remind me of yard work.

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Re: Good sound buffer for generators?

Post by BBadger » Sat Jul 19, 2014 3:30 pm

I plan on powering my camp with 15x leaf blowers and weed whackers, that each only power up in short bursts at a time.
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Re: Good sound buffer for generators?

Post by GreyCoyote » Sat Jul 19, 2014 4:02 pm

I want to bring an old air raid siren and wait for some idjit to crank-up his Big Box Store Noisemaker. I will give him about an hour and then let the siren rip. Just leave it on and walk away. Pointed in his direction, of course.

Sure, he has a "right" to make noise with that thing... and so do I. The only difference is my noise is "historic art" and I am "gifting" its sounds to all my "friends" and neighbors.
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Re: Good sound buffer for generators?

Post by Molotov » Sat Jul 19, 2014 5:39 pm

If you can afford it (and the gas) here is a Chrysler Hemi-powered air raid siren-a relic of the Cold War.
[media]

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Re: Good sound buffer for generators?

Post by theCryptofishist » Sat Jul 19, 2014 11:01 pm

Dustdevil beat you to it, Grey Coyote.
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Re: Good sound buffer for generators?

Post by GreyCoyote » Sun Jul 20, 2014 5:36 am

theCryptofishist wrote:Dustdevil beat you to it, Grey Coyote.
Wow! You are right! And with just a bit of luck we will all get to see this!

Its the ultimate battle for the Earth as the humans attempt to repel and burn the evil Alien Seige Machine. Details here: viewtopic.php?f=362&t=68183&p=1012424#p1012424

Good catch, Fishy. :mrgreen:
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Re: Good sound buffer for generators?

Post by FlyingMonkey » Thu Jul 24, 2014 8:10 am

I just saw this at work this morning so I of course had to go check them out. They are very simple hinged pieces of plywood with carpet on the inside. I'm assuming the carpet has some padding between it & the plywood. Considering that these were only positioned on one side of the generators, they did a very good job reducing the noise. I think if they completely surrounded the generators & sealed the hinge joints with strips of the same carpet/foam these would be very effecting at reducing the noise. I tried to get decibel readings from front & back but my sound meter app wasn't working (curse you Android). All I can say is there was a very noticeable difference in sound levels.
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Re: Good sound buffer for generators?

Post by --Ever-- » Thu Jul 24, 2014 3:16 pm

Thinking something like this for my first baffle.

I'd like it to flat-pack (more or less). And I like the approach at http://www.PlayaTech.com's which allows for tool-less construction on the playa.

Take pieces of thick wood, glue some sound dampening material to each piece within the slot cuts then slip it together on the playa. Lay down a larger piece of plywood to protect the generator from the playa, put the box on four bricks, maybe throw a shade structure on it. Hook it up to a 6 or 12-gallon external tank. Profit.

Image isn't to scale, would likely make it taller as some have suggested.

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Re: Good sound buffer for generators?

Post by FIGJAM » Thu Jul 24, 2014 3:21 pm

If the top is open I wouldn't put it on bricks.

To much noise will escape through that gap.
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Re: Good sound buffer for generators?

Post by --Ever-- » Thu Jul 24, 2014 3:24 pm

FIGJAM wrote:If the top is open I wouldn't put it on bricks.

To much noise will escape through that gap.
That's what I thought. Would be great to hear a second opinion on this. Earlier on Motskyroonmatick suggested raising a box even if it has an open top.

Motskyroonmatick: Definitely do not put a top on the box unless you want to waste valuable power providing lots of forced air ventilation for the box. Also the sound needs to go somewhere and the best somewhere is up. I would build a 4 side baffle out of plywood lined with the thickest shaggiest carpet you can find. Make one side easy to open so you can get in to start and mess with the generators. Do not allow the generators to rest against the side and make sure there is good space between them so they breathe well. A generator that is trapped in a hot space will suffer from much lower output, frequent breaker tripping, stalling and possibly engine failure. To that end elevate the box off of the playa 3/4 to 1 inch to allow air flow in the bottom so that the generators can pull in fresh air and so heated air and exhaust does not get trapped in the box. I would run the generators in full power mode when starting the AC and then switch them to eco mode after a minute or so. Installing a Hard start capacitor or soft start capacitor(same thing but different names- Google supco SPP5) along with the run capacitor on the AC pump motor could dramatically change how hard the generators have to work to get the AC going. At altitude that can be an issue depending on the size of AC one is trying to run. There is much info on RVing forums about hard start capacitors so look around there if you are curious about it.
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Re: Good sound buffer for generators?

Post by FIGJAM » Thu Jul 24, 2014 5:15 pm

I interpret that as "elevate the whole box" and have some holes drilled in the floor for circulation.
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Re: Good sound buffer for generators?

Post by GreyCoyote » Thu Jul 24, 2014 5:24 pm

Important point: with two or more generators in the same box, make a divider down the middle to acoustically decouple the two. Especially with variable speed generators, the notes combine to make a beat-note that can be more obnoxious than the sum of the other noises combined. A little insulation down the middle goes a long way to eliminate these types of effects.
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Re: Good sound buffer for generators?

Post by mosquito » Fri Jul 25, 2014 10:57 am

FIGJAM wrote:I interpret that as "elevate the whole box" and have some holes drilled in the floor for circulation.

I agree.

It's the same idea as elevating an ice chest cooler off the playa to help keep it cool. The box sends the noise upward-ish and elevating the box helps keep the whole box/generator assembly cooler.

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Re: Good sound buffer for generators?

Post by bm_cricket » Sat Sep 13, 2014 11:03 am

You could put the generator inside a Hexaurt and you could sleep outside in a tent? You could even air condition your tent if you had a nice big generator!
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Re: Good sound buffer for generators?

Post by Canoe » Sat Sep 13, 2014 3:50 pm

GreyCoyote wrote:Important point: with two or more generators in the same box, make a divider down the middle to acoustically decouple the two.... A little insulation down the middle goes a long way to eliminate these types of effects.
Now that was a very good point.

The biggest bang for the buck is the box to channel the noise upwards.
But the plywood is modulated by the noise inside the box.
- the inside surface acts like a microphone
- the outside surface acts like a speaker

Carpet on the inside dampens the noise/vibration/modulation received by the plywood. That dampens, but doesn't not eliminate the plywood getting modulated by the generator noise. So add carpet to the outside too. That dampens the noise projected from the outside surface of the plywood.

The carpet on the inside of a simple open topped box also cuts down on the noise reflected back across the generator and over the other side.
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Re: Good sound buffer for generators?

Post by Captain Goddammit » Sat Sep 13, 2014 9:13 pm

And while you're at it, I'd recommend a nice floral pattern carpet, with tassels around the edges.
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Canoe
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Re: Good sound buffer for generators?

Post by Canoe » Sat Sep 13, 2014 10:02 pm

If you really want to go to town, spray the plywood with rubberized undercoating first. Make sure it's the kind that fully dries (doesn't moop), but doesn't go rigid/hard, but stays flexible. Max mass damping and higher frequency absorption.

Helps keep the carpet mounted solidly too, so the fibre's of Captain's florals last longer. Although you will have a fair amount of UV exposure.
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That's one word I regret googling during breakfast.
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Video games are giving kids unrealistic expectations on how many swords they can carry.
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, but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

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