Anybody ever build a hush box?

[FlyingMonkey]

Anyone had any luck making an effective hush box? I saw one at Lakes of Fire that used cement board & pink fiberglass insulation. It seemed to make a considerable difference but didn't cover all sides.

I have also seen people that have put automotive mufflers on their generators. If I can find a cheap muffler I’m going to try that & use a hush box.

I was embarrassed by how loud my generator was and won’t be taking it back Home unless I get it down to a reasonable level.

If this works I will post my results. I doubt it will get down to a level that I would consider neighborly but I want to try just the same. It also never hurts to go around to everyone camping around you, introduce yourself, & let them know that if they think it’s too loud to let you know. Oh..... & offer to share your power with them.

[BBadger]

Remember that the main issues with making a good baffle is that it needs to provide proper ventilation and not get too hot.

It's actually pretty hard to absorb sounds with materials. So when you build a baffle, and are trying to block the sound all around, it just isn't that efficient. It's better to reflect or block the sound, which is no doubt why people just put their generators behind a wall-surface to the chagrin of people on the generator-side of the wall.

In that light, something I'd like to try or see someone try is making a parabolic reflector that aims the sound upwards. There's a whole sky of unoccupied space that can absorb the sound. Plus, the reflector being open at the top means that heat can vent out the top as long as there is proper ventilation below (which can be provided via holes), Though the reflector wouldn't have to be perfect, it would need to be relatively large compared to regular baffles, which is a logistical concern. Still, it could look like a nice art piece.

[unjonharley]

Tried the muffler thing. Not worth the money.. Then tried six inch stack out of a garden tractor, Four feet up.. That work fair.. Needed some thing on the outside of the stack.. Don't think it was hot enough to melt foam.. But want to try some other that is that dense.

[FlyingMonkey]

Remember that the main issues with making a good baffle is that it needs to provide proper ventilation and not get too hot.

It's actually pretty hard to absorb sounds with materials. So when you build a baffle, and are trying to block the sound all around, it just isn't that efficient. It's better to reflect or block the sound, which is no doubt why people just put their generators behind a wall-surface to the chagrin of people on the generator-side of the wall.

In that light, something I'd like to try or see someone try is making a parabolic reflector that aims the sound upwards. There's a whole sky of unoccupied space that can absorb the sound. Plus, the reflector being open at the top means that heat can vent out the top as long as there is proper ventilation below (which can be provided via holes), Though the reflector wouldn't have to be perfect, it would need to be relatively large compared to regular baffles, which is a logistical concern. Still, it could look like a nice art piece.

Yeah, getting air inside for ventilation is a pretty important design consideration. I made a big foam cutter so I was thinking about cutting pyramid panels like those used in anechoic chambers and also reflecting all the sound up. I have found some medium density foam that doesn’t cost too much so I may give it a try. Mostly I just want to see if it can be done for a reasonable price. I like the challenge of this project.

[JayBobBoy]

I found a suggestion on here a while back that proved to work pretty well. I have a Generac 3250 generator for my camp that makes a pretty big racket.

I built a baffle box using thin wood products, wood screws, some of the thin pink insulation sheets, and one of the square floor fans. I built the box to be completely enclosed except for a square hole on top. I taped the floor fan over the hole and plugged it into the generator to blow up and out of the box. It directed the noise up rather than towards other camps and the fan worked great to ventilate the heat and fumes. Only some slight melting and discoloration at the exhaust.

For what it was, it worked well and easily reduced the racket to a dull roar. Not quite down to Honda decibel levels, but way better than nothing. It cost about $45 to build and my neighbors were appreciative of the effort.

My next one will be way better, and will be made of recycled materials.

[atomicray]

Curious why the standard auto muffler did not help or was not worth it?



How about using a sport motorcycle after market muffler? Certain internet auction sites can be useful in finding a couple good deals...$20-$30?

I have dealt with sound proofing with military and disaster response missions. We had money and resources so many of our choices are not so readily available, but surely the auto/cycle muffler and an extended final pipe (up) would make a large difference.

The box....heat quickly becomes a major issue, much more so than the sound itself...so I placed a squirrel cage fan in each box with the intake, bringing in fresh outside air...



Sealing is the issue...the lower unit edges must be air sealed...the direct up is a good idea but you will need a partial cover to protect against the sun...

This is an interesting thought...I will put some materials together from my shop, I have three portable generators out there, and see if I can build something useful for a reasonable budget. I will use my sound meter before and after to gauge the results.

Should be fun.

[The CO]

If there's no decent resolution to such a situation in the future, I suppose you could always see how tolerant the neighbor is of your liberal use of a bullhorn! Assholes on bullhorns is another fact of life in BRC!
"HEY, NICE GENERATOR! HOW MANY WATTS DOES IT PUT OUT? DID YOU GET A GOOD DEAL ON IT? I THOUGHT ABOUT GETTING ONE LIKE THAT! HOW LONG HAVE YOU HAD IT? WOULD YOU RECOMMEND THAT UNIT TO YOUR FRIENDS?"
"WHAT? YOU WERE SLEEPING? OH, SORRY, I WAS TRYING TO BUT COULDN'T!"

This. This is what I'm doing from now on.

I've always put it in economical terms.
spend $300 on a shit loud genny.
spend $20-100 trying to baffle it.
In the next 1-2 years, spend another $300 on another shit loud genny, because the old one sucked and failed after 1-3 years.
Spend another $20-100 trying to baffle it, since the baffle from last year didn't work or got lost.
Repeat this cycle until you've spent $1000+ in 3-5 years.

Or, spend $800 on a honda eu2k or equivalent. Use it for 9 years without having to build a baffle.
After 9 years, spend $60-120 on a tune up.

[BBadger]

Yeah, getting air inside for ventilation is a pretty important design consideration. I made a big foam cutter so I was thinking about cutting pyramid panels like those used in anechoic chambers and also reflecting all the sound up. I have found some medium density foam that doesn’t cost too much so I may give it a try. Mostly I just want to see if it can be done for a reasonable price. I like the challenge of this project.

Those anechoic chambers are really for the benefit of those inside the chamber, not outside. Though the surfaces are supposed to absorb sound energy, it also means that it can be transferred to the surrounding environment unless contained. For lower frequency sounds, the sound will pass right through it.

If you want to actually reflect the sound you need something dense to reflect the sound waves. Foam will not cut it, though it may provide some nice structural support for something that is heavier such as metal sheeting or cement board.

I found a suggestion on here a while back that proved to work pretty well. I have a Generac 3250 generator for my camp that makes a pretty big racket.

My next one will be way better, and will be made of recycled materials.

You may look into some cement board for the paneling. It has extra mass so that it'll reflect the sound better and also won't get damaged by heat. The boards weigh more of course, but not all that much.

Curious why the standard auto muffler did not help or was not worth it?

Well using a muffler assumes that most of the noise comes from the exhaust. While this may be true of engines that are designed to not vibrate and transmit noises in other means, noisy generators are often not designed to be quiet and noise will radiate out of all parts of the engine. You'll also need to spec out a muffler that works well for your setup. For example, the muffler should not be too restrictive, as it may damage your engine. Some mufflers may seem to amplify the noise, or at least not do very much. You'll have to experiment with what works for you.

[maladroit]

This. This is what I'm doing from now on.

I've always put it in economical terms.
spend $300 on a shit loud genny.
spend $20-100 trying to baffle it.
In the next 1-2 years, spend another $300 on another shit loud genny, because the old one sucked and failed after 1-3 years.
Spend another $20-100 trying to baffle it, since the baffle from last year didn't work or got lost.
Repeat this cycle until you've spent $1000+ in 3-5 years.

Or, spend $800 on a honda eu2k or equivalent. Use it for 9 years without having to build a baffle.
After 9 years, spend $60-120 on a tune up.

I spent $400 on a quiet 2000 watt generator. We had two of them in our camp, along with a veteran EU2000i...the sound level was the same. It took me several days of hunting down reviews and video comparisons before finding it. It is possible to get quiet power without screwing around with baffles OR breaking down and spending about $1000. I don't have personal experience with durability, though reviews seem to agree they won't fall apart after one year.

[trilobyte]

I'm splitting this conversation from the earlier thread.

I'll also add another tip that I use with our camp and highly recommend for anyone else using a generator - regardless of wattage or noise output. Don't put your generator at the edge of your camp. Keep at least one vehicle between your generator and your nearest neighbor. That (along with any baffles) will help with noise abatement and help keep dust at bay. And if you can arrange it so that vehicles block your generator from neighbors and from street view, you get double bonus theft deterrent points.

[unjonharley]

Yeah! put one of those little EU fuckers next to my camp..

A smoke filled van is just what I'm looking for.. They are the most toxic thing on the playa..

[unjonharley]

oooo

[Captain Goddammit]

I've tried car and motorcycle mufflers on loud generators and they made no difference.
As mentioned, the noise isn't all coming from the exhaust. It radiates out of the whole engine.
Baffle boxes usually don't make them library-quiet but they help.

[gyre]

The idea of a deliberately reflective box is interesting.
How about angling the boards outwards?
Anyone tried this?

Bbadger, who apparently knows something about acoustics, is right about the mass/density law of acoustics.
Mass per thickness is preferable for isolation.
Interestingly, glass is a good material.
Decoupling is a technique I was taught to block different frequencies.
You layer different materials.

It may be worth considering sacrificial materials for those traveling a long way.


For muffling, a flex joint can important to isolate the engine and exhaust from stress and vibration.

The intake can be just as important, and noisy.
Look at how solid many intakes are on cars.

[MikeGyver]

The actual exhaust on a generator isn't the loud part. they are loud as engines in general. TK's Husband Ken's box seems to work great, I was five feet away from it and didn't know the generator was running. 4 pieces of plywood with an old rug nailed to the inside. Had a roof that he used last year, but i don't think it ever went on this year. It was a cheap Harbor Freight generator.

[gyre]

They vary a lot.
Some of the worst are loud when the outlets are completely sealed.
Sounds like thin sheet metal rattling around.
Truly horrible.

[mudpuppy000]

If you had enough of them, you might be able to make a sound wall out of water barrels/containers. Just don't splash water all over the generator.

We had a yamaha in camp this year and it was amazingly quiet.

[gyre]

Great idea!

[Ratty]

Wow Colonel, Thank you. I just learned more about generators in the last few minutes than I had in my entire life. Albeit, I don't plan to ever own one....But it's still nice to be able to walk up to someone and SHOUT my knowledge to them. The details fascinate me.

Remember those printed notices that people would leave under a car wiper about taking up two parking spaces? Maybe there should be a generator Rat Patrol that goes around haranguing inconsiderate camps. They could award patches to every buttwipe putting their generator closer to their neighbors camp than it is to their own camp. I've only had one bad experience but it came at the end of the week when I couldn't move away. Lesson learned. Park my van so no motorhome can pull up to the back of it and spew generator exhaust and noise in my sleepy face.

[Drawingablank]

I'm not sure how this applies to small generators, but I used to scuba dive with a guy who rented generator trucks for film crews on location.

In a conversation about quietening them so they don't interfere with the filming, he mentioned that its not the exhaust that is the noisy part - but the air intake. His generators had pretty much standard mufflers, but had extensive custom baffling on the intakes.

Although his were large truck mounted units, this may be an avenue worth experimenting with on smaller gennys.

[theCryptofishist]

Anyone else get unholy visions of trapping and keeping people in these?

[GreyCoyote]

Anyone else get unholy visions of trapping and keeping people in these?

"...Shuddap, Mr. Hoffa or it will be curtains instead..."

[TT120]

I'm not sure how this applies to small generators, but I used to scuba dive with a guy who rented generator trucks for film crews on location.

In a conversation about quietening them so they don't interfere with the filming, he mentioned that its not the exhaust that is the noisy part - but the air intake. His generators had pretty much standard mufflers, but had extensive custom baffling on the intakes.

Although his were large truck mounted units, this may be an avenue worth experimenting with on smaller gennys.

This is true. When I raced RC cars, some of the tracks I raced at had noise level restrictions. We had to put baffles on the intakes of our little engines. Made a huge difference.

[Ugly Dougly]

Also you don't need an inverter if you're just powering lights.

[Canoe]

Don't forget the outside of the box.

Build a box or channel it upward, both absorb sound. You want sound dampening materials on both sides of your sound barrier, the receiving side and the transmitting side.
Dampening materials on the inside surface absorb sound and reduce it vibrating the sides of the box, and on the outside of the box they dampen the sound projected.
Put a layer of old carpet on the outside of the box.

[unjonharley]

is a oil bath intake filter enough baffler on a small engine?

[Admiral Fukkit]

I'm here to say the good Hondas are the cheapest!
First, there's everything you just said.
Next, I had a pair for 12 years. They'd been to the equipment-wrecking playa many times, rode hard and put away wet, etc.
They still worked fine, but resale is so high on them I decided to put them up for sale at $700 each. Sure enough, a guy bought both!
That means I paid only a couple hundred dollars to have a pair of the best sets on the market for twelve years!
Then I took my $1400, added $400 to it and ordered myself a fresh brand new pair.
Try that with an irritating, neighbor-infuriating cheap loud one!

[FlyingMonkey]

How did this thread get dredged up from the depths?

I went solar years ago & it's been meeting my needs quite nicely.

[Amedao]

Remember that the main issues with making a good baffle is that it needs to provide proper ventilation and not get too hot.

It's actually pretty hard to absorb sounds with materials. So when you build a baffle, and are trying to block the sound all around, it just isn't that efficient. It's better to reflect or block the sound, which is no doubt why people just put their generators behind a wall-surface to the chagrin of people on the generator-side of the wall.

In that light, something I'd like to try or see someone try is making a parabolic reflector that aims the sound upwards. There's a whole sky of unoccupied space that can absorb the sound. Plus, the reflector being open at the top means that heat can vent out the top as long as there is proper ventilation below (which can be provided via holes), Though the reflector wouldn't have to be perfect, it would need to be relatively large compared to regular baffles, which is a logistical concern. Still, it could look like a nice art piece.

Sooo i'm not an expert or an engineer at all just had thought and throwing it out there... in the hush box you would want baffling foam but your worried about heat and melting. Would the baffling foam still work if you sprayed it down with say a High heat rust O leum that they use for engine blocks? or some kine of reflective metal spray that you can put on it.. (honestly don't know if that is a thing)
The reason for my question was I was because the first thing that popped in my head for a hush box was a dog igloo, and if you took the bottom off and some how closed the big opening on the side and put ventilation in with maybe big fans behind the baffling foam and sprayed the foam so it dosn't melt... then you could pick up and set down this dome over your generator and it would muffle a lot but not all of the noise.. and if you happened to have a dog then you could still potentially use the dog house during the winter months and it would be extra toasty inside.. *shruggs* Like I said <---- not an expert just had a thought
I observed a large dog igloo for around 40-50 on amazon, saw a company selling 12x12x2 12pack for 30 bucks, rattle can of high temp black abyss and some fans a bit of wiring.. all the gluuues... let me know if i'm waaay off

[BBadger]

I think the high-heat paint is more to protect the spray itself from incineration, not the material it's sprayed on. Typically the spray is on metal stoves or BBQs and stuff like that which are already able to radiate enough heat away to not melt. Its purpose is mostly to protect the metal from rusting, not heat.

A dog igloo could possibly melt if too close to the exhaust. With enough space for the exhaust to cool down and waft away it might be okay. I don't know if the foam on the interior would do much good though. It may not absorb that much noise at the low end. The shelter may also rattle, which isn't good. Maybe experiment with it?