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-   -   Generator sound reduction? (http://www.airforums.com/forums/f448/generator-sound-reduction-99396.html)

AldeanFan 12-11-2012 07:09 PM

Generator sound reduction?
 
I've been thinking about generators recently, and the Honda 3000 or two 2000's I want are out of my price range right now.
We only need a generator for race weekends and music festivals and that's only 2-3 weekends a year. My father has a 4000w generator we can borrow for free, but it's really noisy, and if I can't stand the noise my neighbours must really hate it, unless they have a louder generator than i do:rolleyes:

As a temporary solution I've been thinking of building soundproofing box/wall to partially surround the generator and cut off the sound.
I was thinking about using foam board insulation with a 1/4" plywood backing for strength on the outside and the foil backed insulation on the inside to avoid too much heat on the foam. I have most of these things at the house left over from renovations. I would surround the generator on 2 or three sides and no top so the generator would get lots of air flow.

I think this would significantly cut down on the sound or atleast direct it away from me and my neighbours.

Any thoughts?

nilesrob 12-11-2012 07:25 PM

My recommendation - save your time and money. I have never seen sound reduction for noisy generators that made a particle of difference; sorry.

dwightdi 12-11-2012 07:27 PM

To be effective, the box should have an open cell foam lining to absorb the sound. Most of the noise is fairly high frequency, so 1/2 inch plywood would be stiff enough not to resonate. A closed top would also help. An air entry and exit on opposite ends, using a baffled foam lined path would prevent the sound from directly radiating to the surroundings. The box does not need to have a bottom. It is essentially a sound absorbing cover for the generator.

TBRich 12-11-2012 07:54 PM

I'm with nilesrob...I'd not waste my time or money and look for a good used 2000w or 3000w Honda generator. If you are patient and act quickly you'll find one. Also check your local equipment rental places...they sometimes sell used generators...friends of ours got one that way at a very good price...

Colin H 12-11-2012 08:17 PM

Quote:

Originally Posted by AldeanFan (Post 1237210)
I've been thinking about generators recently, and the Honda 3000 or two 2000's I want are out of my price range right now.
We only need a generator for race weekends and music festivals and that's only 2-3 weekends a year. My father has a 4000w generator we can borrow for free, but it's really noisy, and if I can't stand the noise my neighbours must really hate it, unless they have a louder generator than i do:rolleyes:

As a temporary solution I've been thinking of building soundproofing box/wall to partially surround the generator and cut off the sound.
I was thinking about using foam board insulation with a 1/4" plywood backing for strength on the outside and the foil backed insulation on the inside to avoid too much heat on the foam. I have most of these things at the house left over from renovations. I would surround the generator on 2 or three sides and no top so the generator would get lots of air flow.

I think this would significantly cut down on the sound or atleast direct it away from me and my neighbours.

Any thoughts?

Years ago when I was heavily involved in car racing, a buddy added a muffler from a 60's era Austin Mini to a cheap generator, & it made a huge difference to the noise level. The mufflers are really cheap & the inlet & outlet are about an inch in diameter. Keep in mind that the original Mini's were only 850 cc's. I'm sure you can chase one down online somewhere as there is a big following of the original mini's.
Good luck,
Colin

dznf0g 12-11-2012 08:28 PM

There are all sorts of "stuff" on the web about attempts with building boxes, adding mufflers...on and on..... Search and you will eventually come to the conclusion that you can't reproduce building an engine and muffler system which has a design parameter to noise reduction. It is a "clean sheet" design requirement that can't be reproduced.

This is one of those areas where one of our members here is correct in their signature line. (paraphrased)

"spend the bucks and do it right the first time".

BTW, I now own a total of 5 generators on the journey to this conclusion.....

SteveH 12-11-2012 08:54 PM

I've got a Boliy 3600, and it's pretty noisy. But, if I run it in the back of my truck with a bed mat and a camper shell, close the tailgate, and the back glass, from about 20 ft away, it's pretty quiet.

However, it only runs for about 15 minutes and then shuts down on high temp. :rolleyes:

mefly2 12-12-2012 09:09 AM

You can do it, but is it worth the effort for limited use ... suggest: rent / borrow a quieter gen ...

Protagonist 12-12-2012 11:06 AM

Simplest things you can do to minimize the disruption to your neighbors:
1 - Place the generator as far from them as you can. If you can double the distance, you reduce the perceived decibels by 6.
2 - Point the exhaust directly away from the neighbors. It's the main noise producer, and noise levels will be loudest in a direct line from the exhaust.
3 - Place a large solid object between the generator and your neighbors. An Airstream or a tow vehicle is a good choice, since you already have one. Sound that has to go around a solid object has to travel a longer distance than sound traveling in a straight line, so see item 1 above.
4 - Make sure the generator is sitting on a grassy surface, not in the back of a truck, not on concrete or anything else that transmits vibrations easily.

So far, these steps have cost nothing but a little effort.

If you really want to go the box route, let me suggest this: Make a plywood box, with a top, three sides, and no bottom. The open side of the box faces the exhaust pipe to minimize the chance of fire. The box should be as big as you can make it, to allow adequare airflow around the generator. Supplement the airflow with a fan, if necessary.

Cover the inside surfaces of the box with plush carpet. With the foam backing, if possible. There are more efficient sound insulators than carpet, but you should be able to scrounge carpet remnants cheap. Make sure the carpet is tacked securely against the box so it won't sag onto the generator and start a fire.

Then, when you set up, follow the guidelines I outlined above. You still want the exhaust facing away from the neighbors, etc.

crisen 12-12-2012 11:25 AM

Quote:

Originally Posted by SteveH (Post 1237244)
I've got a Boliy 3600, and it's pretty noisy. But, if I run it in the back of my truck with a bed mat and a camper shell, close the tailgate, and the back glass, from about 20 ft away, it's pretty quiet.

However, it only runs for about 15 minutes and then shuts down on high temp. :rolleyes:

Over temp is even more of an issue inside an insulated box, they are aircooled afterall.

SteveH 12-12-2012 11:28 AM

Quote:

Originally Posted by crisen (Post 1237396)
Over temp is even more of an issue inside an insulated box, they are aircooled afterall.

I'm sorry so many people don't understand my attempts at humor. :blush:

crisen 12-12-2012 11:46 AM

Quote:

Originally Posted by SteveH (Post 1237398)
I'm sorry so many people don't understand my attempts at humor. :blush:


Your right I'd didn't understand you were trying to be funny. I just thought you were pointing out a valid issue. Trying to put an aircooled engine inside a box is a problem if you want it and the electrical componets on the generator to live and be happy.

AldeanFan 12-12-2012 12:54 PM

Thanks for the feedback, I had been thinking this over for a while and figured the idea would be beat up pretty good here.

So after I posted last night I checked Kijiji classifieds, and found a pair of Honda 2000's about 30min from home for a great price. I'm going tomorrow after work to buy them!

So much for my redneck foam and carpet generator soundproofing, it's Honda Time!:D

Protagonist 12-12-2012 12:57 PM

Quote:

Originally Posted by AldeanFan (Post 1237418)
So much for my redneck foam and carpet generator soundproofing, it's Honda Time!:D

That's for the best.


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