Noise Suppression

How about a detached but well ventilated shed?

How often do you need to produce power yourself? If you're well off the grid, then a permanent installation maybe precisely what you need.

I have seen do it yourself solutions that have worked well...

http://joelsgarage.blogspot.com/2006/03/quiet-generator-muffler.html

http://www.alpharubicon.com/altenergy/gensetquiet.htm

My two cents worth:

If stationary, either approach will work, but the "big" muffler will be cheaper.

I like the add-on mufflers, if properly braced.

An additional thought, sound decays as the square of distance, so the higher the muffler OUTLET is above your head the quieter it will be. Pointing it "up" will allow the sound to disperse equally in all directions.

In the late 80's I worked on the development of:

Active noise control - Wikipedia, the free encyclopedia
Cool, but pricey.

You can make it as quiet as you wish. The whisper diesel compressors do this with a very very large rigid muffler with internal baffles. I believe is is a casting. This stops the walls of your muffler from becoming a sounding boar, this muffler is also a lot longer and it has flow dividers and combiners with multiple different paths so there is a degree of cancellation - they make them tuned to attenuate their most efficient running speed and try to run it there. In addition, the engine is also externally muffled with multiple hard shells with fiberglass liners to prevent direct coupled block noise. This has an cost if efficiency, perhaps 5% is lost to the muffler and baffling - perhaps more.

Remember though, this is a heat engine and cooling is needed, a muffled shrouded engine will run hotter = shorter life?? Possibly the use of synthetic oil will extend the life of the engine?

A lot of the noise is produced by the engine itself and not the exhaust.

If you run it inside the confines of a roofless enclosure then you won't hear it so much. Unless you are on the roof of your house.

This could be as simple as hay bails stacked around it or between the genset and the place you want quieter.

See how an after market muffler works if you like. A length of ordinary pipe also muffles to some extent.

I solved that problem on a noisy garden tractor. Selected a larger, generator muffler, that I could fit on the top of its cheap muffler by bolting thru it. Problem solved. I also pointed the exhaust up and away from me. Much of the low rumble remained, but the high pitched, disturbing part was very well dampened. Loud conversation was possible, when it was running, ad I was sitting on it.

I've had great success by enclosing a similar unit inside a 1m cube made from flooring grade particle board, lined with rock wool. There was a lined, baffled path (~3m) for cooling air and a large fan to force the air through

I also fitted an over temperature switch it would shutdown if anything went wrong.

The quietest diesel Genny I came across was on a trailer built reception unit for Marlboro Mclaren, I was fitting out the kitchen and whilst working I was told that the engineers were going to test the Genny, I was standing right over where the Genny was and all I could feel or hear was a slight vibration under my feet, no sound whatsoever,needless to say I had a good look at it,It was built into a sound proof box slung under the back of the chassis, The Genny was then mounted on a rubber mounted sliding platform,(to facilliate maintenance), It had a big fan attatched to the front, when shut & running the fan drew air in from underneath & blew it out through a grill on the side,the exhaust went through a silencer attatched to the engine,(so it slid in & out with the genny) & was vented in to the box & because of the amount of air pulled through with the fan you could stand by the outlet grill & not see any smoke or smell any fumes. this was a 27Kw unit. You could do somthing simular, if its in a garage against a wall exhaust it through the wall, suck the intake air from inside the garage if it's too air tight put some vents in the doors,

Bazzer