On another forum, I responded to a chap who asked how to reduce even more, the DB's from his use of his portable invertor generator. I responded with the following:
You can build a sound box...or (and this is so easy) you buy a large aluminum garbage pail/can, one that you'd throw your street side plastic garbage bags into. Cut the bottom out, and leave a 2 inch rim of the just cut out bottom (for integrity) Then, you glue pink insulation wrap to the inside walls, and you'd place this entire round garbage can on top and over your portable generator. This will take 20 to 30 DB right out of the mix. KEEP THE LID...for you can NOT run this generator (or any other portable generator) in open wet/raining conditions. Right in the Owner's Manual which will void the warranty.
BEFORE you do ANYTHING to try and run your brand new invertor generator----read the ENTIRE Owner's Operating Manual---FIRST! For instance, I wanted to run my 1706FB's 13,500 BTU A.C. as my first ever test...****NOT***! In reading my entire Owners Manual, Firman specifically states NOT to run more than 50 percent load capacity for the first five hours of break-in! I could have crippled and/or outright damaged my new generator, by firing it up with the most heavy load it will see...starting and running the 13,500 BTU roof air.
Glad that I am not like most males...I actually RTFM!
Cheers n' Beers!
So...if it starts to rain, or is threating to rain that day, you would place the garbage top lid over the top of the open upside down garbage can. The rain will hit the lid and shed right off, leaving the Firman running and totally dry. The Firman 3650iR was designed to operate at the top end of the heat range (ambient air temp) ***at 104 F***, so you will not harm or overheat the Firman while it is in the sound box (your modified metal garbage can)!!!! Also, out of sight, out of mind, even if there is some noise coming from the upside down metal garbage can. Do this, and you will have a very pleasant usage experience amongst other campers, as well as being able to run it no matter what the weather turns out to be. Again...and nobody on any of these vids talks about it...you can NOT run these generators in open rain! You will kill them....for they are NOT ***100 %***WATERPROOF,
and designed to run under rain showers, or being cleaned by a spray from your hose.... If the metal garbage can does not turn your crank, merely create your own sound box design. Make sure that in your own design, that heated atmosphere inside your sound box, can escape. Also, you can add three small blocks of green treated wood blocks, to elevate the bottom of the upside down garbage can, so air can be drawn in by the chimney effect of the heated air escaping from the cut out top hole. You'd only need to raise it 1/2 to 1 inch off the ground, so as not to allow too large a gap that would somewhat defeat the insulating sound cushioning effect being created here.