I want to, first, thank everyone for your suggestions, even for the ones that I did not adopt. All of your ideas were valuable to me. I cannot literally think of even one post which did not have some bit of useful info or food for thought.
I am almost at the end of the work of making a generator enclosure and soundproofing it. I bought lead sheet and attached it to plywood panels. I need (and can) do a better job at sealing all holes and in fact on one side I have not even completed the enclosure.
I ran the generator today.
Despite this incompleteness, the enclosure appreciably reduces the noise. At 10 feet, with the access door open, the noise is 85 dB. With the access door closed, it is 79-80 dB. It also feels rather tolerable to be around this working genset. I would not mind it working all day long. It is much quieter than, say, my snowblower (87-89 dB).
Another good news is that, perhaps due to its weight as well as vibration isolation by two used tires, the enclosure basically does not vibrate.
I have hopes that when I am really done with this work -- have fewer and smaller and baffled gaps and openings etc -- I can slash 3 or so decibels from this, bringing noise down to sensible 76-77 dB.
The enclosure's panels are held by wingnuts and it is designed for very quick disassembly, because it is relatively heavy.
Plans:
- Finish the opening for cooling air intake and seal gaps better.
- Weatherproof the enclosure, I will use epoxy on top and oil based deck stain on the sides (to match the deck and shed nearby).
- Finish the electrical panel. I will make it based on a 12x24 1.5 mm thick aluminum sheet that I bought at Menards. The current electrical panel will be junked. The new one will have numerous gauges, a ON/OFF switch, and easy access to connect the power cable.
- Make a foundation from 2x2' patio blocks.
- Install the genset on it.
- Install transfer switch of some sort.
Thanks to all!
i