Quote Originally Posted by Shedguy View Post
. . . . . Any tips on sound proofing materials , I was thinking I might enclose the dc in a small area and sound proof the walls etc . I see Harvey Norman sell sound proofing panels for home audio systems , anyone know how effective these are ,thanks again Gordon
Sound treatments used for Audio rooms/studios are somewhat different from reducing the amount of noise escaping from a room.
Those corrugate acoustic panels are designed to absorb some sound and scatter sound to reduce echo effects inside a room but the latter is of no benefit to DC noise reduction. Those panels also won't absorb much in the way of low frequencies.

For an external DC system enclosure two main types of materials are useful.
- Dense (heavy) stiff materials will reflect sound back into the enclosure. This is by far the most effective method
- thick layers of still soft material like encapsulated air in a foam or fibre will absorb a small amount of sound as the sound passes through it. This is far less effective unless this material is backed by a dense layer to (re)reflect the sound back thru the material where a bit more sound can be absorbed by the trapped air. To completely absorb the sound requires multiple passes thru the soft material ie it bounces back and forth inside the enclosure.

Use of only dense materials is a problem only if someone has to work inside the enclosure but because no one usually does this in a DC enclosure, the best materials would be concrete (a concrete bunker is VERY effective), lead sheet, brick or lesser blocks (ie all expensive). The next best thing is thick heavy timber (I used 32 mm Melamine on my enclosure - I didn't buy it, but found large pieces of it in a skip outside an office reno), plaster, fibre cement and even chipboard or MDF.

If you have it available - ie don't buy it, then lining the inside with something like an old foam mattress or carpet will help a bit. If you have to buy something then the acoustic rock wool insulation available at bunnings is as good as anything but it will need to be sandwiched between something. Foam or carpet does not need to be sandwiched.

My enclosure has Colourbond exterior cladding over a 32 mm melamine. then comes a 50mm regular rock wool insulation sandwiched by 16 mm MDF. The front of the enclosure is 3 Large doors on removable hinges. - Colorbond, Melamine and 100 mm of foam - they weigh about 45kg each.

In practice even a shed metal garden shed will produce some reduction and for some members here that is all they have. One thing to remember is that most small metal sheds are pretty "drummy" so some stiffening is usually required this can often be done by adding wooden cross bracing. Also don't forget to treat the ceiling the same way as the walls.

One thing not to rely on are ears to assess noise reduction as they are too insensitive to small changes in sound pressure levels (SPLs). Apps that measure SPL are readily available - to learn how to use then look here DRAFT: FAQ - Dust Extraction (Practical Aspects)

Significant gains in noise reduction can usually be quickly obtained (ie a sheet metal or fibre cement enclosure clad internally with carpet may get you far enough) but to progressively reduce sound levels becomes much harder and more expensive. I have a very fussy neighbour and didn't stop until my DC noise emissions were quieter than his pool pump at the fence line.