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Soundproofing/Electrical Isolation

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  • Soundproofing/Electrical Isolation

    Soundproofing is not something I ever spent much time focusing on; usually, the concern is acoustics and behavior of the system in the room. But I needed to do something to quiet the sound of my air compressor- I used to hear the small one and now that I supersized, it is annoying to hear it kick on and cycle. It is in an adjacent small room- more like a big walk-in closet where I keep some extra records, tools and miscellany for the system.
    I bought some mass loaded vinyl (MLV) and ran some 1" x 3" vertical wood strips along the relevant walls inside the closet. like studs, but I'm not tearing out any sheetrock. I'm now waiting for the MLV to arrive. I also bought an industrial acoustic 'blanket' which did arrive, and I hung it on the largest wall in the closet- the one facing the listening area. That alone has made a huge difference. I also filled the several cable-pass throughs with melamine foam--e.g. the same stuff that is Magic Eraser- it was first developed as an acoustic treatment and is easily cut to fit snug into smaller spaces- it is pretty dense, too. Even without the MLV mounted yet, the compressor noise, when cycling, has abated considerably. I haven't gone crazy, because our plan is to get out of this house, so no major investments in more 'infrastructure.' But the MLV is interesting since it forms a pretty effective barrier for its weight and I may consider using it when I do a build out in Texas. I know folks use double sheetrock, perhaps with something in between. This MLV functions like a membrane that is very dense while not rigid- it is nailed in between studs and is flexible. So, the sound wave hits it and theoretically just drops, rather than rebounding. First I've explored this, so perhaps I'm telling you something you already know.

    As an aside, I also did an experiment with a non-audiophile isolation transformer. I have a big assed transformer across the room- runs from 240v outlet and was the only thing that eliminated the nasty electrical 'snap' of the compressor motor through the system when the compressor motor cycled. When I replaced compressors and went from a small one to an oversized one with two motors, the load was actually causing the fuses on the 240 v step down to melt. Reason- I had to run a long heavy duty extension from the compressor to that step-down, given the its location (due to the 240 v outlet) across the room. The voltage loss over that distance also meant I was drawing some serious current. So, I contemplated having an electrician convert one of my dedicated lines to 240 or running another line right next to the compressor. I found a simpler solution. I have an extra 20 amp 120 line, and bought a medical grade isolation transformer- smaller than big one, but sufficient. (Also, since it is not a permanent installation, I can take it with me and use it elsewhere). It has a 20 amp NEMA plug, and it went into the dedicated line closest to the compressor closet. It does an excellent job of isolating the compressor motor from the system, electrically, and was far cheaper than an "audiophile grade" product. Built pretty well, too, since it is apparently designed for medical apparatus.

  • #2
    First, let me tell you that MLV is some heavy stuff. Apparently, in the old days, lead was used as shielding for, among other things, noise. Well, they may have improved things with plastics, but they certainly didn't make it much lighter in weight. The other thing is, this stuff is really meant for inside a wall while you are doing construction. I'm not tearing out existing sheetrock, so aside from mounting it effectively, you then need another 'layer' of something on top of it--it is too reflective. One wall now has panels of MLV behind a heavy acoustic blanket (Singer Safety, which makes all kinds of sound and safety barrier products for industry). That works fine. Mounting naked, not good.


    • #3
      Myles B. Astor, PhD, Administrator
      Senior Editor,

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      • Bill Hart
        Bill Hart commented
        Editing a comment
        Right now, not very pretty. Maybe when I get done.