insulation

Discussion in 'Home Theater Projects' started by MikeHeath, May 23, 2003.

  1. MikeHeath

    MikeHeath Extra

    Joined:
    Jan 21, 2003
    Messages:
    23
    Likes Received:
    0
    Trophy Points:
    0
    is sound insulation in an enclosure neccassary? What thickness and how much do you use? What are the pro's in doing it?

    Thanks
     
  2. Chris Tsutsui

    Chris Tsutsui Screenwriter

    Joined:
    Feb 1, 2002
    Messages:
    1,865
    Likes Received:
    0
    Trophy Points:
    0
    I think it's necessary for most loudspeakers.

    Damping, isolation, and absorption are the key factors in the liner.

    The thickness depends on what type of material you use such as that duplex, egg crate foam, blackhole5, or lining it with fiberglass or polyester. I'd say generally no more than an inch.

    Some pros are it absorbs vibrations, and reflected sounds in the enclosure and reduces standing waves that can cause distortion. It basically improves sound quality.

    In a subwoofer, lining the walls has much lesser of an effect because the lower frequencies cannot be absorbed as easily. Some people use polyester fiber fill (stuffing) in subwoofers to affect the sound. I do know that people line the walls of their subs with things like egg crate foam, and even vibration dampeners, but I don't know why. [​IMG]
     
  3. ThomasW

    ThomasW Cinematographer

    Joined:
    Nov 6, 1999
    Messages:
    2,282
    Likes Received:
    0
    Trophy Points:
    0
    Damping serves two purposes.

    1)absorbs higher frequencies
    2)makes the box appear 'larger' to the speaker
     
  4. MikeHeath

    MikeHeath Extra

    Joined:
    Jan 21, 2003
    Messages:
    23
    Likes Received:
    0
    Trophy Points:
    0
    if it makes the box appear larger, would that not affect my calculaions to acheive the desired frequency. I made the box accordin to researching calculations and did not put insulation in mind, how much will it affect the outcome?
     
  5. ThomasW

    ThomasW Cinematographer

    Joined:
    Nov 6, 1999
    Messages:
    2,282
    Likes Received:
    0
    Trophy Points:
    0
    Most speaker dseign programs have the ability to model differing fill levels.

    HERE'S a link that might be useful
     
  6. MikeHeath

    MikeHeath Extra

    Joined:
    Jan 21, 2003
    Messages:
    23
    Likes Received:
    0
    Trophy Points:
    0
    okay, so the question is, to insulate or not to insulate....

    my box is 1.82^3(ported). that is what I wanted it to be. So I should not stuff it than? If I do the volume increases, that is not what I want right? What about the advantages it gives like absorbing higher frequencies, do I want it for that?

    Some people say do , some don't.

    I guess there is no for sure answer

    Thanks for all help
     
  7. ThomasW

    ThomasW Cinematographer

    Joined:
    Nov 6, 1999
    Messages:
    2,282
    Likes Received:
    0
    Trophy Points:
    0
    Mike

    There is no question.

    Use insulation it improves the sound of any box. Yes you want to absorb the higher frequencies.
     
  8. Rob Formica

    Rob Formica Stunt Coordinator

    Joined:
    Feb 20, 2003
    Messages:
    225
    Likes Received:
    0
    Trophy Points:
    0
    Thanks for the link Thomas ... i had seen that page many moons ago but bookmarked it this time around... [​IMG]

    I use WinISD pro... there doesn't seem to be a fill option? Do you know if it can model it?

    Or should i just build my box smaller according to Tom N. list in the link?
     
  9. Todd Nichols

    Todd Nichols Auditioning

    Joined:
    May 11, 2003
    Messages:
    10
    Likes Received:
    0
    Trophy Points:
    0
    Is there anything out there that is similar to Blackhole 5, but does not cost an arm and a leg? I want to use it for some AV1's, but can't see spending that much on some insulation.

    Thanks
     
  10. ThomasW

    ThomasW Cinematographer

    Joined:
    Nov 6, 1999
    Messages:
    2,282
    Likes Received:
    0
    Trophy Points:
    0
    Viscous membrane sheets are really beneficial for damping 'live' surfaces like sheet metal/fiberglass/etc

    There are generic sheets like Blackhole (Parts Express sells them) but IMO poly or acoustical foam is just as good. Acoustical felt is the finest damping material available (note that it's quite expensive)

    I've never used WinISD so I can't comment...

    Build the box according to what the program says, don't try to compensate for the damping with changes in the box size. Then fine tune the performance with damping material.

    For ported designs I line the enclosure with a layer of foam or acoustical felt. For sealed designs I use .5-1.5 lbs of fill/cu ft. Then for either design, I add additional damping a few onces at a time. Everytime the bass will get tighter. When the bass no longer gets tighter, but only the overall output level drops, fall back to the previous amount.
     

Share This Page