Cabinet building: Internal Padding Yes Or No?

Discussion in 'Amps and Cabs [BG]' started by MudgBass, Oct 27, 2003.

  1. MudgBass


    Oct 21, 2003
    Im currently cutting down my 2-15 cabinet and fabricting 1-15 and a 2-10 out of it. My question is should I use internal padding for it. It started out with what looked like regular insulation in it. I re-did it with carpet sub floor padding, now Im questioning whether it actually serves a purpose. This isnt a B.S. question.
  2. i think it serves a purpose dont destroy eveything
  3. embellisher

    embellisher Holy Ghost filled Bass Player Staff Member Supporting Member

    I'm sure that some of our experienced cabinet builders in the Amps forum can answer this. I am moving it over there, since that is where these type of threads belong.
  4. xyllion

    xyllion Commercial User

    Jan 14, 2003
    San Jose, CA, USA
    Owner, Looperlative Audio Products
    I'm no expert but sound absortion material makes the cabinet behave as if it were a larger box. Generally some sort of fiber fill is used for this purpose. I'm not sure how well carpet padding will work. I suspect not well at all.

    The other problem that you have is to find drivers with appropriate specs to match your box. Drivers don't work well at all if not matched to the right size box.
  5. Rules of thumb for stuffing cabs:

    -closed or ported subwoofer: no stuffing. Low frequencies will go through everything
    -ported full range: pad all walls with wegde moulded polyether foam to suppress standing waves (resonances)
    -closed cab: stuff entire cabinet loosely with polyester BAF wadding to suppress standing waves and increase the effective internal box volume. This does NOT work for ported cabinets.

    Always make sure cones can move free, even after years of (ab)use

    Keep at least 5 inches away from internal port openings.

    Carpet is bad. Soft wadding is good for stuffing, wegde foam is good for wall padding.

    All the advice above was mostly taken from "the loudspeaker design cookbook" by Vance Dickason. A must read for anyone even loosely thinking about building a cabinet.

    I hope this helps.
  6. Petebass


    Dec 22, 2002
    QLD Australia
    What Joris said!
  7. NeedMoreBass

    NeedMoreBass unregistered

    Feb 14, 2003
  8. jdombrow

    jdombrow Supporting Member

    Jan 16, 2002
    Colorado Springs, CO
    One thing to keep in mind - just because it's soft doesn't mean it's good for cabinet damping. Many cabinets are lined with fiberglass for one reason; because it works (acoustically). There are other materials that work well also, but they have been well researched and tested. As someone suggested, do some reading. Although some foam works well in acoustic applications, don't assume any foam works well.

    And I strongly agree with "xyllion" about choosing the right drivers and cabinets sizes. You need to understand the theory and specs before building a box.
  9. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    Also keep in mind that mineral wool can affect your health.
  10. cjgallen


    Oct 19, 2001
    I have a mini 15 cab that has no padding at all. Would this stuff be adequate?
    I was also thinking of repadding my Avatar 2x10. It's got flat pads of some sort in there now. Would this foam make any noticeable improvement?
  11. jani_bjorklund


    May 22, 2002
    It's allways good to use som sort of padding in basscabins. Padding the cab prevents it from sounding "boomy".
  12. xyllion

    xyllion Commercial User

    Jan 14, 2003
    San Jose, CA, USA
    Owner, Looperlative Audio Products
    I don't agree. I've only ever built one speaker cab, but I found that I didn't need any sort of padding to get a good sound. Mind you, it wasn't my goal to create a super accurate cab. I went into the project figuring that I'd make a small cab that I could practice through.

    With that in mind, I built a cab with two chambers. The first chamber houses a 10" JBL speaker and the second chamber houses a 5.5" midrange driver. I have a port on the 10" driver and the midrange driver is in a sealed chamber.

    When I started that project, I was thinking that I'd probably have to put fiber fill in, but it didn't turn out to be necessary.

    Of course, every project is different. I agree with everyone that has refered you to reading "the" book.
  13. "boomy" sound is usually due to poor tuning.

    The sound alteration caused by padding could be described as "less nasal" or "darker"
  14. notanaggie

    notanaggie Guest

    Sep 30, 2003
    Two reasons for "padding"

    1) A layer on the inside of the box tends to reduce the higher frequencies coming off the back of the speaker so they don't bounce and come out thru the cone and muddy up the sound.

    2) A full stuffing of appropriate material like fiberglass does increase the apparent cabinet size. (Adiabatic vs isothermal compression....)
    Or it can give the same effect at a somewhat smaller volume.

    You need to take the stuffing into account in figuring the box size.

    Caution: If you use the fibery stuff that is white or blue etc, and seems like solidified pocket lint... its flammable, and if your cab has a tweeter and a lightbulb limiter, the bulb can start it smoldering ... keep it away.
  15. basss

    basss Supporting Member

    Aug 27, 2001
    Would egg crate foam work good for lining speaker walls? I just happen to have some lying around. It looks like this:
  16. ESP-LTD


    Sep 9, 2001
    I have used it in a few cabs without any problems, but I can't say how it compares to other products. I'd guess it does fine for controlling reflected highs, but is somewhat less effective at increasing effective cabinet volume.
  17. That's the stuff I always use with ported cabinets. Closed cabs require a different approach, as said in my first post.
  18. rossco

    rossco Unregistered

    Mar 8, 2003
    One approach which we use is to destroy the internal parallel and perpendicular alignment of the enclosure*** does he mean????.......simple really, the whole issue here is about standing waves and what happens when they join and multiply. This is basically what happens in any box structure such as a cab. One way to get arround this is the to use the ratio of 1:1.6:2.6 when working out the size of the box.......

    Trouble is often the 'ideal' is far from ideal when it comes to picking it up or just living with it.......

    A third way to stop the old standing waves is to do what I said at the beginning and make the intenals of the box as far from parallel and perpendicular as possible......ok so that doesn't mean we build trapezoidal boxes (although we have) it just means fitting a baffle inside the cab which sits at different angles to each internal face. The effect is to limit the build up of standing waves to the point where they become irrelevant......if you do this though make sure there are some large circular holes in it to allow for correct air movement throught the box........ok so now i'm as confused as the rest of you.....

    Goodnight and thanks for coming

    Rossco......ex-pro cab builder :bawl: