MM 840 Sub

alaska_av8r Posts: 2
edited May 2013 in Car Subwoofer Talk
What is the recommended box size for the MM840? Is it the 0.54 cubic ft VAS value? Also is this a ported box and ssealed?
Post edited by alaska_av8r on


  • custopper30
    custopper30 Posts: 252
    edited May 2013
    ported will be better for air movement, as for the size I would not know to be exact.
    Receiver: Denon 1912
    Fronts: Polk Audio Monitor 70s (x2)
    Rears: Polk Audio Monitor 50 (x2)
    Center: Polk Audio Monitor 70
    KLH Sub GFX-550
  • docjl
    docjl Posts: 41
    Pretty sure it is .33 cu ft. I have 2 of these, in .33 cu ft sealed boxes I picked up from Crutchfield. I think the brand is Sound Ordinance - they were pretty cheap, not real heavy duty but for 8" subs they don't need to be.
  • Mine are in separate .33 cu ft boxes. One is stuffed with poly while the other is not. In my opinion, Polk states .33 as people want more in less space. The sub in the stuffed box hits deeper notes than the other, thus confirming a bigger box is achievable for better bass. They can be in bigger boxes. I plan to build .50 boxes for them this next week. BTW, does anyone have any info on ported dimensions? I would like to build a ported box and see what one sounds like.
  • docjl
    docjl Posts: 41
    Agree, prob MOST manufacturers do this, esp with subs that are designed and marketed to work best in small sealed boxes. I use polifill in ALL of my subs, it only costs a couple bucks and takes an extra minute to place. I also take the time on prefab boxes to caulk the insides on all seams and around the inside surfaces of the binding posts - again, just takes a couple of minutes to insure everything is sealed well.

    Let us know how your project turns out. Personally never been a fan of ported subs.
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