sealed cabinet; should it be totally air-tight?

Options
nadams
nadams Posts: 5,877
edited October 2004 in Vintage Speakers
On Polk's sealed cabinet speakers, should they be totally air-tight? On both of my Monitor 10's, if I push the PR in, the active drivers will push out, but then slowly go back to their resting position. If I then let go of the PR, the active drivers will pull in, and slowly return to resting.

Is this the way they're supposed to be? Or could the seals around the speakers be wearing out?
Ludicrous gibs!
Post edited by nadams on
· Share on FacebookShare on Twitter

Comments

  • madmax
    madmax Posts: 12,434
    edited October 2004
    Options
    No. I believe air escapes through the speaker cones over time anyway. So long as air leaks slowly enough the drivers won't notice the leak. A good example was a car sub box (2 drivers in a single box) I had one time. Every effort was made to seal it even though it really doesn't matter. In the end you could push one in, the other one came out then slowly sank back in.
    madmax
    Vinyl, the final frontier...

    Avantgarde horns, 300b tubes, thats the kinda crap I want... :D
    · Share on FacebookShare on Twitter
  • Tour2ma
    Tour2ma Posts: 10,177
    edited October 2004
    Options
    Interesting question...

    max,
    I am sure some materials are air permeable to some extent, but not be so porous that a sizable leak occurs in seconds (which is what I read into nadams' observations).

    With all externally removable parts, e.g., drivers, gasketed and all wood/ MDF joints glued (I presume), a good seal is certainly the goal. Is the goal a perfect seal? I doubt it, but a "practically perfect seal" would seem a resonable goal...

    minutes later...
    Just checked my SRS's and...
    Pushing and holding the PR produced an immediate thrusting out of all MW's followed almost immediately by the MW's retreating about half-way back to their "resting" position.

    Held the PR in for 30 seconds and the MW's stayed at half-way point until I released the PR. At release the MW's returnde to their resting position, they did not "suck in " as nadams described. This indicates a pretty damn good seal.

    Maybe the MW's retreat is just giving back the momentum they had being thrust out???

    more minutes later...
    Just checked my 10's and much less MW "retreat", although I saw a little. The 10's seemed tighter to me...

    Need Matt or Stu in on this....
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "Death doesn't come with a Uhaul." - Dennis Gardner
    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
    · Share on FacebookShare on Twitter
  • tryrrthg
    tryrrthg Posts: 1,896
    edited October 2004
    Options
    For sealed subwoofers my understanding is that you want absolutely NO air leaks. Air leaks could cause nasty "farts" (as some people call them). I believe an air leak in a sealed cabinet would cause similar results at port chuffing - not enough "breathing room" I would imagine the same would hold true for sealed speakers...
    Sony KDL-40V2500 HDTV, Rotel RSX-1067 Receiver, Sony BDP-S550 Blu-ray, Slim Devices Squeezebox, Polk RTi6, CSi3 & R15, DIY sub with Atlas 15
    · Share on FacebookShare on Twitter
  • nadams
    nadams Posts: 5,877
    edited October 2004
    Options
    Good information, everyone. I think that what I'm seeing would not effect sound too much. A quick bass beat would be over before too much air would be able to escape. When I get home, I'll check to see if they go all the way back to their resting position or not.
    Ludicrous gibs!
    · Share on FacebookShare on Twitter
  • madmax
    madmax Posts: 12,434
    edited October 2004
    Options
    Originally posted by Tour2ma
    Interesting question...

    max,
    I am sure some materials are air permeable to some extent, but not be so porous that a sizable leak occurs in seconds (which is what I read into nadams' observations).


    Well, thanks for correcting me again. I'll leave it up to you guys.
    madmax


    Edit: you may want to check and see what type of coil cooling system your particular drivers have. Many pull air from one side of the cone, usually the front, across the coil and exit the air at the back. The more the cone moves the more air is pumped over the coil.
    Vinyl, the final frontier...

    Avantgarde horns, 300b tubes, thats the kinda crap I want... :D
    · Share on FacebookShare on Twitter
  • George Grand
    George Grand Posts: 12,258
    edited October 2004
    Options
    A certain amount of air leak is expected, and not harmful to the sound of sealed-box systems.

    George Grand (of the Jersey Grands)
    · Share on FacebookShare on Twitter
  • RuSsMaN
    RuSsMaN Posts: 17,987
    edited October 2004
    Options
    Maybe they need the fluid checked and refilled, since they are fluid-coupled speakers.

    Cheers,
    Russ
    Check your lips at the door woman. Shake your hips like battleships. Yeah, all the white girls trip when I sing at Sunday service.
    · Share on FacebookShare on Twitter
  • madmax
    madmax Posts: 12,434
    edited October 2004
    Options
    If you turn them upside down the ferro-fluid will leak out. :eek:
    Vinyl, the final frontier...

    Avantgarde horns, 300b tubes, thats the kinda crap I want... :D
    · Share on FacebookShare on Twitter
  • Tour2ma
    Tour2ma Posts: 10,177
    edited October 2004
    Options
    max,
    My apologies for tweeking your beak above... Went into my full-blown analytical mode, which forces the limited sensitivity I posess out the window.

    Actually followed up on this with Polk Paul this past weekend, and the seal should be substantially air tight, but perfect is not required. Per Paul, unless there's an obvious tear in an MW/ PR surround, the tweeter is a more likely escape route.
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "Death doesn't come with a Uhaul." - Dennis Gardner
    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
    · Share on FacebookShare on Twitter
  • nadams
    nadams Posts: 5,877
    edited October 2004
    Options
    Thanks, tour!
    Ludicrous gibs!
    · Share on FacebookShare on Twitter
  • Tour2ma
    Tour2ma Posts: 10,177
    edited October 2004
    Options
    U B Welcome...
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "Death doesn't come with a Uhaul." - Dennis Gardner
    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
    · Share on FacebookShare on Twitter