Ported to Sealed...would this work?

I recently scored a small Martin Logan ported sub which I may try out in the hi fi rig. Would it work better as a sealed sub for music if I plugged the 2 small ports in the back? Or....would this just sound like crap....

Comments

  • F1nutF1nut Posts: 37,360
    Some ported subs can be plugged (they come with plugs) and some shouldn't be. In your case, check with ML to see if it can be before doing it.
  • pitdogg2pitdogg2 Posts: 6,612
    F1nut wrote: »
    Some ported subs can be plugged (they come with plugs) and some shouldn't be.

    Agree some wooofers need the free flow. My old sub I plugged the port with a Nerf ball. That poor woofer dimpled badly every time on the push out.

  • BlueFoxBlueFox Posts: 8,967
    For those with sealed woofers adding an air hole will make a difference.
  • mdaudioguymdaudioguy Posts: 3,900
    BlueFox wrote: »
    For those with sealed woofers adding an air hole will make a difference.

    Yep, and you can charge your iPhone in the microwave.
  • F1nutF1nut Posts: 37,360
    BlueFox wrote: »
    For those with sealed woofers adding an air hole will make a difference.

    Only if it's a cardboard box.
  • tonybtonyb Posts: 27,218
    kevhed72 wrote: »
    I recently scored a small Martin Logan ported sub which I may try out in the hi fi rig. Would it work better as a sealed sub for music if I plugged the 2 small ports in the back? Or....would this just sound like crap....

    Check with ML as already suggested. Some subs yeah you can plug some ports and normally they come with those plugs but I never heard of plugging ALL the ports. To me that goes against the design of the sub and might cause some damage.
  • mhardy6647mhardy6647 Posts: 13,913
    mdaudioguy wrote: »
    BlueFox wrote: »
    For those with sealed woofers adding an air hole will make a difference.

    Yep, and you can charge your iPhone in the microwave.

    once.


  • mhardy6647mhardy6647 Posts: 13,913
    edited January 21
    there's all sorts of fun that may be had with (re)tuning ports. try "aperiodic loading"; stuff some athletic socks in the port or something more porous (to be truly "aperiodic") like some "Mr. Coffee" style coffee filters (a few or a bunch of them, 'telescoped', so to speak).

    Another classic hack for tuning ports is stuff 'em full of drinking straws -- one may try the straws full length or trimmed to various lengths (although I would suggest them to all be the same length -- else things could get weird).

  • mhardy6647mhardy6647 Posts: 13,913
    edited January 21
    I'm actually not being facetious above -- needless to say, I know zilch about the subwoofer in question, but I do know that different designers may choose to tune their products to different Qtc values to emphasize extension vs. "whoompf" factor, depending I guess on their own tastes, the expected application, and or their (shall we say) target market demographic.

    I am sure you guys all know the effect of Qtc on the bass behavior of a loudspeaker system -- but it won't hurt to share a picture (being worth 10^3 words and all that). Qtc of 0.707, of course, will give the flattest, most extended bass response. Qtc much above 1 and it's like listening to WalMart hifis :)

    thiele%20-%20small%20graph.gif
    source: http://www.mh-audio.nl/tsp_ex.asp

    My point, if indeed I have one :) -- perhaps (????) a little judicious retuning might improve (i.e., decrease) the boominess of a given subwoofer.

  • pitdogg2 wrote: »
    Agree some wooofers need the free flow. My old sub I plugged the port with a Nerf ball. That poor woofer dimpled badly every time on the push out.

    Maybe I'm misunderstanding what you're saying, but otherwise, this is the number one misconception I have ever seen on subwoofers. By adding a port you are not letting a subwoofer freely move, you're not decreasing the air pressure. It's actually the opposite. Ported subs have quite a bit higher internal air pressure than sealed ones. If you plug a port, at the tuning frequency you are actually decreasing air pressure and the cone will freely move more. This is because of the backpressure from the port which keeps the cone in check. The difference in the air pressure inside the box between a tuned port at the tuning frequency and a simple hole in the box is huge, it's not the same thing.
  • MetropolisLakeMetropolisLake Posts: 128
    edited March 27
    tonyb wrote: »
    Some subs yeah you can plug some ports and normally they come with those plugs but I never heard of plugging ALL the ports. To me that goes against the design of the sub and might cause some damage.

    You can do it with some subs because they have DSP settings that allow you to do it. The most popular is the SVS PB-13. You can plug the port but you need to put the DSP into sealed mode. If your ported sub doesn't have a DSP setting that lets you do sealed, I wouldn't mess with it myself.
  • pitdogg2pitdogg2 Posts: 6,612
    pitdogg2 wrote: »
    Agree some wooofers need the free flow. My old sub I plugged the port with a Nerf ball. That poor woofer dimpled badly every time on the push out.

    Maybe I'm misunderstanding what you're saying,

    yep you are. The dust cap would collapse and pop, the woofer cone would also wrinkle. Something that didn't happen with the port open.

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