How many ports do you block on your SVS?

Discussion in 'Speakers' started by mitch, Nov 11, 2007.

  1. mitch

    mitch Stunt Coordinator

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    Hi all,

    I'm still experimenting with my new SVS PB 12/Plus 2 sub and was wondering how many ports do most of you block to get the best balance of low frequency bass and output?

    Right now, I'm blocking one port to get 20 Hz. and it sounds unbelievable! I'm going to experiment and block the other port to get it down to 16 Hz. to see what the effect is. I know that my output and upper lever bass may suffer, at least that's what my understanding is.

    Please let me know what your experiences have been in blocking the ports and what effect it had as you made the changes. What did you wind up keeping your setting at?

    Thanks as always,

    Mitch
     
  2. Barry_B_B

    Barry_B_B Second Unit

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    No ports blocked for me; I've had the 20-39PC Plus since July. For some reason it did not come with the port blockers (yes, I quadruple checked/searched the box), but I've been enjoying the default 20Mhz tune so much I've never gotten around to requesting the blockers. To go through my movie collection or TV programs and get that "I didn't know that was there!" sensation is a blast!
     
  3. mitch

    mitch Stunt Coordinator

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    Barry,

    If you contact SVS they would be happy to supply you with the port blockers. Speak with Eric. He is extremely helpful.

    Mitch
     
  4. Barry_B_B

    Barry_B_B Second Unit

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    Thanks Mitch, I need to do this; I was in church today when the pipe organ cut loose, 16Mhz is tempting [​IMG]
     
  5. BrianTwig

    BrianTwig Second Unit

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    Have the PB12-NSD/2 and for music I block no ports, but for movies I block 2.
     
  6. mitch

    mitch Stunt Coordinator

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    Brian,

    When you block the two ports, do you lose any gain [volume] or high end bass? What is the biggest difference that you notice?

    Thanks,

    Mitch
     
  7. Bertrand-R

    Bertrand-R Agent

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    When you block 1 or 2 ports do you need to recalibrate?
     
  8. mitch

    mitch Stunt Coordinator

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    That's a good question Bertrand. I'll call Erik over at SVS today and find out.

    Mitch
     
  9. Robert_J

    Robert_J Lead Actor

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    Two high excursion 12's and a single 4" port. If you do the math, a 4" port is barely enough area for a single 12 much less for two. I'm surprised that no one had heard any chuffing.

    -Robert
     
  10. Kevin C Brown

    Kevin C Brown Producer

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    I go for the lowest extension. I've measured in my room, and I am -3 dB to 11 Hz with an Ultra/2. Most of us are probably nowhere close to volumes where you'd see any limited output with blocking both ports.
     
  11. Shannon W

    Shannon W Stunt Coordinator

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    Blocked 2 for my PB12+2! 16hz all the way.

    Shannon
     
  12. Robb Roy

    Robb Roy Supporting Actor

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    Yes. You can, however, note your receiver's sub out level with each port setting so you can adjust without breaking out the meter each time. I.e., you would know -5 is for no ports blocked, -3 for one port blocked, 0 for two ports blocked (these numbers are just examples!).

    -Robb
     
  13. JohnRice

    JohnRice Lead Actor

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    Barry, the cylinder subs have one set tuning, so no port blockers. I think that is one of the nice things about the SVS subs which have this feature. You can change the sound of the sub a bit, if only for a change.
     
  14. Ben-S

    Ben-S Extra

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    ditto for me baby!!
     
  15. Robb Roy

    Robb Roy Supporting Actor

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    The PCi cylinder subs do not have variable tuning, but the PC Plus line has three ports and variable tuning.

    -Robb
     
  16. JohnRice

    JohnRice Lead Actor

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    Oops
     
  17. Barry_B_B

    Barry_B_B Second Unit

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    [​IMG]
     
  18. Robert_J

    Robert_J Lead Actor

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    You can play with the tuning of the PC line as well. It just requires buying a new 4" flared port. Parts Express or Thriller Audio are great sources of the ports and port parts.

    -Robert
     
  19. BrianTwig

    BrianTwig Second Unit

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    There is a slight loss of headroom, but the addition on the bottom end more than compensates in my opinion.

    I notice that there is far more loss of volume and even bass when listening to music with 2 ports blocked. It just doesn't work. Especially since normal instruments do not go anywhere near teens in hz. If memory serves me right, an open E on a bass is 32hz.
     
  20. Jeff_CusBlues

    Jeff_CusBlues Supporting Actor

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    Pipe organs might go that low. I'm not sure about that though. If they do though, you might want to keep some TP close by. LOL
     

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