SVS 20-39 PC+ vs PCi

Discussion in 'Speakers & Subwoofers' started by EdW, Jul 10, 2004.

  1. EdW

    EdW Auditioning

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    All other things equal, will the SVS 20-39 PC+ be "louder" than the 20-39 PCi before bottoming out? By bottoming out I mean the distorted whoosh like a fart coming from the top port. I think I should have gotten the 20-39 PC+ for a room 15x20x8 open to a 11x20x8 room.

    And yes all calibrated with a SPL meter.

    Help.

    Thanks!
     
  2. JohnSmith

    JohnSmith Supporting Actor

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    Did you talk to Tom regarding which model to go for?

    Considering you have a large room, which opens up to another large room I would have gone for one of the dual driver box subs.

    Yes the Plus will play louder than a PCi (of the same tune) I'm sure Tom or Edward will clarify the exact dB of maximum possible output.
     
  3. steve nn

    steve nn Cinematographer

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    The PLUS driver will give you 3 to 5 more dbs.

    I think I should have gotten the 20-39 PC+ for a room 15x20x8 open to a 11x20x8 room.

    If it's really open like a no wall situation, I would step up to the 2-ISD or 2-PLUS. You do also have the option of going with two of what you have now if room permits. Bang for your $$ though, the dB driver is hard to beet.
     
  4. Edward J M

    Edward J M Cinematographer

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    The dB-12 used in the Plus is a more capable woofer than the Improved Standard Driver (ISD) used in the PCi. Expect a PC+ to outperform a PCi by about 5 dB below 30 Hz. Above 30 Hz, the advantage is less, about 2-3 dB.

    Regardless, if you are pushing a PCi hard enough to induce audible port noise (not the same as bottoming, BTW), then you probably need more sub.

    Of course room placement, room acoustics, and the proximity of the sub to the listener all play an important role in how hard the sub is working to produce a given sound pressure level.

    Even though you calibrated with an SPL meter, it is possible the location you selected for the subwoofer is not optimal with respect to boundary reinforcement, room gain, and the avoidance of standing waves and nulls, etc.

    Before giving up on the PCi, shoot Tom V a sketch of the room and where the sub is currently located. He might be able to help you get more from the PCi and/or give you guidance on any upgrades to more powerful models.
     
  5. ChrisBee

    ChrisBee Stunt Coordinator

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    EdW

    I'd shine a torch (flashlight) down the port first (through the grill) to see if the port is clear. There may be some sound deadening blanket blocking the port reducing the smooth flow.

    I've often wondered if the SVS top grill has a beneficial acoustic effect on the port(s). Or is it too open to offer any air resistance? The grill reminded me of the acoustic resistance panels in the backs of loudspeaker boxes of my youth. Has anyone experimented with a grill-less SVS cylinder in comparison with a normally grilled one? [​IMG]

    ChrisBee
     
  6. Leigh_M

    Leigh_M Stunt Coordinator

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    I have a similar room, 12x20x10-15 at peak. However, my room does not open to a large area. I have not had an opportunity to optimize my 20-39Pci, but it has no problems and doesn't come close to maxing out. Tom suggested this sub or the 2-isd, depending on how loud I play my movies. For me, the 20-39Pci was the correct choice. Except for the fact that my wife has made it clear she hates the size. Oh well, I guess she will have to learn to love it! [​IMG]
     
  7. Joey_V

    Joey_V Second Unit

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    i had my pci reach port turbulence before i could get the pc+ (same enclosure size, 25-31) to reach port turbulence (at stock tuning)... this is due to the fact that the PC+ has more port surface area than the pci.
     

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