How important is the phace control in a sub?

Discussion in 'Archived Threads 2001-2004' started by Luis M, Mar 20, 2003.

  1. Luis M

    Luis M Second Unit

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    I am about to pull the trigger on a SVS 20-39V CS+ sub which needs external amplification. The SVS site states that with an external amp you have no level control, auto ON-OFF, etc, which is fine with me. but the site also mentions that there is no phase control. I have always used this feature with the powered suv that I now own and have always noticed more bass in one possition over the other. Is the auto-phase situation mute with an external amp and a passive sub?
     
  2. Luis M

    Luis M Second Unit

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    I meant phase-control.
     
  3. ColinM

    ColinM Cinematographer

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    Reversing the wires from amp to sub will give you 0/180 phase control. Level can be adjusted from the receiver's sub level control.

    In any case you'll be fine and happy, I think.
     
  4. Luis M

    Luis M Second Unit

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    ColinM, When you say reversing the speaker wires, you mean just on one end Right?
     
  5. Geoff L

    Geoff L Screenwriter

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    Just wire the sub backwards at the sub or at the subs amp, "but not both". Do it at which ever is easiest, either the sub or sub amp.

    + to + and - to - = 0
    + to - and - to + = 180

    It will act just the same as a powered sub with a 0 to 180 phase switch.

    Not variable but 0 and 180

    Follow me?
     
  6. Luis M

    Luis M Second Unit

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    Thank you Geoff L. So, I should leave it where I get the most bass?
     
  7. Geoff L

    Geoff L Screenwriter

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    Yes

    If the sub is placed in the front with the mains, more than likely wire it for 0 phase. Everything + to + and - to -.
    If you move the sub close to, or behind the listening postion, you may find that you need to wire for 180.
    At ("only one end"), either the amp or the sub, reverse the wires.

    Just experiment and make sure to calibrate your system.
    If you have trouble, shoot an email of to Tom or Ron they will take care of you.

    Regards
    Geoff
     
  8. Luis M

    Luis M Second Unit

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    That sounds good. Thanks for the information
     
  9. Jim A. Banville

    Jim A. Banville Supporting Actor

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    The variable phase control was a BIG reason I got the PartsExpress 250 watt plate amp for my DIY sub. I get the best response with my phase control set at about 100 degress. 0 or 180 cause the bass to cancel a few db's. Why not pick up an amp like this and build a little box for it? You can build it out of anything! Doesn't have to be airtight. You could even mount it to a board and lean it against a wall!
     
  10. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    If you'll only have one sub and it'll be placed near the front speakers then don't worry about phase control at all. You'll only need to match the phase of the sub to the mains at the crossover point (presumably 80Hz). 0 degrees is the ticket and its what you'll get by default.

    On the opposite side of the spectrum - if you'll have multiple subs in different locations and far from your mains then you'll have a challenge to keep things in phase even with phase control. Without it you might really be in trouble.
     

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