Sub and Mains cancelling each other out! Help!

Discussion in 'Archived Threads 2001-2004' started by Philip A, Sep 26, 2002.

  1. Philip A

    Philip A Agent

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    I have an M&K 12" sub (older, without any phase adjustment--either knob or switch; it just has frequency and volume gains) with some Dahlquist QX10's on the front. They are powered by a Yamaha 1200 (80wpc). The Yammy has three different setting options for the sub: sub, main, both.

    When I set it for "sub," it seems (looks) like the mains aren't cranking and I'm not getting anything to the M&K, when I use the "main" the mains totally crank--I'm impressed but afraid by the cone excursion (so far the Dahlquists have handled it with frightening ability, but I wonder what I'm missing without the sub), when I use "both" the mains calm down and sub is engaged, but the bass isn't any bigger than when the mains are getting the whole thing.

    Help!

    I'm thinking it is a polarity problem, but I don't know how to (or if I can) change the polarity of the sub.
     
  2. Neil Joseph

    Neil Joseph Lead Actor

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    Is moving the sub to another location an option for you?
     
  3. Philip A

    Philip A Agent

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    Neil,
    Thanks for responding. When I first did the set-up I tried to move around for the best sound, but that was before I got the Dahlquists. Do you think that will make a difference?
    Phil
     
  4. steve mm

    steve mm Agent

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    first off you could simply switch the positive and neg on the sub itself witch would do the same thing as a faze switch. the other thing is your mains were not designed to play below 25hz some dvd go as low as 5 hz and yes you are definitely getting faze cancellation when running both if your mains are big enough and i am assuming they are i would run the receiver as low as it will go (if it has the capability)i don't think the yams do 60 70 80 hz and adjust the sub to match that way you have a good blend im pretty sure the yamy is fixed at 90 hz you should be running all the speakers as small and just the sub for base that should give you the best sound if you want more bass get a better sub or add another (ebay)if you add another you want one that matches what you have now good luck
     
  5. Philip A

    Philip A Agent

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    Steve,

    Thanks for the reply. However, my M&K sub only has the two line inputs, which I'm using a Y cord to connect to the mono sub out from the Yamaha.

    Any help for that?

    Also, it was interesting to see the difference in cone movement on my mains when I had "both" switched on the Yamaha. I would have thought that the mains would be receiving the same freq. with that switch, but maybe not?!
     
  6. Neil Joseph

    Neil Joseph Lead Actor

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    What happens when you set the mains up as large speakers on the receiver? Just curious.
     
  7. Johnny Mac

    Johnny Mac Stunt Coordinator

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    Steve means actually pulling the speaker out of the cabinet and switching the positive and neagative leads.

    I had a nasty cancellation problem when I had my sub in a corner behind my right main. The remedy was to place it along the front wall. The dip in response disappeared and all I had to do was recalibrate.

    I used to have a Def Tech sub without a phase switch and it sounded best when placed along the same wall as the mains.

    Are you using test tones and an spl meter. Doing it by ear can play tricks on you.
     
  8. Philip A

    Philip A Agent

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    Johhny Mac,
    Thanks for clarifying. I have the RS SPL and the S&V Setup Disk. I'll do so fiddling this weekend. Like you, I have the sub in the right corner, angled in toward to sweetspot. However, I will try moving it in closer to the right main and see what happens.
    Much appreciate everyone's help. I'll post what happens.
    Thanks again, Phil
     
  9. Wayne A. Pflughaupt

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    Philip,
     

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