Calibrating Dual Subs???

Discussion in 'Speakers & Subwoofers' started by RyanJE, Feb 28, 2005.

  1. RyanJE

    RyanJE Second Unit

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    How do you do this. One sub is and 8" and one is 12". At first I thought I could calibrate each separately. Then I realized when they played together it would be to loud. What would happen if I cal. each to 75 db individually?

    P.S. Ill be running them with a y splitter right off the back of the receiver.
     
  2. John S

    John S Producer

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    Got SPL Meter? You should try to get them both to something 75db individually, or whatever actual SBL from the same source I suppose then calibrate them at the same time with the rest of your system, you should have them stacked one on top of another, unless your pre/pro / AVR has left and right sub out, even then you should probably still stack them.
     
  3. steve nn

    steve nn Cinematographer

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    If their colocated? Calibrate each one -6db under calibration, one at a time. After calibrating them each individually> Fire both up and see if you come in at calibration. Your going to have some cancellation issues going though.
     
  4. RyanJE

    RyanJE Second Unit

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    Should I just use the 12 inch sub? John are you saying to stack the wires on the receiver, not use a y? Are the noise cancellations going to be a big prob. I may just not do it. What do you guys think?
     
  5. Robert Cowan

    Robert Cowan Supporting Actor

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    they are telling you to physically stack the subs on top of eachother. i highly suggest against it, being an owner of dual subs. you get more output, but whatever problems that location has, you just increase it. using dual subs allows for the two subs to help each other out, and if they are in the same location, they cant. just my opinion, do a search on dual subs...
     
  6. John S

    John S Producer

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    Robert do you run a totally mono signal to both your subs?
    How are they located?

    I only know one person that runs dual subs, his pre/pro has L/R sub outs though. I have been after him to let me come over with my spl meter and do some playing around with different location schemes, so far he has declined. [​IMG]
     
  7. Carl Gaff

    Carl Gaff Second Unit

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    I now run two subs, a 15" and a 12" and am very happy with the results. I started out with just the 15" alone but due to its slowness decided to ad the 12" one to balance things out. I have tried running them both ways: stacked and unstacked and ended leaving them unstacked. The 15" sub sits in a corner and the 12" sub is on the opposite wall about 4ft from the corner. This setup works well for me although I am going to spend some time on my next vacation expeimenting with sub room placement.
     
  8. John S

    John S Producer

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    Thanks for the information Carl Gaff... Do you run them off of the same mono signal or do you have an L/R Sub out??
     
  9. RyanJE

    RyanJE Second Unit

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    As far as cancellation issues what do you guys think. The 12 is good to 25hz and the 8 is good to 30hz. So actually stack the subs huh? Should it tune each to -6db from ref? Or just go to ref with both?
     
  10. RyanJE

    RyanJE Second Unit

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    anyone?
     
  11. Robert Cowan

    Robert Cowan Supporting Actor

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    i run them both mono lfe. i have dual sub outs on my pre/pro, but its the same signal. i was going to run them left and right, but i already have a splitter on my left/right outs, so another one would be too much. they work great, but if i turn off one, i can hear more bass on one side of the room than the other, but i do have them crossed over a little high (80hz). if you cross over lower, you will get less directionality.
     
  12. steve nn

    steve nn Cinematographer

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    As far as cancellation issues what do you guys think. The 12 is good to 25hz and the 8 is good to 30hz.
    __________________________________________________ _____

    Your going to have cancellations, but it could come in as a gain in some FR? >>Or just go to ref with both?
     
  13. RyanJE

    RyanJE Second Unit

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    Thanks Steve. I think Ill just stick with the one 12. It doesnt seem that adding the 8 would be all that much of an improvement.
     
  14. John S

    John S Producer

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    You never know till you try though, is sort of the real point here. I would only do it, if the 12" alone did not give me what I wanted out of my sub channel.
     
  15. steve nn

    steve nn Cinematographer

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    It really wouldn't Ryan. I'm not sure what subs we're talking about, but I have a strong hunch the 12"er is the better sub. 2 alike subs are the best way to go in your situation, but hey! Nothing wrong with trying it out, if you have it.
     
  16. Robert Cowan

    Robert Cowan Supporting Actor

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    with good placement, even the 8" can add to your bass. its not just about volume, its about filling in the gaps. thats my whole thing about not stacking them. if you get two locations from your subs, you can have them aid eachother's frequency response, and hopefully flatten it.
     
  17. Wayne A. Pflughaupt

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    Ryan,

    Good plan, unless you simply need more output.

    Regards,
    Wayne A. Pflughaupt
     
  18. Carl Gaff

    Carl Gaff Second Unit

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    John I run a mono signal to both subs via a y-splitter.
     
  19. John S

    John S Producer

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    Thanks Carl.. I just to have a couple of examples, if I ever suggest that rout for somebody. Good to know all the details.
     
  20. steve nn

    steve nn Cinematographer

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    Here is a little example for you Ryan, to show what your up against.

    I ordered the PC-ULTRA to run as a second option out in the main and had been running 3 25-31CS+'s. I forget the exact numbers, but I do remember it was a 11-12db difference at 20 Hz. The PC-Ultra on its own would play at say a 100db at 20 Hz and the 25s would play at 88db at 20 Hz. When I calibrated the 4 of them together and ran the 20 Hz signal at the same level, I came in at 94db with all 4 colocated. Still a 6db gain over what I could achieve with the 3 25-31CS+s, but the 25s negated 6db of the 12db gain I realised with the single PC-Ultra at 20 Hz. Above the 25-31CS+s 25 Hz tune it came out the same, a db here and there difference. That could be accounted for inaccuracy on my part.

    I have tried this with other differently tuned subs and it always comes out the same. If your trying to widen the sweet spot in your bass? I would first suggest you try to find a different location for the single 12" sub, if you have that option available? If your looking for more output or headroom, it will come at a sacrifice with differently tuned subs.

    If we bring EQ into the discussion, then, well..... [​IMG] [​IMG]
     

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