Sub calibration question...

Discussion in 'Archived Threads 2001-2004' started by Mike__D, Apr 11, 2002.

  1. Mike__D

    Mike__D Supporting Actor

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    I have a JBL PB10, and used VE to calibrate it. I use the standard Radio Shack sound meter. When playing the test tone for the sub, it bounces the needle back and forth, and as I move the meter away from the sweet spot (further from the sub), the sound increases, but the needle still jumbs back and forth.

    It's been a while since I calibrated, but I'd say it's about a 5db span the needle moves when it goes back and forth. With my other speakers and test tones, the needle is near rock solid.

    I currently have my sub in the front, right corner of my room. I'd rather not move it since space is tight until I get a bigger place. Is this normal, or should the test tone for the sub have a steady reading like the rest of my speakers?

    Thanks in advance,

    Mike D.
     
  2. Steve_Ma

    Steve_Ma Second Unit

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    It's pretty normal.

    --Steve
     
  3. Kerry Hackney

    Kerry Hackney Stunt Coordinator

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    Mike, I think the bass test tones on VE and Avia are actually warbles to help eliminate standing wave problems. I may be completely off but my sub wavers as you describe using the VE disk.
     
  4. Jonathon Tillman

    Jonathon Tillman Stunt Coordinator

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    Mike-

    I have encounted this problem before and I have ask pretty much the same question you are. The answer I got was this, set the sound level meter on the C weighting and make sure that the needle level is on slow.

    Now set the level to where the needle hangs around or stays in one spot for a moment or if your sub does not do that, set it in the middle of the bouncing around. I have a Paradigm PS-1000 and that is the procedure I use.

    Also I don't use the test tones from VE or Avia I use the test tones from my receiver it is best to do it with your receiver if your receiver supports test tone sounds.

    Make sure to set all your speakers to 75db and your sub to about 79db some say set it to 75db but 79db is the norm some even set it to 85db that are really bass boomers, but 79db is the norm for most.

    And stand over the sweet spot with your arm extended out and the level meter facing up so you can see the needle.
     
  5. Jeremy Hegna

    Jeremy Hegna Supporting Actor

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    "...it is best to do it with your receiver if your receiver supports test tone sounds."

    I don't agree with this statement, Jonathan. Those are generic test tones in your receiver and you are not calibrating it to your source (DVD, CD player, etc). AVIA and Video Essentials is definitely the way to go. If you set the needle to slow and "C" weight as someone else mentioned, you should be fine.

    Jeremy
     
  6. Mike__D

    Mike__D Supporting Actor

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    Thanks for the responces...

    I do use weight "c" as per VE instructions, and also set it to "slow". I've read here before not use receiver test tones. Also, on my particular receiver, Onkyo 595, I heard the sub test tone is not correct.

    Here's a new question... How do most of you calibrate the sub, do you set the sub's volume all the way up, and adjust from receiver, or vice versa? I currently adjust the level using the sub's level. Should I do it the other way around?

    Thanks,

    Mike D.
     
  7. Bill Kane

    Bill Kane Screenwriter

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  8. Mike__D

    Mike__D Supporting Actor

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    Thanks Bill!

    I setteled on adjusting the receiver to 0db (-12 to +12db range) and setting the sub at the half way point, then I just used the subs control to adjust the level.

    I still don't understand why the bass is the weakest in the sweet spot. If I move to the left or right of the sweet spot, the sound increases as much as 10db! Is that normal? I guess it's the accoustics of my room?

    Thanks again!

    Mike
     
  9. Bill Kane

    Bill Kane Screenwriter

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    Room acoustics? yes, very likely.

    what can you do about it? sometimes very small relocations make a big difference -- mere inches. If possible move the sub closer to the corner of the two longest walls. Turn the driver face this way or that. you might be able to recapture the sound waves at the sweet spot.

    your amp-sub calibration settings are very good -- not maxed either way.
     
  10. Steve_Ma

    Steve_Ma Second Unit

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    Mike,
    I agree w/Bill 100% (not that he needs my support [​IMG]) It sounds like the room is now the culprit. Most rooms will mess with your bass response. It sounds like you're on the right track. Most of us just experiment with various placements and tweak calibration to do the best we can, until a BFD or some room treaments become reasonable solutions.
    Regards,
    --Steve
     

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