SPL Meter Calibration

Discussion in 'Beginners, General Questions' started by Doug MacGregor, Apr 16, 2004.

  1. Doug MacGregor

    Doug MacGregor Stunt Coordinator

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    Just getting ready to calibrate my 18 month old HT with my new RS analog SPL meter.
    I have read Vince's primer on the process and I have just one question.
    When I set the SPL meter on the tripod at ear level and the viewing position and angle it upwards at 40 degrees, do I point the meter at the various speakers when I play the pink noise and frequency spreads or do I just point it strait forward and leave it there for the duration of the testing?
    Thanks.
     
  2. SteveLeach

    SteveLeach Stunt Coordinator

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    Point it strait forward and leave it there for the duration of the testing. At least that's what I do.
     
  3. Frank Zimkas

    Frank Zimkas Supporting Actor

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    No, No, No! Read the instructions people! Do I have to come over there and do it for you![​IMG] Straight up is the way to go. Maybe this will help a bit.
     
  4. Doug MacGregor

    Doug MacGregor Stunt Coordinator

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    Thanks Frank.
    I read everything I could find, including that article.
    There is no reference to "holding it straight up" as you suggested.
    Thanks just the same.
     
  5. Frank Zimkas

    Frank Zimkas Supporting Actor

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    Okay I was wrong, the manual actualy say's that the meter works best when pointed at the source (In my maual it's on pg.11). But as i was told,and I believe it was on this forum, you don't point your ears directly at the source, therefore you should point the meter straight up. If you have the new model, you can look on page 12 under the section titled "Microphone." Here's the new model's manual if anyone needs a copy.
     
  6. Doug MacGregor

    Doug MacGregor Stunt Coordinator

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    Thanks again Frank.
    I'll do a little experimenting.
    After all, that's half the fun, isn't it?
    Cheers.
     
  7. Frank Zimkas

    Frank Zimkas Supporting Actor

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    Sure is, and the other half is upgrading![​IMG]
     
  8. douglas-b

    douglas-b Stunt Coordinator

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    Location:
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    Straight up is how I do it.[​IMG] [​IMG] [​IMG]
     
  9. Doug MacGregor

    Doug MacGregor Stunt Coordinator

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    Wow!
    What a difference.
    Just finished my first calibration go-round.
    I can't get over how "off" my settings were.
    My Mains have magically re-appeared due to the fact that my Center speaker was turned up too high.
    And I didn't realize that my Sub was up way too high too.
    I also didn't realize that "reference level" was so high.
    I set the meter to 80dB "pointing straight up" and the pink-noise test was almost deafening (not really but it was loud).
    At least I know where reference level is now.
    Actually I've never had my receiver up that loud before.
    (JVC 6010 VBK).
    Going to do the frequency spreads next and the fixed frequency tests.
    To anyone wondering if calibration is really worth it...
    It's indespensible.
    Watched Thelma and Louise last night (not my choice) and not the best surround test but...
    The part where the cop gets locked in the trunk and Thelma throws the keys away...
    I heard them hit the ground just to the left of me!
    LOTR next up.
    Thanks guys.
     
  10. ChrisWiggles

    ChrisWiggles Producer

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    See page 12 of the linked .pdf manual, to see the microphone response.
     
  11. Bill Blank

    Bill Blank Stunt Coordinator

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    The mic in the RS meter is non-directional so it doesn't really matter where you point it. Straight up s recommended and probably most often used because it doesn't bias the front three speakers as pointing it straight forward could.

    Congrats on what appears to be a successful calibration. It's amazing what proper speaker placement, levels, and delay can do for a system. I'm now on to the next step, addressing room problems...

    Bill
     
  12. ChrisWiggles

    ChrisWiggles Producer

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    Yes it is. See the brochure that was previously linked, and that I was referring to. It shows the response on and off axis.
     
  13. Bill Blank

    Bill Blank Stunt Coordinator

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    Chris,

    From my Radio Shack Sound Level Meter Owner's Manual:

    "Microphone - Electret condenser omnidirectional becoming slightly directional with increase in frequency"

    So I was wrong in saying it was non-directional, I should have said omnidirectional which means being in or involving all directions. Since he's only "measuring" pink noise to get levels equal (as opposed to taking a frequency response plot) the "slightly directional with increase in frequency" doesn't come into play.

    Bill
     
  14. ChrisWiggles

    ChrisWiggles Producer

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    It actually would very slightly, but as you will find out with some experimentation it shouldn't make much of a difference at all.
     

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