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Radioshack SPL meter: I need help calibrating my dB levels!

Discussion in 'Home Cinema Speakers' started by tk2001, Jan 24, 2002.

  1. tk2001

    tk2001
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    Hi,

    I just recently brought a digital Radioshack SPL meter and have managed to calibrate (or try to) my speaker levels so that all 5 speakers are at 75dB. Setting each speaker level to 75dB seems to be straight foward - place the SPL meter at where the ear-level would be and point the SPL's microphone at the direction of each speaker.
    However, when it comes down to setting my subwoofer level to 75dB, even by lowering the subwoofer level from my amp by -15dB, I can't seem to get the sub's level at 75dB - its always well over 75dB.
    Am I doing something wrong? Or is the optimal (recommended) subwoofer level above 75dB.

    Please Advise.

    PS There seems to be this option which allows you to choose 2 different 'Weighting' option:

    A - weighting picks up frequencies from 500-to-10,000 Hz range.

    C - weighting picks up frequencies from 32-to-10,000 Hz range.

    Which one should I choose?
     
  2. Jase

    Jase
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    You want the sound meter set to C-Weighting and either pointing straightup at the ceiling or at angle of 45 degrees towards the ceiling, not pointing at each speaker.

    Sounds like you need to turn down the subwoofers volume level. Maybe to around halfway or less.

    cheers
     
  3. tk2001

    tk2001
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    I own the Mission FS2AV package and there isn't a volume level on the subwoofer, theres only a 'Bass & Contour' control level. I've lowered the subwoofer level on my amp to -15dB and it won't go any lower than that.

    Isn't there any thing else I can do?
     
  4. Jase

    Jase
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    If the Bass & Contour level is the only thing its got, try playing around with that.

    If your amps set at the lowest it will go, you´ve got no other alternative but the subwoofer controls.
     
  5. tk2001

    tk2001
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    Does the sub level have to be set at 75dB along with the speaker levels?

    Would there be any differences other than loudness if I set my sub level at 85db along with all my speakers?

    PS Is there any advantages/disadvantages of having your speaker levels at 75dB vs 85dB? What about 'Response'. Do I have it on 'slow' or 'fast'?
     
  6. Jase

    Jase
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    You dont HAVE to have the sub set at 75db, some people do, others have it higher, mines about 77db. Any higher and theres too much bass which buggers up the sound, in my case.

    The important thing is balance the main speakers all to the same level whether it be 75db or 85db. The sub level can be down to personal taste and whatever you prefer. It depends whether you like lots of bass or not.

    The meter should be set to SLOW.

    My system is balanced to 75db (apart from the sub). This corresponds to about -15 on my volume control, but I never have it up that loud as it blows my head off! I usually listen at about -25.
     
  7. bob007

    bob007
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    jase.......I have a denon and set my levels to 75db.......when the test tone comes on it reverts to defalt setting which is 00db then the channels are set from that...........how would you set the levels if you have no defalt test tone only the volume control which determines the test tone volume. All volume dials read different so i was wondering how they get the right defalt to start adjusting their levels...........would i be right in saying that they adjust the volume of the test tone with the first speaker so the spl reads 75db then work from that..........it's that i have a friend who wants to borrow my spl and his amp does not have a defalt setting like mine............Cheers
     
  8. magnatom

    magnatom
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    tk2001,

    I have the same problem that you have. The subwoofer has a level about 10 db above the speakers. I could get it lower but I am sure that when I play music and movies that the bass is not excessive.
    I wonder if it is something to do with LFE channel setting on my sub.
    I know there is a seperate setting that has three options LFE= off, 0dB -10dB.

    When I look at it with nothing playing I know it is set to 0dB. Is it possible that when I am playing a CD or DVD that it is set to -10dB?

    I have a Marantz SR5200.
     
  9. Jase

    Jase
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    bob007

    I originally used the 00db tone on my Denon amp but kept ending with -6,-8 figures etc for the speaker settings (also the test tone was LOUD!)

    Now I use the AVIA test disc and do as you say, turn the volume level down until it reads 75db on the meter for the Front Left speaker (0db for my channel level & about -15 on the volume level display) then balance all the rest. In my case I ended up with 0db across the front 3 channels and -3 for each surround, -6 for the rear centre.

    To balance it all properly you really need a test disc.

    The internal test tones are ok but dont take into account the dvd player which can affect the levels quite a bit. My left surround had to be upped a few db compared to the levels achieved with the internal test tone.

    cheers
     
  10. bob007

    bob007
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    My readings are -7 to -9........ and on some DVDs have to turn the volume round to -10 on some tracks. As you say the most important thing is that the levels are equally set either at 75db/85db. Will give 85db a try.....The only thing i have to hand for tests is the THX optimode you find on some R1 discs.......wouldn't think this is a suitable test disc.....if not what one would you suggest.....cheers bob
     
  11. Jase

    Jase
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    The THX optimiser is ok. A test disc such as AVIA or Video Essentials would be better.

    AVIA is available from

    www.ovationsw.com

    Video Essentials from

    www.ezydvd.com.au

    Ive got AVIA.
     
  12. bob007

    bob007
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    Looks as if the plastics coming out again...............cheers for your advice jase........;)
     
  13. tk2001

    tk2001
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    Where can I get hold of a copy of 'AVIA' in the UK?

    I read in 'sound & vision online forums' that they are releasing a HT tune-up DVD called 'Sound & Vision Home Theater Tune-Up' which is suppose to be similar to Avia but with more features such as DTS & 6.1 channel tones.
    Will this DVD be availible in the UK?
     
  14. Jase

    Jase
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    tk2001

    Not heard about the disc you mention, until now!

    I bought my AVIA disc direct from their website.

    www.ovationsw.com

    I think there is a new version of Video Essentials coming out with the DTS test tones, 6.1, PAL etc etc. I would imagine AVIA will follow suit with a new version as well.

    Both AVIA & Video Essentials are for calibrating NTSC not PAL (apart from the audio side) so make sure your TV can support it.

    cheers
     
  15. Ken

    Ken
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    tk2001
    Just a thought, if your amp has individual control for all your speakers, try setting your sub as the reference sound level at 75db and turn up all the other channels to match.
    Ken
     
  16. gwbailey

    gwbailey
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    So which is the best meter to use...

    Some say digital, others say analog!

    Which?
     
  17. Jase

    Jase
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    Got the Digital one myself.

    But others say the Analogue is more accurate when testing the Subwoofer.
     

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