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Why 65db ?

Discussion in 'Home Cinema Speakers' started by jonnyv, Apr 14, 2002.

  1. jonnyv

    jonnyv
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    When setting up my home cinema speakers with setup dvd it says to setup speakers to 65 db (or whatever),

    Why set up the speakers to 65db ?
     
  2. lmccauley

    lmccauley
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    It's actually 75db. I believe the reason is because that is the reference level for a film soundtrack in the cinema.

    Cheers,
    Liam
     
  3. Dubbing Mixer

    Dubbing Mixer
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    It's actually 85dBa per channel apart from the sub. This is pretty much the standard monitoring level when mixing movies although there are variations.

    However, you will probably find this uncomfortably loud in domestic conditions.

    Check out the Dolby website for more information than you probably want or need on the whole subject.
     
  4. Zone

    Zone
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    Highes bid 85db any more takers? :clown:
     
  5. Darth Vader

    Darth Vader
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    Dubbing Mixer is right, its 85 dBA's for sound mixing, but this is generally too loud for HC's, so 75 dBA used more often.

    85 dBA is generally regarded as safe levels to be exposed to for longish periods of time. I must point out that 85 dBA is only the average monitoring level (calibrated using Pink Noise). Peak levels can go much higher momentarily and the levels can also go much lower as well, depending on the the material being monitored. So a loud sound track like Black Hawk Down for example, has averages louder than 85 dBA. Adversely quiet sound tracks will average lower than 85 dBA.

    Cheers.
     
  6. lmccauley

    lmccauley
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    Oh, I bow to the greater knowledge of the other two posters. Always happy to learn.

    Cheers,
    Liam
     
  7. Dubbing Mixer

    Dubbing Mixer
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    Of course it all depends on the dynamic range. I.e. the difference between the quietest and loudest sounds you actually want to hear.

    Assuming you have good sound proofing (or understanding neighbours) 79dBa is a reasonable compromise and, coincidentally, the reccomended level for TV mixing.

    I usually run at 85dBa watching DVDs with full dynamic range but knock it back to 79dBA (or lower) for watching with the family. But then you have a choice of using the dynamic range compression features of the decoder (Dolby Digital) or not hearing parts of the dialogue or continually 'riding' the level on the remote control;-)
     
  8. Ramius

    Ramius
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    Hi.

    Dolby Digital reference level is 105dB peaks for the main channels and 115dB for the LFE.

    The test tones on the Video Essentials DVD (and the majority of receivers and processors) are recorded -30dBfs (or 30 below full scale). This is why you measure 75dB on the SPL meter.

    75dB + 30dB = 105dB.


    The Avia DVDs tones are recorded at -20dBfs. So when calibrating using Avia you measure 85dB on the SPL meter (as it tells you to do).

    85dB + 20dB = 105dB.


    You don't need to 'add' 10dB to the LFE as this is done by the processor/receiver.


    It's loud, but good.

    Cheers
    Boris
     
  9. petrolhead

    petrolhead
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    All I can say is that when the Denon is set at 0 reference its bloddy loud!!
     

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