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Playing at reference level, is it 75dB or 85dB?

Discussion in 'AV Receivers & Amplifiers' started by rbacha, Oct 3, 2002.

  1. rbacha

    rbacha
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    Hi there,

    I have the following setup:

    Speakers: 7.1 system with KEF THX ultra and two 34DS (dipole) at the back

    Integrated amplifier: Pioneer VSA-AX10.

    I have been told different stories regarding playing at reference level:

    from a SPL meter: the wide pink noise should be 85dB from the listening position.

    however, I also heard that the above is only applicable if you are using a non-THX controller. If using a THX controller, then the right figure is 75dB. The reason for the decrease of 10dB is apparently to compensate for the several THX refinemet to the sound (Re-equalisation etc...)
     
  2. S H A D O

    S H A D O
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    Hi

    If you are using the amps internal test tones or Video Essentials setup disc then balance to 75db. If you are using the AVIA set up disc, balance to 85db. Set the amp to 0db volume level & when played back it will equate to Reference Level which is peaks of 105db per channel and 115db for the LFE channel. Bloody loud!
     
  3. rbacha

    rbacha
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    Hi Jase, thanx for replying.

    I have both the Video essentials and Avia discs. Why is the video essentials 10dB lower than the Avia test tone?

    Cheers.:)
     
  4. groundy

    groundy
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    Jase,

    does that mean if I calibrated everything to 75db using AVIA, then at 0 on my Amp, it's really only 65db :confused: .
     
  5. S H A D O

    S H A D O
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    Video Essentials test tones are recorded at -30db from a 0db input signal, AVIA at -20db. So they both peak at 105db when played back at 0db. Have a look at this article for a better explanation, diagrams etc. See Fig 1

    HERE

    Cheers:)
     
  6. S H A D O

    S H A D O
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    Just means your levels are 10db below Reference Level when you set the amp at 0db. You´ll have 95db peaks on the channels and 105db on the LFE channel.

    The most important factor is that all the channels are balanced in relation to each other, which is what you´ve done. Reference Level is VERY loud, way louder than I can stand.
     
  7. micb3rd

    micb3rd
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    Jase if you calibrate with avia or test tones it is the same
    75+30 is the same at 85+20.

    Both methods give full dolby reference which is peaks of 105 from speakers and 115 with LFE, if bass management is used (i.e. speakers are set to small the LFE is bumped to 121db.
     
  8. S H A D O

    S H A D O
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    Yes, both give the same results. Though whether your sub can hit 115db is a different matter, Velodyne HGS 18 owners should be ok though!:eek:
     
  9. micb3rd

    micb3rd
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    Yep Jase very little subs are up to the job full reference, if a the HC is in a large room the oftern two subs will be required.

    I use a IPL Acoustics DIY kit subwoofer.

    I listen around -18 to - 25 in films and I do run my sub a shade hot.

    I find peaks of approx 105db loud enough for me.
     
  10. S H A D O

    S H A D O
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    Same for me, maybe -15 if the soundtrack seems to be recorded at a low level (The Phantom Menace!). LOTR is fine at -25 though!:)
     
  11. garmtz

    garmtz
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    What level to calibrate to you really must look up in your manual. To get proper THX reference levels, the amp will generate test tones at either 75 dB (likely) or 85 dB (in the past), but you will have to find in the manual to which level you should calibrate. Use internal test tones! In THX amplifiers, these are pretty accurate and have a big advantage: they also have tones for the rear channels, which most calibration discs have not. With calibration tones, you must know at what level the tones are recorded and how much dialogue normalization is used. You need to compensate for that.

    I listened to LOTR with the level at -13 dB a few days ago. This is LOUD! LOTR is recorded with -0 dB of dialogue normalization and will sound at least 4 dB louder than most DVDs. I am talking about the R1 version, don't know if its the same with the R2.
     
  12. S H A D O

    S H A D O
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    I use the AVIA disc for my Surround Back channels as well, just means I set the amp(Denon) to NON MATRIX mode and this sends the Surround Left channel to Surround Back Left and the same for the Surround Right channel. Just means I have to disconnect the Surround speakers temporarily, easily done with banana plugs on the speaker cable. Then its just start the test tones and balance to 85db.:)

    Only one thing to watch is that the Surround Backs receive a mono signal on playback and having both running together seems to be too loud (combined output louder than 85db maybe??). I´ve just reduced each Surround Back channel by 3db and it sounds spot on.:)
     
  13. garmtz

    garmtz
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    Alright, you CAN do it like that, but easy it ain't! :)

    I have a THX Surround EX demo disc I use to check levels with an external disc. I think the Sound & Vision Home Theater Tune-Up disc also has 6.1 test signals.
     
  14. S H A D O

    S H A D O
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    I´m lucky as the Surrounds are easily disconnected, might be hassle for other people though.

    Isn´t the new Video Essentials 2 setup disc going to have 6.1 test tones? When it´s due to come out though is a mystery!:confused:
     
  15. Philip Newton

    Philip Newton
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    I use a denon amp and have set right and left surround to 75db at 0 on amp and same for the two centre rears wired in parrallel (8 ohms per speaker). On normal 5.1 playback with non matrix set should I reduce the centre backs or disconnect them totally. This a problem because I am unable to use bannana plugs as the bimding posts have plastic filling the holes. I have them at the same height as the left and rights but about two feet apart. new to the ex and es thing so help would be cool. Many thanks Phil
     
  16. S H A D O

    S H A D O
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    Philip

    I only use the NON MATRIX mode to set the channel levels with external Test Tones (the AVIA disc), not for normal playback of dvds etc.

    In my case the combined output was too loud, so I just reduced it. If yours sounds ok to you, then leave it as it is.

    When you playback in 5.1, your surround backs aren´t active, so no need to unplug them or reduce the levels.
     
  17. Apone

    Apone
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    Interesting thread...

    I did an A/B comparison of a lexicon DC2 that I had on loan from my dealer that I purchased my speakers from and found that when calibrated at 75db with an spl meter at 0 ref it was MUCH louder at reference level than my existing processor with is a cambridge audio v500 linked to 5 marantz ma500 monoblocs.The existing processor had been set at 75db also.

    I re checked the levels to make sure that I had not made a mistake and all seemed correct. The one thing that really set the two apart was the bass that was coming out of the lex.

    Any ideas?

    Mahmood
     

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