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Is it true I have to turn up LFE 3dbs,???

Discussion in 'Archived Threads 2001-2004' started by David Ruiz, Dec 24, 2001.

  1. David Ruiz

    David Ruiz Second Unit

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    Hello Everyone,

    I was watching a movie with a friend of mine, and he said that the "Bass" was too low. I told him that I had calibrated everything to 75 DB with the Radio Shack "DIGITAL" meter, and he said that the Radio Shack meter has a very hard time with BASS, so you need to set it 3 dbs higher to get it correctly set at 75 Dbs. He said that 78 DBs = 75 DBs (because of the radio shack meter that can't correctly display subwoofer tones).

    Anyway, is this true? Should I infact re-calibrate to 78 Dbs for my sub?
     
  2. Jack Gilvey

    Jack Gilvey Producer

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    From what I recall, the RS meter actually reads about 2-3 db low on low-frequency pink noise (kinda makes sense, given how much one needs to add to the bass readings according to the "correction table") such as with a calibration tone. So, if you're reading 75db, it's probably 77-78db in reality. This would probably depend on the actual bandwidth of the noise and the sub, also.
     
  3. Greg Robertson

    Greg Robertson Stunt Coordinator

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    Ya know I've seen that calibration chart several times, but can never remember how to get to it. But I'm pretty sure that Jack is right. However, many of us calibrate our subs to 85db.. Can't recall if it's because of some Dolby or Thx spec, or because it just sounds better, but it sounds just about right to me.
     
  4. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    the RS meter reads about 2-3dB low during a typical subwoofer calibration tone(usually one octave noise 40-80hz).

    If the (radio shack)meter reads 75 for the woof, it's an actual 78dB(ish).

    You might try measuring the subwoofer tone in various seats around the room. You might be sitting in a seat that's a few dBs higher than his seat.

    TV
     
  5. ColinM

    ColinM Cinematographer

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    Here it is...

    10Hz +20.5

    12.5Hz +16.5

    16Hz +11.5

    20Hz +7.5

    25Hz +5

    31.5Hz +3

    40Hz +2.5

    50Hz +1.5

    63Hz +1.5

    80Hz +1.5

    100Hz +2

    125Hz +0.5

    160Hz -0.5

    200Hz -0.5

    250Hz +0.5

    315Hz -0.5

    400Hz 0

    500Hz -0.5

    630Hz 0

    800Hz 0

    1KHz 0

    1.25Khz 0

    1.6KHz -0.5

    2Khz -1.5

    2.5Khz -1.5

    3.15Khz -1.5

    4KHz -2

    5KHz -2

    6.3KHz -2

    8KHz -2

    10Khz -1
     
  6. ColinM

    ColinM Cinematographer

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    Take your measurement -

    Say you read 70 db at 20 hz -

    The actual level is 77.5 hz.

    Enjoy!
     
  7. John Kotches

    John Kotches Cinematographer

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    Greg,

    If you set your sub at 85dB, you're "overcalibrating".

    The DD and DTS automatically pad the LFE channel by 10dB, and the test tones take this into account.

    It's fine if you want to run your subwoofer hot, given the physics of the setup however, keep in mind you've just required that your subwoofer has to be capable of +10dB or more above reference levels if you listen at reference levels.

    Have you tried backing the subwoofer level back into line with the other speakers, then increasing the overall volume? You might find that this sounds much better, and you won't obliterate detail because your LFE channel is too high.

    Regards,
     

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