SPL for Subs re: Video Essentials

Discussion in 'Archived Threads 2001-2004' started by Aaron Garman, Apr 7, 2002.

  1. Aaron Garman

    Aaron Garman Second Unit

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    Hello all. I use the Video Essentials DVD to setup my A/V system. Is there a trick to setting up the SPL on my sub with the tones that VE offers? I know I set the rest of the system for 75dB, how about the sub? Thanks!

    AJ Garman
     
  2. Vin

    Vin Supporting Actor

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    Aaron, in theory, all channels including the subwoofer channel should be set to 75dB when using VE. However, a lot of people will set the sub channel slightly higher, say 3-5dB. Doing this will make up for the loss of low freqency impact (our ears are much less sensitive to lower frequencies) when listening below reference level.

    Also, it's a good idea to leave some room for adjustment of the sub output channel from your receiver so that when you do listen at reference levels, it will be very easy to back off on this setting (if you choose to do so) from your receiver's remote.

    Hope this helps,

    Vin
     
  3. Harold_C

    Harold_C Stunt Coordinator

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  4. Rick Radford

    Rick Radford Supporting Actor

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    Harold,
    Good point. I suppose the caveat should be that if you like to listen at reduced volume levels (how many folks really listen at ref level anyway?), you should be safe cranking the sub up 3-5 dB over calibrated settings.
    Otherwise, set it at the calibrated level.
    I know we listen (at night) around 15-25 dB under ref. (depending on what I can get away with) [​IMG]
     
  5. Harold_C

    Harold_C Stunt Coordinator

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  6. Robert EW

    Robert EW Extra

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    Harold, that is great information to know. I just happened to find that feature on my receiver this weekend while watching Toy Story 2 with my wife.

    What happens if you have it on, forget about it and then calibrate with AVIA like I did. I assume I need to recalibrate, and will, as soon as I can find longer spikes for my speakers. Anybody have a solution for longer spikes?
     
  7. Harold_C

    Harold_C Stunt Coordinator

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    That's a darn good question. If the calibration tones were recorded at -30 dBFs (30 dB below full digital signal) which would be used to calibrate to 75 dB output, the compression shouldn't make any difference because -30dDFS is the mid-point that should remain fixed while louder and softer sounds are compressed.

    However, the Avia's tones are recorded at -20dBFs for playback at 85 dB. The compression might well change the calibration results.

    Actually, Dolby Digital material is generally encoded with MAX compression. If you select no compression, the decoder actually scales the dynamic range UP.

    To be safe, I would do the calibration with the no compression setting.
     
  8. Robert EW

    Robert EW Extra

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    The calibration I made with the compression on was my second calibration in a week (somehow I defaulted my setting back to zero) and I did not write my first setting down on paper. Otherwise I could tell if it made a difference. This time I wrote my calibration setting down and I will compare them to the new setting and see if it makes a difference. However, I hope to have speaker spikes installed and may not be able to make and apple to apple comparison. Plus I am new to this and do not want to rule out human error.
     
  9. Rick Radford

    Rick Radford Supporting Actor

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    >the Dolby Digital dynamic range compression feature.<
    I think that's called Midnite mode.. or something like that on my Onkyo 989.
    I've always wondered whether it should be set to max or min (no mid setting).. and now I see it should be min. The OM has little to say about this feature. [​IMG]
    I'll hafta remember this next time we watch a movie at night.
     
  10. Harold_C

    Harold_C Stunt Coordinator

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    The Pioneer receivers have two different compression settings. One is the actual Dolby Digital dynamic range setting and it's buried in the menus with the speaker delay settings, etc.

    Pioneer labels this one OFF (no compression, MID (mild compression), and MAX (max compression. But, you have to be careful to read the manual. Some companies label MAX (for max dynamic range, MIN (for minimum dynamic range.) This setting is a part of the Dolby decoder and ONLY applies to Dolby Digital source material -- not Pro Logic decoding, not DTS. It relies on instructions embedded in the Dolby Digital datastream.

    The Pioneer also had a "MIDNIGHT" mode, which is clearly a compression scheme of some sorts (along with perhaps a bass boost?). This appears to be generic and applicable to all surround modes. Probably done in the digital post processing or DSP chips. Rather than a buried menu setting, this one is just a button that you turn on or off.
     
  11. Aaron Garman

    Aaron Garman Second Unit

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    Hello all. Another question, how do I set the sub level precisely to 75dB? I forgot to mention earlier that the needle varies with the sub test tone from Video Essentials. Should I average levels, and if so what levels? I'm still trying to fine tune my JBL sub the best I can. Thanks again!

    AJ Garman
     
  12. Rick Radford

    Rick Radford Supporting Actor

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    Harold,

    Ok, I looked it up in my OM. Onkyo calls it Late Night mode (not midnite). And it does work strictly with DD material.

    Here's Onkyo's description: "... When this parameter is set to "High" or "Low," the dynamic range of the sound is narrowed down to allow you to easily hear minute sounds at low volumes..."

    Since high and low are relative terms, I have no clue as to which is best for reduced level listening. What does "high" and "low" refer to?

    Whenever I think to try it.. we're always watching a movie and it's too distracting to switch back and forth and evaluate it while we're trying to watch.

    ... back on track ->

    Aaron, just average the swings for your LFE setting. I'd guess the swings are due to room interaction with the LFE test tones. It's pretty common to see that.

    Also, note that due to inaccuracies of the RS meter at lower freqs, a setting of 75 dB will be 2 to 3 dB hot.
     
  13. Harold_C

    Harold_C Stunt Coordinator

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  14. Vin

    Vin Supporting Actor

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  15. Aaron Garman

    Aaron Garman Second Unit

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    Hello all. Thanks for the help. I'm gonna give these ideas a shot. Just to give you all a reference, my room is a modest 9.5' by 11'. Small, but nice enough for a college student's home theater needs.

    AJ Garman
     
  16. Aaron Garman

    Aaron Garman Second Unit

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    Hello all. Well, I find nice levels for the room to be around -10dB of reference. As for bass, I merely adjust the sub accordingly for when I listen at lower levels. So far, everything is good. Cheers!

    AJ Garman
     

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