How Do I Determine My "Reference Sound Level" For A Particular DVD?

Discussion in 'Archived Threads 2001-2004' started by Rob Tomlin, Oct 30, 2001.

  1. Rob Tomlin

    Rob Tomlin Producer

    Joined:
    Jan 8, 2000
    Messages:
    4,505
    Likes Received:
    0
    Trophy Points:
    0
    Often when someone is giving a critique about a certain DVD's sound mix, they often mention whether they were listening to the DVD "at Reference level".
    What is Reference level? How is it determined on a particular setup and with a particular DVD? Does Dialnorm play a part?
    When using my Video Essentials DVD to set up the various channels volume using a SPL meter, they state that the sound level should be at 75 dB after adjustment. The only way I get to 75 dB is by turning the volume on my receiver to the 00 mark (I am using a Denon AVR-3300). So, does this mean that my volume level should be at 00 to be at reference level?? If so, I must admit that "Reference Level" is way too loud on my system, as I usually have the volume set at around -14 to -17, depending on the DVD (Higher for TPM!! [​IMG])
    Sorry if this sounds like a newbie question, but better to ask than remain in the dark... [​IMG]
     
  2. Mark Zimmer

    Mark Zimmer Producer

    Joined:
    Jun 30, 1997
    Messages:
    4,300
    Likes Received:
    40
    Trophy Points:
    0
    To find reference level, turn the volume knob up until your ears bleed. Then put it up one notch higher.
    Seriously, whoever came up with the idea of "reference level" at 75 dB was completely nuts. I value my hearing, and after listening to a couple movies at reference level, I wouldn't have much of it left.
    ------------------
    "This movie has warped my fragile little mind."
     
  3. Vince Maskeeper

    Vince Maskeeper Producer

    Joined:
    Jan 18, 1999
    Messages:
    6,499
    Likes Received:
    0
    Trophy Points:
    0
    And (yet again) ref level is not "75 db". If it was 75db peak, you would be struggling to hear the sound at all.
    Ref level is:
    Peak output from any main speaker would be 105db of SPL (sound pressure).
    Peak output from the LFE would be 115db of SPL.
    So how do you know if peak level is 105? Well, you could take a DVD that has a tone that is LOUD AS POSSIBLE (this loud as possible level is encoded, in the digital world as 0db)... this tone encoded at 0db would then be played back to your speakers and you turn them up till they measure 105db on a meter.
    But that would be painful. Sustained tone of 105db would be enough to make you sell all your HT gear!
    So, calibration discs like Video Essentials, instead, prove a tone that is 30 steps below the loudest possible tone (in the digital world known as -30db or -30dbfs)... If you play that tone back and remember that it is actually 30db below maximum, you can use a meter to set your system 30 steps below maximum: 75db
    105db max minus 30db steps below max = 75db. If you set your stsem with this tone, and it measures 75, then when you get maximum output it is 105!
    The 75db number is only relative because the tones on VE are 30 steps below the maximum level. It has no other real meaning, so when people refer to it as "75db ref level", this is false-- and when people (like Mike Knapp for example) go into a mixing studio and ask for 75 db level- they are talking about two different things.
    The Avia tones, for example, use the same idea- only their tones are set 20 steps below the maximum. So the max is supposed to be 105, minus 20 steps, is 85. So if you use AVIA they want you to set your levels to 85. This doesn't mean it will be LOUDER than it was with VE- they should be right about the same... all that is happening is Avia's tone are encoded at a higher level and thus will measure at a higher level (85db spl) on a properly calibrated system.
    Hope that helped. If not, tune in next week, I'll probably explain it again.
    [​IMG]
     
  4. Jack Gilvey

    Jack Gilvey Producer

    Joined:
    Mar 13, 1999
    Messages:
    4,948
    Likes Received:
    0
    Trophy Points:
    0
    Here's a good article:
    http://www.hometheaterhifi.com/volume_7_2/feature-article-misunderstood-lfe -channel-april-2000.html
    quote: I felt the same way until I invested in a good speaker setup- the harshness of the upper mid is really what kills you. I usually listen at about 5db below ref (small room so the sound gets a big harsh due to the room)-- but in an open space with a nice set of speakers, Ref level really isn't that loud.[/quote]
    Interesting points, Vince. I know that my system, which I run at 10db below reference, "sounds" much too loud at reference, even though it's ostensibly the same level as a movie theater, which never sounds loud to me. I figured the reason for this is that my system is not capable of ref. level without strain, but I never considered the room itself (12x13) as a cause of this harshness.
    ------------------
    [Edited last by Jack Gilvey on October 31, 2001 at 10:17 AM]
     
  5. Mike Miskulin

    Mike Miskulin Second Unit

    Joined:
    May 31, 1998
    Messages:
    383
    Likes Received:
    0
    Trophy Points:
    0
    Personally, I just adjust the sound to what I feel is comfortable on a movie to movie basis. It is almost always in the same general range, but I'm not going to get locked into setting a specific level for my movie enjoyment. Don't get me wrong, I've calibrated my equipment (huh,huh,huh) so as to be pleasing, but the volume always gets adjusted to the way I feel during a particular movie. Special FX movies almost always get "cranked" a little more than, say classics or comedies. But, to each his own I always say.
    mike.
     
  6. Doug_L

    Doug_L Stunt Coordinator

    Joined:
    Jun 22, 2000
    Messages:
    124
    Likes Received:
    0
    Trophy Points:
    0
    Vince,
    Great post. Sadly I never made the connection between 105db peak, 75db reference and the 30 db difference. 2 follow up questions.
    1) Is the 30 db difference btwn 105 and 75 the SAME 30 db that correlates to Dialogue Normalization?
    2) If peak spl of LFE is 115db, should I be calibrating it to 75db (assuming that's the level I'm setting all other channels to) or 85db? In other words, does the LFE track have 30db of headroom built-in, or 40db? I know that there's some difference bewteen DD and DTS, and does this effect your answer?
    Thanks.
     
  7. Brian Perry

    Brian Perry Cinematographer

    Joined:
    May 6, 1999
    Messages:
    2,807
    Likes Received:
    0
    Trophy Points:
    0
    The only thing I would add is that certain DVDs are encoded with different dialnorm values. (Some processors tell you this info.) Standard offset is -4 dB, but some discs -- such as Air Force One and Super Speedway -- are higher, so you would need to reduce your volume for these discs.
    ------------------
    Home Theater Pictures
     
  8. Adam Lenhardt

    Adam Lenhardt Executive Producer

    Joined:
    Feb 16, 2001
    Messages:
    17,979
    Likes Received:
    2,360
    Trophy Points:
    9,110
    Location:
    Albany, NY
    Normally, I have my audio level set at n and adjust it as needed for each flick (Mallrats was n-2, Episode I was n+4).
    I don't know how your sound setup works, but find a good average level to be your "reference" and adjust based on that.
    ------------------
    My DVD Collection
    My Preorders
    My Wishlist
    Potter is coming...
    [Edited last by Adam Lenhardt on October 31, 2001 at 06:16 PM]
     
  9. Vince Maskeeper

    Vince Maskeeper Producer

    Joined:
    Jan 18, 1999
    Messages:
    6,499
    Likes Received:
    0
    Trophy Points:
    0
     
  10. Rob Tomlin

    Rob Tomlin Producer

    Joined:
    Jan 8, 2000
    Messages:
    4,505
    Likes Received:
    0
    Trophy Points:
    0
    Vince-
    Thanks for the great responses to my post! You clarified a lot for me! [​IMG]
    One more question though:
     
  11. Vince Maskeeper

    Vince Maskeeper Producer

    Joined:
    Jan 18, 1999
    Messages:
    6,499
    Likes Received:
    0
    Trophy Points:
    0
    quote: I was not aware of this! Is it safe to assume that the LFE pad control is properly set up on the Denon? If not, could you tell me how to get to this menu on the Denon 3300 (since you are using it as well)?[/quote]
    Hmmmm. I don't have mine connected right now (it hooked up, just not hooked up in such as way as to allow me access to on screen menus).
    I have checked the manual PDF online, and I found it on page 47. I believe you have to actually have the reciver locked to a DD or DTS signal (something must be playing to it)- and then you press the SURROUND PARAMETER button. This brings up a menu with the Cinema EQ setting, Dynamic Ragne Compression, and LFE level.
    quote: Also, when calibrating the volume for the Subwoofer (to get to an average of 75db on the SPL meter) I have been using the volume control on the Subwoofer, not the level control for the Sub on the Denon "Channel Level" menu. Is this the correct way of calibrating the Sub?[/quote]
    Well, I have talked about this at length in the past. Although some have disagreed with me, here's my take:
    The volume pot on MOST subwoofers isn't a "volume" control, really, as it really doesn't control the output of the subwoofer. Rather it is a stage which controls how much signal the AMPLIFIER in the unit is getting. The amplier is waiting to amplify whatever signal it gets, and this knob on the sub allows you to tern down the amount of signal it gets.
    These knobs usually can't BOOST the signal passing to the amps, rather it just regualtes it-- all the way open isn't like boosting the signal- rather it is simply allowing all the voltage it receives to pass the the amplifier un effected.
    Unfortunately, this process isn't always a reliable one. In many cases this is a very cheap filter, which not only lowers the level of signal, but also has other effects on the tone color.
    I usually suggest to turn the knob on the sub ALL THE WAY UP and let the reciever regualte volume. This way, you bypass the filter on the sub- and all signal is passed onto the sub's amplifier uneffected by the filter... essentially you bypass it completely.
    Then use the level control in the receiver to adjust volume. If you can't get the sub low enough with the knob all the way open and your receiver SUB outout lowered all the way, then go ahead and lower the knob on the sub. But if you can make it work this way, that is how I would suggest to do it.
    The other issue is with AUTO POWER ON, some people have said their sub comes on more frequently when WIDE OPEN. If this is a problem for you, go ahead and turn it down. But, if at all possible to run your system with the receiver doing all the volume regulation- you will probably find a more pleasing sound.
    -Vince
    ------------------
    http://www.musicianassist.com
    AIM: VinceMaskeeper
    Do you want SOUTH PARK on DVD in order, rather than themed sets? Join our overwhelming majority !!
    [Edited last by Vince Maskeeper on October 31, 2001 at 07:11 PM]
     

Share This Page