Volume confusion

Discussion in 'AV Receivers' started by Rob Wallenberg, Feb 9, 2005.

  1. Rob Wallenberg

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    Hi, im new here on the forum and needless to say im a layman. I was curious about my amp and speaker combination. I was wondering if there is a safe number anyone can recommend for the loudest possible listening level, is it safe to go to "zero". I have a denon 2803, paradigm monitor 11's ver. 4's as well as ADP-170's and a CC-370 for a center.

    Thanks alot
     
  2. Nathan Stohler

    Nathan Stohler Second Unit

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    On many receivers, the actual volume number is meaningless. To know exactly how loud your system is at a given level, you would need an SPL meter.

    By "safe", I'm not sure whether you mean for your ears or for your equipment. Although a lot depends on the size of your room, your receiver's power rating and the sensitivity of your speakers, it's quite possible that your system has more than enough power to damage your hearing, if you so desire.

    As for your equipment, the most common problem is clipping. If your receiver doesn't have adequate power to drive your speakers at a high level, you will hear distortion. At this point, you should turn it down, if not before that.
     
  3. Rob Wallenberg

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    I really doesn't seem to be that loud at say -5db, i believe the control goes up to +10 or +20. Ive never turned it up past "Zero" although sometimes i am temped. This is my first home theater system and i dont want to destroy it by blowing anything up. Does anyone else have a similar set up as me, and if so how loud can you take it up to without frying your gear.

    Thanks again guys.

    Please be patient with my lack of knowledge i trying to learn about this stuff as much as i can
     
  4. Rob Wallenberg

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    I guess what im really asking is, if zero is what they call reference level is that an acceptable volume to be at without wrecking my hard earned gear?
     
  5. John S

    John S Producer

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    I'm of the opinion it is only to loud when you percieve it to be, or the audio is degraded. Crank it up!!!

    The 1st time the T-Rex roars in Jurassic Park, it should truely frighten you, just like it did in the pay theater. [​IMG]
     
  6. Nathan Stohler

    Nathan Stohler Second Unit

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    "Zero", as defined by your receiver, and reference level are totally different concepts.

    Sometimes, the receiver defines zero to be max power. Sometimes, it's arbitrary. Some receivers use positive numbers, some use negative, some use both (as in your case).

    Reference level, on the other hand, is the same no matter what system you have. If you calibrate your system with an SPL meter, you'll know exactly what setting on your receiver gives you reference level. In my system, reference level reads "-10" on my receiver, but yours would be different.

    The display on your receiver alone will tell you nothing about where you are in relation to reference level. Even if someone has the exact same speakers and receiver as you, you would still have to take in account room size and layout, speaker position, the location of your sweet spot, and some of the other settings on your equipment.

    Simply put, the only way to determine reference level in your system is through calibration.
     
  7. John Garcia

    John Garcia Executive Producer

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    Loud is one thing, but I'd say that receiver doesn't have the oomph for those particular speakers at ref level for any length of time, unless you have a very small room. You will run the risk of clipping and damaging them.
     
  8. StephenL

    StephenL Second Unit

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    That depends on whether your receiver has enough power to drive your speakers at reference level, at your listening distance, without clipping. The Denon AVR-2803 is no slouch. Sound & Vision magazine test report:
    http://www.soundandvisionmag.com/art...&page_number=1

    If the Denon AVR-2803 automatically sets the master volume to the reference level (00 on the master volume display) and you adjust each channel to produce 75dBc SPL at the listening position, then the master volume display is an accurate indicator of reverence level.
    http://www.usa.denon.com/support/faqs_ht.asp#Q7

    Why is 0 dB near the high end of the volume scale on some receivers and processors?

    In digital recording, 0 dBFS (decibels full scale) is the peak level that can be recorded before digital clipping or overload occurs. Full scale is the level at which the binary number describing the signal is 1's in all places; it can't get any larger. All other measurements expressed in terms of dBFS will always be less than 0 dB (negative numbers). 0 dBFS is a logical reference for full scale because it can be used for any digital format regardless of the number of bits used to represent the signal. On some receivers and processors, the master volume level of 0 dB corresponds with the 0 dBFS level in Dolby Digital recordings.
    http://www.jimprice.com/prosound/db.htm

    If 0 dB is the maximum level before digital clipping or overload in a digital soundtrack, why does the master volume control go above 0 dB on some receivers and processors?

    It's possible play back a digital soundtrack above the 0 dB reference level without clipping provided your amplifiers and speakers are capable. However, the dynamic range (the difference between the loudest peak and the softest level) will remain the same.

    What is reference level?

    Dolby or THX reference level is the volume level (sound pressure level) used in theaters for movie presentations (although this level is sometimes turned down). Digital formats are adjusted in the theater so that a digital signal level of -20 dBFS (20 dB below the 0 dB full scale level) will produce a sound pressure level of 85 dB at a distance two-thirds back in the theater. This allows a full-scale level of 105 dB per channel at the same distance.
    http://www.audiovideo101.com/diction...-reference.asp
    http://www.audiovideo101.com/diction...-reference.asp
    http://www.jblpro.com/pub/cinema/cinedsgn.pdf

    Some of the more sophisticated receivers and processors for home use (including those that are THX certified) provide individual speaker level calibration with the master volume at a designated, preset reference level corresponding with 0 dBFS. These receivers and processors automatically set the master volume to the reference level when the individual speaker levels are calibrated. This reference level is typically displayed as 0 dB on the master volume.

    Why should speaker levels be calibrated relative to reference level?

    Accurate calibration relative to 0 dBFS (the full-scale reference level) ensures that the sound pressure level produced by a sound system is the level intended by the sound engineer when the film's audio was mixed, regardless of whether the sound system is in a studio, commercial theater or home theater.

    How loud is reference level?

    Dolby Digital soundtracks have a dynamic range (the difference between the loudest peak and the softest level) of 105 dB for each channel. All recording levels are referenced to the 0 dBFS peak, so the minimum level in a Dolby Digital soundtrack is -105 dBFS. When a speaker receives a 0 dB full-scale signal from a Dolby Digital soundtrack, the sound pressure level should be 105 dB from each full-range channel and 115 dB from the Low-Frequency Effects channel. The ability to actually achieve the peak SPL in your home theater depends on the speakers, amplifiers and room.

    If the 0 dB reference level corresponds with an SPL of 105 dB, isn't reference level too loud for normal listening?

    Remember that 105 dB is the potential peak SPL at 0 dBFS (full-scale reference level). Dialog is typically well below the full-scale level. But many people find that the 0 dB reference level is too loud for most soundtracks. You can always reduce the master volume to provide a comfortable SPL.

    What is dialog normalization?

    The Dolby Digital recommended target level for dialog is -31 dBFS Leq(A), which is an output level 31 dB below 0 dB full-scale digital output, averaged over time using the equivalent loudness method. In order to maintain volume level consistency, Dolby Digital soundtracks contain a dialog level parameter (also known as dialogue normalization or dialnorm), which the decoder uses to automatically attenuate soundtracks that have a dialog level greater than -31 dBFS. The dialog level parameter is part of the soundtrack's metadata, which is data embedded in the digital audio data stream when the soundtrack is encoded. The scale used in the dialogue level setting ranges from -1 to -31 dB, in increments of 1 dB, where -31 dB represents no level shift. The Dolby Digital decoder adds the dialog level parameter to 31 dB to obtain the value of the level shift. For example, if a film has a dialogue level of -27 dBFS Leq(A), the sound engineer would include that dialog level parameter in the soundtrack's metadata. Your Dolby Digital decoder would add the -27 dB dialog level parameter to 31 dB resulting in a level shift of 4 dB. Your decoder would automatically reduce the volume by 4 dB. For dialog normalization to work as intended, the sound engineer must provide an accurate dialog level parameter in the metadata when the soundtrack is encoded.
    http://www.hifi-writer.com/he/dictio...gnormalization
    http://www.dolby.com/metadata/pa.st.0102.MDGuide.pdf
    http://www.soundonsound.com/sos/dec0.../surround5.asp
    http://www.hometheaterhifi.com/volum...on-6-2000.html
    http://www.tweakers.net/nieuws/18061
    http://www.globaldisc.com/Dolby/DDNorm.html
    http://www.tvtechnology.com/features...12.10.03.shtml
    http://etvcookbook.org/glossary/#D
    http://etvcookbook.org/audio/dialnorm.html
    http://www.smr-home-theatre.org/optimode/page3.html

    How do I calibrate my home theater system at reference level?

    Some receivers and processors (including those that are THX certified) have an internally generated test signal (pink noise) that is accurately calibrated relative to the 0 dB reference level. The internally generated pink noise in THX certified home equipment has a value of -30 dBFS. The Sound Pressure Level (SPL) that should correspond with the -30 dBFS test signal is 75 dB because the 0 dB full scale reference level corresponds with a peak SPL of 105 dB, and 105 dB - 30 dB = 75 dB. The user adjusts the individual speaker levels by observing a sound pressure level meter at the listening position so that each speaker produces 75 dBc (C-weighting, slow response) SPL with the internally generated pink noise and the master volume at the reference level of 0 dB.

    Professional processors have a test signal with a value of -20 dBFS, so commercial surround sound systems are calibrated to 85 dBc SPL. Note that correctly calibrated home and professional systems will play identical soundtracks at the same SPL.
    If your receiver or processor doesn’t have a designated point on the master volume scale that corresponds with the 0 dBFS reference level, and a test signal that is accurately calibrated relative to that level, you can use test signals from a DVD such as Avia or Video Essentials and note the level on the master volume that corresponds with the calibrated level. The most important objective when calibrating your receiver or processor is to make sure all speakers have the same output measure at the listening position.

    How does room size, speaker sensitivity and speaker distance affect reference level?

    Calibrating the individual speaker levels with the master volume at the 0 dB reference level eliminates variations due to speaker sensitivity, room size and distance between the listener and speakers. All systems that are properly calibrated at reference level will play the same soundtracks at the same SPL when the master volume is at 0 dB, provided the amplifiers have enough power and the speakers are capable of achieving the required SPL. There is no need to adjust the master volume to compensate for variations in speaker sensitivity and distance.

    For example, consider the following two home theater systems:

    The first is playing a Dolby Digital soundtrack at reference level (master volume at 0 dB) in a 2,000 cubic foot room with the listener 10 feet from speakers with relatively high sensitivity.

    The second is playing the same Dolby Digital soundtrack at reference level (master volume at 0 dB) in a 4,000 cubic foot room with the listener 20 feet from speakers with relatively low sensitivity.

    The two systems will produce the same SPL, provided both are properly calibrated, the amplifiers have enough power, and the speakers are capable of achieving the required SPL.
    http://www.htguide.com/forum/archive/index.php4/t-2939


    Related topics:
    http://www.jimprice.com/prosound/db.htm

    http://www.usa.denon.com/support/faqs_ht.asp#Q7

    http://www.audiovideo101.com/diction...-reference.asp

    http://www.hometheaterhifi.com/volum...on-6-2000.html

    http://www.hometheaterhifi.com/volum...pril-2000.html

    http://resmagonline.com/articles/pub...ticle_93.shtml

    http://www.keohi.com/keohihdtv/exper.../avia_a2z.html

    http://www.worldhistory.com/wiki/B/Bel.htm

    http://www.free-definition.com/Bel.html

    http://hometheaterhifi.com/forum/arc....php/t-61.html
     

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