Volume

Discussion in 'Archived Threads 2001-2004' started by Bryan_Tams, Dec 4, 2002.

  1. Bryan_Tams

    Bryan_Tams Agent

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    Can someone explain the volume levels to me? I am not used to the -25 db reading. What is normal? How do I know what is half way? Full?

    Also, should I expect the volume level to vary much when switching between video sources?

    Thanks.
     
  2. Bob McElfresh

    Bob McElfresh Producer

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    Hi Bryan.

    Different vendors do different things with the display.

    When your receiver reads 0.0 db - this means it is putting out it's maxium rated power.

    Power and volume are ... related, but not identical.

    Imagine the receiver manufacturer did this: they hooked up a "reference" speaker, put a SPL meter 1 foot in front and calibrated the dial to show how the sound went up/down.

    Will this tell you what the volume is on your couch? No, that depends on your speakers, how they are aligned and how far away you are sitting. But it does show you how close to maximum output your receiver is pushing.

    Hint: Search for "Calibration" to find out how to use a Radio Shack SPL meter to really find out your volume, and how to calibrate your speakers.

    Yes, the volume will shift when you switch sources. Video Tapes are typically much louder than your DVD player. Your CATV box & Sat receiver ... they will be different as well. It's both a function of the output electronics, and how loud the source material is recorded at.

    Hope this helps.
     
  3. Bryan_Tams

    Bryan_Tams Agent

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    Perfect. Thanks.
     
  4. Kevin P

    Kevin P Screenwriter

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  5. Barry BB

    Barry BB Stunt Coordinator

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    Just to add to the already great answers here, the reason that the volume display is a negative number is that the volume adjustment attenuates the volume from reference. So with 0db being reference, -25db means that the volume is attenuated 25db below reference.
     
  6. AndrewDavid

    AndrewDavid Auditioning

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    I was just going to ask a similar question:

    Is this why my CDs are super loud at around half the max volume of the receiver, but then DVD and other Video sources are (comfortably) loud at approx 80% max volume? I was getting worried that turning up my Video sources so high was bad for the receiver... but it seems it's normal, it's the CDs that are output too high!

    Thanks!
     
  7. Drew Eckhardt

    Drew Eckhardt Stunt Coordinator

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  8. Bob McElfresh

    Bob McElfresh Producer

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    Drew: well, higher end processors DO adjust the display to show offset to some reference volume. (Some of them have a push-button that jumps the volume to reference - drool)

    But volume is .. very speaker/placement/position/frequency dependent. And the receiver controls POWER, not volume. So many of the Onkyo, Kenwood, Dennon, HK units show a volume number, but it's saying:

    "I'm putting out enough power to create -XXdb volume in my 'reference' speaker system, relative to my maximum power output."

    And the convention varies from model to model and year to year.

    For example, my older Yamaha receivers (RX-V793) have a little indicator on the volume knob. They were adjusted so that when the mark was at the 12 O'clock position, the receiver was pumping out it's RATED power at it's rated THD. (Yes, you could turn the volume up past this point, but you get increased distortion, not to mention heat.)

    The current generation Yamaha receivers dont do this.

    So the volume knob, and display are not always consistant even within a manufacturing line.

    Read your manual to learn what your make/model is saying when it says "- XX db".
     
  9. Vince Maskeeper

    Vince Maskeeper Producer

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  10. Drew Eckhardt

    Drew Eckhardt Stunt Coordinator

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    This is all simple mathematics. Cut voltage in half, power output (V^2/impedance) decreases by a factor of 4 - which is 6dB. Assuming a perfect speaker, SPL decreases by 6dB too. (at higher output levels, speakers compress dynamically - so a 6dB boost in power may only increase SPL by 5dB).

    Call measured output at 0dB your reference volume (which may or may not correspond to Dolby reference), and setting it to a different level will measure about the indicated difference except when you make it louder and run into clipping.

     

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