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SPL Metering????

Discussion in 'Recording' started by shaun, Feb 13, 2004.

  1. shaun

    shaun Guest

    I have a question about measuring levels with a little radio shack spl meter. If with nothing playing i measure around 70 dB or so, then let my music play and its around 85 or 90 dB then how loud am i really referencing my music?? I measure in my car while driving and in the control room all the time and dont really know nor understand exactly how loud i am listening. I know they say to reference around 85 dB SPL but with the noise that the spl meter pics up how do you really know what your music SPL really is?? Thanx for the help
     
  2. David French

    David French Well-Known Member

    I think I see what you're getting at, and if you take the fact that 70dB + 85dB = 85.14dB, you'll see that the 70dB of background noise is quite insignificant compared to the volume of your music.
     
  3. AudioGaff

    AudioGaff Well-Known Member

    You have to average your measurement(s) over a specifc period of time. What time that equals is is up to you and also needs to relate to the dynamics of the music your listening too. I usually pick the mid part or most intense part of the song as the highest limit. I no longer mix at any specific level but I do check and adjust my mix at low level, mid level and loud level from what I perceive and based on my experience of what I think and believe is low, med, and loud.
     
  4. Thomas W. Bethel

    Thomas W. Bethel Well-Known Member

    Most studios and control rooms used for mixing are suppose to be NC20 or less. If you are measuring 70 dBSPL without anything playing then you have something that is very noisy in your studio. You should be using slow and C weighting. Also try A weighting and slow and see if your measurements go down. You can check out what the different curves mean at - http://www.kbase.castlegroup.co.uk/acoustic/frequency_response.htm

    What do you have running in your studio? A computer? Try turning it and everthing esle off when you do your background measurements. Best monitoring is about 83 dBSPL. More information on monitoring levels at http://www.digido.com

    Hope this helps
     
  5. shaun

    shaun Guest

    What is NC20?
     
  6. David French

    David French Well-Known Member

    Means the ambient noise in your recording environment should not exceed 20dB. This is pretty much impossible in a home studio. A quiet home is typically about 40dB.
     
  7. shaun

    shaun Guest

    I work at a studio in orlando, fl, called Transcontinental. I measured our studio A and my meter doesnt go below 50 db spl, but the room was definetly going lower. Its pretty damn quiet in there with the exception of a really noisy EMT 250 we have in there. But i was just originally wondering if its (lets just say) around 20 db with nothing really on, then i play music in the room and i measure around 86 for example. How loud am i monitoring my music?? What is the equation to figuring this stuff out. Thanx for the help
     
  8. Thomas W. Bethel

    Thomas W. Bethel Well-Known Member

    You should monitor music at about 83 dBSPL. This is where the human ear is the flattest in response and were you can listen all day without fatigue. The higher you go in dBSPL the less time you can monitor without potentially destroying your hearing. If you are in a quiet room or a somewhat noisier room it does not matter. What matters is what the sound level meter reads as to the total SPL or Sound Pressure Level. The only thing different between a quiet room and a somewhat nosier room is that with the quiet room you can hear more of the subtleties of the music since you will not have any other noises completing with the music.

    Go to http://www.digido.com and read the article on monitoring levels. I think you will find it useful.

    Hope this helps
     
  9. AudioGaff

    AudioGaff Well-Known Member

    The highest value you measure is the loudest it is. In your example it is 86dB. If the room were to measure 20dB when quiet and the music was an average of 86dB, that is still a total average of 86dB. If the room with no music measured 80dB and 86db with music, the total average would still be 86dB as that is the highest measured total value. The higher the measured value with no music playing means your diminishing your ability to hear and judge the music's total dynamic range. That your going to have a much harder time be able to hear all the low level details in the music unless you turn up the total volume to hear them. But then this would of course turn up the louder parts and make your overall total much higher than the 86dB you were listening to before.
     
  10. David French

    David French Well-Known Member

    I could tell you the equations if you really want to know, but I don't think that's needed here. Just keep in mind that since dB is a logarithmic scale, that 20 to 30dB on the bottom is completely insignificant with respect to the total SPL. Remember from my first example that 70dB in reference to 85dB accounted for only 0.14 dB of the total SPL. Now, you can imagine that 30dB would be even less significant.
     
  11. doctorfish

    doctorfish Guest

    I've been thinking about getting an spl meter to help set my monitoring volume as well as to check what the actual noise level of my room is. A project soon to be followed by building a quiet box for the computer which I know is much too loud.

    My question is about where to take measurements from. Do I take measurements from my listening position? I read in another post that measurements should be taken form one foot in front of the speaker. Why is that? And would I get very different results either way?

    Thanks

    Dave
     
  12. shaun

    shaun Guest

    Quote: Do I take measurements from my listening position? I read in another post that measurements should be taken form one foot in front of the speaker. Why is that? And would I get very different results either way?


    I've always measured from around the area that I sit when i'm monitoring, thats where I feel i get the closest measurement to my ears. I usually sit the same distance back from the speakers as they are apart( to make a triangle). As far as measuring 1 foot in front of the speaker, your measurement will jump up alot from the distance that you monitor and 1 foot from the speaker. I once tried that and when i measured @ 86 dB from my spot, which was about 3-4 feet away from the speaker, the level jumped to @ 100 dB when i measured right in front of the speaker, but i'm not too sure how that would help u seeing that you will rarely be monitoring with your ears that close to the speaker.
     
  13. steveotoole

    steveotoole Guest

    Just remember to put the SPL meter away before the band comes in or they'll turn it into a Fartometer! :D
     

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