Asking help to any forum member with both analog and digital RS level meter

Discussion in 'Speakers & Subwoofers' started by WarnerL, Jan 12, 2006.

  1. WarnerL

    WarnerL Agent

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    If there are any forum members that have access to both analog and digital radio shack level meters at the same time would you be able to verify the difference in readings as posted here: http://www.nextlevelav.com/forum/showthread.php?t=907

    What the person did was have both the analog and digital level meters set up side by side and then played sine wave test tones from 16 Hz to 160 Hz, 1/6 octave apart, and posted the results and showed that he had a difference in readings between the two meters. Can at least one other person verify this?

    Thanks.
     
  2. Dan Driscoll

    Dan Driscoll Supporting Actor

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    I can't verify it, but I'm not surprised. The RS meters are best suited for making relative measurements, where you are comparing the SPLs of one speaker to another. Neither of these meters are very good for making absolute measurements where you are tring to determine the true SPL of a speaker or other noise source.

    The reason the analog and digital meters get different readings when measuring the same source is that they have different sensitivity ratings. To make even moderately accurate absolute measurements with an analog or digital Radio Shack meter (or most other inexpensive meters) you need to apply a 'calibration factor'. That is, a reading is taken from a known source and the true value is compared to what the meter actually detected. The difference is the calibration factor for that frequency and SPL level. To fully calibrate a meter a wide range of known frequencies and SPL levels need to be measured and a chart created, showing the calibration factor for each.

    BTW, there are such charts for the RS analog meter availabel on-line if you do a search. They won't be completely accurate, because each meter has to be calibrated individually to obtain the most accurate calibration factor. But using one of the on-line charts will get you closer to the correct absolute values. I assume there are similar charts available for the digital meter.
     
  3. John S

    John S Producer

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    Yeah what can you do? Two Digital RS meters will read differently even, I have proven it. You sure don't get precision at this price point. [​IMG]


    My analog meter suspiciously disappeared one night while helping with a live sound application. UUHHGGG

    Do you have room eq wizard? It can help sort if out, through calibration. Not only will make the proper offsets for the meter / mic, but the sound card and pre-amp electronics as well. Highly reccomended.
     

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