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I have designed an A weighting network circuit. but i cant understand how to convert it's voltage output in to corresponding sound pressure level in dB. So How can I convert these voltage readings into dB?

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  • \$\begingroup\$ Perhaps with a logarithmic amplifier. \$\endgroup\$
    – venny
    Aug 31 '14 at 10:36
  • \$\begingroup\$ OP, please wait before accepting an answer, I feel mine can be expanded quite a lot and there are probably people who will be able to provide a better insight. \$\endgroup\$ Aug 31 '14 at 10:53
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I am assuming your output is also driving an amplifier and then some loudspeakers.

If that's the case the best way to calibrate your vu meter is put some pure tone in the amp and measure the spl with a microphone nicely placed.

You can also search for a parameter called "sensitivity", the manufacturer of your loudspeakers should be able to tell you it. Sensitivity is measured in \$\frac{\text{dB}}{\text{W}\cdot\text{m}}\$, i.e. is the spl in decibel the loudspeaker outputs for each watt of power you give to it, measured at a distance of 1m. Problem is that sensitivity depends on frequency and on the enclosing and probably other parameters.

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  • \$\begingroup\$ +1, since different speakers will have different efficiency; some speakers will generate nearly no sound at a given drive voltage, while other speakers may generate quite a lot of sound with exactly the same drive. \$\endgroup\$ Aug 31 '14 at 14:24
  • \$\begingroup\$ and that's why a 15W Marshall high end amp can blow out any 100W "Hi-Fi" system \$\endgroup\$ Sep 1 '14 at 17:44

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