A-weighting

Shreder001 · 28th October 2009, 02:12 AM

Hello, i am very new to this forum and also very new to audio. I just completed my first audio circuit, consisting of an electret condenser microphone and a preamp ciruit. The pre-amp will then go to a PIC microcontroller. I would like to apply an A weighting (dBa), but the problem is, i am having the most horrible time understanding it all. First off, do i need to use passive components to do this or should i program it into my pic? is there an equation to convert dB to dBa? Thanks!!!

Iain McNeill · 2nd November 2009, 03:43 AM

Hi,
Welcome to DIYaudio!

'A' weighting is really just a specific bandpass filter and as such can be done with a passive or active filter or in DSP using digital filtering techniques. The trick is getting the break points in the right place.

See Rod Elliotts discussion:
A-Weighting Filter

Conrad Hoffman · 2nd November 2009, 04:29 AM

You can do a filter or apply the factors in software. I like this site as they use the accurate coefficients-
Aweighting - DiracDelta Science & Engineering Encyclopedia
It's just a matter subtracting the appropriate number of dB at each frequency of interest. A-weighting reduces mainly the low frequencies, and is suited to determining the "annoyance factor" of noise. It can make specs look better than they should with audio equipment, but IMHO isn't really suited to hi-fi measurements.

28th October 2009, 02:12 AM	#1
Shreder001 diyAudio Member Join Date: Oct 2009	A-weighting Hello, i am very new to this forum and also very new to audio. I just completed my first audio circuit, consisting of an electret condenser microphone and a preamp ciruit. The pre-amp will then go to a PIC microcontroller. I would like to apply an A weighting (dBa), but the problem is, i am having the most horrible time understanding it all. First off, do i need to use passive components to do this or should i program it into my pic? is there an equation to convert dB to dBa? Thanks!!!

2nd November 2009, 04:29 AM	#3
Conrad Hoffman diyAudio Member Join Date: Mar 2007 Location: Canandaigua, NY USA	You can do a filter or apply the factors in software. I like this site as they use the accurate coefficients- Aweighting - DiracDelta Science & Engineering Encyclopedia It's just a matter subtracting the appropriate number of dB at each frequency of interest. A-weighting reduces mainly the low frequencies, and is suited to determining the "annoyance factor" of noise. It can make specs look better than they should with audio equipment, but IMHO isn't really suited to hi-fi measurements. __________________ I used to be an audiophool like you but then I took an arrow to the knee.

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2nd November 2009, 03:43 AM	#2
Iain McNeill diyAudio Moderator Join Date: Oct 2007 Location: Santa Cruz, California	Hi, Welcome to DIYaudio! 'A' weighting is really just a specific bandpass filter and as such can be done with a passive or active filter or in DSP using digital filtering techniques. The trick is getting the break points in the right place. See Rod Elliotts discussion: A-Weighting Filter

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