Re: How would you calibrate a sound level meter RESTATING THE PROBLEM

From: legg (legg_at_nospam.magma.ca)
Date: 09/01/04 

Date: Wed, 01 Sep 2004 02:04:03 GMT

On Wed, 25 Aug 2004 20:48:47 GMT, "Norm Dresner" <ndrez@att.net>
wrote:

>I originally wrote:
>
>"Norm Dresner" <ndrez@att.net> wrote in message
>news:v3UWc.512527$Gx4.104653@bgtnsc04-news.ops.worldnet.att.net...
>> Any microphone with a suitable amplifier and an AC voltmeter makes a sound
>> level meter. Suppose I wanted to make one to set up a stereo system where
>> the input is single tone at a time and the goal is to adjust a
>multichannel
>> equalizer to get approximately overall flat response from voltage/power in
>> to sound level out. I don't need OSHA or any particular "weighting"
>scheme.

You are attempting to calibrate the amplifier and loudspeaker in the
described exercise.

To do this, the measuring equipment, signal source and test setup must
be pre-calibrated and standardized to your application, even to the
point-source or physical shape of reception (say - location of ears on
a standard head).

If the measurement is made with simple VU or SPL measurement, then the
source must vary over the frequency range of interest - say a slow
sweep or spot signals.

Formatted signals for this are available from

http://www.marchandelec.com/sweeps.htm

http://62.242.11.12/midiutil/index.htm

Whether what you get will be better than just dumping the equalizer
altogether is moot.

To calibrate metering - the standard technique is to compare it to
reference calibrated standards. The calibration standards are produced
by gnomes in secret laboratories in the Black Forest.

RL

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