[Boatanchors] Microphone Output

[Al Klase]

David,

You need to look at the datasheet for your mic or a similar device. 
Heres a snippet from the Shure SM-58 specs.

Sensitivity (at 1,000 Hz, Open Circuit Voltage): –54.5 dBV/Pa (1.85 mV) 
(1 Pa = 94 dB SPL) [[ i.e. referenced to 1 volt RMS]]

Impedance: Rated impedance is 150Ω (300Ω actual) for connection to 
microphone inputs rated low impedance

So, they specify an output level, usually a open-circuit voltage, for a 
specific sound-pressure level at a particular frequency.
Then they give you a feeling for the output impedance, which is a little 
more difficult to nail down.

The really big difference is Hi-Z versus Lo-Z microphones.

Al

On 1/11/2013 11:21 AM, D C _Mac_ Macdonald wrote:
> Or it might be 0 dBmv which is 1 millivolt rms.
> However, these values must be referenced to
> the load resistance!  AND, if I'm not mistaken,
> reference dB values are actually given based
> on power; dBmw, dBw, etc.  It is common,
> though to quote them based on either power
> OR voltage.  Of course, a given value means
> different things depending upon the system.
> Full details must be given to mean ANYTHING!
>   
> * * * * * * * * * * *
> * 73 - Mac, K2GKK/5 *
> * (Since 30 Nov 53) *
> * k2gkk at hotmail.com *
> * Oklahoma City, OK *
> * USAF & FAA (Ret.) *
> * * * * * * * * * * *
>   
>   
>> From: mwtallent at comcast.net
>> To: Boatanchors at mailman.qth.net
>> Date: Fri, 11 Jan 2013 10:56:01 -0500
>> Subject: Re: [Boatanchors] Microphone Output
>>
>> Usually is 0 DBv which is 1 V rms.
>>
>> Mike Tallent
>>
>> ----- Original Message -----
>> From: "David C. Hallam" <dhallam at knology.net>
>> To: <Boatanchors at mailman.qth.net>
>> Sent: Friday, January 11, 2013 10:17 AM
>> Subject: [Boatanchors] Microphone Output
>>
>>
>>> When a microphone output is given at say -52db, what exactly does that
>>> mean? -52db referenced to what?
>>>
>>> David
>>> KW4DH
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-- 
Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/