Re: Mike element

iz oos
 

Thanks Jerry, I had always thought the opposite, the lower the more sensitive just like sensitivity in a receiver. So, I was wrong. What about sensitivity in headphones and speakers?


Il 17/lug/2018 04:29, "Gordon Gibby" <ggibby@...> ha scritto:
With that level of sensitivity, perhaps no preamp at all is needed with the bitx  series.

Available for three dollars at digikey. 

Thanks for pointing it out and giving that educational lecture!



On Jul 16, 2018, at 21:51, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

Yes, you have it right.

For a given sound pressure into the mike,
the -24 dB mike creates a voltage that is 10 times bigger than the -44 dB mike.
A 10 times bigger voltage into a fixed resistance means 100 times more power,
since power in watts = volts * amps =   volts * volts/ohms.
With 100 times more power, that's 10 * log(100) = 20 dB more power.

If the mike were zero dB, we'd get 1 volt from the mike.
Since the voltages we are dealing with are less than one volt, 
we get negative numbers when representing the values in dB.

Jerry, KE7ER


On Mon, Jul 16, 2018 at 04:58 PM, iz oos wrote:

So, would - 24db be 20db more sensitive than - 44db?


Il 16/lug/2018 22:26, "k1yw via Groups.Io" <k1yw=mail.ru@groups.io> ha scritto:
. . .

 

0 dB = 1 volt per Pascal
-24dB = .0.063 V/Pa
-44 db = 0.0063 V/Pa


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