Frome the QMX SSB page at QRPlabs
"All development has been done with this particular Electret microphone from Digikey, part number 668-AOM-5024L-HD-F-R-ND:
This is NOT the same microphone as the QMX supplied onboard microphone. Many thanks to?Paul?W9PEM who gifted me this microphone, beautifully enclosed with a PTT button and 3D printed enclosure."
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Here's how microphone sensitivity is measured:
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A lower negative dB (such as -24dB) means more Volts out of the microphone for a given sound pressure
than a higher negative dB (such as -44dB).
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The spec might use units of dB, dBA or dBV for the gain.
My guess is that these units are all directly comparable.
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Mouser has a selection of 179 different electret microphones:
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Selecting for only those with a sensitivity better than 30dB gives 11 microphones:
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Three of those are not in stock, and two of the remaining expect a supply greater than 3 volts.
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SNR is not given in the selection summary,? it is spelled out as "signal to noise" in the datasheets so search for "noise".
Of the remaining 6 microphones that have a sensitivity better than -30dB, the SNR is generally 60 or 70 db.
The two from PUI claim 77 and 80 dB of SNR, and are the most expensive at around $3.
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If Hans really does use -24dB microphones with an 80dB SNR, those are not typical of what's on the market.
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Jerry, KE7ER
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