For those new to the list, I have created an Excel spreadsheet that
calculates the Total Noise for any combination of microphone and preamp,
when you know the noise figures for both. This helps in choosing a
recorder preamp to use with a particular microphone.
Here is the link:
https://www.dropbox.com/s/54xcyl4kdlosf3e/calculations.xls
The default values in the spreadsheet represent the Rode NT4 stereo
microphone (output noise -114 dBuA) and the Olympus LS-11 recorder (EIN
-122 dBuA). The result shows the Noise Difference between the Microphone
and the Total Noise is less than 0.8 dB and therefore a good match.
The spreadsheet also calculates the microphone output noise in dBu when
you know the self noise in dB SPL and the sensitivity in mV/Pa. Again the
NT4 is the default example (self noise = 16 dB SPL and sensitivity = 12
mV/Pa).
Because some microphone manufacturers give sensitivity in dBV/Pa instead
of mV/Pa I have also included a conversion between dBV (re 1.0V) and mV
and dBu.
I don't know how this works on other devices, but on my computer the link
does not immediately download the spreadsheet. It displays a page in HTML
that shows the content of the spreadsheet, but is not a form that allows
calculations to be entered. To do the calculations you need to click the
download button in the upper right corner and of course you have to be
able to work with Excel files.
I hope this is useful to others. I use it a lot.
For those list veterans who remember, I posted a similar spreadsheet about
a year ago, but I have added the dBV conversion calculations and I have
changed the location of the file.
best wishes,
John
John Crockett
Let us live in harmony with Earth
And all creatures
That our lives may be a blessing.
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