From: liz@poppyrecords.invalid.invalid   
      
   Tobiah  wrote:   
      
   > The Rode NT1-A lists an "Equivalent Noise Level" of 5 dBA.   
   >   
   > So I can look at that figure, and compare it to other mics.   
   > But then I thought, what about sensitivity?  If the noise   
   > figure measures the raw noise level coming into the preamp,   
   > then a high sensitivity mic would have a larger signal to   
   > noise ratio, making the self noise figure meaningless on   
   > its own.  Or does the noise figure take that into account   
   > somehow?   
      
   I presume they mean that the noise coming from the mic connector is   
   equivalent to a sound pressure level of 5 dBA.   That is useful because   
   it tells you the signal to noise ratio of the mic at any given sound   
   pressure level (assuming it is connected to a 'perfect' pre-amp).   
      
   What it does not tell you is the actual electrical output power at that   
   sound level, so the overall noise level of the whole microphone channel   
   (mic + pre-amp) can't be calculated.  Perhaps that figure is hidden   
   elsewhere in the specification?   
      
   As long as the pre-amp noise is more than 6dB below the mic noise and   
   similar in character, there is little point in spending a lot of money   
   on a quieter pre-amp.  You can check that by measuring (or listening to)   
   how the noise changes when you disconnect the mic and connect a dummy   
   plug with a resistor across the pins, with the same resistance as the   
   mic's output impedance.   
      
      
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   ~ Liz Tuddenham ~   
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