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Re: "Real world" self-noise of BP4025?

Subject: Re: "Real world" self-noise of BP4025?
From: madl74
Date: Sat May 3, 2014 6:06 pm ((PDT))
> I make a simple comparison test on three stereo mics, including BP4025.
> Such audible comparison gives me more information than any specification
> sheet.
> http://fieldrecording.net/mic-test/

Magnus, 

I've had a good listen to your test recordings and plotted a power spectrum 
of the quietest bits of each. Only look at over 1KHz. What I was looking for 
is thermal noise which rises at 6db/octave which indicates the lowest level 
of noise you can get. 

I do this test under a pile of bedclothes, which reduces the HF house noise 
and can give a good indication of mic and/or input noise at high frequencies 
where it matters. As I've said before, you can't get quieter than thermal 
noise which rises with frequency. 

I can't get a consistent sensitivity measurement from the variable radio or 
the clock ticking. In both cases the room resonance is prominent and anyway 
different mic pickup patterns will change these readngs. To get a realistic 
sensitivity test you need an anechoic chamber or the next best thing, 
outdoors away from HF noise and reflections - a poor man's anechoic. :-) 

I'm attaching the three power spectrums and a 1KHz warble tone which you can 
play on any device outside to give a reference signal for sensitivity tests. 
I can do a longer version of this if needed by looping. 

David Brinicombe 














"While a picture is worth a thousand words, a 
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.



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