Dear Rob,
Yes, I was very lucky to find a relatively quiet time window between all th=
e
cars and jets that usually pass by.
The soft 5.2 kHz noise must originate from electronic devices in my office
(perhhaps the fax machine).
As you already noticed, there was slighltly more urban noise during the 722
test period. It is also important to take into account the lower cutoff
frequency of the SD722 compared to the other two recorders.
This one of the reasons why the 722 picked up more low frequency rumble tha=
n
the MT and 671.
The connsistent hiss that is present in all samples should be almost
exclusivley the ME66's self noise.
This is not surprising because such a sensitive microphone (50mV/Pa) can
also be considered as an insensitive microphone (5mV/Pa) with an intergrate=
d
"zero noise" 20 dB preamplifier.
What we can learn from this example is, that you don't have to care much
about the preamplifier noise as long as you use a very sensitive microphone=
.
Raimund
>Hi Raimund--
>Great to get a chance to consider the 671 too.
>There doesn't seem to be as much urban "rumble"
>where you are.
>Any thoughts about the consistency in the higher
>register hiss? Looking at a sonogram, there's a
>band-shelf across all three segments, dropping
>off at ~5.2KHz.
>http://www.uwm.edu/~type/Mic%20Preamps/Raimund_MT2496_M671_SD722.pdf
>I'm not familiar with the ME66. It seems a mic
>with a self noise of 10 dB(A) would be low enough
>to reveal important differences. There is more
>lower-register "room tone" evident in the 722
>segment, but to my ears, most of the differences
>are effectively masked by the consistent hiss.
>Could it possibly be the ME66's self noise, as
>illogical as it seems? Rob D.
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