At 5:25 PM +1000 5/29/10, Paul Jacobson wrote:
>
>
>
>On 29/05/2010, at 2:49 PM, Rob Danielson wrote:
>>
>> Hi Paul--
>>> 11K and 20 beats/second seems distinct enough for audio engineers to
>>> recognize. I found one other file combining the DR680 and a 3032
>>> that appears to be recorded at another time. Its the one labeled
>>> "Boundary Array." The other file in the folder is the same
>>> 3203->DR680 clip that you found the noise in.
>>> <http://tinyurl.com/2w4dqoj>http://tinyurl.com/2w4dqoj [2mb
>>>download] Rob D.
>
>The Boundary array recording doesn't have the ticking but the clip
>you used in the comparison does, so obviously it was an
>environmental sound.
>
>I've put together a file comparing indoor and outdoor recordings
>with the 3032's which is perhaps a little unfair. I taken a chunk of
>a recording I'd made at Gundabooka National Park in predawn. From
>memory the gain was set at about "9" on the super mod hdp2, which
>with the +6dB gain mod roughly equates to 10 on a standard version.
>The hiss above 1khz seems to be fairly closely matched.
>
>The first 8 seconds is DR680/3032, followed by 12 seconds of
>SuperMod HDP2/3032 recording predawn still, then a short segment of
>a 4wd starting up back at camp. I've checked on google maps and this
>was 1.6km/1mile away as the crow flies.
>
><http://demo.mactrix.com.au/dr680/Indoor_Outdoor_3032.wav>http://demo.mact=
rix.com.au/dr680/Indoor_Outdoor_3032.wav
>[5.5mb]
>
>Some of the quieter portions of the Gundabooka recording are -70dBFS
>(a-weighted) and as gain at "9" is in the region of 44-46dB this
>would translate to a mic output of -114 to -116dBU(a-weighted).
>Given that the output for a mic with the sensitivity of 19.9mV/Pa
>(AT3032) in a sound field of 10dBSPL would be -116dBu(a-weighted)
>this should be pretty revealing of mic performance.
>
>cheers
>Paul
re:
><http://demo.mactrix.com.au/dr680/Indoor_Outdoor_3032.wav>http://demo.mact=
rix.com.au/dr680/Indoor_Outdoor_3032.wav
>[5.5mb]
Very helpful. Between this test, Paul's and mine we have eight+ 3032
recordings made with 5 very low noise mic pre/recorders in quiet
settings at high gain. Your test is consistent with Paul D's and I
conclusion yesterday that there's a peaky range in the 3032's
self-noise circa 3800-4300 Hz-- often in 3-4 very narrow bands. 4022
exhibits it too. This is very useful information for me when I mix.
Curt and Mike Rooke asked, off-list, about the self-noise of NT1-A
being louder and a rough audible match to that of the 3032/4022's in
Paul D's test. I think its a fluke, product of several factors. The
common "airy" environmental noise the NT1-A clip also has, the NT1-A
being further away and off-axis and the NT1-A's weaker upper bass and
lower mid range response downplaying the rumble. In the LF-Lower Mid
Range saturated test environment, the playback level of the NT1-A had
to be increased 5dB to compensate for its weak bass response compared
to the AT's. I believe this is why the 6 dB(A) mic has more
self-noise hiss then the ~8dB(A) mics. Rob D.
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