On 05/10/2009, at 5:01 AM, Rob Danielson wrote:
>>
>> The high frequency complexities of the wing whirs was the first thing
>> I noticed when I heard the unprocessed mp3 material. I'll take a
>> listen to the original and see what else we might be able to learn.
>> Did you reach an opinion about whether there is some "sizzle" in the
>> recording from the vegetation? My memory of the situation can be
>> useful in guiding tone shaping in post. Rob D.
>
> Given the amount of steady sustain and the "grainy" character of the
> "hissy" noise, I do suspect its not just from environmental
> vegetation/wind interaction. You can see from the EQ curve, much of
> the noise is between 4K Hz and 6K Hz with a large concentration
> around 4300 Hz. The amount of noise is different from channel to
> channel and pretty fixed in ratio which also suggests its not
> environmental. I cannot account for what others may hear above 10Hz
> with my ears. I bet others can hear plenty up there. This noise is
> not typical for AT-3032 recordings I've EQ'd before.
>
> There seems to be stridency in the loud calls in the original too,
> but less than in the mp3. I didn't address this in interest of time.
Hi Rob,
I've spent a bit of time playing around with the recordings and going
back to the quietest bit of predawn recording I can find on the Round
Hill recording and one I made in still conditions a week earlier. I'm
now fairly sure the difference is down to the wind and vegetation
noise. Listening back to the raw recording the noise of the wind in
the background is quite apparent, and the background noise during
"silence" does seem to be primarily wind related.
I've also tested the phantom voltage output of the HDP2 right down to
shutdown. I had to unplug one mic and measure the voltage on the
channel so it isn't a perfect test. The HDP2 finally shut down when
the output of the external battery went below 7.5V DC. At this point
the output of the Li-ion pack was dropping rapidly - in final 10
minutes it went from just above 10V to shutdown level. The phantom
voltage remained steady at 46V right until the unit powered down. I'd
have to drag my scope out of storage to check if there is an increase
in rail noise as the voltage drops.
I'm struggling to find a clean Spiny-cheeked Honeyeater recording on
the net as an example. Try this lowbit rate mp3 or a recording by Fred
Van Gessel :
http://www.birdsinbackyards.net/images/audio/acanthagenys-rufogularis.mp3
These birds have an unusual call that is quite buzzy. I commented to
my partner during the trip that their calls made you feel like your
ears are distorting so I'm cautious about ascribing the distortion to
the recorder or mics.
regards
Paul
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