At 8:04 AM -0700 8/23/06, Tim Nielsen wrote:
>Rob, am curious what software you're using to look at the
>frequencies, are you using a sonogram or a RTA plugin of some kind?
Hi Tim--
By ear first. The resonant frequencies in the mic/system are subtle,
sustained tones. To help me "tune" my ears for your mics/your system,
I edited quick snippets from each location in your file,
http://www.wildecho.com/Filechute/Schoeps%20MS%20Stereo%20Sample.wav
so that I could listen for the tones that seem to stand out in all of
the recordings/settings. Here that is:
http://ad2004.hku.nl/naturesound/NielsonSchoepsMSnips7Locs.wav
Then I took the pink noise section about 3.55 in and created a narrow
band of parametric EQ in Eqium. Next I move a +4dB boost curve and
slowly up and down the spectrum in the range I believe I'm hearing an
exaggerated tone. When I think I've found the most pronounced one, I
see if I can lower its volume until the pitch sounds more in balance
with the adjacent tones. This process usually reveals another tone
that seems exaggerated. I repeat the process until only very subtle
tones stand out when I fade up the volume. To offset subjectivity
somewhat, I usually perform this step 2 or 3 times from scratch with
a new Eqium plug to see I'm finding the same notes each time. With
this pariculat mic rig, there seem to be about 8 resonate tones in
the mid mic that repeat across the locations (3 tries) and 5 or 6 in
the side mic. This does not include the high Hz hiss/graininess in
the two mics.
I hoped to output the EQ'd result but I found that decoding from MS
to LR and then back from L-R to M-S did not work well with three
separate plugs designed for this. There were some fairly pronounced
phase oddities created.
As for the mic bumps, the resonance is quite pronounced, and for some
reason, the bumps are mostly in the Side mic. I've indicated their
much smaller presence on the Mid mic in the sonogram:
http://ad2004.hku.nl/naturesound/Side&MidMicsSonogramp.jpg
and the (split) files they were made from:
http://ad2004.hku.nl/naturesound/WindLeavesMicBumps_M.aiff
http://ad2004.hku.nl/naturesound/WindLeavesMicBumps_S.aiff
The Side mic cable rubbing might produce this asymmetry but I don't
know your rig. Based on what I can hear and these sonograms, an 80Hz
shelf filter probably wouldn't remove their presence and the balance
of the recording would take quite a hit if eliminating them was the
goal. It looks like the harmonics from the bumps extend over 200 Hz
with some quite audible tones coming in as high as 105Hz.
As I've described before, I avoid low Hz shelf filtering because I
feel that the lowest frequencies create the closest thing to a
"horizon" in most natural locations. The lowest frequencies are those
that arrive from the greatest distance. I do address exaggerated
"lows" in recordings all the time but I attenuate it with individual
bands of parametric EQ. I seldom have to attenuate much of the signal
below 60 Hz unless I'm shaping the channel for a subwoofer. Another
thing I've noticed about the few mk8/mkX Schoeps I've played with
(maybe someone with more Scheops experience like Greg or Eric can
comment?) they don't seem to have quite as much "rising" low Hz
response and other mics, including the mkh30/40. Here's the weighting
I get from a quiet moment from your samples .wav file:
http://ad2004.hku.nl/naturesound/NielsonSchoepsM-SLocationPres.jpg
This could be more incentive to not use low Hz "roll-off" but to
address the problem Lo Hz bands individually with parametric EQ. Rob
D.
>
>In that recording, I would argue that you could easily roll off below
>80k, even sharply, and not miss a thing, getting rid of all the mic
>bumps. That one might not have been rolled off, or might already have
>been rolled off gently. But I agree that it's pretty hard to handhold
>for very quiet sounds, and those bumps aren't probably cables
>bumping, but just hand adjustments on the handle that are being
>transmitted through the cables.
>
>But with that tree and it's location, to set up a stand would have
>been a royal pain, so for me, a less than 100% clean recording is
>better than not having got it.
>
>But I'm curious how you're analyzing the sounds, would love to do the
>same and have a 'look' inside them.
>
>
>On Aug 23, 2006, at 7:02 AM, Rob Danielson wrote:
>
>> At 7:21 PM -0400 8/22/06, Walter Knapp wrote:
>> >Posted by: "Tim Nielsen"
>> >
>> >> But what I've found with a single zepp MS setup, hand-holding, is
>> >> that I'm much more free to experiment with mic placement. I can
>> walk
>> >> around, moving the mics, listening to the response. Poke it up
>> close
>> >> to something, aim it all around, and hear what I can hear. With
>> stand
>> >> mounted stereo pairs, this just seems like it'd be much more
>> >> cumbersome. With the MS rigs, I'm just so much more mobile and
>> >> flexible.
>> >
>> >About the same as I do. Even small variations in direction or
>> location
>> >sometimes make a big difference. My tall rig I usually also do some
>> >listening before setting it up. And one big use of it is to set it
>> when
>> >I go to bed camping in the truck. I normally set it close enough I
>> can
>> >reach out and rotate it if I picked the wrong direction. Kind of
>> luxury
>> >recording with the recorder right beside me I don't even have to
>> get out
>> >of bed. Though no mobility.
>> >me weight. The Telinga is also nice and light, though the dish is
>> >always a problem stuffing through the brush. The large diaphragm
>> setup
>> >I'm working on is going to be a problem for weight (2 Rode
>> NT2000's). I
>> >don't think I'll hand hold it much.
>> >
>> >Walt
>> >
>>
>> I think it also depends on what one's
>> applications for the recording are. Ambience in
>> quiet locations can present a whole new order of
>> limitations. For example, I noticed that in the
>> rustling leaves section of Tim's Schoeps M-S rig
>> example that I looped (~3:55 in), there's a
>> fairly steady patter of >35Hz "bumps" which sound
>> like the mic cable movement in shock mount he's
>> using. Some folks use shelf filtering and "roll
>> off" this part of the spectrum, but for full
>> fidelity playback on speakers or headphones, such
>> bumps restrict one's options. Jeremiah's comment,
>> "There's no way around using a stand/tripod if
>> you need to record very quiet sounds." is
>> consistent with my experience. Rob D.
> >
>>
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