At 9:39 PM +0000 3/27/09, Greg Simmons wrote:
>--- In
><naturerecordists%40yahoogroups.com>=
m,
>Rob Danielson <> wrote:
>
>> Interesting string. I think we are talking more about "mixing," than
>> "editing."
>
>In my case, I was referring to editing/mastering direct-to-stereo
>field recordings that would be classified as either phonography
>and/or nature recording. Some would involve music, but that would be
>a street musician or similar, and in those situations I like to
>place the musician in the context of the surrounding 'noise'.
>
>As for mixing, the less of that I have to do, the better! These days
>I'd rather tear off my own head or chew through my leg than sit
>behind a console (or screen) full of faders. Aaarrgghh!
>
>> A discussion about how to address the lowest octaves in field
>> recordings should probably be prefaced with mic and array
>> information.
>
>Good point. That is very important contextual information for this
>discussion...
>
>Most of the recordings I'd apply a high pass filter to are made with
>an MS pair with cardioid M capsule. Both capsules in such an array
>have an inherent low frequency roll-off that begins somewhere below
>200Hz and comes into effect at distances over about 30cm from the
>subject. So the mics are already attenuating the LF - for better or
>worse!
>
>
>In those handheld MS recordings I'm attempting to feature a specific
>sound within the context of its surroundings, but without being
>subdued by them. That type of presentation usually benefits from
>high pass filtering. But in situations where that low frequency
>energy is important, I'll try to 'reverse' the inherent LF rolloff
>in the mics by creating appropriate LF compensating curves before
>decoding: one tailored for the M capsule, one tailored for the S
>capsule.
Very true. I often resort to EQing the mid and side mics separately
with my 30/40 pair because the character of the figure 8 mic's lowest
octaves is so different. It was with my mkh-30 that I first began to
notice how the harmonics in the lower mid range become simplified and
less lively when the lowest octaves are feeble.
>
>Furthermore, because MS uses a coincident pair of mics, it cannot
>capture the interchannel LF phase/timing differences that contribute
>to a sense of spatial immersion. It is good for transporting the
>listener to a place, but it cannot immerse them within that space in
>the same way that a spaced pair of omnis can. It can, however,
>provide pin-point imaging in a way that spaced omnis cannot;
>pin-point imaging is my preference for the sort of recordings I'm
>making with the MS pair. (Having said that, MS provides a nice sense
>of 'place' in headphones, probably due to the inversion of the S
>signal between the ears...)
I do sense the same trade off between coincident and spaced pairs. In
the only thorough localization test I've come across (by James Boyk),
his Blumlein pairs seem to outperform his M-S pairs pretty evidently.
Boundaries and barriers seem to add other variables that the
coincident-spaced dichotomy doesn't include. These and other
important arrays missing from Boyk's comparisons. Maybe a key purpose
of "testing" is to not become comfortable with the stereo imaging
that one array provides. All seem to have weaknesses; but maybe
there's hope!
> > When using mics in an stereo array that captures the breadth of the
>> energies down to 15-30 Hz, I usually find that the representation of
>> acoustic space suffers dramatically when I use high pass or
>> "roll-off" filtering of any kind.
>
>Agreed. In such recordings, one would choose microphone arrays that
>have decent LF response when used at a distance; i.e. spaced omnis
>or perhaps wide cardioids.
>
>A few years ago I sat my MS rig among a group of about eight or so
>Asiatic elephants. I had hoped that I could pitch shift the
>recording up and hear those very low frequency signals they make to
>each other (you can certainly feel the rumblings when riding them).
>Alas, there was nothing there. Which means either a) the LF rolloff
>of the MS pair was too much, and/or b) the recorder wasn't capturing
>it properly, and/or c) Asiatic elephants don't use LF communication
>(therefore the rumbling one feels when riding them is related to
>digestion!).
>
>> When one uses high-pass filtering, one is also removing the
>> fundamentals of the "good," un-exaggerated bandwidths too. I find
>> its harder to establish the "body" of the recording--its substructure
>> when all of the lowest fundamentals have been "zapped." All of the
>> frequencies in a field recording have been "tuned" by physical
>> dimensions of the "enclosed" space. Less desirable sounds often fill
>> the space from afar and mask other, more desirable sound sources, but
>> they do so in specific bandwidths, not evenly across the lowest
>> octaves.
>
>Agreed. However, my take on this stuff is that most people can't
>reproduce stuff below about 80Hz properly anyway. Some systems
>simply don't reproduce it, others will exaggerate it (e.g. sub
>turned up too loud!). And even less people have rooms with
>sufficient acoustic design or treatment to guarantee that such low
>frequencies will be reproduced properly at the listening position.
>Exaggerated LFs can mask a lot of important midrange information (LF
>masking is the worst of all masking, IMHO). With that in mind, I
>feel it is better to get rid of it altogether - prevention being
>better than cure!
Its a big step to realize when one is choosing what will be lost and
what will be maintained. It is hard to paint with "transducers." (I
like Dan choice of this term because it sounds like a nasty job).
But when it all does come together, and the impression of the space
is solidly there, its definitely worth it. I'll take and try to use
all the octaves I can get. Rob D.
>
>But it does depend on the goals of the recording, as discussed above...
>
>> Equalization of this nature really challenges one's monitoring
>> facilities. "Flat" monitoring of the lowest octaves with both
>> headphones and speakers is pretty much mandatory and room peaks and
>> dips in the lowest octaves (where they most often occur) make the
>> practice futile.
>
>Frustrating, isn't it?!?! At least with a good set of headphones you
>can take the room out of the monitoring equation. But we have to
>learn to 'hear' the lows rather than 'feel' them, and they're never
>as apparent in that respect. Out comes the spectrum analyser and/or
>sonogram, and we switch to thinking and observing rather than
>listening and feeling.
>
>- Greg Simmons
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