Hi Brian--
Seems like a good set of variables to try out. Open air vs.
absorptive barrier vs. hard and soft boundaries and other options--
all make changes in diffuse field stereo imagery that are well worth
learning more about. When I can set-up test conditions where each
rig records the same stimulus in a quiet setting, it makes huge
difference in what I can deduce and build-upon. There are a number of
respected rigs that use hard wood boundaries besides Curt's designs.
One of the discussed characteristics is increased left/right
contrast. Forward (or near forward-facing) omni capsules that are
parallel to and attached to a boundary doesn't seem to have received
much exploration until recently. Mike is right that there are clever
ways to realize boundary and "head shapes" that can be coated and/or
filled with different materials. As for your compact disk material
quest, Rich Peet uses ~10" thick closed-cell high density foam in his
Cube Mic to reduce left-right cross-talk and it seems to do a pretty
good job above 1KHz. Jecklin was apparently a thorough experimenter
and he was adamant about his specs for his Jecklin Disk,. Did he test
his rig in conditions similar to those we encounter? I have no idea.
I almost always come away from each test with a surprise or two.
Judging by that posts on this and other lists, there could be much
better descriptions of the differences created by array options.
Many recordists would be interested in hearing the mkh-8020's
compared to other known mics. Let me know if this seems like
something you'd be interested in. Rob D.
= = = =
At 11:27 AM +0000 3/16/08, Brian D. Farrell wrote:
>Hi Rob, thank you for the comments. Yes, I angled the mics up 30
>degrees as well, aimed
>into the canopy, and was set up on a small wooden bridge over an
>arroyo with the mics
>facing towards the end of the bridge in front of me so as a capture
>up and down stream,.
>This was a very compact portable set up using a 8.5 inch AKG
>(folding) stereo bar on a 40
>inch compact Hakuba mini tripod.
>
>I've been looking at different kinds of compressible foam, both in
>blocks to enable making
>a headshape (in two or four pieces for portability), and in sheets
>to fashion Jecklin-like or
>boundary-layer circles to attach to the stereo bar. The ~ boundary
>layer approach would
>comprise a smaller diameter pair of discs, one per mic, attached to
>the inside of each mic
>holder with extra long bolts with washers. I thought I would set up
>three configs (my so
>called boundary layer, a foam head, and a Jecklin disc), and compare
>them for stereo in my
>backyard as soon as it warms up enough. Birds have just started here
>in eastern MA. I've
>benefited enormously from the postings on this listserv and
>especially from your website
>on DIY boundary mic rigs (following our communications a year or so
>ago). Your class
>produced some very informative experiments! I welcome suggestions on
>foam types and
>may also try the wood config of Curt Olson. I'm shooting for a rig
>that can be (mostly)
>carried in a belt pack alongside the 702 and 8020s w/ stereo bar for
>porting deep into the
>field (hence the idea for smaller discs than a Jecklin).
>
>Incidentally, in addition to using standard software ( I'm on mac),
>I found a bit of
>shareware called Spectrograph that is a plug-in for the Apple Itunes
>visualization function
>(<http://www.dr-lex.be/software/spectrograph.html>http://www.dr-lex.be/software/spectrograph.html).
>
>The code runs left and right channels
>together but colored red vs. green (and yellow for mono). It's fun
>to see the stereo effect in
>color, and helps students pick out different signalers in a recorded
>soundscape. Nice thing
>about it is one can carry this on a thumbdrive and download it to
>anyones (non Leopard)
>mac to show visuals of sounds. It's a bit coarse, and with no
>controls other than speed,
>but kind of fun to watch (my son's second grade class was as mesmerized as my
>undergrads!).
>
>Well, sorry for the long post....
>
>B
>
>--- In
><naturerecordists%40yahoogroups.com>
>Rob Danielson <> wrote:
>>
>> Beautiful recording. Thanks for sharing it, Brian. I thought a baffle
>> might be good to try as well. Along the Jecklin theme,
>>
>><http://en.wikipedia.org/wiki/Jecklin_Disk,>http://en.wikipedia.org/wiki/Jecklin_Disk,
>>
>>angled out a little less
>> and separated 14" might be good to try too. Did you direct the mics
>> up, a bit, to place more of the canopy in the heart of the polar
>> patterns?
>>
>> It can be very telling and assuring to try different array variables
>> and compare the results. It really helps if you can run the two
>> arrays/recorders at the same time or precisely duplicate a good
>> number of sound stimuli spread around the mics.
>>
>> There's a lot of interest in the mkh-8020's. What's your opinion of
>> them so far? Rob D
>>
>>
>> At 12:27 AM +0000 3/16/08, Brian D. Farrell wrote:
>> >Thanks Suzanne, this was an interesting soundscape, with a broad
>> >array of acoustic
>> >signalers. Without a barrier between the mics, it was interesting to
>> >see how the higher
>> >frequencies had greater separation between the sides than the lower
>> >ones. I wish I had
>> >rigged some kind of barrier or baffle though. Next time! I will post
>> >some sounds from the
>> >Domnican Republic next, and then maybe from here in MA. Thanks for
>> >your comments, I
>> >appreciate it.
>> >
>> >B
>> >
>> >--- In
>>
>> ><naturerecordists%40yahoogroups.com><naturerecordists%40yahoogroups.com>
>> >"Suzanne Williams" <scw1217@> wrote:
>> >>
>> >> Brian,
>> >>
>> >> I enjoyed the recording. There are lots of interesting bird sounds
>> >> in it, for sure!
>> >>
>> >> ----------------------
>> >> Suzanne
>> >> Suzanne Williams Photography
>> >>
>>
>> >><<http://web.tampabay.rr.com/swilli41/www>http://web.tampabay.rr.com/swilli41/www><http://web.tampabay.rr.com/swilli41/>http://web.tampabay.rr.com/swilli41/
>www
>> >> Florida, USA
>> >>
>> >>
>> >>
>> >> --- In
>>
>> >><naturerecordists%40yahoogroups.com><naturerecordists%40yahoogroups.com>
>> >>"Brian D. Farrell"
>> >> <Bfarrell@> wrote:
>> >> >
>> >> > Dear group, I just posted a recording made a few weeks ago, and
>> >> would very much
>> >> > appreciate any and all comments and suggestions for improvement.
>> >> It's not terribly stereo,
>> >> > and was made with two MKH 8020's mounted 9 inches apart on a stereo
>> >> bar, facing forward
>> >> > (but angled out at 30 degrees each from parallel- 60 degrees
>> >> total). Recording to a SD 702.
>> >> >
>> >> > Best,
>> >> >
>> >> > Brian
>> >> >
>> >>
>> >
>> >
>>
>>
>> --
>>
>>
>>
>
>
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