At 1:15 PM +0000 7/4/08, Greg Simmons wrote:
>--- In
><naturerecordists%40yahoogroups.com>=
m,
>"oryoki2000" <>
>wrote:
>
>> In my brief experiences with small recorders, the LS-10 stands out
>in
>> the way its built-in mics produce a "wider" soundscape. Most small
>> recorders have mics that point forward, parallel to each other. The
>> LS-10's mic capsules, in contrast, point away from each other in a
>90
>> degree spread.
>
>The LS10 uses a technique similar to one mentioned by the late great
>Michael Gerzon in an article about stereo shuffling and spatial
>equalisation published in the July 1986 issue of Studio Sound
>magazine. This involved two cardioids crossed around 115=B0 to 120=B0,
>facing outwards, and spaced 5cm apart. The LS10's quoted width of
>48mm puts the capsules the right distance apart, although they seem
>to be at a narrower angle than Gerzon suggested (which may strengthen
>the centre image a little due to it being less off-axis).
>
>According to Gerzon:
>
>"Remarkably, for normal stereo listening configurations, it turns out
>that the 5cm spacing produces roughly the same phase/amplitude
>relationships between the two ears of a listener in the stereo seat
>as does a live sound from the same apparent direction up to about
>2kHz =96 and in this respect is better than true coincidence. Such 5cm-
>spaced crossed-over cardioids, angled about 115=B0 to 120=B0 apart, seem
>to be an optimal cardioid technique for stereo imaging accuracy."
>
>Perhaps this explains the LS10's impressive stereo imaging
>capabilities?
The manufacturers do seem more prone to use
post-processing with the signals from built-in
mics on these hand-held units. Wouldn't the LS-10
recorder have to be employing spatial
equalization (shuffling) under 600 Hz to achieve
these benefits? (Here's a copy of the article I
scanned through
http://www.audiosignal.co.uk/Resources/Stereo_shuffling_A4.pdf)
I saw mention that the lowest octaves seem to
play a larger role in the enhancement technique
and signal captured with the LS-10's internal
mics seems to have considerable low frequency
roll-off under 100Hz (probably to reduce handling
noise).
Most stereo arrays should be able to capture the
spatial cues Greg Peterson and I assessed in his
Brush Warbler recording. To my ears, Vicki's
Shure 183 rig which positions two omni
forward-facing at ear spacing exhibited a
significantly a wider stereo field over the
built-in array in her LS-10.
In a couple of cases when we attempted to
evaluate stereo imaging between different arrays
on this list, people's preferences varied more
than I would have guessed. That doesn't mean we
couldn't learn a lot from more testing/comparing
stereo array performance-- but I do think the
tests would have to be done very carefully for
one to come away with observations that would but
widely agreed upon.
>Interestingly, Gerzon's article also mentions the technique of
>spacing the mics a small distance apart and angling them inwards (as
>used in the Zoom H4), but suggests that although it livens up the
>sound, it degrades the stereo imaging - something my own experiences
>with the H4 agree with.
I think Gerzon also suggests that the spatial
equalization settings required can vary from
situation to situation so using a fixed setting
(as I assume would have to be done within the
electronics of LS-10) would prove less effective
at times. Rob D.
>
>- Greg Simmons
>
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