There should be some definite tonal balance and
stereo field performance differences between
unfinished wood and coated high-density foam.
Here are just wood, coated and uncoated foam segments:
http://tinyurl.com/yjyu7af from the affects of
boundary materials and shapes video:
http://tinyurl.com/ydj4r6d
The pink noise is pretty tough to interpret by
ear, but the sonograms are pretty revealing. For
each test material, I start off with the mic
against the boundary and facing directly at the
sound source (12 o'clock). After a pause, I
rotate the mic array 90 degrees and pause to get
a better view of the off-axis response at 9
o'clock. Then I rotate it back to 12 o'clock.
Following are some differences that one can
predict, personal use and preference may vary:
A. The 4-8K Hz lift from 9 o'clock to 10 o'clock
that gives the perp2wood boundary array
considerable contrast and high frequency bite at
hard Right and hard Left edges is lessened
considerable with hi Density Foam. This effect at
the very edges is probably part of the enhanced
horizontal feel to the array.
B. There's more emphasis between 700 and 1700 Hz
in the off-axis with wood over coated hi-density
foam which is within the influential range where
we see that SASS contributing enhanced spatiality.
C. The blue concentrations where I drew the X's
are what I call the, "10 o'clock and 2 o'clock"
gain bumps. These also add contrast within the
stereo field and should be more noticeable with
perp2wood boundary arrays over perp2high-density
foam boundary arrays. The effect of these is
mixed in my opinion.
D. On the plus side, the 2.5 - 3.5 KHz "hole" in
off axis response is considerably less pronounced
with Hi-Density foam.
When one uses a boundary rather than a baffle, it
will do something and the nature of the surface
forming the boundary will impact sound qualities.
The differences may not pound one over the head,
but on the scale of what arrays can do to
influence tonality in positive ways, the
differences seem to be significant. Because one
is "messing with" the normal response of the mic,
lots of audio engineers frown on the use of
boundaries. But, in my opinion, this assumes that
mics are already "perfect" for all types of
recording and,...well,.. people who love SASS's
love boundary mics that "mess-up" $1000+ mics.
Note that even uncoated foam has some, audible
boundary effect. However, I know from Rich Peet
testing his "Cube" array for me, that it is a
challenge to detect the presence of high density
foam if positioned where its only behind the
capsule plane which is how most folks use it,..
but not so in the SASS,.. Rob D.
=3D =3D =3D
At 2:24 PM -0500 3/14/10, Curt Olson wrote:
>Hmmm... I wonder if some foam insulation board might give pretty much=A0
>the same results as your yoga block. I ask because I have most of a 4'=A0
>x 8' sheet of the stuff in my garage. It's looking like my recent=A0
>break from tinkering with mic rigs might be over. (Please don't tell=A0
>my lovely bride, okay?)
>
>Curt Olson
>
>John Hartog wrote:
>
>> Hi Curt,
>>
>> I have noticed some yoga blocks use higher density foam than others,=A0
>> and they also come in cork. So far, I have only used thrift store=A0
>> scavenged material and have not yet searched the retail market for=A0
>> an ideal source. As far as handling noise, I would say there is=A0
>> little or no perceptible difference compared to wood - at least when=A0
>> using AT3032 microphones which are fairly stable anyway. I found my=A0
>> parallel boundary yoga block array to be the best rig with handling=A0
>> noise I have built so far =AD at least I could carry it down a trail=A0
>> or adjust the tripod without having to turn down the headphones. I=A0
>> am wondering how the yoga block might work on a boom pole with=A0
>> wl-183s.
>
>
>------------------------------------
>
>"While a picture is worth a thousand words, a
>sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause
>Yahoo! Groups Links
>
>
>
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