At 12:55 AM +0000 10/7/10, hartogj wrote:
>
>
>
>> By "fold" are you referring to possible reflections from the barrier
>> back onto the mics?
>
>Hi Rob,
>
>No. I will try to explain, though maybe I am insane. When I play a
>stereo recording through loudspeakers or headphones I hear
>everything in front of me. The sounds that were to the rear of the
>microphones are now to the front. That is what I mean by folding.
>Almost every sound that is folded in this manner is likely to be
>dissimilar except at the extreme sides where broad sourced sounds
>can fold in on themselves. What affect would this have on the
>resultant recording?
>
>John Hartog
Hi John--
Yes, the known trait of front-rear confusion. What are you asking
about it exactly?
Are you thinking that almost equal amplitude sensitivity to the rear
contributes more to the effect of the bass being more centralized
around the speakers with Jecklin? It could some above 500 Hz, but
response to the lowest octaves I'm discussing is very
omni-directional for most arrays.
Front-rear confusion typically becomes a concern when one wishes to
locate sound sources accurately opposed to capturing as many events
as clearly as possible. For example SASS produces (a) significantly
lower amplitude when the sound arrives at angles greater than 90
degrees off axis. (b) tonality that is noticeably warmer and (c)
depth cues (such as reflections from surfaces in front of the array).
M-S arrays with a cardiod mid mic produce some of the (a) and (b)
effects. X-Y and ORTF with cardioid mics do as well.
Front-back distinction with Perpendicular to Boundary arrays is a
challenge and therefore these arrays are good when wants to pick-up
sounds from the rear with almost equal clarity. Blumlein is very good
for this too. Jecklin Disk and Spaced Omnis produce less of the (a)
and (b) effects than M-S and X-Y in my opinion.
Large diaphragm mics are inherently more directional and tend to
produce less front-back confusion (except for Rode NT2000's which are
actually hotter at 90 degrees than at 0 degrees in omni mode). Rob D.
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