[78-L] Blumlein

[DAVID BURNHAM]

.......  Blumlein and others didn't always use a pair of 
bi-directional with one facing forward and the other facing sidewards.  
Sometimes a cardioid is used facing forward and the bi-directional 
pattern is facing sidewards.  I think this is what is meant in this 
description.  Using a cardioid as the forward facing mic instead of a 
bi-directional reduces pickup from the rear, such as audience noise and 
hall reverberation.  Stereo mics like the AKG C-24allowed for the 
changing of the patterns -- in the case of the C-24 even from the 
control room while listening to the results live!

Mike Biel  mbiel at mbiel.com

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What you're describing here is M-S, (Mid-Side), or Sum and Difference miking.  I 
was discussing only XY sets-up.

But  in fact, for over 30 years, I have recorded using the Sum and Difference 
system almost exclusively, employing either an AKG C24 or its solid state 
replacement, the C422.

As far as I know, Blumlein never had cardioid mikes for his experiments, however 
I think he did introduce the concept of using a single ribbon which was divided 
in half with one half exposed at the rear to produce a bi-directional 
characteristic and the other half sealed at the rear, acting like an omni mike, 
and combining the outputs of the two halves to produce a cardioid 
characteristic.

But once again, neither the XY nor the MS coincident systems produce the 
inter-aural time differences necessary for binaural recording and, in fact, the 
Styrofoam head used to mount the mikes for binaural recording also has 
artificial pinnas since this is what the ear uses to locate sounds up and down 
or front and back.  Surprisingly to some, the hearing mechanism uses inter-aural 
time differences almost exclusively to locate sound sources;  inter-aural level 
differences are almost irrelevant.

db