Quote:
Originally Posted by
voltronic
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I believe he experimented both with and without a baffle, and spacing up to 22 cm. I can't locate that right now, but I do remember the diagram in the original patent showing a 20 cm pair with a block of wood between them.
Also, please accept my apology. The 2.1/d formula appears in the Gerzon 1986 paper on page 3. The 5.4/d forumla for width in cm is also very helpful. Either way, your notion that the result is meant as the lower corner frequency seems to be correct, but I find it interesting that Gerzon lowered the corner frequency significantly between 1986 and 1994.
Gerzon's statements in the 1986 paper seem to support the idea the Griesinger's 'spatial equalisation' is meant to be a different animal than Blumlein's Delta.
There's nothing in the '31 patent about 22cm
unbaffled omnis.
I don't know where that claim came from.
He describes only three stereo mic techniques:
1. 20cm baffled omnis.
2. Coincident figure-8s at 0 and 90 degrees (MS with fig-8 for M, as there weren't any cards yet).
3. Coincident fig-8s at 45 degrees L and 45 degrees R (the config that now bears his name).
And no reference to anything "Delta"; must be a term coined by someone else.
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22cm
unbaffled omnis is more like something I associate with Onno Scholze, not Alan Blumlein.