I figured out the reason for difference adapters for the GR (WE, HP, Gefell) 1" (.946') microphones and the B&K mikes. The core comes from the different grids on them. The original WE640AA has a retaining ring on the front and the diaphragm is recessed. it was not designed as a measurement microphone but worked well for that application. The WE, GR, HP and Gefell microphones copied the WE grid, with a flat face with a hole pattern on it. B&K redesigned the structure with the diaphragm closer to the front surface and no retaining ring. The "famous" B&K grid was to allow off axis response to better match the grid off and has the openings down the side. The adapters for the GR type grid won't seal properly on a B&K microphone. The B&K adapters will have an o-ring to seal behind the grid. There is also a difference in the front volume between the WE and the B&K that would require spacing the microphone back a little to correct or correction values (the Omnical manual has a lot of correction values and matching confusion. . .). I have not seen this specifically documented at all except in an old writeup in the B&K journal.
Now I can move forward with some of what I want to do. I'll still need some adapters. I'll PM Conrad with what I need. Details on the 1559-6080 would be interesting since I can't find references to it.
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