Friday, June 09, 2006
RCA BK5a - Ribbon Mic with Provenance?
Here's an RCA BK5a that has an interesting history. Notice the residual blue paint on the shock absorber and compare that to the blue paint on the 77DX used on The Tonight Show. This particular BK5a, we have been told, was the off camera overhead mic used on that set, during that period of the 60's when pastel blue was in.
Little bits of blue can be found all over the mic, in crevices and interstices, and at the bottom.
We reribboned it, tested it, and then sold it on ebay. The BK5a is a hypercardioid ribbon mic with an internal acoustic labyrinth. The differences between the A and B versions of this mic are small, and consist of the shape of the aperture, and the size, of the side baffle at the concussion filter, which sits ahead of and upon the actual ribbon motor. This was done to tighten up the polar response and reduce sidelobes. The BK5a also has a switchable reactance output like a 77DX.
Posted by Bob Crowley at 10:45 AM