From: Patent Tactics, George Brock-Nannestad
Bob, you wrote:
> -----Original Message-----
> From Eric Jacobs: "Weren't all those math formulas and standards the basis
> of the RCA test record?"
> In terms of public dissemination, the test record predates all of them
> I'm aware of although no doubt there was some sort of internal
> at RCA.
> The 1953 standard specified a series of 23 frequencies ranging from 30 to
> 15k. as is found on the test record. This was only later described as the
> 3180, 318 and 75 microsecond time constants so the RCA test record may
> have been the basis and not the other way around.
----- well, on the cover of my 10" record, next to the equivalent LR, and 2x
RC networks are given the time constants you mention. The text reads:
"The 'New Orthophonic' characteristic (relative stylus velocity vs.
frequency) may be expressed as the algebraic sum of the ordinates of three
individual curves which conform to the admittances of the following networks
expressed in dB".
My record is not dated, and I would be interested to know the date.
Again it should be the
> basis of any attempt at accurate reproduction simply because it was what
> everybody trimmed the response of their cutting systems to match. How
> or wrong the RCA test record is doesn't matter.
----- you are absolutely right and in accordance with the instructions on the
record. If this record was widely distributed, obviously that WAS the