Hi folks, There has been some recent discussion about the point radius of the orange shank chrome plated needles RCA sold for playing their coarse-groove LP records. I remember, in 1979, sending an orange shank needle to Expert Pickups in England. I asked them to measure the tip radius and replace the diamond in a Stanton D 5127 cartridge insert I sent them with a spherical diamond having the same radius. They measured the tip radius measured to be .002".
I recently optically compared the tips of an orange and green shank RCA needle. Although I didn't have the instrumentation to measure each tip separately, I was able to determine that the average radius of the tips of the two needles was 0.1 millimeter. This equates to an average radius of 0.0025". Using the 0.002" figure measured at Expert Pickups, this gives the expected tip radius of 0.003" for the green shank needle. BTY, an RCA advertising piece for the coarse groove records mentions a playing time of 5 hours for the orange shank needle, when used to play the coarse groove LPs. Best regards, Ben H. Tongue
