Hi folks, Here is some more info on RCA coarse-groove LPs:
Several years ago I had occasion to phone Ward Marston with a question about an RCA 12" LP set of Schonberg's Gurre-Lieder by Stoky and the Philadelphians that I had obtained at a garage sale. He mentioned that they were made of a vinyl-like plastic that exuded some its plasticizer over time. The plasticizer that accumulates in the grooves results in bad sound when played with modern low needle pressure pickups having the correct 0.002" point radius. He suggested trying to remove the plasticizer by washing the grooves with white vinegar. I tried it, and it worked for me. The garbled bubbly sound went away. I suppose that if one played the LP with an orange shank needle in original equipment, the much higher needle pressure would push the plasticizer aside. Most, if not all of my 12" LPs are made of the vinyl-like plastic. All of my 10" LPs are made of a harder material, more like a shellac. These records probably have no plasticizer to cause the problem. Best regards, Ben
