New Old Stock (NOS) 6DJ8s and ECC88s produced in the past by major American or West European vacuum tube manufacturers (such as Philips or Amperex) remain extremely popular with and highly sought by audiophiles.
Originally located at 79 Washington Street in Brooklyn, New York, Amperex was a long-established manufacturer of transmitting tubes when they were acquired by the Dutch firm, Philips around 1955.