Heybrook HB1, JPW P1, JPW AP2, JPW AP3, Snell type K.
This classic 8" bass unit is designed for sealed cabinets of between 20 - 40 litres. It features a very high compliance suspension (Vas 81 litres), a magnesium chassis and a treated pulp cone. The highish Qms value gives the M21WG-09-08 a lovely open midrange sound hence it's popularity in various successful historic designs. One of the few excellent 8" drivers suitable for 2 way infinite baffle enclosures. New manufacture with improved foam surround.
These units are now manufactured at the Scanspeak facility in Denmark and may be badged as Vifa or Scanspeak.