I received an unexpected opportunity to perform electro-acoustic measurements on a pair of 604E Super Duplex speakers in early 2008 thanks to a long-time owner seeking improvement in their sound. He had been using the original Altec Lansing N-1500A series type crossovers, and wondered if an improved crossover implementation might make them sound better. I had wondered that too. The drivers had original factory cones and voice coils, as well as identical production date codes of 391611, signifying the 11th week of 1966. My initial measurements suggested weakened magnets, so the drivers were sent to Great Plains Audio in Oklahoma......
604E Super Duplex
Great Plains Audio was born out of the Altec Lansing corporation in 1998. It carries forward the loudspeaker design and manufacturing tradition that began with Western Electric in the early 20th century. Great Plains Audio is the only place where the legendary Western Electric/Altec Lansing sound reproduction technologies live on.
7127 Northwest Third St. Oklahoma City,
Oklahoma, USA, 73127