The M-582 is a microphone amplifier that was built in East Germany by Neumann & Co. starting in 1958. It is a system using an EC-92 (6AB4) tube. The M-582's in the left picture are cardioid and have the same capsules as are found in Neumann's KM-54 & KM-254. The M-582's on the right are a special "H" series with M-71, large, gold diaphram, cardioid capsules.