Here is a vintage 1958 Altec Lansing M11A tube microphone system. This particular example is in very excellent all original condition and features the original Altec 21D capsule, the original 150 A base, the original case, as well as, the original 518 A power supply!
Capsule Serial Number: 11260
Base Serial Number: 5642
Power Supply Serial Number: 3482
Transformer Codes: 642, 716
The M11A features: a 20Hz – 20kHz frequency response, 20Hz – 40Hz – 120Hz frequency cutoff, a satin black finish, and the original power supply.
This matching original set is in very beautiful cosmetic condition, though the original connector cables are not included. The original RCA tube is still within the mic, and the power supply is in all original condition as well. The original power cable for the power supply will need to be replaced, as it has since cracked and deteriorated.