We are offering a Neumann SM69 tube microphone from the 1960s including the original power supply and cable. The microphone has been tested in our workshop and in the studio and works perfectly now. The Neumann SM69 tube microphone can be found in professional recording studios around the world. In principle, these are two independent microphones in one housing. In the capsule head, 2 microphone capsules are arranged close together and can be rotated. Two completely independent amplifiers are housed in the bottom of the microphone. The microphone is wired in such a way that it can be powered both by the special power supply in NSMa 23 and by two separate individual power packs such as the NN 48 B or N52t. The NSMa is included here as can be seen in the pictures.
Technical details:
Each capsule system consists of two fixed electrodes, drilled and screwed together, and two gold-evaporating membranes made of heat-resistant polyester. Each of the two capsule halves of a capsule system has a cardioid characteristic. By applying appropriate polarization voltages to the center electrode and the membrane, the three directional characteristics "omnidirectional", "cardioid" and "figure of eight" result. They can be set for both trolley systems independently of each other using the power supply unit. The upper capsule can be rotated 270° against the lower one. The speaking direction is perpendicular to the microphone axis. It is indicated by the logo for the lower capsule and by a mark on the basket for the upper one. Each capsule is assigned its own amplifier. The proven, low-noise Telefunken Triode AC701k serves as the microphone tube. The output transformers are designed as two-leg transformers and are therefore insensitive to hum interference. The internal resistance of the microphone amplifier is 200 Ω. It can be reduced to 50 Ω by connecting the secondary windings of the transmission in parallel. The portable power pack NSMa 23 is used to power a double microphone SM 69 from the AC mains. Heater and anode voltage are stabilized. There are two switches on the microphone side with which the directional characteristics can be set in nine stages. The device is equipped with a non-heating device plug for connection to the mains.
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