Netzanschlussgerät für Stereo-Mikrophon SM2 NSM

Power supply for the SM2 and SM2c stereo microphone. Delivers 4.5V for tube heaters, 120V for plate supply, and 2x stepped variable control voltages from 0V to 79V, for remote-control of the directivity patterns of the two capsules. Heater supply is stabilized by three Stabilyt cells of 1.5V each. Plate supply is stabilized by a neon regulator.

The NSM was followed by the NSMa, which was a complete redesign on a transistor basis.

Attention: The SM2 has a pinout differing from SM23 and SM69, so PSUs must not be swapped! SM23 and SM69 use two separate heater connections for the two tubes inside, while the SM2 only uses one. Furthermore, the control voltages for SM23 and SM69 range from 0V to 120V, and thus exceed the limit of the SM2.

Suitable original PSUs for SM2 and SM2c are NSM, NSMa, NSK, NSKt.

For SM23, SM23c, SM69 (tube) use only NSMa 23, or two single power supplies like N52t, NN48b, or BB50, via the Z10 or Z11 adaptors.

Here you find 128 models, 118 with images and 47 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Neumann, Georg, Laboratorium für Elektroakustik GmbH; Berlin