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NRU OV 332 - Dutch Broadcast Tube Microphone



After the Second World War, Holland was liberated, but looted. The Dutch broadcast "Pillars", based on their members' conviction (Catholic, Protestant, Socialist or Liberal), who had previously operated independently, all lacked equipment for broadcasts. Thus the broadcasters decided, in 1947, to place all their remaining material and studios in the newly established Dutch Radio Union NRU.

The NRU primarily functioned as a facility company that provided joint technical equipment, orchestras, radio play cores and choirs. It also maintained the news service.

Because the missing equipment was not easy to obtain, it was developed and built by the NRU itself, including mixing desks, portable transmitters, outside broadcast vans, and the most important first link in the recording chain: high-quality condenser microphones.

Led by Prof. Dr. Ir. J.J. Geluk (in English: 'Luck'), the NRU presented its first model in 1947, the OV 302, an omnidirectional condenser capsule mounted on a 'bottle' shaped preamplifier. The capsule could also be used with the Neumann CMV 3A bottle.

From 1949 onwards, work was done on a directional microphone, equal in quality to those made by the German radio station NWDR (Nord West Deutsche Rudfunk), which also co-developed the Neumann M49 and M50.

In 1953, the directional OV 312 was released, with an EF 86 tube and smaller bottle shape. In 1957 the NRU presented the even more compact OV 332 with electronics molded in synthetic resin and a longitudinally mounted and improved capsule. The unique NRU-developed large connector (one fit, no male and female parts), used on all NRU equipment, was replaced by a small Tuchel plug.

The new OV 332s, four times lighter in weight than the old model, were quite successful; in 1959 there were already 120 in use. Further development followed: OV 342 and OV 352, with higher sensitivity and output, the OV 362 stereo model with upright capsules and finally transistor versions.

In 1963 a total of about three hundred microphones had been manufactured, but in the mid-1960s it was decided to end production and to buy studio microphones from other manufacturers in the future; the NRU became too expensive. In 1969 the NRU, merged with the Netherlands Television Foundation, to become NOS - the Dutch Broadcasting Foundation.

The "Gelukjes"("Luckies"), as the nickname of the NRU microphones was, had delivered sound in top quality, for Dutch radio and TV, for almost twenty years. Today OV's can still be found in many studios and are sought after collector's items.

These and many more types feature in my book Witnesses of Words. More information about that can be found at

wow cover

NRU OV 332
VPRO Hoepla

OV 332 open

NRU connector

Top: the NRU OV 332

Middle: 1967 Phil Bloom, Dutch TV's first nude with OV 332, the unique universal NRU connectors and OV 332 inside

Below: OV 352, sound, ZR 401 transmitter/receiver with OV 332, NRU QSL to East German listener, sugar sachet:"Idea?Put it in the NRU suggestion box", Tech info 1947 and Collodium diaphragm foil

OV 352

Listen to the sound of the OV 332:

Transmitter and mic
Condenser mic txt
Collodium foil