Neumann U-67

Neumann U-67

Classic Tube Microphone Daily Rate: $100

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(Content re-printed from the 1966 U67 Specification Sheet)

 

The U 67 Condenser micro­phone is a newly developed multi-purpose studio micro­phone. It has an attractive shape and possesses first-class transmission properties and a number of new advantages. The U 67 Condenser Micro­phone can be used in a multi­tude of cases in recording, broadcasting, and sound reproduction. From a dimension point of view, it lies between the group of miniature micro­phones and that of the older standard type of con­denser micro­phones. By relinquishing the absolute miniature type of construction, it is possible to use reliable standard components as well as an approved easily replaceable micro­phone amplifier tube with plug socket, a type which can be obtained all over the world.

 

By means of three switches, arranged at the base of the head assembly, the three directional characteristics, frequency response, and transmission ratio can be adapted to requirements. The frequency response of the micro­phone, also in the upper audio range, is practically linear for frontal sound pickup and does not show the commonly found rise. This enables the micro­phone to be used especially at a short distance away from the sound source without getting an unnaturally sharp sound impression. A new type of circuit considerably attenuates frequencies below 30 c/s already before the control grid of the micro­phone tube, whilst frequencies above 40 c/s are transmitted unaffected. The often feared overloading of the micro­phone tube caused by excessive movements of the membrane due to wind, floor vibrations etc. has thus been prevented. This was not possible with the commonly used rumble filters at the output. If the bass attenuation exceptionally is not desired, frequency response of the micro­phone amplifier can be linearized by disconnecting a small wire bridge in the micro­phone. The limit frequency of this bass attenuation can be shifted to 100 c/s by means of a switch located on the micro­phone (favorable e.g. for recording of speech or in television studios).

 

When the transmission degree of the micro­phone is reduced by approximately 10 dB by means of the third switch, the micro­phone amplifier will not be overloaded, even with the highest levels occurring in practice. (Application e.g. with pick-up of loud solo instruments from short distance.) The micro­phone tube operates as an anode amplifier into an output trans­former with separate feedback winding. The micro­phone amplifier section may be opened easily without the aid of a screw­driver by unscrewing the fastening ring at its base in a counter­clock­wise direction. This permits the conical housing to be with­drawn. The head assembly may then be removed by pressing lightly against the two length­wise support rails near the head assembly, releasing the latch and freeing the head assembly for unplugging.

 

Cables up to 165 feet in length may be used between micro­phone and power supply. When longer cables are required, the filament potenti­ometer R6 must be readjusted to bring the filament voltage at the micro­phone back to -6.3 volts. Consistency of operations is also increased by the following measures: Gold-sputtered poly­ester foils used as membranes make the unit highly insensitive to temperature, humidity, or aging. Printed circuit used through­out for stability and shock resistance. Great resistance to moisture due to potting of all grid circuit components and use of Teflon tube socket. Protection against RF interference through use of feed-through capacitors on all leads and RF-protected connectors on inter­connect cables.

FEATURES:

The microphone capsule of the U 67 microphone is a pressure-gradient device. It is composed of two identical cardioid systems arranged back to back. By switching of the polarizing voltage these two cardioid patterns can also be combined as to produce the three directional characteristics cardioid, omni-directional, and figure-8. Selection of these patterns is accomplished by a switch located at the front of the microphone directly beneath the wire cage. The symbol of the characteristic selected appears in a window directly above the switch. Two additional switches are located at the rear of the microphone. One switch provides for a sensitivity reduction of appr. 10 dB ahead of the amplifier section permitting transmission of the highest sound pressure levels without danger of overloading the amplifier. The second switch produces a roll-off at the low frequency end beginning at 200 cps. This permits compensation of the normally occurring low frequency rise when a pressure - gradient microphone is addressed at close range. This position further serves to suppress low frequency mechanical interference. These two switches like wise have windows in which their position is indicated. When the sensitivity reduction is effective, the window shows "-10 dB", and when the low frequencies are attenuated, the window shows a horizontal line with its left end bent downward. (These symbols are described as viewed when the microphone is on a stand with its connector end facing the floor.)

 

A special circuit within the amplifier distinctly attenuated all frequencies below 30 cps, while those above 40 cps are reproduced linearly. The microphone amplifier's response may be extended to below 20 cps flat by opening the jumper "S-2" in the amplifier itself.


TECHNICAL SPECIFICATIONS:

See product documentation


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