OPERATING INSTRUCTIONS FOR NEUMANN CONDENSER
Contents
1. is visible through a small window at one side of the power supply cover The strapping board is accessible after removal of the cover 7 Make also sure that the proper value fuse for the voltage used has been inserted in the fuse holder 300 ma for 110 volts 125 ma for 220 volts 8 The output signal from the microphone is fed to a three prong chassis mounted plug on the power supply unit The mating cable connector for this plug is supplied with each unit Connection to the microphone input of the console or recorder is accomplished by means of a two conductor shielded cable of any desired length 9 The U 47 and U 48 microphones are designed to work into a load impedance input impedance of console preamplifier of 250 respectively 1000 ohms or even higher To provide a sufficiently low source impedance from the microphones they have been designed for a source impedance E one fifth the load impedance For a 250 ohm load impedance the source impedance of the microphones is set for 50 ohms and for a 1000 ohm load impedance it is set for 200 ohms This prevents overloading of the preamplifier in the microphone itself The microphones are usually supplied strapped for a 1000 ohm load impedance but on request will be delivered for 250 ohms The 250 ohm adjusted microphones may be identified by a red dot located on the type number tag of the microphone 10 After interconnection of the microphone power supply and A C line the main sw2. OPERATING INSTRUCTIONS FOR NEUMANN CONDENSER MICROPHONES U 47 U 48 A c AND ACCESSORIES May 1958 TECHNICAL DATA Microphones Useable Range of Frequencies 35 to 15 000 cps Directional Characteristics U 47 non directional and cardioid U 48 bi directional and cardioid Source Impedance 200 or 50 ohms Sensitivity U47 approx 2 5 mv dyne cm cardioid U 48 approx 2 0 mv dyne cm cardioid less than 0 809 0 at 1000 cps up to a sound pressure level of 110 db 1 VF 14 M selected Total Harmonic Distortion Tube Complement Power Supply NG Power Requirement Operating Voltage 110 220 volts 50 60 cps 105 volts D C 40 ma the heater voltage is taken from the 105 volt supply Fuse 0 3 0 125 amp Pilot Lamp 110 volts neon Interconnecting Cable UC 4 Standard Length Stand Mount GENERAL The U 47 and U 48 microphones are identical in every way with the exception of their directional characteristics U 47 non directional and cardioid U 48 bi directional and cardioid which can easily be selected by means of a slide switch located at the base of the wire mesh part of the microphones The newer type U 48 is designed in such a way that the plug in head of the U 47 may be inserted in place of the U 48 head thus making possible all three patterns with the same basic unit whereas it is impossible to use the U 48 head in place of the U 47 head PLACING IN OPERATION 1 The U 47 and U 48 microphones are equipped
3. itch may be switched on Operating condition will be indicated by a neon lamp It is not harmful to the power supply if it is operated even for longer periods of time without connection of a microphone 11 The warm up time of the U 47 and U 48 microphones is somewhat over one minute This is due to the 55 volt healer voltage which is tapped off the 105 volt supply voltage TESTING AND MAINTENANCE NEUMANN microphones are made with extreme care and accuracy ond careful handling is required if consistently excellent results are expected Warning The plug in head as well as the amplifier part of the micro phones are sealed at the factory and we recommend that these seals not be broken otherwise the guarantee will be void Should the microphones need servicing it is recommended that they be repaired at our factory or at our authorized service centers The following instructions are given on the explicit understanding that all such operations performed on NEUMANN microphones are undertaken at your own risk 1 Work performed on the microphones should be approached with extreme care and dry hands Such repair should only be attempted by a skilled technician 2 Under no circumstances should one blow into the microphone capsule itself and the diaphragm should remain untouched 3 The microphone head can be removed after unscrewing the three fastening screws and the rotecting cover of the amplifier can be taken off after removal of the sc
4. rew at the microphone ase 4 The amplifier tube VF 14M which incidentally is especially selected for low noise ot our factory and should only be obtained through us or our representatives is of the plug in type and can therefore be quickly replaced 5 The amplifier characteristics can be measured by means of the test capsule Z 9 Instructions for test procedure are furnished with the Z9 test capsule A voltage of 100 mv at the test capsule Z 9 is equivalent to a sound pressure of 70 ubar 110 phon at the microphone capsule For microphones adjusted to a source impedance of 200 ohms the gain of the amplifier amounts to approximately 3 db 6 Without connection of microphone the voltage at the power supply unit is approximately volts 7 Should the diaphragm have become dusty after a long period of service it may be cleaned by means of an extremely soft camel hair brush For that purpose the capsule itself is accessible after removal of the three outer fastening screws located at the bottom of its mounting plate 8 Caution Never remove the four fastening screws located in the middle of the capsule mounting plate F 9 Re strapping from one impedance to the other can be simply performed after removal of the mierophone housing by following the diagram and pictorial presentation of the terminal boord attached 10 When ordering spare parts it is recommended that you include the serial number so that the proper parts for your partic
5. ular model can be supplied RECOMMENDATIONS 1 U47 and U 48 microphones can be suspended from film and television booms by means of special full elastic suspensions type Z 37 which help reduce mechanical shock interference carried through the floor and which permit rapid turning at the end of the boom 2 Where U 47 or U 48 microphones are permanently installed in studios or other locations we recommend the installation of microphone outlets T 3040 into which the microphone inter connecting cable can be pluqged Concealed lines should lead from these wall sockets to the equipment rack or console where type NGK plug in power supply may be installed in a suitable plug in frame 3 Where two or more type U 47 or U 48 microphones ore used in the same location we recom mend the use of double power supply NG 2 Two U 47 or U 48 microphones or one of each can be operated from this unit whose dimensions are identical to fhose of the single type NG power supply Printed in Germany
6. with special 6 pin plugs in their base the No 5 pin corrying the D C supply voltage to the microphone being purposely shortened to make provision that the ground pin connecis before the plate voltage As a Ferther pre caution always make sure that the power supply is switched off when plugging the microphone into the mating receptacle on the UC 3 extension cable or the UC 4 interconnecting cable with microphone stand mount to avoid possible shock to the operator 2 The UC 4 stand mount incorporating a swivel joint comes normally equipped with a 1 right hand thread in the case of U S A use with 27 thread for the purpose of mounting the microphones on stands and booms 3 The four conductor shielded cable comes normally 33 ft long but lengths up to 300 feet are admissible between microphone and power supply and can be supplied on order 33 ft other lengths on request 1 2 right hand thread 5 e 27 thread on request 4 The NG power supply delivers the required single voltage of 105 volts D C at 40 ma to the microphone The required heater vollage is taken from this single voltage 5 The power supply is equipped with a two pole plug to which the power cord has to be connected A mating A C connector for this plug is supplied with the power supply on special request 6 First make certain that the power supply is properly strapped for the A C line voltage 110 or 220 volts required The correct setting of this strap
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