Neumann.Berlin KM 56 User's Manual
Contents
1. NEUMANN 1 10 1 12 l niature Condenser Microphones are undertaken at your own risk Work performed on the miniature microphones should be approached with extreme care and dry hands Such repair should only be attempted by a skilled technician Under no circumstances should one blow into the capsule itself and the capsule diaphragm shouid remain untouched The capsule head is of the plug in type and may be removed by advancing the three set screws at its base Capsules in need of repair must be returned to us or our authorized service centers After the capsule has been unplugged you can remove the amplifier cover by advancing the set screw in the case of the KM 56 there are two set screws at its base After withdrawing the amplifier cover remove the plastic protective cover to gain acce s to the amplifier itself Extreme care must be exercised in changing the tube To do so grip the helically spiralled tube leads in turn with a small pair of long nose pliers and apply a minimum of heat from a miniature soldering iron to the soldering joint The spiral as well as the pliers serve as heat conductors to prevent cracking of the tube s glass envelope by the expanding wire The AC 701 k tube is especially selected for low noise and its connecting leads are properly curled at our factory for quick installation It is imperative for proper operation that replacement tubes be obtained through us or our representatives2. To gain access to the output transformer widen the upper edge of the mu metol shielding sleeve and slide it gently upwards The characteristics of the amplifiers of the miniature microphones can be measured by means of the M 73k test stand the M 74 test cage and the Z 53 Z 54 or Z 56 test capsule Instructions for test procedure are included with the test equipment It is advisable to check the power supply for proper operating voltages every six months An impedance change should it become necessary can only be performed by our authorized service centers When ordering spare parts it is imperative that you include the serial number so that the proper parts for your particular model can be supplied E RECOMMENDATIONS The KM53a KM 54a and KM 56 miniature microphones can be suspended from film and television booms by means of special full elastic suspensions type Z 38 which help reduce mechanical shock interference carried through the floor and which permit rapid turning at ihe end of the boom When using this suspension use the KC 1 extension cable Where miniature microphones are installed permanently in studios or other locations we recommend the installation of microphone outlets 6 pole T 3403 into which the microphone interconnecting cables can be plugged Concealed lines should lead from these wall sockets to the equipment rack or console where a type N 52 t plug in power supply may be installed in a suitable plug in
3. OPERATING INSTRUCTIONS FOR NEUMANN MINIATURE CONDENSER MICROPHONES KM 53a KM 54a KM 56 AND ACCESSORIES A C TECHNICAL DATA Microphone KM 53a Range of Frequencies Directional Characteristic Sensitivity Total Harmonic Distortion Source Impedance Tube Complement Microphone KM 54 a Range of Frequencies Directional Characteristic Sensitivity Total Harmonic Distortion Source Impedance Tube Complement Microphone KM 56 Range of Frequencies Directional Characteristics Sensitivity Total Harmonic Distortion Source Impedance Tube Complement Power Supply NKM NN 48b Line Voltage Input Operating Voltages Operating Currents Fuse Pilot Lamp interconnecting Cable KC 2 Standard Length Stand Mount GENERAL Jan 1964 40 to 15 000 cps omni directional 1 2 mV dyne cm 2 less than 0 8 40 15 000 cps up to a sound pressure level of 110 db 200 or 50 ohms 1 Telefunken AC 701 k selected 40 to 15 000 cps cardioid 1 0 mV dyne cm Jess than 0 6 40 15 000 cps up to a sound pressure level of 110 db 200 or 50 ohms 1 Telefunken AC 701 k selected 40 to 15 000 cps omni directional cardioid bi directional figure 8 0 8 mV dyne cm less than 0 6 40 15 000 cps up to a sound pressure level of 110 db 200 or 50 ohms 1 Telefunken AC 701 k selected 110 220 volts 50 60 cps 4 volts DC filament 120 volts DC plate 100 ma filament 0 5 ma plate 80 ma for 110 volts 50 ma for 220 volt
4. d or a source impedance one fifth the load impedance For a 250 ohm load impedance the source impedance of the microphone preamplifier 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 micro phone 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 near the seria number at the base of the microphone This series of microphones can be exposed safely to heat commonly found in high density lighting for film and TV but should not be exposed to excess humidity After interconnection of the microphone power su ply and AC line the main switch may be switched on Operating condition will be indicated by a pilot lamp It is not harmful to the power supply if it is operated even for longer periods of time without connection of a microphone D TESTING AND MAINTENANCE NEUMANN Miniature Condenser Microphones are made with extreme care and accuracy and most careful handling is required if consistently excellent results are expected Warning Should the Miniature Microphones need servicing it is imperative that they be repaired at our factory or at our authorized service centers otherwise the guarantee will be void The following instructions are given with the understanding that all manipulations performed on i
5. frame A self contained battery supply type BB 9k may be used in place of the NKM or NN 486 power supply where AC power is not available To suppress interference caused by wind or by popping resulting from close speaking we recommend the Z 118 wind and close talking screen Printed in Germany
6. rating a swivel joint normally comes equipped with a 2 right hand thread on request with 5 27 thread for the purpose of mounting the microphones on stands or booms The five conductor shielded cable normally comes 33 ft long but lengths up to 100 ft are admissible between microphone and power supply and can be supplied on order Should the microphone be located more than 70 ft from the power supply it is advisable that the filament voltage series resistor in the power supply part 10 which is accessible after removal of the power supply cover be bridged See diagram The M31b floor stand and the MF1 desk stand are intended for most suitable mounting of miniature type microphones The floor stand M 31 b is fitted with a goose neck extension incorporating a mating receptacle for connection of the mierophone Electrical connection to the power supply is made through a 33 ft long cable inseparably belonging to the stand itself The desk stand MF1 is equipped with a threaded stud for fastening the interconnecting cable KC 2 or the goose neck extension Z 13 All connectors on microphones cables and power supplies are equipped with screw lype couplings Make sure that these are properly fastened The NKM or NN 48a power supply delivers the required operating voltages to the microphone 4 volts DC filament voltage and 120 volts DC plate voltage The power supply is equipped with a two pole AC plug to which the power co
7. rd has to be connected A mating AC connector for this plug is supplied with the power supply on special request First make certain that the power supply is properly strapped for the AC line voltage required mo or 220 volts The correct setting of this strap is visible through a small window at one side of the power supply cover The strapping board is accessible after removal of the cover Also make sure that the proper value fuse for the voltage used has been inserted in the fuse holder 80 ma for 110 volts 50 ma for 220 volts The output signal from the microphone is fed to a ihres prona chassis mounted plug on the power supply 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 The three fixed directional characteristics of the KM 56 microphone can be selected conveniently by means of a switching ring located at its base Because of the orientation of the condenser capsule KM 53a and KM 54a are positioned pointing toward the sound source while the KM 56 is placed with its body at right angle to the incident sound The KM 53a KM 54a and KM 56 microphones are designed to work into a load impedance input impedance of console preamplifier of 250 respectively 1C00 ohms or even higher To rovide a sufficiently low source impedance from the microphones they have been designe
8. s 6 volts 180 ma 33 ft other ae li on request Yo right hand thread 54 27 thread on request The miniature size type KM 530 KM 54a and KM 56 condenser microphones contain besides the copsule assembly a complete amplifier with tube and output transformer Their individual features are Type KM 53a is a pressure type condenser microphone with omni directional characteristic Its frequency response shows a purposeful slight rise at higher frequencies when exposed to direct sound but remains virtually flat in a diffused sound field Type KM 54a is a pressure gradient condenser microphone with cardioid characteristic Its extra high directionality produces a 25 db front to back attenuation enabling the microphone to be used with extraordinarily good results in relatively poor acoustical surroundings Type KM 56 is a pressure gradient condenser microphone with three fixed directional characte ristics conveniently electronically selectable by a switching ring on the microphone itself Unlike the KM 53a and KM 54a it must be set at right angles to the direction of incident sound for optimum response PLACING IN OPERATION 1 The KM53q KM54q and KM56 miniature microphones are equipped with special 6 pin miniature plugs which should be plugged into the mating receptacle of the KC 1 extension cable or the KC 2 interconnecting cable with microphone stand mount 10 11 12 13 14 15 The KC 2 stand mount incorpo
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