Neumann.Berlin M 269c User's Manual
Contents
1. pin 2 positive pin 3 negative pin 1 ground The M 269c has an internal resistance of 200 a which can be re strapped to 50 n The connections are clearly shom on a connec tion board The input impedance of the following amplifier should be 5 times as big or bigger i e 1000 a or 250 a The micro phone is usually supplied strapped fora 200 a internal resistance The 50 a strapped microphones may be identified bya red dot locat ed near the serial number of the microphone Most of the American preamplifiers and consoles are designed for operation with dynamic microphones For proper matching of the M 269c microphone to such amplifiers the power supply unit NN 48hu has a special pad built in which permits such direct connection The microphone itself remains strapped for 50 a The output impe dance behind this pad is 150 250 a It may be restrapped for an output impedance of 30 5002 See schematic diagram NN 48hu This pad permits the connectionof the M 269c microphone to ampli2. Z 69 and the test device M 273 From the 50 9 output of a signal generator feed a 1000 cps tone at a level of 18 dB to the input of the M 273 You may use the model Z 69 dummy headorcan proceed with the regular head assembly plugged in The three switches are set for F full sensitivity and linear response The following output levels are to be ob served at the output across a 1 kn load resistance using a vacuum tube voltmeter 1000 cps 20 dB 1 dB 40 cps 24 dB E 1 dB 1500 cps 26 daB 1 4B When communicating with the factory or its representatives or when ordering parts be sure to include the serial number of your microphone Accessories The M 269c microphone may be suspended in a full elastic suspen sion Z 48 providing complete mechanical isolation and permitting any operating position desired A wind and close talking screen Z 67 is available for use outdoors or when speaking or singing into the microphone at close range For permanent installations of the M 269c microphone we recommend the use of the rackmounted plug in power supply unit N 52t Up to ten units can be fitted side by side into one plug in shelf Ss 167 10 Instead of the power supply units NN 48h and N 52t the battery supply unit BB 50h may be used as well making the operation inde pendent from the mains The operating time is approximately 50 hours 1
3. gt Iw OPERATING INSTRUCTIONS for the NEUMANN MODEL M 269c CONDENSER MICROPHONE M 269c 920 02 01 Technical Data M 269c microphone Frequency range 30 16 000 cps Directional characteristics omni directional cardioid figure of eight Output levels app omni directional F 0 9 mV ub cardioid F 791 0 mV ub figure of eight F 1 1 mV ub cardioid 1 55 mV ub Electrical load resistance 1 000 na 250 a Electrical source TesistanllOr oonmo ooo oon o 200 2 502 20 Total harmonic distortion 0 5 up to 114 dB SPL NN 48h hu power supply unit Mains voltages 117 127 220 240 V 10 50 60 eps PUES aid 80 mA for 117 127 V sl bl 50 mA for 220 240 Vm sl bl DC output voltages 4 V 120 V O 120 V General The microphone capsule of the M 269c microphone is a pressure gra dient device It is composed of two identical cardioid systems arranged back to back By switching of the polarizing voltage these two cardioid patterns can so be combined as to produce the three directional characteristics cardioid omni directional and figure of eight The switch for selection of the directio nal characteristics located at the capsule head has three positions marked by the symbols F cardioid and F Due to technical conditions the position F appears twice Both positions are identical in function When the switch is set for one of t
4. 0 may be ordered special Cable lengths between microphone and power supply unit up to 100 feet are permissible If the microphone shall be operated with a cable longer than 65 feet the resistance R 10 in the filament circuit of the power supply unit must be bridged When using the table stand M 270 or the floor stand M 272 the ex tension cable is to be mated with the connector of the stand The power supply unit is equipped with a 2 pole power connector The proper mains voltage strapping is readily controlled through the lucite window at the side of the power supply unit A coin operated latching screw is located under the power supply unit s carrying handle When the slot is in its length wise posi tion the power supply unit s cover may be romoved upward while the carrying handle remains on the power supply unit chassis Make certain that the proper fuse has been inserted in the fuse holder 80 mA for 117 127 V and 50 mA for 220 240 V The connection between the audio output socket for NN 48h T 3081 for NN 48hu Cannon XLR 3 32 and the console is to be mede using any suitable two conductor shielded microphone cable of any length For purposes of phasing of the M 269c microphone the following is of importance For increasing sound pressure on the front diaphragm the following are the polarities at the various connectors microphone connector and power supply unit receptacle pin 1 positive pin 2 negative at the NN 48hu
5. ent microphone is addressed at close range This position further serves to suppress low frequency mechanical interference These two switches likewise 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 attenuates 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 it self Operating Instructions 1 The microphone is equipped with a 7 pole plug NT 3470 which is to 2 be connected by means of any of the KC 5 KC 7 KC 9 or C 228s cables with the corresponding 7 pole receptacle T 3471 on the NN 48 h hu power supply unit The extension cables of the power supply unit carry the designation KC 5 or KC 7 The cables KC 9 and C 228s have a swivel stand mount permitting the microphone to be attached to floor stands and booms having either a 1 2 or 5 8 27 thread The KC 7 and C 228s cables are double shielded and equipped with the RF proof connectors T 3468 and T 3469 The KC 5and KC 9 cables provide normal shielding and terminate in connectors T 3460 a
6. he two positions F the direc tional characteristic can from the polarizing voltage potentiometer of the respective power supply be changed continuously variable from omni directional over cardioid to the figure of eight characteristic The adjustment continuously variable permits the selection of any intermediate position wanted between two charac teristics 321 M rz 66 When the cardioid symbol appears in the window of the selection switch the rear diaphragm of the capsule is switched off and the microphone works as cardioid microphone only Thus the rear dia phragm has in this position no polarizing voltage The output level increases compared with the remote controlled cardioid by about 4 dB The equivalent sound pressure level improves by 3 phon The absence of the polarizing voltage offers the possibility of feeding the microphone fromapower supply unit for miniature microphones For connection with the NXMa the adapter Z 51 is necessary the NKMh can be connected directly Two additional switches are located at the rearof 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 be ginning at 200 cps This permits the compensation of the normally occurring low frequency rise when a pressure gradi
7. nd T 3461 The microphone cables have a normal length of 33 feet Other lengths lis 12 la fier inputs having nominal input impedance of 150 250 a as shipped or 30 50a when restrapped The effective output level behind this pad is only a few dB higher than that of the usual high quality dynamic microphone For a sound pressure of 10 ub this EFFECTIVE OUTPUT LEVEL is as follows omni directional F 45 dB cardioid F 44 dB figure of eight F 43 dB Cardiol sss ns cows es lt 40 AB For a sound pressure of 1 dyn on 1 yb these figures are lower by 20 dB After connection of the microphone with the power supply unit and the mains the main switch can be switched on The power is on at the power supply unit when the neon lamp lights Our power supply units are equipped with two latches which are to be screwed between O Volt and screenor between housing and screen These latches can be separated in order to avoid ground circuits which can cause hum interferences The following three alternatives are possible a A mains cable connected with ground is used on the power supply unit and the following amplifier rack is connected with ground both latches must be opened b When the mains line isnot connected with ground and the ampli fier rack is connected with ground separate latches O Volt and screen and leave latch housing screen connected c When havingamains line connected
8. with ground and an amplifier rack not connected with ground connection as under b Testing and Maintenance Should your NEUMANN microphone require servicing we recommend that you either return it to our factory or to our nearest re presentative for repair Beyond that we offer the following help ful hints for the testing or repair of these microphones All work performed on the microphone should be done in a most care ful and workmanlike manner Only experienced personnel should be permitted to do such work To gain access to the microphone s preamplifier unscrew the bottom fastening ring after which the conical housing tube easily slides off The head assembly canbe unplugged after the two latches which lie within the side struts have been pressed together at the top The amplifier is now accessible and the AC 701k tube may be easi ly changed Around the perimeterof the lucite base of the head assembly there are three screw heads visible one of which is sealed When these screws are taken out the entire capsule assembly can be removed from its cage Should there be dust on the diaphragms it may easi ly be removed by gently brushing it off using a very soft paint brush The use of either compressed air or vacuum can lead to de struction of the capsule The plexiglas dome belowthe capsule may be cleaned using a cleaner intended for such plastic The actual properties of the amplifier can be ascertained using the dummy head
Download Pdf Manuals
Related Search