Nagra 4.2 Portable Analogue Audio Instructions Manual
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N A G R A 4.2 PORTABLE ANALOGUE AUDIO TAPE RECORDER INSTRUCTION MANUAL (KSA code No. 20 04 004 151) Kudelski S.A. NAGRA Tape Recorder Manufacturer CH-1033 Cheseaux / SWITZERLAND phone (021) 732 01 01 Copyright reserved for all countries telex 459 302 nagr ch February 1991 Edition Printed in Switzerland telefax (021) 732 01 00 http://www.nagraaudio.com
NAGRA, KUDELSKI, NEOPILOT, NEOPILOTTON NAGRASTATIC, NAGRAFAX are registered trade - marks, property of KUDELSKI S.A. NAGRA Tape Recorders Manufacture NAGRA / KUDELSKI certifies that this instrument was thoroughly inspected and tested prior to leaving our factory and is in accordance with the data given in the accompanying test sheet. We guarantee the products of our own manufacture against any defect arising from faulty manufacture for a period of one year from the date of delivery. This guarantee covers the repair of confirmed defects or, if necessary, the replacement of the faulty parts, excluding all other indemnities. All freight costs, as well as customs duty and other possible charges, are at the customers expense. Our guarantee remains valid in the event of emergency repairs or modifications being made by the user. However we reserve the right to invoice the customer for any damage caused by an unqualified person or a false maneuver by the operator. We decline any responsibility for any and all damages resulting, directly or indirectly, from the use of our products. Other products sold by KUDELSKI S.A. are covered by the guarantee clauses of their respective manufacturers. We decline any responsibility for damages resulting from the use of these products. We reserve the right to modify the product, and / or the specifications without notice.
CHAPTER I INSTRUCTION MANUAL TABLE OF CONTENTS 1.1 INTRODUCTION..............................................................................................................7 1.2 CONTROLS: DESCRIPTION AND USE...........................................................................10 FRONT PANEL........................................................................Error! Bookmark not defined. 1. TAPE / DIRECT SWITCH (LINE AND PHONES)...................................................................10 2. TAPE / DIRECT (SNAP SWITCH).......................................................................................10 3. POWER SELECTION SWITCH (EXTERNAL / BATTERIES)............................................10 4. MAIN FUNCTION SELECTOR (SIX POSITION ROTARY).......................................................10 5. PINCHWHEEL LIFTER (STOP + TEST ONLY).....................................................................11 6. LEVEL CONTROL (RIGHT) MIC INPUT 2.............................................................................11 7. LEVEL CONTROL (LEFT) MIC INPUT 1..............................................................................11 8. REFERENCE OSCILLATOR (PUSH BUTTON)....................................................................11 9. LINE & PLAYBACK POTENTIOMETER..........................................................................11 10. MANUAL/AUTOMATIC SELECTOR..............................................................................11 11. LID CATCH.................................................................................................................11 12. MODULOMETER MODE SELECTION SWITCH............................................................11 13. FILTER SWITCH.........................................................................................................12 14. MODULOMETER.........................................................................................................13 15. PILOT INDICATOR......................................................................................................13 16. SPEED AND POWER INDICATOR...............................................................................13 17. HEADPHONES OUTPUT.............................................................................................13 18. HEADPHONES VOLUME CONTROL...........................................................................13 19. REEL FIXING NUT.......................................................................................................13 TAPE DECK........................................................................................................................14 20. SPEED AND EQUALIZATION SELECTOR.................................................................14 21. MOBILE TAPE GUIDE.................................................................................................14 22. PINCHROLLER...........................................................................................................14 23. REWIND AND FAST FORWARD SWITCH....................................................................14 24. & 34. TAPE REELS......................................................................................................14 25. & 33. TENSION ROLLERS.........................................................................................14 26. ERASE HEAD..............................................................................................................15 27. STROBOSCOPE ROLLER...........................................................................................15 28. RECORDING HEAD....................................................................................................15 29. PILOT HEAD...............................................................................................................15 30. PLAYBACK HEAD.......................................................................................................15 31. CAPSTAN SHAFT.......................................................................................................15 32. PINCH WHEEL AND TAPE GUIDE CONTROL LEVER..................................................15 33. TAPE TENSION ROLLER (OR TIMER) (SEE 25)............................................................15 34. TAKE-UP REEL (SEE 24)..............................................................................................15 1.3 CONNECTORS..............................................................................................................16 36. MIKE 2 INPUT...............................................................................................................16 37. MIKE 1 INPUT...............................................................................................................16 38. RX..............................................................................................................................16 39. ACC (ACCESSORIES)......................................................................................................16 40 MIXER.........................................................................................................................17 41 LINE INPUT..................................................................................................................17 42 VOL.............................................................................................................................17 43 MICROPHONE INPUT SELECTOR...............................................................................17 44. PILOT AND CLAPPER INPUTS....................................................................................18 45. LINE OUTPUT.............................................................................................................18 46. GROUND (BANANA SOCKET)..........................................................................................18
47. LOUDSPEAKER..........................................................................................................18 48. POWER PACK............................................................................................................19 49. FIXTURE FOR CARRYING STRAP/HANDLE................................................................19 50. CASE FIXING SCREW.................................................................................................19 51. PLATE SHOWING RECORDING AND PLAYBACK EQUALIZATION..............................19 2.1. POWER SUPPLY..........................................................................................................20 DANGER OF REVERSED POLARIZATION........................................................................20 MEASURING BATTERY CONDITION AND POWER SUPPLY VOLTAGE............................20 BATTERY RESERVE.....................................................................................................20 VOLT / CELL.................................................................................................................21 MEASURING THE MOTOR CURRENT..............................................................................21 SPEED & POWER INDICATOR.......................................................................................21 EXTERNAL POWER SUPPLY..........................................................................................21 3.0 OPERATION..................................................................................................................22 3.2 TAPE SPEED AND STANDARD SELECTION...............................................................22 2.3 LOADING A TAPE ON THE RECORDER......................................................................22 RECORDING....................................................................................................................23 RECORDING WITH MICROPHONES.................................................................................23 RECORDING A LINE SIGNAL............................................................................................23 FAST FORWARD / REWIND.............................................................................................23 PLAYING BACK A RECORDED TAPE...............................................................................24 WORKING WITH HEADPHONES.......................................................................................24 2.8 PRECAUTIONS...........................................................................................................24 4.1. DIRECT AND TAPE CHAINS..........................................................................................25 GENERAL.........................................................................................................................25 AUDIO INPUTS.................................................................................................................25 MANUAL LEVEL CONTROL..............................................................................................25 LIMITER...........................................................................................................................25 AUTOMATIC LEVEL CONTROL (ALC)...............................................................................26 MEASUREMENT OF SIGNAL LEVEL.................................................................................26 5.0 PILOT............................................................................................................................27 INTRODUCTION...............................................................................................................27 RECORDING A PILOT SIGNAL.........................................................................................27 RECORDING THE INTERNAL CRYSTAL...........................................................................27 RECORDING AN EXTERNAL PILOT SIGNAL.....................................................................27 SYNCHRONIZING A RECORDED TAPE............................................................................28 FREQUENCY METER (OPTIONAL ACCESSORY QFM).....................................................28 QUARTZ CRYSTAL PILOT GENERATOR (OPTIONAL ACCESSORY QGX-3).....................28 PILOT INDICATOR............................................................................................................28 INTERNAL SYNCHRONIZER (OPTIONAL ACCESSORY QSLI)..........................................29 SPEED VARIER QSV-2.....................................................................................................29 USE OF SPEED VARIER WHILST FILMING ON PLAYBACK..............................................30 RECORDING OF FACSIMILE AND SIMILAR SIGNALS.......................................................30 PILOT PLAYBACK USING A NAGRA 4.2 L NOT EQUIPPED WITH QSLI SYNCHRONIZER.30 PILOT PLAYBACK MADE BY NAGRA 4.2 L FITTED WITH QSLI SYNCHRONIZER.............30 PILOT CONNECTORS......................................................................................................31 6.0 BASIC THEORY.............................................................................................................32 CONTROL OF THE INPUT SENSITIVITY (MODULATION),DYNAMIC RANGE, SIGNAL-TO- NOISE RATIO, DECIBELS.................................................................................................32 COMPRESSION OF THE DYNAMIC RANGE.....................................................................32 WHEN SHOULD COMPRESSION BE DONE?....................................................................33 5.3. INTERFERENCE........................................................................................................34 ELECTROSTATIC INDUCTION..........................................................................................34 ACTION TO BE TAKEN AGAINST ELECTROSTATIC INDUCTION.....................................34 MAGNETIC INDUCTION....................................................................................................35 CABLE PREAMPLIFIERS..................................................................................................35 5.4. VOLTAGE OR CURRENT FEED.................................................................................35 FILTERING PREAMPLIFIERS............................................................................................35 MAGNETIC HEADS...........................................................................................................36 ADJUSTEMENT OF HEAD AZIMUTH................................................................................36
Theory..........................................................................................................................36 Variation of the High Frequency Level with Azimuth Error.................................................36 Secondary Maxima........................................................................................................37 Orientation of the Heads on the Nagra 4.2.......................................................................37 Bias..............................................................................................................................37 Effect of Bias Signal Amplitude on the Recording.............................................................37 High Frequency Pre-emphasis........................................................................................38 Relation between Pre-emphasis and Bias.......................................................................38 Practical Conclusions.....................................................................................................39 DETERMINATION OF THE BIAS LEVEL............................................................................39 Tape Characteristics......................................................................................................39 General Procedure.........................................................................................................39 Variation of k.................................................................................................................39 7.0 CALIBRATION AND CARE..............................................................................................40 HEIGHT OF THE NEOPILOT HEAD...................................................................................40 AZIMUTH ADJUSTMENT OF THE PLAYBACK HEAD.........................................................40 AZIMUTH ADJUSTMENT OF THE RECORDING HEAD......................................................40 6.2. MAINTENANCE OF THE MOTOR COMMUTATOR......................................................41 Remedy for Motor Noise.................................................................................................41 Metalization of the Commutator.......................................................................................41 Cleaning of the Commutator...........................................................................................41 6.3. LUBRICATION............................................................................................................42 8.0 MICROPHONES.............................................................................................................43 INTRODUCTION...............................................................................................................43 5.2. THE MICROPHONES.................................................................................................43 MICROPHONE CHARACTERISTICS.................................................................................43 Sensitivity......................................................................................................................43 Frequency Response.....................................................................................................43 Coloration. Transient Reproduction. Reverberation..........................................................43 Use at High Sound Levels..............................................................................................44 Signal-to-noise Ratio......................................................................................................44 Directional Characteristics..............................................................................................44 SECONDARY CHARACTERISTICS RELATED TO DIRECTIONAL CHARACTERISTICS.............................45 PRACTICAL ADVICE ON THE CHOICE OF THE MICROPHONES......................................45 Omni-directional Microphones (pressure)........................................................................45 Bi directional Microphones (velocity)...............................................................................45 Switchable Microphones.................................................................................................46 Choice between Condenser or Dynamic Microphones......................................................46 5.6. MAXIMUM GAIN OF THE RECORDING CHAIN OR SENSITIVITY OF THE MICROPHONE INPUTS....................................................................................................46 Nagra 4.2 Preamplifiers..................................................................................................46 Changing the Plug-in Preamplifiers.................................................................................47 Plug-in Preamplifiers......................................................................................................47 STATIC 5 Code: QPM-3-5............................................................................................47 HIGH LEVEL LINE Code: QPM-6.................................................................................47 UNIVERSAL Code: QPAUT & QPUT............................................................................47 SPECIAL PLUG-IN PREAMPLIFIERS................................................................................48 Filtering Versions of the QPSE........................................................................................48 Cable Preamplifiers........................................................................................................48 LOW FREQUENCY ROLL-OFF ATTENUATORS................................................................48 Why Filter?....................................................................................................................48 When should Filtering be done?......................................................................................49 Conclusion....................................................................................................................49 METERING..........................................................................................................................50 MODULOMETER OR V.U. METER....................................................................................50 MODULOMETER..............................................................................................................50 V.U. METER......................................................................................................................50 CONCLUSIONS................................................................................................................51 REMARKS ON THE CALIBRATION...................................................................................51 9.0 SPECIFICATIONS..........................................................................................................52
DIMENSIONS AND WEIGHT.............................................................................................52 POWER SUPPLY.............................................................................................................52 TAPE TRANSPORT..........................................................................................................53 WOW AND FLUTTER........................................................................................................53 AMPLIFIER CHAIN............................................................................................................53 MAGNETIC TAPE.............................................................................................................53 AUTOMATIC LEVEL CONTROL........................................................................................53 FILTERS...........................................................................................................................54 REFERENCE GENERATOR..............................................................................................54 OUTPUTS.........................................................................................................................54 BUILT-IN LOUDSPEAKER.................................................................................................54 OPERATING CONDITIONS...............................................................................................54 MODULOMETER..............................................................................................................55 INPUTS............................................................................................................................56
1.1 INTRODUCTION The NAGRA 4.2 was introduced originally in 1971. It is a portable 6.35mm (1/4) mono analogue audio tape recorder designed for high quality recording having radio, cinema and television applications. Many mechanical and electronic modifications have been made to the machine since its release, to adapt it according to modern day requirements. Despite all these modifications, the machine remains remarkably similar to the original. The Nagra 4.2 can be delivered in two different versions both of which are available in either NAB or CCIR equalization. These versions are as follows: NQ-LSP Non pilot NQS-L Pilot Each version has three speeds: 38 cm/s, 19 cm/s and 9.5 cm/s (15, 7½ and 3 3/4 ips) with the following standards: NAB and CCIR. The Nagra 4.2 is a mono recorder recording full track audio on 6.35mm tape, and the Neopilot synchronization system. The audio inputs may be used with either the two internal microphone pre-amplifiers (switchable between Dynamic, T power and Phantom power depending on the microphone pre-amplifier which is fitted) or as a line input, via the QCE cable. The NAGRA 4.2 also contains a switchable limiter, a built-in loudspeaker, and an internal reference generator for line up, and calibration purposes. Optionally the machine may be fitted with the NEOPILOT pilot option. The machine may also be powered from either an external supply ATN-3 or internal batteries. The 4.2 may also be used with the QGB 10 reel adaptor, to allow the use of larger reels for longer recording and playback.
1.2 CONTROLS: DESCRIPTION AND USE FRONT PANEL 1. TAPE / DIRECT SWITCH (line and phones) When in TAPE position, the signal is reproduced directly from the tape. When in DIRECT position, there are two possibilities: A. When recording, the signal is available before arriving on the tape. B. When playing back, the signal may be adjusted by means of the level control and corrected by filter switch (13). 2. TAPE / DIRECT (snap switch) This switch affects the meter in the same way that the previous switch affects the output. Thus when it is held to the left, the meter will display the OFF TAPE signal whereas normally it displays the DIRECT (EE) signal. 3. POWER SELECTION SWITCH (EXTERNAL / BATTERIES) The NAGRA 4.2 may be powered by either internal batteries or by an external source which may be selected using this switch. See also the POWER SUPPLY section of this manual. 4. MAIN FUNCTION SELECTOR (six position rotary) STOP Stops the machine completely from any function, and will slightly move the pinch wheel away from the capstan to prevent a flat being caused on the pinch roller. In this mode no circuits are powered. TEST Will power all circuits and allow level adjustment by means of level controls (6), (7) and (9). In this mode the motor is not powered. All indications of the modulometer will be of the DIRECT input, irrespective of the position of tape / direct switch (1). RECORD Is the first of the two RECORD positions and corresponds to RECORD WITH LIMITER where the recording level is limited to +4 dB. This level remains constant when the input level is between +4 dB and +10 dB. Thus in this position tape saturation cannot occur and distortion is avoided. RECORD The limiter is inactivated in this position so(no that recordings that should be saturated can be limiter) made. (e.g. gun shots or explosions). PLAYBACK Is the first of the two playback possibilities and corresponds to playback of the tape to the headphones and line output only. PLAYBACK This position is exactly as above, only it allows (with monitoring via the internal loudspeaker at the same speaker) time. This is also the only position of the main function selector that permits the FAST FORWARD function to be performed.