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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
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Related Manuals for Nagra PORTABLE ANALOGUE AUDIO TAPE RECORDER
Summary of Contents for Nagra PORTABLE ANALOGUE AUDIO TAPE RECORDER
- Page 1 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...
- Page 2 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.
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Page 3: Table Of Contents
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 ( ) ..............10 LINE AND PHONES 2. TAPE / DIRECT ( ) .................. - Page 4 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 ......................
- Page 5 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 ...............
- Page 6 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 ....................
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Page 7: Introduction
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:... -
Page 10: Controls: Description And Use
"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. -
Page 11: Pinchwheel Lifter (Stop + Test Only)
5. PINCHWHEEL LIFTER (stop + test only) 6. LEVEL CONTROL (right) mic input 2 7. LEVEL CONTROL (left) mic input 1 These are the main level controls for the two microphone inputs. 8. REFERENCE OSCILLATOR (push button) On the lower edge of the front panel, between the line and playback potentiometer and the mic 2 potentiometer, there is the reference generator push button. -
Page 12: Filter Switch
PILOT PLAYBACK This indicates the level of the pilot signal played back from the tape. PILOT FREQ This indicates on the +4 to -4% scale of the modulometer, the frequency deviation as determined by the QFM frequency meter circuit (if fitted), between the pilot signal being recorded or played back and the 50/60 Hz reference. -
Page 13: Modulometer
(If this occurs during normal operation, then contact your nearest NAGRA agent.) c.) WOW & FLUTTER is out of tolerance. (Contact NAGRA agent). Thus, when a white segment is indicated, the operator can be absolutely sure that the power supply is sufficient, that the motor current is correct, and that the tape speed is within tolerance. -
Page 14: Tape Deck
TAPE DECK 20. SPEED AND EQUALIZATION SELECTOR This is a six position rotary switch permitting the selection of the speed and equalization of the 4.2 in both record and playback. Possible settings are: 3 3/4 (9.525 cm/s) 7½ (19.05 cm/s) (38.10 cm/s) For each of these speed selections there are two possible positions labeled I (STD) and II (LN) these correspond to different tape types. -
Page 15: Erase Head
The two rollers can be replaced by either the QTIM or QLEN tape measuring rollers. The QTIM is supplied in the place of the take-up reel tension roller as standard equipment. QLEN instead of QTIM is optional. (To be stated when ordering). 26. -
Page 16: Connectors
1.3 CONNECTORS 36. MIKE 2 input = Input signal Ground 2+3 = Balanced signal Input 37. MIKE 1 input Identical to No 36 above. NOTE: The microphone inputs are convertible into symmetrical and floating line inputs by installing, in place of the microphone preamplifiers, preamplifiers type QPM-6 and using the corresponding potentiometer to control the input level. -
Page 17: Mixer
40 MIXER For connection to external mixing console. (connector type: T 3478 corresponding plug T 3475/1). 1. Input with fixed sensitivity, 560 mV to obtain 0 dB, input impedance 9 k Ohm. (2.5 Vpp to obtain +4 dB) 2. -10 V stabilized voltage, Maximum current 50 mA. Noise level < 5 V rms. -
Page 18: Pilot And Clapper Inputs
"Tape", the line output voltage is 4.4 V into 600 Ohm while playing back a tape recorded at 0 dB. The Nagra 4.2 can record at a level 4 dB higher than this, thus the maximum line output voltage will be 7 V. -
Page 19: Power Pack
48. POWER PACK 6 pole connector for external power supply and pilot signal output. - BATT: Negative pole of battery compartment. + BATT: Positive pole of battery compartment. PILOT PLAYBACK: Pilot playback output. SPEED CORRECTION: Tape speed correction input. EXTERNAL -12 to -30: Input for external power supply -12 to -30 V negative pole. -
Page 20: Power Supply
New batteries will give about 18 V whereas the Nagra can be powered by up to 30 V. This explains why, with new batteries, the needle of the meter will only indicate about 40% full scale, when it is... -
Page 21: Volt / Cell
It is also possible to monitor the external power supply voltage. If when in the position "Batt. Reserve" position the indication is that the Nagra is not receiving sufficient voltage, but the Volt/Cell indicates that the power supply voltage is correct, this means that the Nagra requires an abnormally high voltage. -
Page 22: Operation
On the right-hand side of the front panel is the main function selector, which determines the mode in which the Nagra works. By putting it into the position "Test", all the circuits are powered, but not the is motor. If the meter switch, on the upper right-hand side of the modulometer, is switched to the "BATT. -
Page 23: Recording
Depending on the position of "TAPE / DIRECT" switch (1) it is possible to monitor either the input signal, or the "off tape" signal on the headphones output during the recording. This is possible because the NAGRA 4.2 is a three head machine. (Moving this switch will not affect the recording). RECORDING A LINE SIGNAL Recording a line input signal rather than a microphone signal is very similar to working with microphones. -
Page 24: Playing Back A Recorded Tape
The pinch wheel is automatically disengaged in the position "Stop" of the Main Function Selector. This enables the Nagra to be stored with the Pinch Wheel and Tape Guide Control Lever in the closed position. If this lever is in the disengaged position, the lid of the recorder can not be closed. -
Page 25: Direct And Tape Chains
The modulometer measures the level of the "Direct" signal. It is operational even in the absence of a tape. On the other hand, there will be no "Tape" signal in this case. When the Nagra is in playback, the level control potentiometer "Line and Playback" is used to adjust the "Tape" signal. -
Page 26: Automatic Level Control (Alc)
MEASUREMENT OF SIGNAL LEVEL The Nagra 4.2 is equipped with a device for measuring the signal level. Normally, this is a modulometer, but a v.u. meter is available on special request. -
Page 27: Pilot
(QGX-3) if fitted. If a recording is made with a pilot version of the NAGRA 4.2 it is later possible, during playback, to lock the speed of the NAGRA by means of the pilot synchronizer (QSLI) to an external reference signal. -
Page 28: Synchronizing A Recorded Tape
The output signal of the generator is connected to pin No 3 of the pilot socket. To record it, it must be re-introduced into the Nagra by bridging pin No 3 to pin No 4. This is done with the aid of a dummy plug, which is supplied with the generator, or by a standard plug with the two pins connected. -
Page 29: Internal Synchronizer (Optional Accessory Qsli)
SPEED VARIER QSV-2 This is an external accessory for the Nagra 4.2. It is plugged into the ACC socket (39) on the left hand side of the recorder. It enables the speed to be varied manually up to ±12%. The QSV-2 is... -
Page 30: Use Of Speed Varier Whilst Filming On Playback
If this is not possible, correction can be made with the Speed Varier (see above). RECORDING OF FACSIMILE AND SIMILAR SIGNALS A Nagra equipped with a Quartz Crystal Pilot Generator and a QSLI Synchronizer can reproduce, on playback, frequencies with a precision of the order of 0.001%, as any slipping or stretching of the tape is automatically compensated for. -
Page 31: Pilot Connectors
1.7 V corresponds to full scale deflection. PILOT CONNECTORS On the Nagra 4.2, the pilot playback signal is to be found on the Power Pack connector (48), which is a 6 pin Tuchel socket, located on the right-hand side of the recorder. -
Page 32: Basic Theory
µbar. At 1 kHz, these decibels are the same as phons but as the Nagra does not have psophometric filters, it cannot be considered as a phon meter. With a potentiometer control placed on X dB, a sound of X dB, captured by a normal microphone (0.2 mV/µbar into 200 ? ) and attacking a normal sensitivity... -
Page 33: When Should Compression Be Done
Nagra. It is possible, to adjust the sensitivity in such a way that the fortissimo reaches 0 dB. As the maximum level of the Nagra is +4 dB, there is, therefore, a safety margin. The compression can be done according to the needs in the studio whilst working on the final recording. -
Page 34: Interference
ELECTROSTATIC INDUCTION The microphone and the cable, which connects it to the Nagra and the plugs, should all be well shielded. If these conditions are respected, no electrostatic induction can occur. -
Page 35: Magnetic Induction
Thus the standard pre-amplifiers for the Nagra 4.2 use the voltage feed method, but current feed preamplifiers are available for special cases, where desired. -
Page 36: Magnetic Heads
MAGNETIC HEADS There are four tape heads on the NAGRA 4.2, these being ERASE, RECORD, PILOT and PLAYBACK (see "CONTROLS at the front of this manual for their location). Contact between the magnetic head and the tape must be perfect. Some tapes leave deposits on the heads. -
Page 37: Secondary Maxima
Orientation of the Heads on the Nagra 4.2 The heads of the Nagra 4.2 are pressed down on a cam. On turning this cam, the azimuth is varied. The outside of the cam is in the form of a gear wheel meshed with a pinion, which is visible in front of each head. -
Page 38: High Frequency Pre-Emphasis
High Frequency Pre-emphasis The signal-to-noise ratio of the magnetic tape is perhaps the least satisfactory of its characteristics. Great efforts have been made to improve this defect. It is possible to imagine, for example, a tape recorder, which sends to the recording head a current, which is proportional to the input signal, independent of the frequency (recording at constant current). -
Page 39: Practical Conclusions
Practical Conclusions The result is: It is possible to modify the pre-emphasis, within certain limits, by adjusting the bias level but still remaining within the limits of the standards. To record sounds particularly rich in high frequencies, it is possible that the use of tapes, which permit high recording level of the high frequencies, could give better results. -
Page 40: Calibration And Care
HEIGHT OF THE NEOPILOT HEAD The middle head of the Nagra 4.2 is used to record and playback the pilot signal. Its azimuth is not critical, but its height should be correct. The cam of this head does not vary the angle, but only its height. -
Page 41: Maintenance Of The Motor Commutator
Cleaning of the Collector Open the Nagra and pull off the motor shielding (being careful not to deform it). Switch on the motor and clean the collector by rubbing with a rag or absorbent cotton soaked in a solvent. The insulation between the segments of the collector should be the same colour as that on the top of the collector. -
Page 42: Lubrication
6.3. LUBRICATION In the case of intensive use, it may be necessary, from time to time, to lubricate the ruby pressure ball on the take-up reel clutch. This ball can be found in the middle of the pulley, which drives the take-up reel. -
Page 43: Microphones
8.0 MICROPHONES INTRODUCTION There are several different types of microphone pre-amplifiers available for the NAGRA 4.2, in order to accommodate almost all of the different types of microphones presently available. Microphone technology is not stable, and each year new models are put on to the market. Many of them require power supplies, which exist in different forms. -
Page 44: Use At High Sound Levels
(- 273 C) the electron movement in this impedance will produce a noise signal called the thermic noise. The preamplifier adds to the thermic noise its own inherent noise, but in a recorder such as the Nagra 4.2, the thermic noise is by far the most important. -
Page 45: Secondary Characteristics Related To Directional Characteristics
which the sound comes does not affect the pressure, except at very high frequencies, when the microphone makes its own shadow. On the other hand, the velocity of the air molecules can be used in a microphone. The word velocity implies a combination of speed and direction. -
Page 46: Switchable Microphones
5.6. MAXIMUM GAIN OF THE RECORDING CHAIN OR SENSITIVITY OF THE MICROPHONE INPUTS In general, the Nagra 4.2 is used to record the "master tape", that is to say, the original from which copies are made. In consequence the recording level should, in certain cases, be lower than normal so that correction can be made during transfer. -
Page 47: Changing The Plug-In Preamplifiers
Changing the Plug-in Preamplifiers These preamplifiers are coupled to the rest of the Nagra by a connector. They are physically held in place by a small screw accessible from the bottom of the recorder. On turning the Nagra over, that is, placing it on its cover with the battery compartment upwards, the screw for preamplifier No1 can be seen, on the left viewed towards the front panel. -
Page 48: Special Plug-In Preamplifiers
Cable Preamplifiers These preamplifiers are placed near a dynamic microphone. Their power supply is derived from the Nagra and is transmitted along the same cable as the signal. The Nagra should be equipped with a condenser microphone preamplifier (see above). -
Page 49: When Should Filtering Be Done
In addition to re-establishing the linearity, it has been found that in certain cases, an attenuation of the low frequencies can, although falsifying the reality, improve the subjective result. In particular, it can increase the intelligibility. On the other hand, it is sometimes necessary to have recourse to the attenuation of stage noises. -
Page 50: Metering
The scale of a modulometer can be logarithmic, i.e. linear in decibels. In the case of the Nagra, it is possible, for example, to have a range of 70 dB. This allows the exact appreciation of even the lowest sound levels. -
Page 51: Conclusions
CONCLUSIONS The problem to be resolved is to know if the Nagra should be fitted with a modulometer or a VU meter. The modulometer allows the use of the full dynamic range of the recorder whether for noise, speech or music. -
Page 52: Specifications
9.0 SPECIFICATIONS DIMENSIONS AND WEIGHT Dimensions of the case with the lid closed, without knobs, feet, carrying handle, or carrying handle mountings: L X W X H 12.6 x 8.8 x 4.4 " (320 x 223 x 111 mm) Overall dimensions without handle L X W X H 13.2 x 9.6 x 4.5 "... -
Page 53: Tape Transport
3¾ ips 9.525 cm/s ±0.12 % AMPLIFIER CHAIN NAGRA 4.2 with QPSE-200-XOYO preamplifiers Overall frequency response, 200 Ohm microphone input, line output without load from 50 Hz to 20 kHz ±1 dB Total distortion at 0 dB, 10 mV input, output load 600 Ohm <0.3 %... -
Page 54: Filters
FILTERS LFA 1 (low frequency Attenuation attenuation) 4 dB at 50 Hz LFA 2 8 dB at 50 Hz HP 1 (high-pass) 10 dB at 50 Hz HP 2 20 dB at 50 Hz HP 1 + LFA 1 (combination) 14 dB at 50 Hz REFERENCE GENERATOR 1.1 kHz sine wave signal with 10 kHz component... -
Page 55: Modulometer
MODULOMETER Integration time for - 2 dB 7.5 ms Usable scale -30 to +5 dB Frequency response from 40 Hz to 20 kHz ±0,5 dB RECORDING AND PLAYBACK CHAIN Nominal recording level 0 dB= 320 nWb/m Maximum peak level (M.P.L.) + 4 dB Magnetic tape used for Calibration : CCIR... -
Page 56: Inputs
INPUTS NAGRA 4.2 with QPSE-200-X0Y0 preamplifiers Microphone input 1,200 Ohm 0.2 to 43 m V Microphone input 2,200 Ohm 0.2 to 43 m V Unbalanced line input, impedance 100 k Ohm admissible voltage 0.37 to 120 V Unbalanced line input at accessory connector, admissible current 3.7 to 1,200 µA...