Nagra 4.2 Portable Analogue Audio Instructions Manual

							 
VOLT / CELL 
 
The meter switch in this position works as a simple voltmeter. The centre scale is graduated from 0 
to 1.6 V, it indicates 1/12 of the total voltage or the average voltage of 1 cell. 
The position Volt/Cell is essentially designed to monitor the voltage of some accumulators, which 
would be damaged if they were allowed to discharge below a certain value. This value is 1 V /Cell 
for certain manganese dioxide alkaline accumulators. 
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. Under these conditions the motor and motor collector should be examined. 
 
MEASURING THE MOTOR CURRENT 
 
The meter will measure the motor current when the meter switch is in the position Mot. There is no 
corresponding scale on the meter but the Volt/Cell scale can be used. 
Full scale deflection corresponds to a motor current of approximately 250 mA. In no load running, 
i.e. without tape and with the pinch wheel separated from the capstan (but not in the rewind mode), 
the needle should indicate between 0.2 and 0.3 V. If this value is exceeded, see paragraph 6.2. 
 
SPEED & POWER INDICATOR 
 
At the lower right-hand side of the front panel there is a rotary indicator marked SPEED & 
POWER. Under normal circumstances a white cross should appear, but it will disappear when: 
 
a.) the power supply voltage becomes insufficient. 
b.) the motor current reaches its maximum value. In this case, the speed 
stabilizer requires the motor to go faster, but this is not possible as the 
current limiter has already reacted. Thus there is a strong probability that the 
speed will not be correct. 
c.) tachometric WOW is out of tolerance. 
 
 
 
In summary, if a white cross appears on the indicator the operator may be sure that the power 
supply is sufficient, that the motor turns at the correct speed, and that the tape speed is correct. 
 
EXTERNAL POWER SUPPLY 
 
On the right-hand side of the machine there is a 6 pin Tuchel-type T 3403 connector marked 
POWER PACK. The corresponding plug is the T 3400/1.  
 
The connections are as follows:  
 
 pin 1 Battery negative  
 pin 2 Chassis (positive)  
 pin 3 Pilot playback output  
 pin 4 Speed correction signal input  
 pin 5 Negative external supply  
 pin 6 -10 V stabilized output. 
 
  
						

							 
3.0 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. RESERVE position, the needle of the modulometer indicates that the Nagra is powered. (if 
this is not the case see POWER SUPPLY in this manual).  
With fresh batteries, the needle will not advance to more than half way up the scale. It only reaches 
the extreme right of the scale with an external power supply. 
 
After checking the power supply, put the meter switch to the LEVEL position (recording or 
modulation level). A microphone can receive sounds of a very variable intensity. The tape must be 
recorded as fully as possible, but without the high frequencies passing a level called the saturation 
level. The modulometer indicates the level of modulation. The needle can deflect up to the mark 
Max on the right of the scale, but should not pass this limit. If the needle is deflected less, the 
recording will be of a lower level. 
 
The sensitivity, that is to say, the level of recording for a given sound, can be controlled either 
manually or automatically. The choice is made by means of the AUTOMATIC/MANUAL switch on 
the upper left of the front panel. In the position MANUAL the level can be controlled by means of 
potentiometers (6) and (7).  In the position AUTOMATIC an Automatic Level Controller controls 
the level. The modulometer deflects with respect to the incoming signal without reaching the 
extreme right-hand end of the scale. 
 
3.2 TAPE SPEED AND STANDARD SELECTION 
 
The NAGRA 4.2 is capable of running at three different speeds, which can be selected by changing 
the position of SPEED AND EQUALIZATION selector (20) on the top deck of the recorder 
between the two spools.   
 
The speeds available are :  
 
 3¾ ips (9.525 cm/s)  
 7½ ips (19.05 cm/s)  
 15 ips (38.10 cm/s)   
 
Each position of this selector automatically selects the correct equalization of the machine 
according to the chosen speed. There are two different positions available for each speed and they 
are marked I and II which represent Standard and Low noise respectively.  
 
For adjustments of equalization and checking of tape speed refer to the 4.2 SERVICE MANUAL.  
 
NOTE: The NAGRA 4.2 is only equipped with one recording bias oscillator and it is therefore only 
possible to bias the recorder for one specific tape type at any one time. However, it is 
possible to optimize the equalization in the second position (LN) for a different tape. 
 
2.3 LOADING A TAPE ON THE RECORDER 
 
Select STOP, then release the tape path from the heads, guides and capstan shaft by pulling 
lever (32) forward, until it comes to a complete stop. Remove the spool retaining nuts and place a  
reel of tape on the left-hand turntable, with the loose end of the tape coming from the left-hand side 
of the spool. Pass the tape around the left-hand guide roller and across in front of the heads, and 
around the right-hand guide roller. Attach the end of the tape to the empty spool on the right-hand 
turntable. Replace the two spool retaining nuts, and close lever (32) until it reaches its original 
position, thus putting the tape into contact with the heads.   
  
						

							NOTE: It is important to lower the head-shield before loading a tape, otherwise the tape may 
pass behind it, and thus not be in contact with any of the heads. When the tape has been 
loaded and lever (32) has been restored to its original position, the shield may be lifted in 
front of the heads.  
 
RECORDING 
 
The NAGRA 4.2 can make a recording using either microphones or a DIRECT line input signal. 
 
RECORDING WITH MICROPHONES 
 
When using microphones, connect a microphone to one or both of the two XLR type connectors on 
the left-hand side of the recorder. If the QPUT/QPAUT microphone pre-amplifiers are installed in 
the recorder, check that the switches corresponding to each of the microphone inputs are in the 
correct position corresponding to the type of microphone to be used. The possible selections are T-
power, +12 V and +48 V phantom, powering or 200 Ohm dynamic.  
 
The level of the signal coming from the microphones may now be observed by putting the machine 
into the TEST position and switching modulometer switch (12) to the LEVEL position. The gain 
may now be adjusted using potentiometers (6) and (7) on the front panel. 
 
Turn the main function selector to either of the two RECORD positions, depending upon whether 
the limiter is required or not. Observe the modulometer to see that the levels remain correct 
throughout the recording. The modulometer indicates in both RECORD modes the Direct signal. It 
is possible to show the off tape signal during the recording by moving the LINE AND PHONES 
snap switch to the left.  
 
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. Firstly set the microphone potentiometers (6) and (7) to their fully anti-clockwise 
positions. (this is to prevent any noise being amplified by the high gain microphone pre-amplifiers, 
being recorded on the tape). 
Connect the line input signal to the line input connector (41) on the left-hand side of the recorder. 
Set the main function selector (4) to the TEST position and adjust the level of the incoming signal 
on the modulometer by means of the level potentiometer (9) marked LINE AND PLAYBACK. 
Finally switch the main function selector to one of the two RECORD positions to start the 
recording. When the recording is completed, select STOP.  
 
FAST  FORWARD / REWIND 
 
To rewind a tape put the main function selector in the STOP position, and open the pinch wheel 
gate by using operating lever (32) then select TEST and rewind the tape by means of toggle 
switch (23) located on the top left-hand front corner of the top deck.  
 
When the tape is fully rewound always place operating lever (32) back in the fully closed position 
(this will prevent a flat portion being made on the capstan O ring). 
 
To wind a tape fast forward use switch (23) as for rewind. However, it is not necessary to open the 
pinch roller gate. The FAST FORWARD position of the toggle switch is only active when the main  
						

							function selector is in the PLAYBACK (with loudspeaker) position. This is done to prevent accidental 
winding of the tape during RECORDING.  
 
While fast forwarding the tape, the audio on the tape will be heard through the internal loudspeaker. 
To avoid damage to the loudspeaker, use the volume control (42) to decrease the level. 
 
PLAYING BACK A RECORDED TAPE 
 
Rewind the tape as explained above, then set main function selector (4) to one of the two possible 
PLAYBACK positions (either with, or without loudspeaker). The signal from the tape is now 
available on line output banana output connectors (45/46) on the right-hand side of the recorder. If 
line and phones switch (1) is in the TAPE position, the signal is fed directly to the line outputs with 
no possibility for adjustment. However, if it is in the DIRECT position then the output may be 
adjusted with the LINE AND PLAYBACK potentiometer.  
The frequency response may also be modified using FILTER switch (13). 
 
WORKING WITH HEADPHONES 
 
If headphones are to be used, they can be plugged into the jack socket (17) on the lower left-hand 
front side of the machine.  
 
The level of the headphones may be adjusted using potentiometer (18). In record, the signals can 
be monitored either off tape or directly, depending on the position of the line and phones switch.   
 
NOTE: When the machine is in the TEST position, the headphones output is always fed with 
the DIRECT signal.   
 
The headphones output will accept a 1/4 stereo JACK connector (type 297) and can be used with 
headphones having an impedance from 50 Ohm to 600 Ohm. (Optimum value is 200 Ohm).  
During playback, the headphones may be used for monitoring. In the position Tape the signal 
coming from the tape can be heard. In the position Direct a mixing of the signals coming from the 
microphones and from the tape can be heard. The mixing of these signals can be controlled by 
means of the potentiometers Mike 1, Mike 2 and Line and Playback. 
To listen to the recording on an external amplifier/loudspeaker installation, connect it to the Line 
Output on the right of the recorder. This output receives the same signal as is transmitted to the 
headphones. Loudspeaker signals should not be allowed to feed a microphone. Under these 
conditions, the signal passes from the loudspeaker to the microphone, which retransmits it, 
producing a howling known as the Larsen effect (acoustic feedback). 
To avoid this effect, the Line and Phones switch should be placed in the position Tape, or the 
potentiometers Mike 1 and Mike 2 turned down.  
To playback in the headphones or to an external installation, the position Playback of the Main 
Function Selector should be chosen. The internal loudspeaker is thus disconnected.  
 
2.8 PRECAUTIONS 
 
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. 
 
Do not store the recorder with the Main Function Selector in any position other than Stop, as this 
will cause a flat to be formed on the pinch roller and this will cause Wow and Flutter problems 
during future uses. To avoid the accidental discharge of the batteries, put the Power switch into 
External, thereby disconnecting the internal batteries (if installed). 
If the recorder has to be stored for a long period of time, remove the batteries, as a corrosive liquid 
can leak from discharged batteries. 
  
						

							4.1. DIRECT AND TAPE CHAINS 
 
GENERAL 
 
Signals coming from the microphone(s), line and mixer inputs, once they are amplified, filtered, 
controlled and mixed, form the Direct signal, which will be recorded on the tape. 
The signal played back from the tape gives, after amplification and equalization, the Tape signal. 
During recording, the Tape signal is that which has already been recorded on the tape, and 
therefore is not that which is being recorded. 
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. 
The Direct signal is therefore made up not only of the input signals, but also by the playback 
signal. This allows for example, the superimposition of a commentary to the signal being played 
back form a tape. On the other hand, the Tape signal will always be exclusively the playback 
signal from the tape. 
The line output amplifier, which also feeds the headphones, can be connected either to the Tape 
signal or to the Direct signal, the choice being made by the Line and Phones switch on the front 
panel. The loudspeaker amplifier is only fed from the Tape signal. Acoustic feedback therefore 
cannot be produced, even if the microphones are in service, unless, of course, this takes place from 
the headphones. 
The Line and Phones snap switch allows meter readings of the playback signal while recording. It 
always snaps back into the DIRECT position. 
 
AUDIO INPUTS 
 
The Nagra 4.2 has 4 inputs: 
 
a.)    two microphone inputs 
b.) one asymmetrical line input transformable into 3rd microphone input with the  
aid of an external preamplifier. 
c.) one mixer input at fixed level 
 
 
MANUAL LEVEL CONTROL 
 
When using manual level control the position of the microphone potentiometers, which are in use, 
adjust the input in such a way that the loudest sounds to be recorded do not exceed the maximum 
level. The potentiometers corresponding to the unused inputs should be kept in their anti-clockwise 
position. 
The active potentiometers can be equally used to give a compression, by increasing the sensitivity 
during the soft passages, and vice versa. 
 
LIMITER 
 
The Nagra 4.2 is equipped with a safety limiter, which instantaneously reduces the gain of the 
recording amplifier when the signal exceeds the maximum level providing that the RECORD with 
limiter position of the Main Function Selector has been selected. This limiting evidently causes 
distortion, but it is less objectionable than that caused by saturation of the tape. Normally, the limiter 
will only be brought into action when accidents occur. It is possible that, in the middle of a dialogue, 
for example, a short but high power sounds exceeding the maximum level can occur. Under these 
conditions it is preferable to saturate rather than to limit because the saturation will be practically 
unnoticeable due to the short duration of the sound. On the other hand, the limiter requires a certain 
recovery time before the normal sensitivity of the chain is re-established. This sensitivity variation  
						

							can affect the ambient sound and can be a greater nuisance than saturation by a brief sound. To 
avoid this phenomenon, it is necessary to reduce the recovery time of the limiter. Detailed 
instructions as to how this can be done will be sent on request.  The limiter can be switched off by 
setting the Main Function selector to position RECORD - NO LIMITER. This may be advantageous 
for certain recordings, e.g. gunshots, explosions, where tape saturation is desired. 
 
AUTOMATIC LEVEL CONTROL (ALC) 
 
The Nagra 4.2 is fitted with an Automatic Level Control. It replaces the manual potentiometer when 
the selector switch placed on the left of the meter is on the position Automatic. In the position 1-
Automatic, only microphone No 1 has its sensitivity controlled automatically. Microphone No 2 is 
controlled by its respective potentiometer. In 2-Automatic, the ALC circuit controls both 
microphone inputs. The operation of the ALC is complex. It is useful to place the meter switch in the 
position Compression as needle will indicate by how much the sensitivity of the amplifier chain has 
been reduced. The extreme left position corresponds to a maximum gain; the extreme right to a 
reduction of gain or compression of approximately 30 dB. 
When a signal, whose amplitude is sufficient for the maximum recording level to be exceeded, 
arrives from the microphone, the Automatic Level Control will instantaneously reduce the gain to 
avoid over-modulation (similar to the limiter). If the signal is short, the Automatic Level Control 
concludes that it is accidental, and forgets it rapidly, i.e. it returns to its previous sensitivity. On the 
other hand, a longer signal is considered useful.  
 
The sensitivity is therefore memorized and maintained. This avoids the increase of background 
sound level between words. It can happen, however, that an interfering signal is long. This will 
therefore produce a long reduction of sensitivity. To avoid that, the Automatic Level Control has a 
circuit of rapid recovery, which enters into action if the level remains less than -10 dB for about 1.5 
seconds. Therefore, if a long and loud noise upsets the recording, the recorder can be reset to its 
normal sensitivity by keeping quiet for 1½ seconds. 
Experience has shown that the Automatic Level Control allows an absolutely automatic recording to 
be made for reporting interviews etc. and of a quality, which is difficult to attain with manual control.  
 
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. 
The meter is connected to the Direct signal. During recording it measures this level. If the line 
amplifier is connected to the Direct signal (Line and Phones switch in Direct), the measurement 
will thus be of the signal sent along the line. On the other hand, if the Line and Phones switch is in 
Tape, the level sent along the line will be independent of the Direct signal and will consequently 
not be measured. In any case, the level of this signal cannot be altered. A signal recorded at 
nominal level will give a line signal of nominal level.  
						

							 
5.0 PILOT 
 
 
INTRODUCTION 
 
The NAGRA 4.2 (NQ-L version) is equipped with a Neopilot system. This system developed by 
KSA, records a synchronization signal simultaneously with the audio, of 50 Hz (60 Hz in NTSC 
countries). Two signals are recorded in phase opposition so as to avoid any interference with the 
audio replay chain. The pilot signal serves as a speed reference to ensure that when the tape is 
replayed, it is always replayed at the same speed at which it was recorded. The pilot signal can 
either be supplied from an external source (a film camera for example) or can be generated by the 
internal crystal generator (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. This means that providing the start point of the recording is known for both the film camera 
and the NAGRA then the two can remain in perfect synchronization throughout the tape. 
To obtain a film with a synchronous sound it is necessary to keep the image and the sound 
continually slaved to one another. The acceptable tolerance is in the region of 40 msec. 
 
RECORDING A PILOT SIGNAL. 
 
A pilot signal can be recorded when recording either a line input signal or with microphones. 
 
RECORDING THE INTERNAL CRYSTAL 
 
For the 4.2 to record its internal crystal the QGX-3 crystal generator must be fitted to the machine. 
This is a circuit that is located on the left-hand end of the battery compartment inside the machine. 
There are two operating frequencies for this circuit 50 or 60 Hz. Check by means of the switches on 
the circuit that tha correct frequency has been selected. Once this is done then switch the main 
function selector to the TEST position. The pilot indicator (15) on the top right-hand side of the 
front panel should show a white segment. If this is not the case then check that the pilot crystal 
shorting plug is located in the pilot socket (44). 
This shorting plug is like a blank screw in jumper with the letters XTAL marked on it. If this is 
installed and the rotary indicator does not show a white segment then check that the machine is 
correctly powered and that the power selector (3) is in the correct position with respect to the 
supplied source. If this is all correct but the indicator remains black then consult your nearest 
NAGRA agent. 
Once the indicator shows a white segment then the recording is made in exactly the same way as 
described for recording the audio, the pilot signal will be recorded automatically. No further 
manipulation of the pilot system is needed. 
 
RECORDING AN EXTERNAL PILOT SIGNAL. 
 
Remove the crystal shorting plug in the connector (44) and feed the Pilot input socket (44) by 
means of the QCP cable. The other end of the cable must then be connected to the source (either 
an ATN-3, camera...). Check that the external pilot signal is present by switching the machine to the 
TEST position as above. While making a recording the cable must always be left connected. 
Make the recording as above. 
 
 
 
 
  
						

							SYNCHRONIZING A RECORDED TAPE. 
 
Check that the machine is fitted with the QSLI synchronizer circuit. This circuit is located at the right-
hand end of the battery compartment inside the machine. The circuit faces downwards, and has its 
front right corner cut away. 
Feed the pilot input connector (44) with the reference signal either from the pilot out socket on the 
ATN-3 (for synchronization to mains) or from the machine to which the 4.2 is to be synchronized. 
Turn the main function selector to the playback WITH loudspeaker position, and after a short period 
(typically 1.5 secs) the pilot indicator (15) should once again show a white segment. Check the level 
of the pilot signal from the tape by switching the modulometer switch (12) to the position PILOT 
PLAYBACK The needle should deflect about half way. If the modulometer selector is switched to 
the position SYNCH the meter will indicate the deviation between the external pilot reference and 
the pilot signal from the tape. 
 
FREQUENCY METER (OPTIONAL ACCESSORY QFM) 
 
This device measures the frequency of the pilot signal. If the meter switch is in the Pilot Frequency 
position, the meter will indicate the frequency. The scale is from +4% on the left hand side to -4% 
on the right. The accuracy is about ±0.1% on the centre of the scale. In addition, the frequency 
meter circuit gives a warning if the frequency is more than 5% out from its nominal value. If this is 
the case then the rotary Pilot indicator turns black. The QFM exists in two version for 50 Hz and 
60 Hz (QFM 50 and QFM 60). 
 
QUARTZ CRYSTAL PILOT GENERATOR (OPTIONAL ACCESSORY QGX-3) 
 
This accessory is designed for synchronous filming without a cable between the camera and the 
Nagra. It supplies a signal whose frequency is 50 Hz ±0.001%, and is very stable within a wide 
temperature range. 
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. The solution of using a dummy plug rather than a switch has been adopted in order to 
reduce the risk of human error. The QGX-3 is switchable and gives a 50 Hz or 60 Hz signal. 
 
PILOT INDICATOR 
 
This device is found on the upper right of the front panel. It shows a white cross when the Nagra is 
in operation and if a pilot signal of sufficient amplitude is provided, and if there is no Alarm signal 
in the pilot system. The Alarm signal will appear and turn the indicator black if the following 
conditions occur: 
 
A) if the frequency of the pilot signal is incorrect (on condition that the QFM 
frequency meter circuit is installed) 
 
B) if the pilot signal does not reach the pilot head (on condition that the QSLI 
synchronizer circuit is installed) 
 
This is indicated in the position Test of the main function selector. When the Nagra is in playback, 
this indicator will only show a white segment when a pilot signal is being played back from the tape 
and another pilot signal is being fed from outside. If one of these two signals is missing, the 
indicator will remain back. This is very important when using the QSLI. 
 
 
 
 
  
						

							INTERNAL SYNCHRONIZER (OPTIONAL ACCESSORY QSLI) 
 
This device has two functions: 
 
A) It measures the amplitude of the playback pilot signal on the tape. With the meter 
switch in the position Pilot Playback the meter indicates the amplitude. The 
normal value should be between 1 and 2 V on the lower middle scale. 
 
B) It can modify the tape speed of the Nagra in order to render the playback pilot 
signal synchronous with a pilot signal coming in on the Pilot socket on the right 
side. For this speed correction to take place, the Nagra must be switched to 
Loudspeaker Playback and the Pilot indicator should show a white cross. The 
white cross is only shown if the external pilot reference signal is correct and a pilot 
signal is played back from the tape. 
 
When the meter switch (12) is in the SYNCH position, the meter is connected to the QSLI, and 
shows the difference of phase between the external pilot signal and the playback pilot signal from 
the tape. Thus, if the signals do not have exactly the same frequency and phase the needle will 
oscillate. This can be seen on Playback (without the loudspeaker). One complete oscillation left, 
right, left, every 2 seconds corresponds to a speed error of 1%, which can be corrected by the 
QSLI. 
By putting the main function selector in the (Loudspeaker Playback) position the QLSI is switched 
on, and the needle should be stationary. If it continues to oscillate, then the frequency exceeds the 
synchronizing capacity of the QSLI. If the Nagra is equipped with frequency meter circuit QFM, and 
the needle is stationary and if the pilot indicator shows a white cross, synchronization is practically 
certain. 
There is one exception, however, if the playback frequency from the tape is grossly incorrect (e.g. 
100 Hz instead of 50), the needle will not be able to follow the beat and will remain stationary in the 
center of the dial.  
 
If this is suspected, switch to Playback. The needle should oscillate. If need be, upset the tape 
speed by blocking the left hand tension roller momentarily. If the needle remains in the center, the 
recorded pilot signal is incorrect. 
The speed varier QSV-2  is very useful in these cases. In attempting to adjust the speed (on slaved 
playback) the QSLI has to adjust itself in order to prevent the speed varier from operating. The 
needle of the meter will show this adjustment and will prove that synchronization is correct. 
 
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 
used for the following applications: 
 
A) To transfer a tape whose pilot signal originated from a camera whose speed was 
out of tolerance. 
 The QSLI synchronizer allows the automatic correction of speed errors up to ±2%. 
It is not unknown for cameras to have a speed error greater than this tolerance. 
The speed Varier allows the offsetting of the average speed, which will then be 
corrected by the Synchronizer in the normal manner. Naturally, under these 
conditions, the tone of the sound will be altered, but this is inevitable. 
 
B) Transfer of a tape whose pilot signal is interrupted. A very convenient method of 
indicating the start marks (or end of takes) as well as the take identification is by 
short interruptions of the pilot signal. During these interruptions, the slaving 
between the Nagra 4.2 and the film recorder is suppressed. It is important that the 
speed change during the suppression is not brutal, otherwise audible wow will be 
heard. To avoid this, it is sufficient to make approximate correction with the aid of  
						

							the Speed Varier and to allow the Synchronizer to make a final adjustment to 
ensure the slaving. 
 
This can be done as follows: 
 
Method A 
 
1. Play back the tape to be transferred without slaving. When using the QSLI internal 
synchronizer, put the Nagra into Playback without loudspeaker. 
 
2. Adjust the speed with the aid of the Speed Varier QSV-2 in such a manner that the 
playback pilot signal and the mains are approximately synchronized. The needle of the 
Nagra meter (switch on SYNC) will not swing. 
 
3. Rewind the tape and make the transfer in the usual manner. Under these conditions, 
the speed correction achieved by the Synchronizer will be very small. 
 
 
Method B 
 
Make the transfer in the classic manner and adjust the Speed Varier so that the needle 
(in the position SYNC) remains at the center of the scale (QSLI). This method is less 
precise, but it is sufficient in practice. It should be noted, however, that the 
interruptions of the pilot signal happen at the beginning of a sequence, and it is almost 
always necessary to make a trial playback, adjust the speed, rewind and then make 
the transfer. 
 
USE OF SPEED VARIER WHILST FILMING ON PLAYBACK 
 
Whilst filming on playback, it is possible that the camera may run at an incorrect speed. It will 
therefore be necessary to adjust the camera, if possible, to avoid any change in the tone of the final 
sound. 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. This applies to average frequencies for, inevitably, 
mechanical tolerances and longitudinal vibrations of the tape will affect the instantaneous speed 
(wow and flutter). 
Experience has shown that this precision is more than sufficient for the recording and reproduction 
of facsimile signals. Other telemetering applications are, of course possible. 
 
PILOT PLAYBACK USING A NAGRA 4.2 L NOT EQUIPPED WITH QSLI SYNCHRONIZER 
 
Output impedance: 47k Ohm ±20% 
Load impedance: from zero to infinity. 
Output voltage from tape recorded on Nagra 4.2 L: 330mV ±3 dB. 
 
PILOT PLAYBACK MADE BY NAGRA 4.2 L FITTED WITH QSLI SYNCHRONIZER 
 
Output impedance: 10 k Ohm ±20% 
Load impedance: from zero to infinity 
Output voltage from tape recorded on Nagra 4.2 L: 0.85 V nominal ±3 dB.