Nagra 4.2 Portable Analogue Audio Instructions Manual

In effect, the human ear cannot appreciate the absolute value of a high frequency sinusoidal 
signal, but, on the other hand, it can determine the harmonic content of a rectangular signal. 
In practice, this becomes a judgment of a tone and to render it as hard as possible. 
 
Procedure 
 
a.)  Thread a tape onto the Nagra whose playback head has already been adjusted 
b.)  Press the button REF. GEN. 
c.)  Record and listen to the signal played back in the headphones (Line and Phone switch 
on the...

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. The best grease to use is an Esso grease, but if the recorder is not to be used at very 
low temperatures, any mineral grease can be used. 
For other oiling points, use an oil designed for aviation instruments, such as Isoflex PDP65 from 
Klüber-Munich, or P10 from the...

 
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. The output voltages can vary, according to the type, 
in the ratio of 1 to 20. This means that it is not advisable to supply a...

to render its frequency response flat. With continuous sinusoidal signals it functions perfectly, but 
when a signal appears suddenly, the resonating device needs a certain time to move. When a 
sound disappears suddenly, the resonator continues to produce a signal. The result is that the 
transient signal (e.g. a percussive sound) will be colored by the inherent resonance of the 
microphones. This explains the difference noted by the ear between microphones with seemingly 
identical characteristics. 
In...

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. A velocity microphone consists of a very light loose 
diaphragm, which follows the displacement of the air. It will be sensitive to waves, which strike the 
diaphragm perpendicularly whether they come from in front of, or behind it....

 
Switchable Microphones 
 
Certain condenser microphones can function as omni-, bi- or unidirectional by means of a simple 
switching. 
 
Choice between Condenser or Dynamic Microphones 
 
Condenser microphones give the best fidelity. In particular their reproduction of transient noises is 
excellent, but they cost more and are less robust than the dynamic microphones. They require a 
power supply either from the Nagra or from an auxiliary device. 
They exist in two types: D.C. polarization and H.F....

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. Immediately to 
its right is the screw for preamplifier No 2. Once these screws have been removed, the Nagra can...

The QPAUT composed of the preamplifier itself and the microphone power supply, is intended for 
the Mike input No 1, whereas the QPUT intended for the Mike input No 2 is composed of the 
preamplifier only, then it cannot be installed alone without the QPAUT. 
The QPAUT is externally switchable and the QPUT internally. 
Dynamic microphones: Impedance 200 Ohm, frequency response ±1dB 80 Hz to 20 kHz, sensitivity 
0.2 mV/µbar, max. input  level  producing  1%  distortion  50 mV.  
Condenser microphone:...

 
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. In this case, choose the lesser evil. 
 
When should Filtering be done? 
 
Two solutions are possible, filtering during the recording, or the editing. Method...

METERING 
 
MODULOMETER OR V.U. METER 
 
To measure the level of an electrical signal representing a sound, there are two devices available, 
the modulometer and the v.u. meter. Both of them are voltmeters whose needle position represents 
the level. Their construction and use are however different. 
 
MODULOMETER 
 
The modulometer measures the peak value of the signal, irrespective of the form or the level, the 
modulometer takes into consideration the strongest positive or negative value. It is...