Nagra KUDELSKI Instruction Manual

MAY 1st 1963

NAGRA

INSTRUCTIONS MANUAL

KUDELSKI

KUDELSKI S.A.

NAGRA Tape Recorders Manufacture CH-1033 Cheseaux / Lausanne SWITZERLAND

phone: [phone] telex: 24 392 nagra ch

NAGRA III TAPE RECORDER

INSTRUCTIONS FOR USE

I. PRECAUTIONS TO BE TAKEN

When out of use, turn the tape transport control to its mid position. In the "ON" position, when not running,
there is danger of producing a flat on the capstan roller. The working surfaces of the fast rewind clutch may
also suffer.

When batteries are exhausted, a corrosive liquid may escape and the containers may corrode. Never leave
discharged batteries in the Nagra If the machine will not be used for sometime (a few months), remove the
batteries, even if they are not discharged, as a precaution.

Take care that the batteries are inserted into the machine with correct polarity. Place them in the battery
compartment as indicated by the small diagram on the bottom of the compartment. When an external power
supply is used. Always check the polarity very carefully. If it is incorrect. the motor will run backwards. A
special protective circuit is used to prevent damage to important parts of the Nagra. But even so it is possible
that some electrolytic condensers could be damaged.

The Nagra III is very robust. But it is better to take no chance. Protect it from sand, sea being dropped or
from mechanical shock. Do not subject it to rapid changes of temperature. or to the curiosity of unqualified
personnel, and above all from vibration. For instance do not carry it unprotected in the baggage compartment
of a car.

II. DESCRIPTION OF CONTROLS AND EXTERNAL MECHANISM

1. Speed and Equalization Selector,

This switch may be operated by a coin in the slot. It simultaneously changes speed and equalization, both for
recording and playback. The following combinations are available:

38.1 cm/sec. = 15 1'/sec. (CCIR or Ampex)
This speed is normally used in broadcasting studios. The use of it insured the best quality; the azimuth
adjustment is not very critical while the response

Page 2
Curve is always excellent and varies little from tape to tape. At this speed the tape is little affected by

repeated play- backs." Another advantage is that editing is easy, and that a suitable machine operating at this
speed can usually be found in studios for playback of recordings.

19, 05 cm sec. = 7.511 sec. CCIR Equalization Standard
This is the normal speed for the general uses of the Nagra in studios working with the CCIR standards.

Where this is not necessary. the following position will be preferred:

19, 05 cm sec. = 7.511 sec. Ampex Equalization Standard
This is a better standard, as the modulation noise. medium range distortions and tape background noise are

reduced considerably.

9.525 cm/sec. = 3.751' /sec.
This speed is for use where high quality is not required and tape economy is important. One hour recording

time can be obtained with the use of 5" reels and using extra thin tape or two hours with 711 reels.

2) Tension Pulley

This pulley is movable and operates a brake on the spool, ensuring constant tape tension.

3) Microphone Input

The microphone should have an impedance of 50 or 200 ohms. This input socket on the Nagra is Cannon
type XLR 3-42. The plug on the microphone cable is Cannon type XLR 3 -11 C. Contact N o .1 is earth and
2 and 3 are the microphone connections. The input is symmetrical and floating, there being no connection
between primary and earth.

4) Shoulder Strap Button

For the attachment of a shoulder strap or ever ready case a small set screw is fitted for safety in the nut (3
mm. Set screw, for Allen key to DIN 913: a key 0.050" (1.27 mm} is provided}.

5) Modulation Level Meter

The upper scale on the meter is for measuring the input level (on Test or on Record), and the output level to
the line on Hi-Fi playback. Normally the pointer will not reach the black segment between 0 and +2db,
which is the region of over modulation. The recorder has a safety factor of about 6 db, so that an occasional
accidental incursion into this region is of no consequence. The level control should be adjusted so that the
pointer only reaches the black zone on the loudest parts of the recording.

6) Battery Indicator

The lower scale of the meter is for checking the state of the batteries. The meter is connected to the batteries
when the selector switch indicates "Play- back and Batteries Meter" that is when playing back on the internal
loudspeaker. The pointer should lie in the marked segment when the batteries are in working condition. This
indication leaves a good factor of safety when

Page 3

employing this speed, headphones should be used for monitoring. Then when the battery voltage falls to a
level unsatisfactory for recording an alarm signal will be heard in the phones. It is well to remember that
batteries used uninterruptedly for, say, an hour, will recuperate when rested for, say, 10 hours. Therefore
exhausted batteries may appear acceptable during a quick test before recording, but then collapse after a few
minutes use.

To recapitulate

- If one is recording at 15"/sec. always use monitoring headphones and read the battery meter
pessimistically.

- If one is recording at 7 ½ ” or 3 ¾”/sec. for fairly short periods. say 15 minutes. a battery test before
starting should be sufficient. On the other hand, if the recording session is of long duration the
batteries should be checked when changing reels.

7) Pilot Signal Indicator

This is an indicator on which a white cross will appear when the Nagra is receiving the pilot signal (Neopilot
Nagras only).

8) Accelerator Button

By pressing this button the motor speed is increased to its maximum. This can be done during play-back for
forward spooling. Although no damage will be done by pressing the button during recording, the speed will
be incorrect.

9) Function Selector Swjtch

This switch controls the functioning of the Nagra. It has two sets of six positions. One set is for working on
internal batteries when the end of the switch knob marked "bat" is used as an indicator and one set is for
working with an external power supply. when the other end of the knob marked I'ext". is used as an
indicator.

The positions are as follows:
STOP in the centre TESTING to the right
In this position the amplifiers are connected but not the motor. so that the incoming signal to be recorded can

be checked. The monitoring phones are connected to the record amplifier.

HI-FI RECORD = Normal recording position.
The phones are connected to the play- back amplifier, so that the actual recording that has been made is
monitored. Incoming signals can be mixed from both microphone and line inputs. The level of each of these
signals can be adjusted by the appropriate volume controls. If the line input is only used, the microphone
level potentiometer should be turned fully anticlockwise to prevent the recording of noise from the
microphone pre-amplifier. On the other hand if a recording is made through the microphone channel only.
the position of the line input volume control is immaterial.

AUTOMATIC RECORD = Recording with automatic control of level and
attenuation of low frequencies. It is not necessary to adjust the level potentiometer but the quality of the
recording is not as good as in the position HI-FI RECORD.