Telefunken Magnetofon 77 Owners Manual

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More Than Just Stereo -��Magnefophon 77

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TELEFIINKEN

Page 2

MORE THAN JUST STEREO - MAGNETOPHON 77

Illustration l:
Ruiating iape
guide roller in
Mugneiophonfi.

The larest polls, conducted with the purpose of
determining the typical tape recorder buyer, show
a very interesting result. According to the findin s
of the poll there are two hasic groups of peopic
who buy tape recorders.

l. The "user, who shows no personal initiative
with his mad-tine but uses it only for recording
any acoustic entertainment ofiered. That his ent-
husiasm for the tape recorder rapidly wanes, is
substantiated by the fact that he generally buys
only two or three tapes. Due to this lack of
keenness, the fact that he owns a tape recorder
can hardly be considered as having an exemplary
effect among his circle of acquaintances.

N

. The tape enthusiast, sound collector, tape corres-
pondent, amateur, player, do-it-yourself man,
call him what you will. This is the man who uses
his tape recorder to the fullest possible extent
and elevates it from a primitive record keeping
machine to a highly sensiive instrument with
boundless possibilities. This is the type of man
who exchan es tapes with his friends, dubs tapes
for slide or me movieprogrammes, makes trick
and playbatlt recordings, records complete plays
and reports,' keeps an acoustic diary on his
children from the day they are born, mixes, trans-'
cribes and cuts.

There were contradictory opinions regarding the
proportionate size of these two groups. Pcssimists
estimated the proportion of people belonging to
groupz in the Federal Republic of Germany at
10%. Then, the TELEFUNKEN Magnetophon 76
fourtradt tape recorder appeared on the scene and
immediately started on a triumphal progress whirli,
for home tape recorders, is outstanding Above all,
the possibility, when playing badt one track, of
being able to hear in perfect syndironization a
recording made previously on another Lradt, proved
to be ideally suited to so many purposes - duhbr
ing, playhadr recordings, learning foreign languages
- that the development engineers adopted the
Magnetophon 76 as a basis from which to work on
the creation of a stereophonic parallel type, the
Magnetophon 77, The idea was to retain the versa~
tility of the monaural machine in the stereo model
and, if possible, to extend this versatility still
further, The degree of success adlieved in this
venture can be seen here.

If one looks at the forebears of the present models
Magnetuphon 75, 76 and 77, one sees from the
whole series, starting with the singlerspeed Magnetor
phon 65 and going on via the two-speed Magneto-
phorl 655 and the ensuing Magnetophon 65X to
the present Magnetophon 75, with its improved
tedinical concept yet practically unchanged outer
appearance, that there is such a thing as ageless
design. Further, and this is far more important to
the buyer, one sees that the retention of a proven
mechanical construction which enables more than
200,000 machines to be made Without retooling, ree
flects in the selling price.

Elecjricul and Mechanical Conflruclion

The Magnetophon 77 is a full stereo madiine. This
means that it is not only equipped for the playbadt
of professionally prerecorded four-track stereo tapes
but also for making stereo recordings. It contains,
therefore, two complete, separate record/playbadt
amplifiers.

if the Magnetophon 75 was so popular for its coin-
paCt design and resulting handincss, how much more
will this popularity apply to the Magnetnphon 77.
There are, however, in this machine, twice as many
electrical components due to the presence of two
complete amplifier circuits.

For reasons of both space and heating. the tran-
sisrorizarion or the input stage, already started with
the Magnerophon 76, has been taken a srep further.
As a result, tad-i channel comprises two transistors,
a twin triode and the output tube and appears as
follows: QC 603 - 0C 603 - ECC 33 - EL 95.
in order not to lose thc advantageous signal-to-noisc
ratio gained by the use of hum-free, low sistorized twin pre. amp. stages, in that section of
the amplifier fitted with tubes, both ECC 83 tubes
are heated with DC. The magnet for the rubber
sheathed pressure rollers is also DC operated in
order to avoid disturbing hum fields in the vicinity
of the recording head.

Naturally, the recording head - as is the case with
all TELEFUNKEN tape recorders - is surrounded by
a double shield of mumetal, while, in the record or
playhadr position, a mumetal flap swings against the
head from the tront thus completing the shielding.

with the Magnetophon 77, as with the MagnetOs
phon 76, special value is placed on the free running
of the tape. The patented TELEFUNKEN automatic
tape tension device (German Federal Republic
Patent No. 840,014 dated 22/9/1950), not only
ensures that tape tension during rewind is constant-
ly kept below 300 gramms, but also, independent of
the tape diameter of the LH reel, ensures even
tension along the entire length of the tape which in
turn effects constantly even tape pressure against
the head. The head assembly with its three height
guides. is pre-assembled as one unit as this system
enables even more exact adjustment of head and

Illuslruiion 2:
Conlmls of Moguetopnon 77.

A Full reel

Slop button 1

Stun button 5

Record iroeir I
selecial buNuns [R7

Q. .
Extension speaker
connsclions,

2 x 2.5 w

bimon built-in speoirer

.. ea'pbon 1 u,

Radiow

P 0 N M
Record release ON/OFF swilch for Backward or
forward rewind

height guides to be made. In this connection, special
mention must made of the rotating tape guide
roller (Ill. 1), unobtrusively inrrodnced by TELE-
FUNKEN some time ago in the Magnetophon 75,
whidi in the meantime has proved itselfso well in the
Magnetophon 76 and 77. Indeed, this device (Ger
man Federal Republic Patent No. 848,271 dated
28/7/1950), is one of the little secrets which contri-
bute to the crystal clear tone quality of the TELE~
FUNKEN Magnetophon raptrecorders. The problem
of obtaining a free running tape is not one which is
solved by sim ly ensuring that tape height is
controlled. Rather the reverse is the cast as the
tape, which is not a rigid body but an elastic mass.
begins to vibrate longitudinally due to the rigidity
of the height guides. These longitudinal vibrations
arc audible during playbads as wide side bands to
originally clear sounds. This phenomenon, known
as rustle effect, is especially audible with pure or
almost pure sinusoidal oscillations, mg. whistled
recordings. The most effective countermeasure to
longitudinal vibration is to steady the tape by
means of a flywheel mass located as near as possible
to the head, For this reason it has long been the
practice with studio machines, to fit a large flywheel
mass between the recording head and the playback
head. A simple experiment will show that the small
flywheel mass represented by the tape guide roller
in the Magnetophon 75, 76 and 77, serves also to
eliminate longitudinal vibration. With the tape
running at 15/4 i.p.s., whistle into the microphone
and, during playbadt, hold the tape guide roller
back with a match. The rustle effect will be
clearly hcard.

Operation and Swilch Possibilities

Here too the thoughtfulness of the development
engineer can be clearly seen. The convenient push
button control system, taken over practicnlly un-

. vpmrphona .

v Remote control

3 Counter c Tape speed D Emply reel

E splicing rnii

F1} Playback irntir
Fa

Micro Radio
swilch

ON/OFF,
modulolion
conlrol

Modulalion
indicaior

t Ki K.
Quick stop Microphone
buuon InpuIs

cunlral

selector bullon