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I-
222
HARTREY
AVE
.
EV:NSTON.
ILL
-
CABLE
SHUREMICRO
-
MICROPHONES AND
ELECTRONIC
COMPONENTS
DATA
SHEET
Model
81
5
and
Model
816
EVANSTON PHONE
DA
8.9000
CHICAGO
PHONE
SH
3.1600
I
I
Magnetic Tape Recordinq Heads
General:
Model 815 and Model 816 Magnetic Tape Record-
ing Heads are high quality recording units designed for use with
paper and
plastic base magnetic recording tapes. Model 815 re-
places Shure Manufacturers Model Numbers TR5,
TRBA, TR5D and
TR5H. Model 816 replaces Shure Manufacturers Model Numbers
TR6C and TRbE.
Model 815 Recording Head comjines the functions of record-
ing, playback and signal erasure
In
a single unit. Model 816
Recording Head is a record and playback unit only.
Applications:
Both the Model 815 and Model 816 are suit-
able for use in all types of tape recording and playback applica-
tions-the professional,
semi-professional and home-recording types.
The recording heads are of rugged construction and immune to
practically all effects of moisture, tenperature and mechanical vi-
brations. The carefully contoured and highly polished surfaces give
uniform response, long operating life, and (in case of the Model
8
15) high erase efficiency.
The outer metal cases are
high permeability shields and afford
excellent hum shielding, which minimizes the
~roblem of mechanical
of hum producing components.
Ins*alla+ion:
The Model 815 and the Model 816 may be
mounted by clamping the recording head at the center top of the
metal case or at the flanged edges. Positioning pins through the
center of the eyelets may be used to accurately locate
the record-
ing head on the mechanism. Care
mtist be taken to prevent bend-
ing or distorting of the
metal shield, which wouid result in loss
of hum shielding effectiveness. Dimensional data is given in
Figure
B.
Care must also be taken to position the heads so that the re-
cording-playback gap is perpendicular to the length of the tape.
This is especially important in using pre-recorded tapes. The Model
815 is assembled in such a manner as to insure that the recording
gap is perpendicular within
&
Y20
to the surface of the mounting
bosses. When properly installed, tho mounting bosses of the re-
cording head should seat on a mounting surface parallel to the
direction of travel of the tape. To insure perpendicularity, the
mounting bosses on some heads are shimmed with a thin tab of
metal held by the eyelets on one side of the head. Deforming or
removing this tab destroys the alignment between gap and mount-
ing bosses.
The Model 815
Tape Recording Head does not have a means
of positioning and
guiding the tape across the recording surface.
Some external
guides will be required. These guides assist the
user in adjusting the tape
parallel to the recording head mount-
ing surface. Also, by proper location of the tape guide, the tape
will enter and leave the recording surface at the correct angle.
See Figure C for information on tape guides and tape angles.
To insure proper contact of the tape against the recording sur-
face of the head, pressure pads may be used. The pressure pads
are made of felt
1
/
16"
thick by
1/4"
square. The pads are mounted
on small metal arms, which are held against the recording head
b
springs adjusted to the force indicated in Figure
C.
Figure
C,
a%o, shows a suggested layout for pressure pad arrangement.
The Model 816 Tape Recording Head does have a means of
positioning and guiding the tape across the recording
surface-
a groove to properly locate the recording tape has been machined
and polished into the recording surface. In this case, the unit is
assembled in such a manner as to insure that the recording gap
is perpendicular within,
2
Y2"
to the BOTTOM EDGE OF THE
TAPE GUIDE GROOVE. Proper contact of the tape against the
recording surface may be insured by use of a pressure pad. Figure
C,
also, shows tape angle and pressure pad arrangement for the
Model 816.
b
L-
-
-
I,,;d
A
Model
815
Model 816
1
FIG. A CIRCUIT DIAGRAMS
ItD
011*61
L5\0
,MD
1LYL
"11101
,."X,.,,O"
e"
."
'
,SAD
,"<k,O
S..,&
LEAD
,",eLD
MODEL
815
RECORD
AND
PLIIBLCK
COlL
RID
O.*NLT
LEAD
-0
l."I*.110*
TIOUND
1
LEAD
,*,EL0
MODEL
816
C~nne~ti~nS:
The internal connections of the record and play-
back coil, the erase coil, the laminations and the shield are shown
in Figure
A.
The Made1 815 recording head is supplied with 12"
shielded flexible leads for convenience in connecting to associated
equipment. The Model 816 recording head is supplied with a
4%"
shielded lead.
Operation:
Both Model 815 and Model 816 Magnetic Tape
Recording Heads arc suitable for use with either the high fre-
quency A.C. bias or the D.C. bias method.
The Model 815 recording head includes both a recording ele-
ment and an erasing element in a single structure. The erase coil
may use
high frequency A.C. or D.C. for erasing the recorded
signal on the tape. The response frequency characteristic in Figure
D is obtained using the data in the typical operating data. Typical
operating data for the Model 815 and Model 816 Magnetic Tape
Recording Heads is shown in Figure E.
In both the high frequency A.C. and D. C. methods of biassing,
the bias currents are dependent to some extent upon the type of
recording media.
Changes in the recording current and bias ele-
ment values may be necessary for tape types other than that
indicated.
If
high frequency emphasis is desired, a compensation circuit
may be employed in the recording amplifier. In some applications,
low frequency boost may be desired. In fhis case, a suitable cir-
cuit should be employed in the playback amplifier.
Guarantee:
Each Tape Recording Head is guaranteed to be
free from electrical and mechanical defects for a period of one
year from date of shipment from the factory, provided all instruc-
tions are complied with fully. In case of damage, return the Tape
Recording Head
to the factory for repairs. Our guarantee is
voided if the Tape Recording Head case is opened.
License Notice:
Shure patents pending.
Copyright,
1951
Shure Brothers
Inc.
27A52
(5-63)
(OVER)
Printed in
U.S.A.