Shure 815, 816 User Guide

I-

222

HARTREY

AVE

EV:NSTON.

ILL

CABLE

SHUREMICRO

MICROPHONES AND

ELECTRONIC

COMPONENTS

DATA

SHEET

Model

and

Model

816

EVANSTON PHONE

8.9000

CHICAGO

PHONE

3.1600

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

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

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

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

16"

thick by

1/4"

square. The pads are mounted

on small metal arms, which are held against the recording head

springs adjusted to the force indicated in Figure

Figure

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,

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

also, shows tape angle and pressure pad arrangement for the

Model 816.

L-

I,,;d

Model

815

Model 816

FIG. A CIRCUIT DIAGRAMS

ItD

011*61

L5\0

,MD

1LYL

"11101

,."X,.,,O"

,SAD

,"<k,O

S..,&

LEAD

,",eLD

MODEL

815

RECORD

AND

PLIIBLCK

COlL

RID

O.*NLT

LEAD

-0

l."I*.110*

TIOUND

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

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.

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.

1951

Shure Brothers

Inc.

27A52

(5-63)

(OVER)

Printed in

U.S.A.

FIG.

DIMENSIONAL DIAGRAMS

MODEL

815

C INSTALLATION DIAGRAMS

FIG.

RESPONSE FREQUENCY CHARACTERISTICS

+I0

g5t

-1

-10

I-

-20

1,000

10,o

FREQUENCY

CYCLES PER SECOND

MODEL 815

FREQUENCY

CYCLES PER SECOND

MODEL 816

CURVES REPRESENT PLAYBACK LEVEL

BELOW SATURATED OUTPUT.

Recording Medium-Minnesota Mining

Mfg. Co., Tape

No.

I I

5RBAI

FIG.

TYPICAL OPERATING DATA

*Determined in accordance with RTMA Standard REC.-134, August 1949.

**Erase Current Chosen for 50db Erasure of Saturated 400 C.P.S.

Recording.

Recording Medium-Minnesota Mining

Mfg. Co., Tape No.

I I

5RBAI.

Pressure Pad Force (Area

.0625

Sq.

In.) One Ounce. See Fig.

MODEL

Recording

Speed

Bias and Erase

Frequency

Standard

Recording

Level

Operating

Bias Current

Erase

Current

Impedance

Erase Coil

Impedance

Recording

Coil

81 6

RUWAY

2 Ounces

4 Ounces

See

Fig. B.

Model

CODE

WORD

Net

Weight

Shipring

We~ght

Dimensions

RUWAT

2 Ounces

4 Ounces

See

Fig. B.

816

3.75" per Sec.

25 kc.

.031 ma.

.80 ma.

5500 ohms

I0O0

C.P.S.

SPECIFICATONS

7.5" per Sec.

50 kc.

.050 ma.

1.50 ma.

---

33 ma.

1260 ohms

50 kc.

1250

ohms

1000 C.P.S.

and

1.875"

3.75,,

per

Sec.

Set.

kc.

.050 ma.

1.25 ma.

27 ma.

780 ohms

25 kc.

1250 ohms

1000 C.P.S.

.095 ma.

.35 ma.

21 ma.

ohms