Shure M7D User Manual

222

HARTREY AVE r EVANSTON ILL. CABLE SHUREMICRO

EVANSTON PHONE OA

89000 . CHICAGO PHONE SH

3

1600

DATA SHEET

I

MODEL M7D STEREO

CUSTOM DYNETIC

CARTRIDGE

(Stylus Model N7D)

1

SPECIFICATIONS

Response Frequency Characteristics:

15,000 c.p.s.

OU+~U+ Voltage:

Channel Separation:

~ecommended Load Impedance:

nel) for Stereo. 22,000 ohms for Monaural (see connections).
Higher values will produce a

sponse.

Stylus:

Number N7D.

Radius .0007" (0.018mm) Diamond.

Compliance:
Tracking Force:

Inductance:
D. C. Resistance:
Terminals:

each channel. (See Fig.

Mounting:

or 4 machine screws. .437 (I l.lmm) mounting centers using #2
machine screws.

Weight:

4 terminals.

Standard

7.9 grams 1.28 ounces).

Packaged Weight:

General:

ridge has been developed for use in all high fidelity applications.

It

has been designed to connect into magnetic and constant ve-

locity inputs.
the Model M7D will

Discs Monaurally, and Stereo Discs Monaurally without excessive

wear and without distortion.

employed in both the Studio and Professional

the same important features, such as:

The Model M7D Stereo Custom Dynetic Phono Cart-

The Model M7D is completely compatible.

The Model M7D utilizes the same Moving Magnet principle

High needle compliance.
Low needle talk.
Low tracking forces.
Wide range frequency response.
Magnetic induction from external fields is reduced to
a minimum.
No magnetic attraction to steel turntables.

5

millivolts per channel.

More than 20 db at 1000 c.p.s.

47,000 ohms (per chan-

slight increase in high frequency re-

1

VERTICAL
HORIZONTAL

4 to 7 grams (5 grams optimum).

420 millihenries.

280 ohms.

2).

1/2'1

2 ounces (56.7 g).

play Stereo Discs Stereophonically, Monaural

3.5 x 10-4 centimeters

1

per dyne

An independent ground terminal for

(12.7mm) mounting centers using

From 20

In other words,

Dynetics and offers

to

#3

Mounting:

mounting centers. Two #3-48 machine screws are supplied with each
cartridge for mounting purposes.
cartridge can be mounted on
is important during installation, that the line on the front of the
cartridge be perpendicular to the turnable or record surface.
no adjustment is available to do this, a paper or metal shim can
be used on one mounting post to adjust angle of cartridge.

5

grams. When replacing magnetic cartridges, adjustment is

is
generally unnecessary. Should
usually be made
of arm. Forces up to
proper

The M7D Cartridge has standard

By

using #2 machine screws, the

.437 (I l.lmm) mounting centers.

DIMENSIONAL DRAWING

FIGURE

The recommended needle point force for optimum results

by adjusting the counter balance or spring at rear

7 grams may be used

cycling of the record changer.

I

it

be necessary, adjustment may

if

needed to provide

y2"

(12.7mm)

It

If

Copyright

27A142

1958

(10-63)

Shure Brothers.

Inc.

Printed

in

U.S.A.

Connections:

ment for connections having a separate ground terminal for
channel. (See Figure 2).

LEFT

CHANNEL
TERMINAL

GROUND

TERMINAL

For Stereo reproduction terminal R and its ground terminal
represent the right channel (outside groove wall). Terminal
its ground terminal represents the left channel (inside groove wall).

To use a 4-lead arrangement connect each section of the
cartridge to separate amplifiers. To prevent "ground loops" and
hum, no common connection should exist between the two amplifier

systems.

When used with a 3-lead arrangement, the
should be connected to both of the ground terminals at the cart­ridge. No other common ground connection should exist.

For single channel reproduction of Monaural or Stereo re­cordings, connect the "hot" lead to both R and
connect the ground or shield lead to both of the ground terminals

marked

6.

For )-lead arrangement and for single channel reproduc­tion, a "double loop" pin
connection between the two ground terminals-simply slide the
loop ends onto the

made before connecting the regular terminal jacks to the cart-

ridge. Connect ground pin jack to either ground terminal.

Caution:

nals. Make all solder connections to terminals jacks provided.

Phasing:

loudspeakers. Although the phasing of the M7D cartridge is care­fully controlled, there are many possibilities where a particular
High Fidelity system can cause opposite phasing of the sound from
the speakers. The phasing can be easily checked by

Play a monaural record using the M7D. Reverse the connections of
the wires to one speaker. This can be done at the amplifier or the
speaker, which ever is more convenient. When the sound appears
to come from
phase. Also, bass reproduction will be much fuller when speakers
are correctly phased.

Associated Equipment:

you require the same basic equipment that you need for playing
monaural records. However, you will need two amplifiers, two pre­amplifiers and two speakers. If you already have a monaural system
then you need to add the extra preamplifier, amplifier and speaker.
You will also have to add another set of leads to your tone arm

the second channel. Figure 3 shows typical stereo systems.

If your system is represented by Figure
the connection instructions that accompanied your stereo preamp­lifiers.

If

your stereo

your system is represented by Figure 3B or 3C, consider

The M7D cartridge utilizes a 4 terminal arrange-

each

RIGHT

I

1

1

\--

1

CHANNEL
TERMINAL

RIGHT

CHANNEL
GROUND

TERMINAL DIAGRAMS

FIGURE 2

iack is provided to make a convenient

ground terminals. This connection should be

Do not make solder connections to cartridge termi-

It

is important to maintain correct phasing of both

a

point halfway between the speakers, they are In

For reproducing stereo records

Tqiiir-1

POWER AMPLIFIER

COMBINATION COMBINATION

TYPICAL STEREO SYSTEMS

FIGURE 3

dynetic as two separate cartridges and connect one set

TERMINAL

L

and

shield lead

L

terminals and

a

listening test.

foi

POWER

AMPLIFIER

3A, merely follow

of leads (see connection) to each
leads should be connected to the "low level" phono input. Again,
the instructions that come with each of your
your best guide in making these connections.

After making the cartridge connection,

balance the system by adjusting the volume from each channel un-

til

they are equal. To do this, play a monaural record with the
stereo cartridge. Adjust the volume control on one preamplifier
until you have the sound as loud as you want
volume on the second preamplifier to match the first.

It

tion that you will have to
every time you wish to raise or lower the volume. There are several

rel'atively inexpensive devices available that provide a solution to
this problem by means of a master volume control that controls the
sound level from both channels with a single control. The dealer
from whom you purchased your stereo
you information on a device of this type.

will become apparent to you when performing the opera-

adiust the balance between the channels

Speaker Placement:

greatly from room to room,
rule of speaker location for optimum results. In general, the
speakers should be placed along the wall of the room opposite the
most comfortable listening area. The speakers should be separated

by a distance equal to
which they are placed.

farther apart the speakers are the farther away you will be able
to sit and still achieve good results. Also, the closer together the

speakers are, the closer you will have to sit and the fewer the

number of people that will be able to listen at one time. By ex-

perimenting with the placement of the speakers, you can determine
the location that will give the best results in your particular room.

1/2

to

It

is well to keep in mind the fact that the

preamplifier. In general, these

~ream~lifiers will be

it

is necessary to

it.

Then, adjust the

dynetic will be able to give

Because acoustic factors vary

it

is impossible to establish a definite

3/4

of the width of the wall against

SO

STYLUS REPLACEMENT

Special Note:

such an extremely important part in the overall perform­ance of the Stereo Custom

certain that any replacement stylus is a genuine Shure

"Stereo Custom

The stylus assembly, when installed in the cartridge is practi­cally immune to damage during normal usage. However, care
should be taken to avoid bending or distorting the stylus assembly
when

it

is installed or removed.

Stylus replacement is simple and fast. (See Figure 4). To
replace (Step I)-Insert fingernail file (or a similarly pointed
tool) behind the lip at the front of the stylus spade. Care must

be taken not to deform needle shank (portion holding needle tip)

or spring wire in the stylus assembly. (Step 2)-Withdraw stylus

by pulling forward out of cartridge-lift completely out with thumb
and forefinger. (Step 3)-grasp new stylus between thumb and
forefinger and insert into stylus socket cartridge. (Step 4)-Press
stylus into socket until
front portion of the spade. Care must be taken not to allow the
finger to slip off of the front of the stylus spade resulting in dam­age to the stylus tip.

Guarantee:

guaranteed to be free from electrical and mechanical defects for
one year from date of shipment from the factory, provided all
instructions are complied with fully. The Guarantee does not cover
needle wear nor does
abuse or mishandling.

Patent Notice:

3,077,521, 3,077,522. and

Because the stylus-magnet assembly plays

Dynetic Phono Reproducer, be

Dynetic" stylus.

NEEDLE REPLACEMENT

FIGURE

it

is firmly seated. Apply pressure at the

The M7D Stereo Custom Dynetic Cartridges are

it

cover damage to the needle assembly from

Manufactured under

D187.230. Other patents pending.

4

U.S.

patents 3,055,988,