Shure 901D User Guide

SHURE BROTHERS

INCORPORATED

Micro-honnc and Acou-tic Devices

225 WEST HURON STREET :: CHICAGO 10, ILLINOIS PHONE DElaware 7-4550 :: CABLE: SHUREMICRO

I	DATE: M A Y 1949
I	SUBJECT: Model 901D Verfical Drive
	'lTurnover1'Crvs+al Ph o no -
	graph Pickup

MODEL 981D

Ver+iea! Drive 'Turnover" Crystail Phonograph Pickgap

General:

Model

901D

"Turnover"

Phonograph

Pickup is

designed

t o

reproduce standard

records

and

the

various

types

o f fine-groove

long playing

records.

M o d e l

901D

uses

a

turn-

over mecl?ar~isman2 the new Shure two-sided "Vertical Drive"

crystal cartridge.

The crystal element

is

a

bimorph,

Rochelle

Salt unit.

This dual-purpose cartridge utilizes the

"Vertical

Drive"

con-

struction

which

results i n a needle-point compliance

in the

order

o f 1.0

x

10-6 centimeters per dyne.

By

combination

o f

this

highly compliant cartridge and the Shure die-cast aluminum

pickup arm, an extremely low needle force for proper record

tracking

has

resulted.

The

dual

purpose

cartridge

has

a

Shure

Model A 5 2 A osmium

tipped

needle

(.003"

needle

t i p

radius)

f o r playing standard

records

a t

78

r.p.m.

and

a

Shure Model

A 6 5 M G

sapphire

tipped needle

(.001"

t i p radius)

for

playing

Columbia,

R.C.A.

and similar

fine-groove

records a t 33-55 r.p.m.

o r 45 r.p.m.

These needles are separately replaceable.

The

Pick-

u p performs

equally

well on

the 7".

lo",

o r

12"

size

records.

Model 901D will give an excellent frequency response with

high output and extremely low tracking

force.

The

design

o f

the pickup provides record reproduction with low surface noise,

low needle talk, end low needle hiss.

LOW record

wear is assured by +he

curved

tone-arm

(which

maintains

the

horizontal projection

o f

the

needle

closely

tan-

I

gent t o the

groove et all times), by

high

needle

point

compli-

ance,

and

low needle

pressure o f

6 grsx:

( ? $ ounce).

A n

adiustment

screw is

provided

for

the

swivel

t o

protect

t h e needie

against damdge'due t o

accidental

touching 'of the

' turntable when recoid is removed.

Model

901D

"Turnover"

Pickup

is

provided

with

a

14"

shielded

lead.

A n arm resf

is

included

for

mounting

on

the

motor-board. -

Applica3ierns: Model 901D is ideally suited for the ex-

perimenter and for use in high quality home

~ h o n o ~ r a p h spor,-

table equipment, and record demonstrators.

This

pickup

is

especially

suited

for

replscunent o f

older,

heavy

~ i c k u p s as

. well as pickups used

in modern

installations.

Because o f low needle talk and needle hiss, the model 901D

may be used with open-type phonograph players with a mini-

I

mum o f arrnaying side tone.

The output voltdge o f			the pickup (see ~ ~ e c i f i c a f i o n sis) suf-
ficient	t o produce	full	output from audio stages o f modern
radio	receivers and	from	moderate gain amplifiers.

i	.	- -	- .. -	- -	A
c. Tighten	the	locking	nuts	securely.

The arm rest should be mounted in any convenient place on

the

motor-board

in such a manner that it does not interfere

with

the playing o f

a

12" record.

If necessary, the length of the leads can be increased con-

siderebly without excessive output loss. Low-capacity shielded

cable is suitable for this purpose.

Nothing should interfere with the free motion o f the Pickup.

Leads (or

cable)

should be allowed to extend several inchtr

before making connections, so that the pickup may rotate freely

obout its vertical

axis.

Suificient

cabinet

ventilation

should

be provided

t o

keep

the ambient temperature about the pickup at the lowest pos-

sible value.

For

best results the ambienf temperature should

not be allowed t o

exceed 100' Fahrenheit, although no damage

will

result to the Pickup below 125' Fahrenheit.

Conaeefisns:

~ o d e l901D

pickup

utilizes

the

pin-jack

method o f connecting the leads

t o the

cartridge.

One side

o f

the

crystal

unit is

connected t o

ground

through the

shield.

In

-

this instance, the pickup may be connected directly into an

amplifier of the type using a single grid input circuit. The cen-

ter conductor should be connected to the grid or

"hot"

lead:

the

shield should

be

connected

t o the ground or

chassis.

Fig-

ure A shows the circuit.

The chassis should be securely grounded

t o eliminete shock

hazard t o the

user.

Bns+rril!a4ioas: The Pickup should be mounted on the motorboard so that the oifset needle furnished with the pickup has an arc o f travel approximately y4" beyond the center o f the turntdble spindle. (See Fig. C). The motorboard should be heavy and well isolated from vibrations o f the motor and the loudspeaker.

A f t e r the		pickup is	securely	m o u n t ~ dthe following	proce-
dure rnay b e followed			t o install	and adjust the needle	protec-
tion	screw.		Assemble one hex nut on the l/z" long
a.	L i f t the	tone arm.

needle protective screw and insert screw into the hole provided in the swivel assembly bracket with the head of

the screw toward the inside					o i the	arm.	Assemble other
hex nut t o the			portion o f the		screw	extendins t h r o ~ l g hthe
bracket.		The screw		and two	hex nuts are		provided j n the
accessory box.
b. W i t h	a	screwdriver		adiust	the screw until the needle
point, upon lowering the tone-arm, Is maintained approxi-
mately		1 /32"	above	the turntable surface.
Copyright	1949, Shure Brothers, Inc.						2-7wr-

A 6 i A

3 MII Radius Needle

PPNO56467 Pdn

On ~ o i dTern~no l

- .

		Arnptil,er
IMil ~ c usd Needle	PNo 56467 Pin J O C ~	Chossls
(Red)	On Sdver Termmot.
Pig. A. F o r A m p l i f i e r s	Using a S i n g l e G r i d lnpuf .

Q)per~*ig311: To play standard (78 r.p.m.) records, set the knob at the front of the pickup so that the letters STD are a t the top. To play microgroove and R.C.A. slow speed records, turn knob in the direction of the arrow until the letters MG are

Printed in U.S.A.

a t the	top. The knob may be used as a convenienf handle t o
set the	pickup on the record.

The needles may b e rzmoved by loosening the knurled nut (which holds thc needle) l/z turn. A new needle should be inserted in the hole provided and the knurled nut tightened securelv ~tsinathe thumb and fore-finner. Care should be taken ,t t o deform the contour o f the needle when the knurled nut

tightened.

Model 901D uses the Shure "Muted Stylus"						needles which
may be procured in any record shop				throughout the country or
a t any	Shure distributor.	The	pickup	is supplied with the A62A
(.003"	t i p radius) precious metal t i p			needle which is o f natural
stainless steel color and the A h S M G				(.001"	t i p radius) sapphire
t i p needle which is dyed		red.	Instead o f A62A,			an A 6 1 A sap-
phire t i p need!* may be used for longer life.					In portable phono-

graphs, when pickup is not in use nsedles can b e protected against accidental damage by rotating the turnover mechanism 90".

Record Wear:				LOWneedle pressure and low needle point
impedance			(resistance t o side-to-side		motion o f the	needle)
are	achieved through			an unique system o f mounfing and coupl-
ing	the	crystal unit.		These features permit the ncedle		t o ride
through		the	record-groove with a minimum o f thrust and wear
on the		side	wal!s. Record wear is still		further reduced	by the
off-set {earl			o f the pickup, which keeps the normal axis			o f rota-
tion	o f	the	needle	closely tangential	t o the record	grooves

throuqhout the plavinq time o f the record. This results in low

trackinn error, dnd'inmaximum fidelitv o f			reoroduction a t	all
frequencies. The pickup should		be carefully	located as specified
under "Installation"	t o derive	full benefit	from this feature.
i ' + ~ q ~ e Response:f ~	The frequency		response curves	o f

the model 901D obtained on Columbia micro-groove test record No. 281 and Audiotone test record No. I are shown in

figure B.	This		type o f		response is very satisfactory				for high
quality reproduction o f records without i h e use o f								compensating
circuit:.	Ton-		con:ro!s		provided in the		maiority	o f	amplifiers
and radio		receivers		may be		employed	t o alter this		frequency
response	t o	suit	the	individual		listener.
I			AFSPOHSE FREQUEhLY CHARACTERISTIC
nv
$+I0
z
0
a
,I
W
2
5-10
IlJ
a
5 0		100				COO0			l0,OOO
			FREQUENCY-CYCLES PER SECOND
	-Audlorone			Test Record No 1, 0 0 2 7 Needle 1lp Rodtur.
		I IVoIxs Output A1 1000C P S
	------CclurnSa			Test Rccrd No281.001 Needle Tap Rod~u,
		94 Volts 0ufi)utAt 1000 C l?S

Fr'g. C. Physiec! Dimensions o f Mode! 901D.

Vo!.kalle Sensi)i\ri*y:			The output voltage depends upon
the individual	recording.		etc.	Model 9 0 i D has	an outpuf o f
approximately	.94	volt at	1000	cycles on Columbia test record
No. 281 and	1.1	volts on	Audiotone test record.		Peak voltage

output on commercial records may reach 10 volts.

!mfertid Ipnpedance: Equivalent t o 650 mmf condenser.

Recommended Load impedcifice: I/,n-egohm or more.

depending upon the response curve desired.

I		MODEL 901D			I
I		--		--	1-
	FINISH			GRAY H A M M E R ENAMEL
	C O D E W O R D			RtJZEL
	LEAD	LENGTH			14"
	ARM REST			INCLUDED
	NET W E I G H T		-	4	02.
	NEEDLES			REPLACEABLE, L O N G -
				LIFE, INCLUDED
-
	SHIPPING W E I G H T			I 2	02.

F i g . R. Typical Response Gharacterisfics of 904D.

-

-

-

Guaranfee:

Every

Shure

Pickup i s

guaranteed

t o be

free

The low-frequertcy response

below approximately 500 cycles

from electrical

and mechanical defects

for one year

from

date

of shipment from the factory,

provided all instructions are

com-

,

depends

upon the

termination

resistance. The user can

thus

plied with fully.

adjust the low-frequency response over wide limits by p:oper

choice o f

resistance

o f the input potentiometer or grid resistor.

License Nofice:

A value

o f I to 2

niegohms will be satisfactory in most cases.

Shure

Crystal Record Reproducers

are

The high frequency response is not affected by the value o f the

licensed under patents o f the Brush Development Company.

termindtion resistance.

Shure patents

allowed

and pending.

j

2 7 ~ 4 2( 5 - 4 9 )