Shure 3B, 10B User Guide

DATA SHEET No. 1o1B

DATE: August 1937
T E L E P H O N E D E L A W A R E 8 3 8 3 C A B L E S H U R E W I C R O	and	10B
SUBJECT: Models 3B

1 Carbon Microphones

MODELS 3B and 10B CARBON MICROPHONES

GENERAL:			Model 3 B Carbon Microphone								is an
			inexpensive two-but t on microphone
			f o r general-purpose use i n medium
f i d e l i t y systems				where		low cost is t h e				impor-
t a n t f a c t o r .			Model		3 B	is	designed		f o r	spring-
suspension		i n microphone rings.
	Model 10B Convertible							Hand Microphone is
equivtlent		t o Model 3B i n					performance.			Remov-
able	Quickway"			Hooks a r e			furnished f o r				con-
v e r t i n g from			hand		type t o			conventional type
f o r spring		suspension i n					microphone			rings.
Model	10B is		f u l l y assembled					and wired,		and is
furnished with 3-conductor							cordage 6 f e e t				long.
APPLICATIONS: Typical						applications			of	Models
			3 B and 10B a r e found						i n low cost
			portable and mobile						public		ad-

d r e s s equipment, announcing and paging systems,

amateur radiophone t r a n s m i t t e r s ,	e t c .	The con-
v e r t i b l e f e a t u r e of Model 10B makes it		especi-
a l l y convenient where limited	equipment must

be used under a wide v a r i e t y of s e r v i c e conditions .

INSTALLATION: Model 3 B is

designed

f o r

spring

suspension mounting

i n

carbon

manner.

microphone

r i n g s

i n

t h e usual

Model 10B is a

hand microphone which

can be quickly converted f o r

stand mounting i n

a carbon

rina.

Loosen t h e t h r e e binder

head

terminal

screws and disconnect

t h e cable.

Re-

move t h e

t h r e e screw?

t h a t

hold

t h e microphone

head

i n t h e

c l o s e - f i t t i n g

r i n g

and

s l i p

t h e

head

out

of

t h e ring.

Screw

"Quickway" hooks

i n t o

t h e

tapped

holes

i n

t h e

frame.

Mount

i n

carbon r i n g with

springs

(Shure A30A

o r A31A)

i n t h e usual

manner.

Simply reverse t h e

pro-

cedure t o

convert back

t o hand-type

microphone.

CONNECTIONS:

Suggested

wiring

diagrams

a r e

shown i n Fir .

A. The button

cur-

t h e r h e o s t a t

r e n t may be

controlled

by

e i t h e r

o r

potentiometer

method

a s indica-

ted. The potentiometer method is preferred by

some engineers

because

it

allows

t h e

current

t o be

gradually reduced

t o

zero

before

t h e

microphone is disconnected,

thus

reducing t h e

p o s s i b i l i t y

of

"packing".

To use Models 3 B an& 10B

n le-button

microphones,

terminals

A and

:s

butto;

and

frame

a s

indicated

i n

the

"end-view

sketch)

a r e

connected t o

t h e microphone

trans-

former

primary,

i n

s e r i e s with the

button

cur-

rent

source.

The recommended and maximum but-

ton

currents

( s e e OPERlTION below)

a r e t h e same

a s

f o r two-button operation.

Suitable microphone

transformers

a r e

a-

v a i l a b l e from

most

r a d i o

p a r t s d i s t r i b u t o r s .

Model 3B

Carbon Nicrophone

	( ~ b o v e )
Model 10B
Convertible Hand
Microphone
( A t		r i g h t )
OPERATION:		The	f ollowing	button - current
		r a t i n g s apply		t o Models 3 B and
		10B:	Recommended Current :		4 t o
7 ma. per button.			Maximum Current: 12 ma.		per
h..++nn
UULILIVII.
Under no circumstances should t h e WImUm
current	r a t i n g be		exceeded. Low button current
r e s u l t s	i n b e t t e r		q u a l i t y of reproduction,low-
e r h i s s	l e v e l , and long l i f e .			lCxcessive	cur-

r e n t w i l l cause burning of the carbon and dia - phragm. Do not leave button current on micro-

phone f o r extended periods when not								i n use.
"Packing".		A d i f ference				between thentwo buttnon
currents exceeding 7 ma.						i n d i c a t e s		packing .
The p o s s i b i l i t y			of		"packing"		can be	reduced		t o
a minimum by:			( a )		c a r e f u l handling t o reduce
shocks and		jars;		( b ) gradually reducing button
current	t o 1 a minimum before disconnect ing									t h e
microphone		o r b a t t e r i e s ;				( c )	turning		off	the
button current			before moving				t h e	microphone.
Should		"packing" occur,					t h e	microphone
can usually		be	r e s t o r e d t o normal condition by
tapping	l i g h t l y on				the	frame with		a	rubber-
tipped	penail while				r o t a t i n g		t h e	instrument.
I f t h i s	procedure			f a i l s ,		t h e	diaphragm		o r car-
bon has probably been burned							and t h e microphone
should	be returned				t o the	factory f o r			recondi-
ti ocing.

Dampness. Excessive dampness may cause coher-

ing	of the carbon	granules, and it is	there -
f o r e	important t o	keep the microphone	i n a d r y
place.

@ SHURE BROTHERS 1997

PRINTED IN U.S.A.

No. 101~		DATA SHEET					2 2 5 W t S l H U R O N S T R f f l C H I C A G O U 0 S . L
					,CLOSED	-C/RCU/T
					METER JACK		#/CROPHONE
							TRANSFORMER
			0 - 2 5
					1 0 0 0 O H M RHEOSTAT.
	0
	(FRAME)				M E r m JACK
			4fWLT DRY CELL			Fig. A.
	SPECIFICATIONS
Voltage	S e n s i t l v l t y :	4 m i l l i v o l t s		R. M. S. pe r
		ba r a c r o s s 200		ohms a t 400
		cycles.
Output	Power L e ~ e l :	Minus 29 db i n 200			ohms a t
		4 0 0 c y c l e s .		( 0 d b = 6 m .
		Sound	Pressure,		1 0 bars.)
Recommended Load		200-ohm	input	transformer.
Impedance :
Button	Current:

Guarantee: Each	microphone		is guaranteed		t o	be
f r e e	from e l e c t r i c a l and mechanical de-
f e c t s	f o r	a period	of	one yea r		from
dat e of shipment	from	t h e factory ,		provided	a l l	in-

s t r u c t i o n s a r e complied with f u l l y .

3B AND 10B

	SHURE MODEL	3B	MICROPHONE
P	AZIMUTH	0	DEGREES
	TERMINATION:		200 OHMS
3 0 4 0	60 8 0 100		I M	2 M	4 M 6 M 8 M l O M
	FRENQUENCY, CYCLES PER SECOND