Bose 901 Series II User Manual

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901 SERIESn OWNER'S MANUAL

TABLE OF CONTENTS

			Page
I.	Introduction..........................................................................................................................		3
II.	Unpacking Your 90U............................................................................................................		3
III.	Installation of Your 901 s.....................................................................................................		3
	A. Speaker Placement
	8. Connecting The Speakers
	1. Selecting The Speaker Wire
	2.	Phasing Your 901 Speakers
	3.	Fusing Your 901 Speakers

C.Connecting The Equalizer

1.Preferred Method

(Using The Tape Monitor Circuit)

2.Alternate Method I

(Using PRE-AMP OUT and MAIN IN Connections with Receiver or Integrated Amplifier)

3.Alternate Method II

(Using separate PREAMPLIFIER and POWER AMPLIFIER)

4.Alternate Method III

(Using FOUR-CHANNEL DECODER)

D.Connecting A Tape Recorder

E.Connecting Headphones or Conventional Speakers

IV.	Getting The Most Out of Your 901 Speakers.....................................................................		10
	A.	Adjusting Speaker Placement
	B.	Adjusting The Equalizer Controls
	C.	Improving Room Acoustics
	D.	Selecting The Right Amplifier
	E.	The Only System Better Than A Pair of 901s
V.	In Case of Difficulty............................................................................................................		14
VI.	Technical Information.........................................................................................................		14
VII.	Accessories and Options...................................................................................................		15
VIII.	Five Year Warranty.............................................................................................................		16

tINTRODUCTION

r. T>i3nk vou for purchasing the BOSE 901 Series D Oireci/Reflecung * speaker syitem. The listening enjoyment ex­

perienced with your BOSE 901s culminates many years of research and dedication to the art of	bringing the finest
musical reproduction into your home.
THE BOSE 901 with its unique shape. 9 drivers, and Active Equalizer incorporates a number of	major advances in

speaker technology. It is designed, installed, and connected differently from conventional loudspeakers. These maior differences contribute directly to the new level of realism of music reproduction provided by the 901 speaker system.

The detailed installation and	placement instructions are important. PLEASE	TAKE THE TIME TO	READ	THIS
MANUAL, as this is the only	way you will obtain the full benefits of the 90V$	unique design. You	will be	amply
rewarded by the listening pleasure which your 901s provide, wf en properly installed.

II. UNPACKING YOUR 901s

The 901 speaker system is packed in two cartons marked "Part 1" and "Part 2." THE ACTIVE EQUALIZER IS

CONTAINED

IN

A

CARDBOARD

WEDGE FOUND IN PART

1.

Unpack

both

cartons

carefully.

(Save

the

cartons

and packing

materials for

possible

use

later.) If either the speakers

or the

Equalizer are

visibly

damaged when

you

un­

pack them,

do

not

place

the system

in operation. Repack the

speakers and the

Equalizer in

the

original

cartons

and

notify your dealer immediately. (See Section V.)

II.INSTALLATION OF YOUR 901s

A.SPEAKER PLACEMENT

One of the most important advantages of the BOSE 901 speaker system is that it is designed to operate properly

in most listening rooms, not in anechoic test chambers. The superior dispersion characteristics of the 901 allow

considerable freedom of placement	and an unusually large "best	listening	area."	To obtain the full performance
of the 901. you must follow the placement guidelines in this section.
The angled (vee shaped) grille cloth	panels are the back of the 901. Point		the vee toward the wall. The distance
of the speakers from the wall is	very important. The point of	the vee	should	be 12 inches from the wall.

(Although the 901 was designed to be placed 12 inches from a reflecting wall, satisfactory performance can be obtained anywhere within the range from 8 to 24 inches.) The point of the speaker should be aimed directly at the reflecting wall, and NOT directly into a corner (See Fig. 11,

The	reflecting	wall ideally should be made of a dense, solid substance such as wood, brick,	cement block, plaster,
or	sheetrock.	Substances like glass, pegboard. cork, or acoustic tile make ineffective	reflecting walls. (The

Equalizer is designed to accommodate surfaces which might otherwise present problems. (See Section IV B.l I

The following guidelines should be followed in placing the speakers relative to other surfaces in the room. The basic idea is to provide space around the speakers to allow sound waves coming from the rear of the speaker to

properly disperse.

0^

1.The speakers should be placed at least 18 inches from the floor.

2.If you are hanging the speakers from the ceiling, they should be positioned no closer than 18 inches from the celling. DO NOT place your speakers exactly half-way between the floor and the ceiling. (See Fig. 1.)

3.The speakers should be at least 18 inches from the side walls or from openir^gs into adjacent rooms.

4.The speakers should be at least 18 inches from nearby massive objects such as bookcases, cabinets, or other large pieces of furniture.

5.The separation between the speakers should be between 4 and 15 feet. (Best results will be obtained with a separation of 6 to 12 feet.)

6.In general, you should use common sense and be sure to select an arrangement which does not appear to

block the radiation and reflection of the sound into the room. The 901s can be placed on pedestals or tables, on top of cabinets, or on shelves, as tong as the preceding guidelines are followed.

7.If the speakers are in a room with a color television, DO NOT place the speakers closer than 3 feet to the

television. All loudspeakers are equipped with powerful magnets which may disturb the delicate adjust­ ments of your color TV.

B.CONNECTING THE SPEAKERS

1.SELECTING THE SPEAKER WIRE

If the wire chosen for connecting the speakers				to your amplifier	has too much resistance, audible colora­
tion of the sound and		loss	of power can	result. The table	below summarizes the permissible wire
lengths for 18. 16. and 14 gauge two-conductor copper wire for one or two pairs of BOSE 901 speaker
system(s). Copper	zipcord	wire is readily available at most electrical and hardware stores. This wire usually				0
has a ribbed line	running	along	one of the two	conductors so that the conductor can be identified at each

end for obtainirtg the proper phasing of your BOSE 901 speakers.

TABLE 1 - WIRE LENGTHS FOR EACH SPEAKER

		Type of Speaker		One Pair	Two Pairs
		Hook-up Wire		of 901s	of 901s
		18 gauge zipcord		33 feet	14 feet
		(or two-conductor wire)
		16 gauge two-conducior		54 feet	23 feet
		wire
		14 gauge two-conductor		86 feet	36 feet
		wire
2.	PHASING YOUR 901 SPEAKER
	It is imporiani that the connections to the		speakers and the receiver or amplifier be the same for both
	channels so that the two speakers are m phase with each other. The two terminals on the bottom of the 901

are marked ”8 OHMS” and ''COM.'*

♦

i

Start	with the Part	1 portion of your 901	system. Place it on the left side of your	room. Connect
this	left speaker to	the left channel speaker	output terminals of your amplifier or receiver.	(If there is a
choice of impedances on the amplifier output, use the terminal marked "8^2" or "8 OHMS''.) *

Connect the "COM" terminal on the left speaker to the "COM" terminal on the left channel output of your

receiver or amplifier output. Connect the "8 OHMS" terminal on the	left speaker to the "8 OHMS” ter­
minal on the left channel amplifier output. Connect the right speaker	(Part 2) in the same manner to the
right channel amplifier outputs {See Fig. 2).

Because of the differing terminology which various manufacturers use on their receivers and amplifiers, we have provided the chart below to assist you in identifyirtg the proper connection points.

STANDARD RECEIVER/AMPLIFIER TERMINAL MARKINGS

"COMMON" Terminal	"COM"	"8 OHMS" Terminal	"8^"
also known as	"0"	also known as	"Hot" or
	"Ground" or		"Positive" (*)
	"Negative" (-1

If stranded wire is used, be sure that the loose strands do not touch or short-out the speaker or amplifier terminals. Also make certain that all amplifier and speaker terminals are tightened securely.

*If two pairs of 901s are being connected in parallel, the terminal marked ”4i2" or ”4 ohms" on the receiver or amplifier should be used. (See Section IV E.)

3.FUSING YOUR 901 SPEAKERS

Any loudspeaker is subject to damage if the amplifier powering it should fail. The use of a fast-acting fuse

in series with each speaker will minimize the possibility of serious damage to your speakers. BOSE Corpo­

ration recommends the	use of a 3-ampere	fuse, such as a BUSS AGC 3 or	a	LITTELFUSE	3 AG
(3 amp). The fuse should be connected in		series with either of the two wires	in	the cable to	each
speaker. A fuse holder,	like a BUSS 3833-1	or a LITTELFUSE 356001. may be used	for convenience. (For
two pairs of BOSE 901s, use two 6-ampere fuses.)

C.CONNECTING THE EQUALIZER

THIS PART OF THE INSTALLATION DIFFERS FROM THAT OF CONVENTIONAL SPEAKER SYSTEMS. BE CERTAIN TO FOLLOW THE INSTRUCTIONS GIVEN BELOW, STEP BY STEP.

1. PREFERRED METHOD

(Using The Tape Monitor Circuit)

To provide the proper balance at all frequencies, the 901 Active Equalizer must be connected in your sound