Bose 901 Series II User Manual
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
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INTRODUCTION
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.
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
0^
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
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
Hook-up Wire
18 gauge zipcord
(or two-conductor wire)
16 gauge two-conducior
wire
14 gauge two-conductor
wire
One Pair
of 901s
33 feet
54 feet
86 feet
Two Pairs
of 901s
14 feet
23 feet
36 feet
0
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
also known as "0"
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
"COM"
"Ground" or
"Negative" (-1
"8 OHMS" Terminal
also known as
"8^"
"Hot" or
"Positive" (*)
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
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