Bose 901 Series II User manual

OWNERSIMANUAINEO)
SOnSERIESM
DinE
GWAR
Egle
CMING
SP
EMWERIS
SIEM
MTUI Sz.

VI
VIL
VIH.
901 SERIES TILT OWNER’S MANUAL
TABLE OF CONTENTS
A. Speaker Placement
B. 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 |
(Using
PRE-AMP
OUT
and
MAIN
IN
Connections
with Receiver or Integrated Amplifier)
3. Alternate Method I!
(Using separate PREAMPLIFIER and POWER AMPLIFIER)
4. Alternate Method II!
(Using FOUR-CHANNEL DECODER)
D. Connecting A Tape Recorder
E.
Connecting
Headphones
or
Conventional
Speakers
Getting The Most Out of Your 901 Speakers
Adjusting Speaker Placement
Adjusting The Equalizer Controls
Improving Room Acoustics
Selecting The Right Amplifier
The Qnty non Better Than A Pair of 901s
mopper

l. INTRODUCTION
Thank you for purchasing the BOSE 901 Series II Direct/Reflecting® speaker system. 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 major
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 901’s unique design. You will be amply
rewarded by the listening pleasure which your 901s provide, when properly installed.
Il. 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
{v 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.)
Ill. 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. 20 Cc
(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. 1).
+18"-36'
46 - FA
~_ DO NOT PLACE HERE
(Half-way point between
ceiling and floor)
É
18”-36”
Ke -4
FIG. 1
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.] )

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.
2.
The
speakers
should
be
placed
18
to
36
inches
from
the
floor,
LC-
34
If
you
are
hanging
the
speakers
from
the
ceiling,
they
should
be
Positioned
18
to
36
inches
from
the
ceiling.
DO
NOT
place
your
speakers
exactly
half-way
between
the
floor
and
the
ceiling.
(See
Fig.
1.)
EG- JA
The
speakers
should
be 18
to
36
inches
from
the
side
walls
or
from
openings
into
adjacent
rooms.
The
speakers
should
be
at
least
18
inches
from
nearby
massive
objects
such
as
bookcases,
cabinets,
or
other
large
pieces
of
furniture.
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.)
A?
2-
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
long
as
the
preceding
guidelines
are
followed.
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.
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
has
a
ribbed
line
running
along
one
of
the
two
conductors
so
that
the
conductor
can
be
identified
at
each
end
for
obtaining
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-conductor
54
feet
23
feet
wire
14
gauge
two-conductor
86
feet
36
feet
wire
PHASING YOUR 901 SPEAKER
It
is
important
that
the
connections
to
the
speakers
and
the
receiver
or
amplifier
be
the
same
for
both
channels
so
that
the
two
speakers
are
in
phase
with each
other.
The
two
terminals
on
the
bottom
of
the
901
are
marked
“8
OHMS”
and
“COM.”

RECEIVER
COM. 8OHMS COM. 8-OHMS
FIG. 2
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 ““8Q2” 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 identifying the proper connection points.
STANDARD RECEIVER/AMPLIFIER TERMINAL MARKINGS
“COMMON” Terminal “COM” “8 OHMS” Terminal "BQ"
also known as so” also known as “Hot” or
“Ground” or “Positive” (+)
“Negative” (—)
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 “492” 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.)
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

system
before
the
final
stage
of
amplification.
The
connection
method
described
in
this
section
can
be
used
with
virtually
all
integrated
amplifiers,
preamplifiers,
and
receivers.
For
the
sake
of
simplicity,
we
will
call
these
various
components
the
“control
amplifier.”
The
901
Equalizer
is
normally
connected
to
your
control
amplifier
as
if
it
were
a
tape
recorder.
It
utilizes
the
TAPE
MONITOR
function
and
connections
of
your
control
amplifier.
CAUTION
TO PREVENT ELECTRICAL
‘SH
Series I
TO
QUALIFIED PERSONNEL.
TAPE RECORDER CONNECTIONS: | Corps COMMERTIONS
RECEIVER
FIG. 3
Referring
to
Figure
3,
connect
the
Equalizer
according
to
the
instructions
in
Steps
a
through
n:
a. Turn off all power to your equipment.
b.
If
you
have
a
tape
recorder,
disconnect
it
from
the
rear
panel
of
your
control
amplifier.
Instructions
in
the
next
section
will
show
you
how
to
reconnect
your
tape
recorder
to
the
system
after
the
Equalizer
has
been
installed.
THE
FOLLOWING
STEPS
WILL
CONNECT
THE
EQUALIZER
TO
YOUR
PREAMPLIFIER,
~
RECEIVER,
OR
INTEGRATED
AMPLIFIER.
READ
THEM
CAREFULLY.
pA
Using
one
of
the
cables
supplied
with
the
Equalizer,
connect
the
RIGHT
channel
OUTPUT
terminal
of
the
Equalizer
to
the
RIGHT
or
“B”
channel
TAPE
MONITOR
terminal
of
your
control
amplifier.
(This
terminal
may
also
be
labeled
TAPE
PLAYBACK
or
TAPE
IN.)
If
your
control
amplifier
has
two
tape
monitor
circuits,
see
Page
9.
d.
Connect
the
LEFT
channel
OUTPUT
terminal
of
the
Equalizer
to
the
LEFT
or
“A”
channel
tape
monitor
terminal
of
your
control
amplifier.
e.
Connect
the
RIGHT
channel
INPUT
terminal
of
the
Equalizer
to
the
RIGHT
or
“B”
channel
TAPE
RECORD
terminal
of
your
control
amplifier.
(This
terminal
may
also
be
labeled
TAPE
OUT
or
REC
OUT.)
f;
Connect
the
LEFT
channel
INPUT
terminal
to
the
LEFT
or
“A”
channel
TAPE
RECORD
terminal
of
your
control
amplifier.
g.
Connect
the
AC
power
cord
of
the
Equalizer
to
a
switched
outlet
of
your
control
equipment
so
that
the
Equalizer
will
automatically
be
switched
on
or
off
by
the
power
switch
of
your
integrated
ampli-
fier,
receiver,
or
preamplifier.
If
the
preceding
steps
are
unclear,
it
may
be
due
to
the
different
nomenclature
which
various
manu-
facturers
employ.
Consult
your
integrated
amplifier,
receiver,
or
preamplifier
instructions
and
refer
to
the
section
describing
steps
for
connecting
a
tape
recorder
to
the
tape
monitor
circuit.
Remember
that
the
Equalizer
connects
like
a
recorder.

THE NEXT SEVEN STEPS ARE TESTS WHICH MUST BE PERFORMED TO INSURE PROPER
OPERATION AND CORRECT INSTALLATION.
Place the TAPE switch on the Equalizer in the MONITOR position. Place the 3 frequency contour
controls so that they coincide with the indicated dots. These are the “NORMAL” positions of the
Equalizer controls.
Place the TAPE MONITOR or TAPE FUNCTION switch on your control amplifier in the NORMAL
or OUT position.
Turn the entire system on. Be sure that the Equalizer is plugged into an operating AC outlet by
observing that the pilot light on the Equalizer is on.
Play your system as you normally would, using a phonograph or AM-FM source (NOT a tape recorder)
to be sure it is operating properly.
This tests the rest of your system, since the Equalizer has not yet been switched into the system.
Any errors must be corrected before proceeding further.
Turn the BALANCE control of the control amplifier to the extreme right and left to check for
correct placement of the right and left channels.
With the system playing, move the TAPE MONITOR or TAPE FUNCTION switch on your integrated
amplifier, receiver, or preamplifier to the MONITOR or “ON” position. The sound should stop. This
TAPE MONITOR switch on your integrated amplifier, preamplifier or receiver should be left in this
position. If the sound does not stop, recheck Steps a through I.
Place the Equalizer TAPE switch in the NORMAL position. The sound should return. If the sound
does not return, and the Equalizer pilot light is on, then the Equalizer is probably connected in-
correctly. Recheck Steps a through |.
NOTE: If the TAPE MONITOR switch of your control amplifier is later switched out, the system
will continue to play but the Equalizer will no longer be functioning in the circuit. Since the system
will be playing and the Equalizer pilot light will be on, it will be possible, especially at low-volume
leyels or with certain musical selections, for you to be unaware that the Equalizer has been removed
from the circuit. Check the TAPE MONITOR switch on your control equipment periodically to
make certain it is still in the ON position.
If you do not have a tape recorder, the installation of the 901 system is now complete, and the system
is operating properly. If you do have a tape recorder, its connection to the system will be explained
in Section III D.

ALTERNATE METHOD |
(Using
PRE-AMP
OUT
and
MAIN
IN
Connections
with
Receivers
or
Integrated
Amplifiers
[Refer
to
Fig.
4.]
)
TAPE RECORDER CONNECTIONS
PRE-AMP MAIN-AMP
RECEIVER
FIG. 4
An
alternate
method
of
connecting
the
BOSE
Active
Equalizer
makes
use
of
the
PRE-AMP
OUT
and
MAIN
IN
jacks
provided
by
many
manufacturers
on
their
receivers
or
integrated
amplifiers.
To
do
this
refer
to
your
receiver
and
integrated
amplifier
owner’s
instruction
manual
for
separating
the
main
and
preamplifier
sections
of
their
units.
(This
is
usually
accomplished
by
removing
shorting
wires
or
plugs
and/or
moving
a
slide
switch).
Connect
the
PRE-AMP
OUT
terminals
to
the
Equalizer
INPUT
terminals,
and
connect
the
EQUALIZER
OUTPUT
terminals
to
the
MAIN
IN
terminals
of
the
receiver
or
integrated
amplifier.
With
this
method
of
connection,
leave
the
TAPE
switch
on
the
Equalizer
in
the
NORMAL
position.
Tape
re-
corders
are
connected
to
the
receiver
or
amplifier
in
the
conventional
manner.
The
disadvantage
of
this
method
of
connection
is
that
it is
difficult
to
use
conventional
speakers
or
headphones,
because
the
Equal-
izer
is
always
in
the
circuit.
ALTERNATE METHOD II
(Using
separate
PREAMPLIFIERS
and
POWER
AMPLIFIERS)
TAPE RECORDER CONNECTIONS] AMPLIFIER CONMECTIONS
OUTPUT
PRE
AMPLIFIER
MAIN-AMP
FIG. 5
The
Equalizer
can
be
connected
in
systems
that
include
separate
preamplifiers
and
power
amplifiers,
between
the
preamplifier
and
power
amplifier
(See
Fig.
5).
The
advantage
of
this
method
of
connection
is
that
the
tape
monitor
functions
of
the
preamplifier
are
still
available
for
connection
to
a
tape
recorder
in
the
conventional
manner.
One
disadvantage
of
this
method
of
connection
is
that
it
is
difficult
to
use
an
additional
pair
of
conventional
loudspeakers
or
headphones
because
the
Equalizer
is
permanently
in
the
circuit.
It
is
advisable
with
most
power
amplifiers
having
gain
controls
that
these
controls
be
turned
fully
clockwise
(consult
your
amplifier
manufacturer’s
owner's
manual
for
recommendations).

ed before the final stage of amplifica-
ally, the Equalizer should be connected
prevent any possible overloading of the
ilable, we suggest carefully reading the
garding system connection. How you
of the Equalizer and/or your associated
Series I
REFER SERVICING TO E]
maa
FIG. 6
Since
the
Active
Equalizer
has
been
connected
to
what
are
normally
the
tape
recorder
terminals
of
your
integrated
amplifier,
preamplifier,
or
receiver,
extra
terminals
are
provided
on
the
Equalizer
for
the
connection
of
a
tape
recorder.
Follow
the
next
five
steps
carefully:
(Refer
to
Fig.
6.)
a. Turn all power off.
b.
Connect
the
RIGHT
channel
TAPE
IN
terminal
on
the
Equalizer
to
the
RIGHT
or
“B”
channel
w
OUTPUT
terminal
on
the
tape
recorder.
ë:
Similarly,
connect
the
LEFT
channel
TAPE
IN
terminal
on
the
Equalizer
to
the
LEFT
or
“A”
channel
OUTPUT
terminal
of
the
tape
recorder.
d.
Connect
the
RIGHT
channel
TAPE
OUT
terminal
on
the
Equalizer
to
the
RIGHT
or
“B”
channel
INPUT
(or
LINE
IN)
terminal
of
the
recorder.
e.
Similarly,
connect
the
LEFT
channel
TAPE
OUT
terminal
on
the
Equalizer
to
the
LEFT
or
“A”
channel
INPUT
(or
LINE
IN)
terminal
on
the
recorder.
Installation
of
the
tape
recorder
is
now
complete.
To
play
the
tape
recorder,
simply
place
the
TAPE
switch
on
the
901
Active
Equalizer
in
the
MONITOR
Position
(down).
A å M
CONTROL
AMPLIFIERS
HAVING
TWO
TAPE
MONITOR
CIRCUITS
Many
modern
preamplifiers,
integrated
amplifiers,
and
receivers
have
two
tape
monitor
functions
providing
the
same
monitoring
features
for
two
tape
recorders
instead
of
one.
However,
most
of
these
controls
are
constructed
to
prevent
both
monitoring
switches
from
being
turned
on
or
“activated”
at
the
same
time.
Since
the
BOSE
Active
Equalizer
must
be
in
the
circuit
while
the
901
speakers
are
being
used,
connecting
the
Equalizer
in
either
TAPE
1
or
TAPE
2
will
require
connecting
your
tape
recorder
to
the
BOSE
Equalizer
tape
monitor
circuit,
not
the
unused
TAPE
monitor
position
found
on
your
control
amplifier.
av

a M
D.
4. ALTERNATE METHOD IlI
(Using FOUR-CHANNEL DECODERS)
As
previously
stated,
the
BOSE
Active
Equalizer
should
be
connected
before
the
final
stage
of
amplifica-
tion
of
the
amplifier
channels
powering
the
901
speakers.
Additionally,
the
Equalizer
should
be
connected
at
a
point
in
the
signal
path
following
the
four-channel
decoder
to
prevent
any
possible
overloading
of
the
decoding
equipment.
Because
of
the
many
different
decoders
available,
we
suggest
carefully
reading
the
owner's
instruction
manuals
of
all
of
the
associated
equipment
regarding
system
connection.
How
you
connect
the
decoder
will
depend
upon
your
own
needs
for
control
of
the
Equalizer
and/or
your
associated
equipment.
CONNECTING A TAPE RECORDER
ROR RRR
CS PO
W x a ion
KX
REONORR SIR RRN
‘BOSE CORPORATION
"AMPLIFIER CONNECTIONS.
FIG. 6
Since
the
Active
Equalizer
has
been
connected
to
what
are
normally
the
tape
recorder
terminals
of
your
integrated
amplifier,
preamplifier,
or
receiver,
extra
terminals
are
provided
on
the
Equalizer
for
the
connection
of
a
tape
recorder.
Follow
the
next
five
steps
carefully:
(Refer
to
Fig.
6.)
a.
b.
Turn all power off.
Connect
the
RIGHT
channel
TAPE
IN
terminal
on
the
Equalizer
to
the
RIGHT
or
“B”
channel
OUTPUT
terminal
on
the
tape
recorder.
Similarly,
connect
the
LEFT
channel
TAPE
IN
terminal
on
the
Equalizer
to
the
LEFT
or
“A”
channel
OUTPUT
terminal
of
the
tape
recorder.
Connect
the
RIGHT
channel
TAPE
OUT
terminal
on
the
Equalizer
to
the
RIGHT
or
“B”
channel
INPUT
(or
LINE
IN)
terminal
of
the
recorder.
Similarly,
connect
the
LEFT
channel
TAPE
OUT
terminal
on
the
Equalizer
to
the
LEFT
or
“A”
channel
INPUT
(or
LINE
IN)
terminal
on
the
recorder.
Installation
of
the
tape
recorder
is
now
complete.
To
play
the
tape
recorder,
simply
place
the
TAPE
switch
on
the
901
Active
Equalizer
in
the
MONITOR
position
(down).
CONTROL
AMPLIFIERS
HAVING
TWO
TAPE
MONITOR
CIRCUITS
Many
modern
preamplifiers,
integrated
amplifiers,
and
receivers
have
two
tape
monitor
functions
providing
the
same
monitoring
features
for
two
tape
recorders
instead
of
one.
However,
most
of
these
controls
are
constructed
to
prevent
both
monitoring
switches
from
being
turned
on
or
“activated”
at
the
same
time.
Since
the
BOSE
Active
Equalizer
must
be
in
the
circuit
while
the
901
speakers
are
being
used,
connecting
the
Equalizer
in
either
TAPE
1
or
TAPE
2
will
require
connecting
your
tape
recorder
to
the
BOSE
Equalizer
tape
monitor
circuit,
not
the
unused
TAPE
monitor
position
found
on
your
control
amplifier.
eF