BOSE 802 I Schematic
-BIISE7
802 Professional
Loudspeaker System
SPECIFICATIONS
GENERAL
The BOSE802 Professional Loudspeaker
System consists of two speaker enclosures (cabinets) and a separate Active
Equalizer. Each cabinet contains eight
identical high-efficiency, fUll-range
drivers. The drivers each have an impedance of one ohm and are wired in
series to give a system impedance of
eight ohms. The cabinet also includes
an Impedance Control Capacitor which
controls the system impedance at high
frequencies, reducing the amplifier
power requirements of the system.
Each driver has a molded, high-impact
polymer frame that reduces flux
leakage to maintain high efficiency.
The driver voice coils are made of flat
aluminum ribbon, edge-wound on an
aluminum bobbin for high efficiency
and high power handling ability. Each
driver has a 12-ounce ceramic magnet
for high efficiency and resistance to
demagnetization.
Each enclosure incorporates two Reac-
tive Air Columns that function to
reduce driver cone excursion at very
low frequencies. This allows the 802 to
produce high output levels at deep
bass' frequencies
distortion.
with a minimum of
The cabinet is composed of mica-filled,
high-density polyethylene structural
foam. This reinforced polymer material
combines light weight, high strength,
and impact resistance for ruggedness
in transportation.
The 802-E Equalizer adjusts the spec-
trum of the audio signal, permitting the
flat
802 system to provide broad,
quency response without using woofers,
horns, or crossover networks that cause
audible coloration. The Equalizer must
be used with the system to achieve
satisfactory performance.
fre-
EQUALIZER
Dimensions:
25.4 cm (10")
x 4.8 cm (1-7/8") H
Weight:
.738 Kg (1.6 Ibs.)
Input Impedance:
4 K ohms (balanced inputs),
50 K ohms (unbalanced inputs)
Output Level:
5 volts into 2 K ohms or higher,
3.5 volts
Gain:
(See Frequency Response Graph)
W x 12.7 cm (5") 0
into
600 ohms.
802-E
EQUALIZER
FREQUENCY
-l~OHt
30 40 60 100 ZOO
Power Requirement:
3.5 Watts, 110 V AC or
V AC (not available in
220
SPEAKER
Dimensions:
41 cm
400
600
FREOUENCY
SYSTEM
(16-1/8") x 51 cm (20-1/4")
x 34 em (13-1/4") with cover
Weight:
16 Kg (36 Ibs.)
Driver Complement:
4-1/2" full-range drivers
8
Impedance:
8 ohms
Magnet Weight:
2.7 Kg (96 ounces) total
Power Handling:
160 Watts continuous
Amplifier Power:
300 Watts maximum
RESPONSE
lkHt
2 :3 4 6 8 10 20
U.S.A.)
© 1979 Bose Corporation
Figure 1 SPEAKERSCHEMATIC
Figure 2 DRIVERPLACEMENT (FRONT VIEW)
I. DISASSEMBLY PROCEDURE
1. GRILLE":'" Remove the two clinch
center. Carefully remove the grille and place in a safe location until needed for reassembly.
2. BACK PANEL - Remove drivers two (2)and three (3) to obtain access to the internal rear panel connections. This will provide access
for repairs associated with the internal connections of the back panel.
3. IMPEDANCE CONTROL NETWORK - Remove drivers two (2) and three (3) to obtain access to the impedance control assembly. This
will allow a continuity check of the bulb
nuts
and grille retainer holding the grille in place.
circuit
and a check of the wiring and impedance control capacitor.
Lift
the grille by pulling from the hole in the grille's
II. TEST PROCEDURE
1. CONTINUITY CHECK - An open driver may be detected by using an ohmmeter and checking continuity. Insert a phone jack in the rear
of the speaker and check continuity by carefully penetrating the black cement covering the flexible conductor on the surface of each
cone
with
Figures 1 and 2.
2. POWER CHECK - Using a 50-watt (20 volt) sine wave signal, sweep the range between 40 and 200 Hz. Check for rattles, buzzing or
voice coil rubbing. Reduce the
ing a sine wave signal on the 802 Speaker System, do not operate the speaker below 80 Hz at levels greater than 20 watts (12.6volts) as
possible damage to the drivers may occur.
3. PHASING CHECK - Using a 6- to 20-volt battery or DC power supply, check that all speakers are in phase (moving together). Connect
the positive portion of the power supply to the
"sleeve" terminal of the phone jack. This will produce an outward motion of all drivers. See Figure 1.
4. IMPEDANCE CONTROL NETWORK - Check the bulb circuitry and wiring of the impedance control circuitry by using an 8 kHz sine
wave signal at 2V RMS
Insert a 0.5 ohm ± 1% resistor in series with the ground lead for the speaker. A voltage drop of 60-77 mV RMS should be measured
across the resistor. If incorrect, check the bulb(s) and capacitor.
an ohmmeter lead. Check continuity between each driver and the speaker terminals until the open driver is detected. See
output
to 5 watts (6.5 volts), and continue to sweep the range between 200 and 16,000 Hz. Note: When us-
"tip"
terminal of the phone jack and the ground connection of the power supply to the
± 1%.
III. SERVICE NOTES
1. When replacing 802 drivers, be certain to use the 802 driver gasket (Part number 110943)to properly seal the driver to the 802 cabinet.
2. Check the coupling control inserts for dirt or dust. If they are clogged, replace them with the spares provided in the top cover of the 802
speaker. Extra coupling control inserts may be obtained through the BOSE Customer Service Department or your BOSE Professional
Products Dealer. One of the unusual features of the 802 is the use of the coupling control inserts. These are polyester
which are installed in the Reactive
of the system.
After
prolonged use, these inserts and their gauze covers may become plugged with dirt or dust, causing them to lose their effec-
tiveness. This results in a
The inserts may be easily removed for inspection or replacement (two spare sets of inserts are supplied with the 802): (See Figure 3):
a. Remove the two clinch nuts by rotating them counter-clockwise.
b. Remove the grille retainer and the grille.
c. Remove the two column extenders by pinching both release tabs and pulling gently. Do not use sharp tools as they could damage
the
thin
seal lip.
d. Remove the snap caps from the column extenders by prying them
e. Examine the coupling control inserts for
f. Wash the gauze-covered ends of the column extenders by swishing them around in warm, soapy water. Rinse in clear water and
allow them to air-dry thoroughly.
g. Reassemble the system by reversing the above procedure, pushing the column extenders in firmly until they snap into place.
Be certain to center the grille retainer before tightening the clinch nuts. Tighten the clinch nuts
h. Extra coupling control inserts may be obtained through the BOSE Customer Service Department or your BOSE Professional Pro-
ducts Dealer.
This is the only periodic maintenance required by the 802 system.
"buzzing"
Air
Columns. Their purpose is to decouple the drivers from one another near the resonant frequency
sound during heavy bass passages.
off
gently with your fingernails.
dirt
or dust. If they are clogged, replace them with the spares provided.
firmly
but
not
"fuzz"
excessively.
discs
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