JBL BASS-2 Service manual

Bass2/Basswave

Powered Subwoofer

TECHNICAL MANUAL

JBL Consumer Products Inc.
80 Crossways Park West
Woodbury, N.Y. 11797
1-800-336-4JBL in the USA

A Harman International Company

Part No.: 1112-BASS2/BASSWAVE

Powered Subwoofer BASS2/BASSWAVE

TABLE OF CONTENTS

Specifications .................................................................1

Features..........................................................................1

Disassembly Procedures................................................2

Packaging Exploded View .............................................2

Bass2/Basswave Exploded View...................................3

SPECIFICATIONS

Nominal Impedance: ........4ohm

Amplifier Power: ...........100W Continuous

Sensitivity: ...............90dBSPL*

Crossover Frequency: .......120Hz(Nominal)

Frequency Response: .......40Hzto120Hz(+/-3 dB)

Amplifier Input Impedance: ....48kohm(Line)/1k ohm (Speaker)

Aural Sweep Test Specifications:

A. System Aural Sweep Test: . . 5.0V Input, 10 Hz to 1 kHz

B. L.F. Aural Sweep Test: ....5.0V Input, 10 Hz to 1 kHz

Test Procedure...............................................................4

Wiring Diagram...............................................................5

Parts Lists.......................................................................6

Integrated Circuit Diagrams ...........................................7

Schematic Diagrams .....................................................8

External Dimensions

Height ..................28.17" (716mm)

Width ...................10.25" (260mm)

Depth...................12.05" (306mm)

Shipping Weight ...........32lbs(14.5 kg)

*1 Watt @ 1 Meter

FEATURES

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The Bass2/Basswave powered subwoofer is part of the
MUSIC 2 System.

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100 watt output.

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Variable level control.

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Line level and speaker level inputs.

* Early versions of the Bass2/Basswave will cycle into a standby mode when the signal source is absent after a
predetermined time; the green LED turns OFF when this happens on the 120 volt version, the LED cycles to RED on
the 230 volt version. The subwoofer’s sensitivity to input signals was increased in later versions and these units stay
ON, even when the input signal is absent. This is a normal condition, and does not compromise the safety, integrity, or
dependability of the product in any way.

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User friendly auto on circuit. Signal sensing
automatically turns the subwoofer on so you don’t have
to; the subwoofer is meant to be left on without use of
a power switch*

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Speaker is magnetically shielded for use near televisions
or computer monitors.

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Powered Subwoofer BASS2/BASSWAVE

DISASSEMBLY PROCEDURE

To Access Amp. Circuit Boards

1. Remove (4) base screws; remove base.

2. Remove (2) large 1/4-20 Torx #30 amp

mounting screws from amplifier bottom.

3. Remove amp assembly from cabinet; unplug the

(2) output wires.

4. Remove the (4) Torx #15 screws from top plate.

5. Remove/scrap adhesive away from the strain

relief plug area in the top cover.

6. Pry strain relief plug from top cover; remove cover.

To Access Lower Woofer

1. Remove (4) base screws; remove base.

2. Remove (2) large 1/4-20 Torx #30 amp mounting

screws from amplifier bottom.

3. Remove amp assembly from cabinet.

4. Unplug the (2) wires from woofer; remove the (4)

8 x 3/4 Phillips screws from the inner baffle.

NOTES:

1. The upper woofer is non-serviceable. Order

replacement cabinet/upper driver assy.
(Part # BASSWAVEENCLKIT)

2. A NEW AMP GASKET, (Part # 75140), between

amp and cabinet is recommended to ensure
airtight seal if the amplifier is removed for any
reason.

3. If amplifier is serviced for any reason: after the

strain relief plug is inserted back in top cover,
an adhesive, e.g. hot melt glue, silicon seal, epoxy
or similar product must be used on the strain relief
junction to ensure an air tight seal.

PACKAGING EXPLODED VIEW

5. Remove woofer.

JBL continually strives to improve its products.
New materials, production methods and design
refinements are introduced into existing models without
notice as a routine expression of our design philosophy.
For this reason, the Bass2/Basswave Subwoofer may
differ in some respect from its published specifications
and descriptions, but will always equal or exceed the
original specifications unless otherwise stated.

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Powered Subwoofer BASS2/BASSWAVE

BASS2/BASSWAVE EXPLODED VIEW

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Powered Subwoofer BASS2/BASSWAVE

TEST PROCEDURES

Equipment needed:

Functional/signal generator

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True RMS Multimeter

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Integrated amplifier

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Cables - line level (RCA) and speaker cables

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RCA Y-cable

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General Function

UUT = Unit Under Test

1.

Connect both right and left line level inputs (RCA)
to signal generator and UUT. Assure input
button is in depressed position. Use Y-cable if
necessary from mono source.

2. Turn on generator, adjust to 50 mV, 50 Hz . Plug

in UUT, turn level control full clockwise.

3. Green LED should light, immediate bass response

should be heard and felt from port tube openings.

4. Turn off generator, unplug unit, disconnect RCA

cables.

5. Connect two pair of speaker cables to high level

input terminal on UUT. Assure input button is in
extended (out) position. Cables should be
connected to an integrated amplifier fed by the signal
generator. Observe polarity of speaker cables.

buzzes or any other noises. If any unusual noises
are heard, remove driver and test.

Driver Function

1. Follow instructions on page 2 (To Access Lower

Woofer).

2. Check DC resistance of driver; it should be

approximately 5.2 ohms. Upper (non-removable)
driver can be checked by disconnecting both the
wires to the amplifier and the lower driver, then
connecting the test meter to the wires.

3. Connect a pair of speaker cables to driver terminals.

Cables should be connected to an integrated
amplifier fed by a signal generator. Turn on
generator and adjust so that speaker level output
is 4.0V .

4. Sweep generator from 20 Hz to 1KHz . Listen to

driver for any rubbing, buzzing, or other unusual
noises.

* The upper woofer in non-serviceable. Order
replacement cabinet/upper driver assy.
(Part#BASSWAVEENCLKIT). Also cone/diaphram
kits not available, defective drivers should be
replaced.

6. Turn on generator and adjust so that speaker level

output is 2.0V, 50 Hz . Plug in UUT, turn level
control full clockwise.

7. Green LED should light, immediate bass response

should be heard and felt from port tube openings.

Sweep Function

1. Connect both right and left line level inputs (RCA) to

signal generator and UUT. Assure input button is
in depressed position. Use Y-cable if necessary
from mono source.

2. Turn on generator, adjust to 50 mV. Plug in UUT,

turn level control full clockwise.

3. Green LED should light, immediate bass response

should be heard and felt from port tube openings.

4. Sweep generator from 20 Hz to 300 Hz. Listen to

the cabinet and drivers for any rattles, clicks,

Service Notes/Revisions

In the event you receive a unit with the complaint that
the unit shuts down after it is on for a while", usually
about 10-15 minutes. (Verify the R46 has not been
changed with a jumper already; then proceed with
modification of the amplifier unit).

This should be performed on units with circuit board
marked Rev. 001 to Rev. 003.

If you have found output devices Q4 or Q5 shorted,
replace with matched pairs only. This is critical for
proper amplifier operation.

Procedure: Locate R46 (33 ohm) and replace it with a
22 gauge jumper wire. After verifying normal turn-on,
load the amp with a 4 ohm watt resistor and apply a
70 Hz, 200 mV signal to one RCA input jack. Let the
amp run for about 20 minutes to confirm the amp no
longer shuts down.

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