Quick Troubleshooting Guide

Quick Troubleshooting Guide
Passionate About Sound
Quick Troubleshooting Guide
Product Model:
Product Series:
Document #:
Initial Release:
Revised Release:
Revision:
KW122, KW152, KW153, KW181
KW Series Powered Loudspeakers
TD-000386-00
April 2012
November 2013
B
QSC Audio Products, LLC
Technical Services Group
Costa Mesa, CA 92626 USA
www.qsc.com
www.qscservice.com
Table of Contents
1.Introduction................................................................................................................................................................................... 3
General service information........................................................................................................................................................................................................... 3
2. Disassembly Procedures............................................................................................................................................................... 4
Removing Amplifier Module from the Cabinet............................................................................................................................................................................ 4
Removing or Replacing PCBs from Amplifier Module................................................................................................................................................................ 4
3. Most Common Failures.................................................................................................................................................................. 6
Broken Components and Power Issues........................................................................................................................................................................................ 6
Preamp Switch IC Failure................................................................................................................................................................................................................ 8
Inconsistent fan behavior among models.................................................................................................................................................................................... 9
4. Commonly Replaced Parts.......................................................................................................................................................... 10
Amplifier Module Replacements...................................................................................................................................................................................................10
Spare Parts.......................................................................................................................................................................................................................................11
5. Specification Sheet...................................................................................................................................................................... 12
2
QSC Audio Products, LLC
1. Introduction
General service information
The information and procedures in this troubleshooting guide is intended to assist a qualified technician or QSC Authorized
Service Center with only the most common or basic repairs found in QSC product. This guide is meant to quickly diagnose
and repair a problem without extreme investigation. If more advanced help is needed, please refer to the more complete
QSC Service Manual.
Contact QSC Technical Services to make sure you have the most up-to-date service bulletins, schematics, and parts lists for
QSC product. Service materials may be distributed in hard copy, via fax, and electronically (Adobe Acrobat PDF) via CDROMs, FTP from the QSC web site (www.qscaudio.com), and e-mail.
Ordering parts for service
Customers and service facilities in the US may purchase parts for service directly from QSC TSG. In other countries, please
contact your QSC distributor. You will need a complete QSC part number when ordering parts; this manual includes parts
lists along with exploded assembly diagrams and schematics. For the convenience of our US customers, QSC maintains a
parts website located at: http://www.qscparts.com/ (for shipment to US destinations only).
If you cannot find a part number or have trouble ordering from the website, please call QSC toll-free at 1-800-772-2834
(within USA only).
Tools Required for Amplifier Repairs:
•
•
•
•
•
•
Digital multimeter (DMM) with RMS AC voltage and current
Digital clamp-on ammeter
Dual-trace oscilloscope
Low-distortion audio sine wave generator
Audio distortion analyzer
Bank of non-inductive load resistors, configurable as 8 ohms (min.
1500 watts capacity), 4 ohms (min. 3000 watts), and 2 ohms (min.
4000 watts)*. See Figure 1.1.
• Variable AC voltage source, such as a Variac™ or Powerstat® variable
transformer; rated up to 50A for high-power amplifier repairs such as
QSC PL380*
• Phillips and flat head screwdriver (electric recommended)
• Soldering iron and solder suitable for electronics
• Desoldering equipment or desoldering braid
• Hex nut driver set, 1/2” and 7/16”
• Desoldering equipment or desoldering braid
Figure 1.1: Typical load bank for testing QSC amplifiers
• Basic tools for electronic repair including various pliers, wire-cutters,
strippers, and crimpers.
* These are maximum values only. Lower-power amplifier repairs do not need to meet these requirements.
Tools required for loudspeaker repairs
•
•
•
•
•
•
Low-distortion audio sine wave generator
Phillips and flat head screwdriver (electric recommended)
Soldering iron and solder suitable for electronics
Desoldering equipment or desoldering braid
Hot glue or plastic tie-wraps
Basic hand tools for electronic repair, including various pliers, wire-cutters, strippers, and crimpers.
Table 1.1. Load resistor bank switch truth table
SW1
SW2
SW3
SW4
∞Ω (no load)
OFF
•
•
•
8Ω
ON
OFF
OFF
OFF
4Ω
ON
ON
OFF
OFF
2Ω
ON
ON
ON
OFF
0Ω (short circuit)
ON
•
•
ON
CAUTION: Always wear safety glasses when servicing power amplifiers or powered
loudspeakers.
TD-0000386-00 rev. B
KW Series Quick Troubleshooting Guide
3
2. Disassembly Procedures
Many service procedures for the KW Series loudspeakers will require some degree of disassembly. Use these guides to
ensure it is done properly. The loudspeakers were designed to be serviceable, so most parts or assemblies—modules and
printed circuit boards (PCBs)—are easily replaceable.
Removing Amplifier Module from the Cabinet
1. Unplug the power cord from the loudspeaker. Set the loudspeaker face down on a pad or cushion to protect the grille
and finish.
2. Remove the 10 screws that fasten the amplifier module to the enclosure.
3. Lift the amplifier module out of the enclosure. You may need to use a putty knife or similar object to pry the amplifier
out.
4. Detach the multi-pin connector from the rear of the amplifier module as in Figure 1.3.
Figure 1.2. You can use a putty knife to pry the
amplifier module out of the cabinet.
Figure 1.3. Disconnect this one connector before you completely pull the amplifier module
out.
Removing or Replacing PCBs from Amplifier Module
Initial disassembly
1. Remove the amplifier module as described above in “Removing Amplifier
Module from the Enclosure”.
2. Set the module on a work surface and remove the 12 screws around the perimeter
of the faceplate, as shown in Figure 1.4.
3. Gently lift the faceplate up with a small flat
head screwdriver or similar tool. To release
the ribbon cable, press down on the white
housing of connector J2B (see Figure 1.5).
Do not pull up forcefully on the ribbon
cable. It should come out easily if you
press the housing firmly.
4. Remove the EMI shield (the shiny box at
the top right of Figure 1.5). It is fastened
with four screws.
4
Figure 1.4. Removing the 12 screws from the faceplate.
QSC Audio Products, LLC
5. Detach the two AC power wires from J14 (brown wire) and J15
(blue wire). This will separate the boards from each other, as shown
in Figure 1.6.
Figure 1.5. Place pressure on the ribbon connector to release the cable.JPG
Removing the Input and DSP PCB
1. Remove the 4 screws that secure the PCB to the rear of the faceplate. Remove all of the screws that secure the XLR
and RCA connectors to the faceplate as in Figure 1.7.
2. Remove the knobs and disconnect the fan. You may now completely remove the PCB from the faceplate.
Removing the Power Supply and Output PCB
1. Remove the 11 mounting screws from the PCB. Carefully lift the board out of the chassis “bucket”. Be careful of the
thermal grease on the underside and on the bucket surface.
Figure 1.7. There are many screws to unfasten
to remove the input & DSP board.
Figure 1.6. The input board faceplate and line filter shield removed
from the amplifier chassis.
TD-0000386-00 rev. B
KW Series Quick Troubleshooting Guide
5
3. Most Common Failures
Broken Components and Power Issues
Speakers and the parts inside them naturally resonate at certain frequencies. Because of vibration issues on the PCB, the KW122 is seen to
have more broken components than other KW Series models. The leads
of the power devices mounted between the PCB and cast-aluminum
bucket are known to break more frequently on the KW122. In all KW
models, the components that typically break are located in the AC line
filter and are heavily weighted components like inductors. In some cases,
AC arcing can burn the PCB and it will have to be replaced.
Symptoms:
No power, dead, intermittent power, smoke/fire, turns off while playing
music, turns off at low frequency peaks
Actions:
Deciding whether to replace or repair the amplifier module depends on
what serial number the loudspeaker has. The first two digits of the s/n
are the month. The second two digits of the s/n are the year. Figure 1.8. The lead on this component has
broken. This was found by melting the solder
joint on the PCB.
Verify which component has a broken lead
1. Remove the amplifier module as described in “Removing Amplifier
Module from the Cabinet” on page 5.
2. Remove the power supply and output PCB as described in “Removing the Power Supply and Output PCB” on page 5.
3. Visually inspect the PCB and electronics for any damage. If any
of the large electrolytic capacitors (mainly C135 and C136) have
bulged or have bursted open please replace the amplifier module
with a new one.
4. Check that the power supply and amp section FETs are not at fault.
This can be done by checking for short circuits across Q13, Q14,
Q2, Q3, Q4, and Q5. These components are mounted from the
bottom of the PCB . If any of these FETs are shorted, do not proceed
below. Please repair or replace the PCB.
Figure 1.9. The common locations to check for
broken leads.
5. Check the following components below for lead breaks. The easiest
way to do this is to heat up the leads from the bottom of the board with a soldering iron. A broken lead will be very
obvious when heated up with solder. Please review the Action column below.
6
Board reference
Description
QSC Part #
Action
L11, L12
Inductor 4mH 4pin
XF-000376-00
Replace component
R140
NTC Resistor 2.5 ohm
RE-000300-NR
Replace component
C45 (on INPUT board)
Capacitor 1000uF 25V
CA-810010-10
Replace component
T2
Transformer
XF-000362-00
Replace module
Q13
MOSFET STP11NM60FD
QD-000376-00
Replace module
Q14
MOSFET STW23NM60
QD-000284-00
Replace module
D33, D34
Diode FFP08S60S
QD-000391-00
Replace module
Q2, Q3, Q4, Q5
MOSFET IRFB4020
QD-000373-00
Replace module
QSC Audio Products, LLC
If the action states “replace component” then follow the steps below. Replace the module if the action states to do so.
6. If you find a device with a broken lead, unsolder all its leads and remove it from the board. If there is any adhesive left
on the PCB, scrape it off with a knife while being careful not to destroy any traces beneath. This will prepare the surface
for a new application of adhesive.
7. Do not attempt to repair a damaged inductor or transformer, such as by reattaching the broken lead or by fashioning a
new lead by unwinding some coils of the remaining wire; always replace it with a new component.
8. Apply adhesive to the mounting surface of the new component and apply it to the PCB. Solder the leads well and trim
them if necessary. Replace the part only with a new one.
9. Perform a quick check for continuity on the whole AC line-filter using a DMM set to diode-check mode:
Apply the positive probe of the DMM to PRI_LO and with the negative probe, check both of the AC lines, “hot” (at J14)
and neutral (at J15). The DMM should read approximately 0.48 V on both points.
Figure 1.10. Broken inductor L12
Figure 1.11. Reheating the leads with solder
will expose any broken leads
Re-install PCB assembly
10. Re-install the PCB assembly into the chassis and fasten it with all the screws and hardware (10 short screws, 2 longer
screws with spring and spring seat). Reconnect the AC wires at J14 (brown) and J15 (blue). Make sure that the ribbon
cable is oriented properly when you place it back into connector J2B. You might have to press down on J2B to insert
the ribbon cable properly.
11. After the amplifier module is reassembled, check its power-up sequence. Connect the power cord to the amplifier and
plug it into the variable AC source. Slowly ramp up the AC voltage to 120 V. (Monitor the current during this ramp-up
and if it exceeds 0.5 A at any point, turn the AC off and troubleshoot the amplifier.)
When the amplifier turns on, the LEDs should light in this sequence:
• RED (limit)
• GREEN (standby)
• BLUE (power)
12. Plug the wiring harness into the connector on the amplifier module. Place the module back into the speaker enclosure
and tighten all ten screws with a light-medium torque.
13. Plug a low-distortion audio sine wave generator into a 1/4” or XLR input connection on the amplifier module. Gradually
sweep the frequency from 20 Hz to 20 kHz. All frequencies should be audible and free of distortion or rattling. You
should notice the sound crossing over from the woofer to the horn at about 2 kHz. The amplifier should not shut off
during the sweep, especially at lower frequencies were the electronic components might naturally vibrate.
TD-0000386-00 rev. B
KW Series Quick Troubleshooting Guide
7
Preamp Switch IC Failure
Lack of protection on mic preamp switch IC U21 and U22 can cause the IC to become damaged when transient voltages
come in through the input line of channel A. Resistors R102 and R103 also become burned when the IC fails. The PCB
has been updated to include a schottky diode clamp to the 15V rails for protection. Older models of the KW series can still
experience this problem.
Symptoms:
No audio, heavily disorted audio, red limit led on when signal is present, turning the mic switch without input turns on the
red limit led
Actions:
A component-level repair is not necessary for this failure. Please follow the instructions below.
Determine the failure exists
1. Plug in the AC cord and turn on the amplifier. Without anything else connected to the amplifier module, turn the Mic
switch all the way to 36dB. If you see the RED limit LED turn on, then IC U21 and U22 have most likely failed.
2. Remove the gain knob of Channel B. From here you can inspect resistors R102 and R103. Most likely they will be
burned or measure out of range. Good resistors should measure 21W. If the resistors are burned, the module should
be replaced with a new one.
Replace the amplifier module
3. Remove the amplifier module as described in “Removing Amplifier Module from the Cabinet” on page 5.
4. Prepare the new amplifier module. Plug in the wiring harness into the connector on the back of the amplifier. Place the
amplifier back into the speaker enclosure and tighten the 10 screws at a light-medium torque level.
5. Using a low distortion audio sine wave generator, plug into the 1/4” or XLR connection on the amplifier and adjust the
frequency from 20Hz to 20KHz. All frequencies should be audible without distortion or rattling with a noticeable crossover frequency at 2KHz. The amplifier should not turn off during the sweep, especially at lower frequencies were the
electrical components naturally vibrate.
Figure 1.12. It is common for these resistors to
burn when a mic switch IC fails.
8
Figure 1.13. The mic switch ICs can fail and
short it’s supply rails.
QSC Audio Products, LLC
Inconsistent fan behavior among models
Class-D amplifiers (like the one in the K and KW series) are very efficient - meaning a high percentage of the power produced by the amplifier is sent to the drivers themselves. A very low percentage of this power is wasted via heat. Because of
this, the fan doesn’t need to turn on in many situations. The only time you will begin to need the fan is when the amplifier
is working very hard and the ambient temperature outside of the speaker is high.
Depending on the serial date code of the speaker, the fan behavior may be different between two speakers. A firmware
change was made to the K and KW series that affects fan behavior in the speakers. If the firmware is “older”, the fan will
spin at idle no matter what temperature the amplifier module is. If the firmware is “newer”, the fan will only spin when the
temperature of the amplifier module reaches a high level.
Symptoms:
Fan doesn’t spin when turned on, fan has different behavior than a similar speaker model or series
Action:
There is no action for this issue other than checking effective dates from the date code table below. Hardware changes
were also performed at the same time as the firmware changes. Programming a different firmware revision would affect
speaker performance. Changing the firmware is not a solution.
Model
Fan “always on” effective date
Fan “mostly off” effective date
KW122, KW152, KW153,
KW181
May 2010 — March 2011
April 2011 — current production
Serial range 0510xxxxx — 0311xxxxx
Serial range 0411xxxxx — current
Serial range GEAxxxxxx — GCBxxxxxx
Serial range GDBxxxxxx — current
TD-0000386-00 rev. B
KW Series Quick Troubleshooting Guide
9
4. Commonly Replaced Parts
Important Note: QSC has switched the high frequency transducer on KW Series loudspeakers from one with a neodymium
magnet to one made of ferrite. Because the two transducers have different performance characteristics, the DSP firmware
in the amplifier module was revised to optimize the new one. QSC supports servicing loudspeakers with either type of HF
transducer by providing both versions of the amplifier module and its PCB assembly.
Whenever servicing either the amplifier module or the HF transducer on the KW122, KW152, or KW153 loudspeakers, it is
important to match the transducers and amplifier modules properly. Always verify which transducer is installed, and use the
manufacturing date code in the loudspeaker’s serial number to determine what firmware version was originally loaded in
the amplifier module at the factory. More info about this change is available in service bulletin KWS0004.
Amplifier Module Replacements
The amplifier module includes both PCB assemblies mounted to the chassis. It’s a complete drop-in module replacement.
Table 1. KW loudspeakers with DSP for ferrite transducer (XD-000027-00)
Table 2. KW loudspeakers with DSP for neodymium
transducer (SP-000184-00)
Model
Model
Serial Number Range
Module Part #
Serial Number Range
Module Part #
China
China
KW122 GKCxxxxxx and newer WP-212204-10
KW122 GJCxxxxxx and older
WP-212204-00
KW152 GLCxxxxxx and newer
WP-215204-10
KW152 GKCxxxxxx and older
WP-215204-00
KW153 GBDxxxxxx and newer WP-215304-10
KW153 GADxxxxxx and older
WP-215304-00
KW181 no change
KW181 no change
WP-218104-00
WP-218104-00
USA
USA
KW122 0313xxxxx and newer WP-212204-10
KW122 0213xxxxx and older
WP-212204-00
KW152 0313xxxxx and newer WP-215204-10
KW152 0213xxxxx and older
WP-215204-00
KW153 0313xxxxx and newer WP-215304-10
KW153 0213xxxxx and older
WP-215304-00
KW181 no change
KW181 no change
WP-218104-00
WP-218104-00
PCB Replacements
The PCB replacement includes both input/display/DSP and supply/output boards. QSC does not have separate part numbers for each board. They must be ordered together.
10
Table 3. KW loudspeakers with DSP for ferrite transducer (XD-000027-00)
Table 4. KW loudspeakers with DSP for neodymium
transducer (SP-000184-00)
Model
Model
Serial Number Range
PCB Module Part #
Serial Number Range
PCB Module Part #
China
China
KW122 GKCxxxxxx and newer WP-212202-10
KW122 GJCxxxxxx and older
WP-212202-00
KW152 GLCxxxxxx and newer
WP-215202-10
KW152 GKCxxxxxx and older
WP-215202-00
KW153 GBDxxxxxx and newer WP-215302-10
KW153 GADxxxxxx and older
WP-215302-00
KW181 no change
KW181 no change
WP-218102-00
WP-218102-00
USA
USA
KW122 0313xxxxx and newer WP-212202-10
KW122 0213xxxxx and older
WP-212202-00
KW152 0313xxxxx and newer WP-215202-10
KW152 0213xxxxx and older
WP-215202-00
KW153 0313xxxxx and newer WP-215302-10
KW153 0213xxxxx and older
WP-215302-00
KW181 no change
KW181 no change
WP-218102-00
WP-218102-00
QSC Audio Products, LLC
Spare Parts
Description
QSC Part #
Reference Designator
RCA Input Jack
CO-000371-00
J12
IEC AC Input Jack
CO-000386-00
Combo XLR 1/4" Input Jack (non-locking)
CO-000414-00
J8, J10
Combo XLR 1/4” Input Jack (locking)
CO-000168-00
J8, J10
XLR Output Jack
CO-000421-00
J9, J11, J13
Wire Trap Connector 10 Position White
CO-000426-00
J2B
IC Opamp MC33078
IC-000048-30
U14, U17
Temp Sensor LM19 3-pin
IC-000315-00
U9
Knob, all models
PL-000636-00
Fuse 10A 250V
MS-10.250-FU
F1
Fuse 5A 24V (KW181 only)
MS-000128-30
F2
MOSFET STW26NM60 N-Channel
QD-000284-00
Q14
MOSFET IRFB4020 Output Device
QD-000373-00
Q2, Q3, Q4, Q5
MOSFET STP11NM60FD N-Channel
QD-000376-00
Q13
Diode FFP08S60S
QD-000391-00
D33, D34
NTC Resistor
RE-000300-NR
R140
AC Power Switch
SW-000088-GP
Switch 3 Position EQ/LED
SW-000112-00
SW1, SW2, SW3
Switch 4 Position, Rotary
SW-000182-00
SW4
Transformer Main
XF-000362-00
T2
Inductor 30 µH 2-pin
XF-000364-00
L1, L2
Inductor 4 mH
XF-000376-00
L11, L12
Inductor 774 µH 4-pin
XF-000391-00
L13
Amplifier Module Only
Loudspeaker Parts Only
KW181 Casters (Wheels, Swivel)
MS-000568-00
Grill Assembly w/ Logo KW122
WP-000390-TS
Grill Assembly w/ Logo KW152
WP-000391-TS
Grill Assembly w/ Logo KW153
WP-000392-TS
Grill Assembly w/ Logo KW181
WP-000393-TS
Front LED Blue
QD-000312-GP
LF Driver KW122
SP-000182-00
HF Driver KW122, KW152, KW153
SP-000184-00
HF Driver Diaphragm (all KW HF)
SR-000145-00
AC Power Cord 120V
WC-000361-GP
AC Power Cord 240V
WC-000362-GP
Wiring Harness KW122
WC-000513-00
Wiring Harness KW152
WC-000513-00
Wiring Harness KW153
WC-000514-00
Wiring Harness KW181
WC-000515-00
LED PCB Assembly Front
WP-212203-00
MF Driver KW153
XD-000001-00
LF Driver KW152
XD-000002-00
LF Driver KW181
XD-000005-00
TD-0000386-00 rev. B
KW Series Quick Troubleshooting Guide
For China build models only with GMYxxxxxx date codes
For USA built models only with MMYYxxxxx date codes
11
KW Series
Specifications
KW122
KW152
KW153
KW181
Configuration
12" 2-way multipurpose loudspeaker 15" 2-way trapezoidal loudspeaker
15" 3-way trapezoidal loudspeaker
18" subwoofer
Transducers
Low-frequency
Mid-frequency
High-frequency
12" cone transducer
—
1.75" diaphragm compression driver
15" cone transducer
—
1.75" diaphragm compression driver
15" cone transducer
6.5" mid range cone transducer
1.75" diaphragm compression driver
18" cone transducer
—
—
Frequency Response (-6 dB) 53 Hz – 18 kHz
47 Hz – 18 kHz
35 Hz – 18 kHz
40 Hz – 112 Hz
Frequency Range (-10 dB)
50 Hz – 20 kHz
44 Hz – 20 kHz
33 Hz – 20 kHz
37 Hz – 129 Hz
Nominal Coverage (-6 dB)
75° axisymmetric
60° axisymmetric
75° axisymmetric
—
131 dB peak
133 dB peak
134 dB peak
135 dB peak
1000 W Class D (500 W LF,
500 W MF/HF) continuous
1000 W Class D continuous
Maximum SPL
1
Amplifiers
Power Output 2
Input Impedance (Ω)
1000 W Class D (500 W LF, 500 W HF) continuous
Channel A XLR / ¼":
0
0
0
0
Mic gain setting
0 dB
+12 dB
+24 dB
+36 dB
Balanced
38k
10k
2.66k
660 Ω
Unbalanced
19k
5k
1.33k
330 Ω
XLR / ¼": 38k balanced / 19k unbalanced
Channel B XLR / ¼": 38k balanced / 19k unbalanced
Channel B RCA: 10k
Controls
Power • Gain A • Gain B • Channel A Input Gain (0 dB / 12 dB / 24 dB / 36 dB) •
LF Mode (Ext Sub / Norm/DEEP™) • HF Mode (Flat / Vocal Boost) Front LED (On / Off / Limit)
Power • Gain • LF Mode (Normal /
DEEP™) • Polarity (Normal / Reverse) •
Front LED (On / Off / Limit)
Indicators
Power • Signal A • Signal B • Standby • Limit • Mic (24 dB and 36 dB settings)
Power • Signal • Standby • Limit
Connectors
Balanced female XLR / ¼" line/mic level input • Balanced female XLR / ¼" line level input • Dual Balanced male
XLR full range line level out • Balanced male XLR “mix” out • Stereo RCA line level input • Remote gain control •
Locking IEC power connector
Dual balanced female XLR / ¼" line
level input • Dual Balanced male XLR
full range line level out • Remote gain
control • Locking IEC power connector
Cooling
On demand, 50 mm variable speed fan
Amplifier Protection
Thermal limiting • Output overcurrent • Overtemperature muting • GuardRail™
Transducer Protection
Thermal limiting • Excursion limiting
AC Power Input
Universal power supply 100 – 240 VAC, 50 – 60 Hz
AC Power Consumption 100 VAC, 2.3 A • 120 VAC, 2.01 A • 230 VAC, 1.13 A
1/8 Power
Enclosure
15 mm painted birch plywood
Finish
Black textured paint
Grille
Black powder coated 16 gauge steel
Dimensions (HWD)
26" x 15" x 15.4"
660 mm x 381 mm x 391 mm
32.1" x 17.5" x 15.2"
816 mm x 445 mm x 386 mm
43.1" x 18.5" x 16.8"
1094 mm x 470 mm x 427 mm
20.1" x 23.4" x 29.9" with casters
510 mm x 595 mm x 761 mm with casters
Weight (Net)
49 lb (22.2 kg)
64 lb (29 kg)
87 lb (39.5 kg)
83 lb (37.6 kg)
Available Accessories
KW SUS KIT 122 • KW122 COVER •
KW M10 KIT
KW152 COVER • KW M10 KIT
KW153 COVER • KW M10 KIT
KW181 COVER
1 For
2
comparison purposes and in accordance with common industry practice, maximum peak SPL specifications are theoretical calculations based upon transducer sensitivity and peak available amplifier power.
Independent of limiters and driver protection circuits.
Specifications subject to change without notice.
12
QSC Audio Products, LLC
Contact information
Quick troubleshooting guides and other service documents are available for download from www.qscservice.com. If you need any further information regarding this service procedure, please contact QSC Technical Services at the addresses or numbers below.
1-800-772-2834 (within USA only)
+1 (714) 957-7150
Fax:
+1 (714) 754-6173
Skype:qscaudio
E-mail:
[email protected]
Web sites:
www.qsc.com (product info)
www.qscservice.com (product service and service center support)
www.qscparts.com (accessory and replacement component sales)
Postal and parcel address: QSC Audio Products, LLC
Technical Services Group
1665 MacArthur Blvd.
Costa Mesa, CA 92626 USA
Telephone:
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