QSC Audio ISA 500T, ISA 300T, ISA 800T User Manual 2
n ISA 300T
n ISA 500T
n ISA 800T
ISA Series
Installed
Sound
Amplifiers
User Manual
n ISA 280
n ISA 450
n ISA 750
*TD-000093-00*
TD-000093-00 rev.C
ISA Audio Power Amplifiers
IMPORTANT SAFETY PRECAUTIONS
& EXPLANATION OF SYMBOLS
CAUTION
CAUTION: TO REDUCE THE RISK OF ELECTRIC
SHOCK, DO NOT REMOVE THE COVER. NO USER-
RISK OF ELECTRIC SHOCK
DO NOT OPEN
The lightning flash with arrowhead symbol within an equilateral triangle is intended to alert the user to the
presence of uninsulated “dangerous” voltage within the product’s enclosure that may be of sufficient
magnitude to constitute a risk of electric shock to humans.
The exclamation point within an equilateral triangle is intended to alert the user to the
presence of important operating and maintenance (servicing) instructions in this manual.
The lightning flashes printed next to the OUTPUT terminals of all ISA amplifiers are intended to alert the user
to the risk of hazardous energy. Output connectors that could pose a risk are marked with the lightning flash.
Do not touch output terminals while amplifier power is on. Make all connections with amplifier turned off.
SERVICEABLE PARTS INSIDE. REFER SERVICING
TO QUALIFIED PERSONNEL.
WARNING: TO PREVENT FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS
EQUIPMENT TO RAIN OR MOISTURE.
This amplifier has a serial number located on the rear panel.
Please write this and the model number down and keep them for your records.
Model: ISA ________________________________
Serial Number:______________________________
Date of Purchase:____________________________
Purchased From:_____________________________
FCC INTERFERENCE STATEMENT
NOTE: This equipment has been tested and found to comply with the limits for a class B digital device, pursuant to part
15 of the FCC rules. These limits are designed to provide reasonable protection against harmful interference in a
residential installation. This equipment generates, uses, and can radiate radio frequency energy and if not installed
and used in accordance to the instructions , may cause harmful interference to radio communications. However, there
is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful
interference to radio or television reception, which can be determined by switching the equipment off and on, the user
is encouraged to try to correct the interference by one or more of the following measures:
- Reorient or relocate the receiving antenna.
- Increase the separation between the equipment and the receiver.
- Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
- Consult the dealer or an experienced radio or TV technician for help.
© Copyright 2000, QSC Audio Products, Inc.
“QSC” and the QSC logo are registered with the U.S. Patent and Trademark Office
2
QSC® is a registered trademark of QSC Audio Products, Inc.
The Audio Precision logo is the property of Audio Precision, Beaverton OR
All trademarks are the property of their respective owners.
TABLE OF CONTENTS
INTRODUCTION:
ISA Series Overview .......................................................................................4
Front Panel Illustration .........................................................................................4
Rear Panel Illustrations ........................................................................................5
FEATURES & SETUP :
Power Switch ............................................................................................6
Cooling Air Inlet and Exhaust Vents ...............................................................6
LED Indicators ........................................................................................7
Gain Controls ........................................................................................8
Input Jacks ..........................................................................................8
DataPort V2 Connector ...................................................................................9
Stereo & Parallel Operating Modes ..................................................................10
Bridge Mono Operating Mode .......................................................................12
Low Frequency Filter ..........................................................................13
Frequency Response Curves ..................................................................14
Clip Limiter ........................................................................................15
Daisy Chaining to Other Devices from the DataPort V2 ................................9
DIP Switch Settings ...................................................................11
DIP Switch Settings ................................................................12
DIP Switch Settings ..............................................................13
DIP Switch Settings ...............................................................15
INSTALLATION:
Rack Mounting ....................................................................................16
Mounting Dimensions .........................................................................16
Cooling Requirements ........................................................................17
AC Mains (AC Power) ..............................................................................17
CONNECTIONS:
Inputs: XLR and Terminal Block Input Jacks ...............................................18
Inputs: DataPort V2 Connections and Notes ...........................................19
Outputs: Using the Screw Terminal Connections ............................................20
Outputs: Direct Low Impedance (2-16 ohm loads) ................................................21
Outputs: Distributed High Impedance (“T” models only) ..................................22
Power Sharing Between High and Low Impedance Outputs (“T” models only) .......24
Securing Output Wiring to the Chassis .................................................................25
OPERATION:
Gain Controls .........................................................................................................26
AC Power Switch .........................................................................................26
Front Panel LED Indicators ................................................................................26
Normal Operating Levels ......................................................................................26
APPLICATIONS:
General Notes, Distributed Line Principles .....................................................27
Low Frequency Filtering, Distributed Output Examples ........................................28
Multiple Low Impedance Loads in Series or Parallel Connections .........................30
DataPort V2 Application Information ...........................................................................32
TROUBLESHOOTING ........................................................................................................33
SPECIFICATIONS ......................................................................................................35
WARRANTY INFORMATION .............................................................................................39
HOW TO CONTACT QSC AUDIO PRODUCTS ............................................................................39
3
INTRODUCTION- INTRODUCTION AND FRONT PANEL ILLUSTRATION
Thank you for the purchase of your new ISA amplifier. To get
the most out of your amplifier, review this manual carefully. The
installation, connection and operation sections provide useful
guidelines to get you up and running quickly and correctly.
The QSC shipping box should contain:
1- The amplifier
2- This user manual
3- #14AWG AC line cord with IEC connector
After you have removed the amplifier from the box, make sure
you save the box and packing material for safely storing or
shipping the amplifier in the future.
The ISA Series amplifiers offer professional-quality performance at an affordable price. Three power-points are offered in
both directly-coupled and autotransformer-coupled output.
Output power at 2 ohms ranges from 430 to 1200 watts per
channel.
The ISA amplifier was designed to fit your installed sound
requirements. The detented gain controls, located on the rear
panel, provide accurate, repeatable adjustments. Each channel
has defeatable clip limiting and selectable-response low
frequency filters. QSC’s rear-to-front airflow cooling helps to
keep other system components in the equipment rack cooler,
enhancing overall system reliability.
For those systems with QSC DataPort accessories (DSP,
crossovers & filters, remote cinema monitoring) a DataPort V2
(version 2) is included on all ISA models. Consult your QSC
representative for accessory compatibility information.
The ISA amplifiers are easy to use. All operating mode
switches are grouped together on the rear panel. A mode
switch configuration chart is printed directly on the rear panel for
easy, accurate reference. This helps to avoid configuration
problems. On the autotransformer-coupled “T” models, separate
screw-terminal output connections are provided for both low
impedance loads and high impedance (25/70/100 volt) loads.
The “connectability” of the “T” models makes them simple to
use in almost any installed sound application.
The ISA amplifiers are built for long service life. XLR and
terminal block input connectors provide tight, noise-free
connections. The chassis design incorporates robust output
cable dressing tie-down points to keep stress off the connections, making them more reliable. All signal processing is done in
side loops and then returned to the main signal path. This
maintains high signal fidelity and provides a more robust system.
Your new ISA amplifier will give you many years of great
sound. It is the best value in installed sound amplification with
legendary QSC durability and performance.
FRONT PANEL
(all models)
4
1. Power indicator LED
2. Power switch
3. Clip and Signal indicator LEDs
4. Cooling air exhaust vents
5. Mounting holes for optional handles
6. Mounting holes for rack mounting
1. Gain Controls
2. Terminal Block Inputs
3. DataPort V2 Connector
4. XLR Inputs
FEATURES & SETUP- POWER SWITCH, COOLING AIR VENTS
The front panel of ISA series amplifiers is tailored for installed
sound. The power switch is the only front panel control; gain
controls are located on the rear panel to minimize control
tampering. LED indicators are provided for power, input signal
and to warn of clipping.
The power switch is a rocker-type switch. To turn the amplifier
on, push in on the top portion of the switch. To turn the amplifier
off, push in on the bottom portion of the switch.
The green power LED should light up when the switch is in the
on position.
When the power is switched off, the LED may takes several
seconds to go out; this is normal.
If the POWER LED fails to illuminate when the switch is in the ON position:
1- Check the AC cord and insure that both ends are fully inserted into their receptacles. If the power LED
still fails to illuminate,
2- Check the AC outlet for voltage with a circuit tester or known good device (lamp, etc.).
3- Check the AC circuit breaker on the rear panel of the amplifier. The illustration at the right shows the
circuit breaker in its normal (operating) position and its tripped position (amplifier AC power turned off by
protective circuit breaker).
If the circuit breaker opens repeatedly with nothing
connected to the amplifier and it is connected to the
proper AC source as labeled on the rear panel serial
number label, then the amplifier requires servicing
.
Keep the inlet and exhaust air vents clear of any obstructions. Insure
that the air exhausted from the vents has an exit from the equipment
enclosure.
Rear panel circuit breaker:
Normal operating position
Rear panel circuit breaker:
Tripped or open position;
press to reset.
Equipment enclosures with insufficient air flow will cause amplifier
overheating. Enclosures must allow fresh air to enter and hot air to
exit.
If dust builds up, clogging the vents, use a soft brush and a vacuum
cleaner to remove the dust. Use the brush to loosen the dust while the
vacuum is used to pull the dust away from the amplifier.
FEATURES & SETUP- LED INDICATORS
POWER: green LED that illuminates when the power
switch is set to the on position and AC power is present
at the IEC cord receptacle.
Normal indication:
nate at half-brightness for 2-3 seconds, then it illuminates to full-brightness.
at power-on the LED will illumi-
SIGNAL: green LED that lights up when the input
signal is strong enough to drive the output to about -40
dB from rated 8-ohm power.
Normal indication:
to strength of input signal.
varying brightness corresponding
If no indication:
items to check.
When power is switched off:
several seconds to extinguish (go out); this is normal.
If no indication:
connections and audio source. If audio source is
extremely low signal strength, signal LED may not
illuminate; this is normal but indicates that the input
signal strength should be increased.
Occasional illumination:
signal strength.
Illuminated dimly all the time with brighter
flashing:
Fully illuminated (on):
amplifier hard. Also, the clip indicator will probably
flash dimly with the beat of the program material and
brightly during extreme peaks in the material.
see previous page for suggested
the LED may take
check gain settings, input cables,
normal for weak input
normal for “average” input signal strength.
normal for “pushing” the
CLIP : red LED that illuminates when the amplifier
clips.
Normal indication:
output power peaks. Occasional clipping (once briefly
every few seconds) when operation at high power
levels is normal. At power-on, the clip LEDs may briefly
flash; this is normal.
Continuous operation at high power may trigger the
thermal protection circuitry, shutting down the amplifier
and fully illuminating the clip LED. Operation will
resume after the amplifier has cooled down sufficiently.
illumination briefly at extreme
If no indication:
very low output levels.
Occasional illumination:
briefly every few seconds) when operation at high
power levels is normal. Continuous operation at high
power may trigger the thermal protection circuitry,
shutting down the amplifier and fully illuminating the
clip LED.
Illuminated most of the time:
output of the amplifier and/or input signal to avoid
thermal shutdown of the amplifier and possible speaker
damage.
Fully illuminated (on):
down. Reduce gain settings or input signal and allow
the amp to cool down. Leave the power on so that the
fan continues to run; operation will automatically
resume after the amplifier has cooled sufficiently.
normal if the amplifier is operated at
Occasional clipping (once
Not normal; reduce the
Amplifier is in thermal shut
7
FEATURES & SETUP- GAIN CONTROLS & INPUT JACKS
GAIN CONTROLS-
The Gain controls are located on the rear panel to minimize
control tampering after installation. When viewing the amplifier
from the rear, they are on the left end, top and bottom, as shown
in the illustration to the right.
The Gain controls are detented (11 steps) for repeatable
adjustment. Surrounding the Gain control, the power attenuation level is shown in dB. To operate the Gain control, rotate the
control’s knob so that the desired level is achieved. There is a
detent in the knob to indicate its position.
Maximum gain depends on the model, see chart, below.
MAXIMUM VOLTAGE GAIN BY MODEL
ISA 280, 300T 30.5 dB
ISA 450, 500T 33.0 dB
ISA 750, 800T 35.0 dB
FEATURES & SETUP- DATAPORT V2
DATAPORT V2-
What It Is- The DataPort V2 is used for connection to optional
QSC DataPort accessories. DataPort accessory devices can
provide remote cinema monitoring, DSP, filter and crossover
functions.
The “V2” DataPort connection is a “version-2” of QSC’s original
DataPort. It has a reduced feature set from the original, while
maintaining essential amplifier monitoring capability.
supply +15 VDC power required by some DataPort accessories.
It does not
FEATURES & SETUP- STEREO & PARALLEL OPERATING MODES
STEREO:
Each input signal is sent to its respective channel. Each channel
has independent low-frequency (subaudio) filtering, clip limiting,
gain control, and output connection.
When to use STEREO input configuration:
for stereo sources (L-R inputs) and any other situation that
requires each channel to be completely separate from the other.
Use stereo mode
How to use STEREO mode:
1- Set the DIP switches for stereo mode operation (see facing
page).
2- Connect the two input signals; one to CH1 and one to CH2
(XLR or terminal blocks)
3- Connect the two speakers; one to CH1’s output terminals, one
to CH2’s output terminals.
PARALLEL:
The channel 1 and channel 2 inputs are connected together,
applying a
signal into any input jack will drive both channels. Each
channel's low frequency filtering, clip limiting, and gain control
still function independently. Each channel drives its own speaker
load.
single input signal
to both channels of the amplifier. A
STEREO MODE OPERATION
NOTE: Ensure that the MODE SWITCHES are set
to STEREO when feeding two separate signals to
the two channels.
You can patch the input signal on to additional amplifiers (daisy
chain) by using any of the remaining input jacks. This feature
eliminates the need for “Y” cables.
When to use PARALLEL input configuration: Use parallel
mode when you need one signal to drive both channels; each
channel having its own control (gain, clip limiter, low-frequency
filter).
How to use PARALLEL mode:
1- Set the DIP switches for PARALLEL mode (see facing page).
2- Connect the one input signal to any one input connector.
3- Connect the two speakers: one to CH1’s output terminals, one
to CH2’s output terminals.
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PARALLEL MODE OPERATION
FEATURES & SETUP- STEREO & PARALLEL MODE DIP SWITCH SETTINGS
SETTING THE DIP SWITCHES FOR STEREO OR PARALLEL MODE- “non-T” models
ISA 280, ISA 450, ISA 750:
Refer to the switch setting keys for each mode, to the right.
These keys are printed on the amplifier’s rear panel for easy
reference when you are behind the equipment rack.
STEREO Mode- Set switch #4, 5, 6 and #7 to the
left.
PARALLEL Mode- Set switch #4 and #5 to the
right; set switch #6 and #7 to the left.
ISA 280, ISA 450 and ISA 750 mode switches.
SETTING THE DIP SWITCHES FOR STEREO OR PARALLEL MODE- “T” models
ISA 300T, ISA 500T and ISA 800T:
Refer to the switch setting keys for each mode, at the right.
These keys are printed on the amplifier’s rear panel for easy
reference when you are behind the equipment rack.
STEREO Mode- Set switch #3, 4, 5, 6, 7 and #8 to
the left.
PARALLEL Mode- Set switch #3, 4 and #5 to the
right. Set switch #6, 7 and #8 to the left.
ISA 300T, ISA 500T and ISA 800T mode switches.
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FEATURES & SETUP- BRIDGE OPERATING MODE & DIP SWITCH SETTINGS
BRIDGE MODE OPERATION-
Note that speaker connection for bridge mono mode is
different than other modes. See section on Connections:
Outputs for proper bridge mode output connections.
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