Lexicon GX-7 User manual

GX-7 Power Amplifier
User Guide

IMPORTANT SAFETY INSTRUCTIONS
1. Read these instructions.
2. Keep these instructions.
3. Heed all warnings.
4. Follow all instructions.
5. Do not use this apparatus near water.
6. Clean only with a dry cloth.
7. Do not block any ventilation openings. Install in
accordance with the manufacturer’s instructions.
8. Do not install near any heat sources such as
radiators, heat registers, stoves, or another
apparatus (including amplifiers) that produces heat.
9. Do not defeat the safety purpose of the polarized or
grounding-type plug. A polarized plug has two
blades with one wider than the other. A grounding-
type plug has two blades and a third grounding
prong. The wide blade or the third prong are
provided for your safety. If the provided plug does
not fit into your outlet, consult an electrician for
replacement of the obsolete outlet.
10. Protect the power cord from being walked on or
pinched particularly at plugs, convenience recep-
tacles, and the point where they exit from the
apparatus.
11. Install the unit so that the power switch can be
accessed and operated at all times.
12. Main Plug is considered to be the disconnect
device for this product and shall remain readily
operable.
13. Only use attachments/accessories specified by the
manufacturer.
14. Use only with the cart, stand, tripod, bracket, or
table specified by the manufacturer, or sold with the
apparatus. When a cart is used, use caution when
moving the cart/apparatus combination to avoid
injury from tip-over.
15. Unplug this apparatus during lightning storms or
when unused for long periods of time.
16. Refer all servicing to qualified service personnel.
Servicing is required when the apparatus has been
damaged in any way, such as when a power-supply
cord or plug is damaged, liquid has been spilled or
objects have fallen into the apparatus, the
apparatus has been exposed to rain or moisture,
does not operate normally, or has been dropped.
• Refer to the manufacturer’s operating
instructions for power requirements. Be
advised that different operating voltages may
require the use of different line cord and/or
attachment plug.
• Do not install the unit in an unventilated rack,
or directly above heat-producing equipment
such as power amplifiers. Observe the
maximum ambient operating temperature
listed in the product specification.
• Never attach audio power amplifier outputs
directly to any of the unit’s connectors.
This equipment has been tested and found to comply
with the limits for a Class B digital device, pursuant to
Part 15 of FCC Rules. These limits are designed to
provide reasonable protection against harmful inter-
ference in a residential installation. This equipment
generates, uses, and radiates radio frequency energy
and, if not installed and used in accordance with the
instructions, may cause harmful interference to radio
or television reception, which can be determined by
turning the equipment off and on. The user is encour-
aged to try to correct the interference by one or more
of the following measures:
• Re-orient 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 electronic
technician for help.
To reduce the risk of fire or electric
shock, do not expose this apparatus to
rain or moisture. Do not place objects
containing liquid, such as vases, on this
apparatus.
WARNING
This triangle, which appears on your component,
alerts you to the presence of uninsulated,
dangerous voltage inside the enclosure -
voltage that may be sufficient to
constitute a risk of shock.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
This triangle, which appears on your component,
alerts you to important operating and
maintenance instructions in this
accompanying literature.

Lexicon Inc.
3 Oak Park
Bedford, MA 01730-1413 USA
Tel: [phone]
Fax: [phone]
www.harmanspecialtygroup.com
Customer Service
Tel: [phone]
Fax: [phone]
Email: [e-mail]
Part No. 070- 18129 | Rev 1 | 10/06
Lexicon and the Lexicon logo are registered trademarks of Harman International Industries, Inc. U.S. Patent Nos. D454,553;
D454,860; 5,796,844; 5,870,480 and other worldwide patents issued and pending.
© 2006 Harman International Industries, Incorporated. All rights reserved.
This document should not be construed as a commitment on the part of Harman Specialty Group. The information it contains is
subject to change without notice. Harman Specialty Group assumes no responsibility for errors that may appear within this
document.

Introduction Lexicon
ii
DOCUMENTATION CONVENTIONS
This document contains general safety, installation and operation instructions for the GX-7 Power Amplifier. It is important to read this user
guide before attempting to use the product. Pay particular attention to safety instructions.
The following symbols are used in the document:
Appears on the component to indicate the pres-
ence of uninsulated, dangerous voltage inside
the enclosure– voltage that may be sufficient to
constitute a risk of shock.
Appears on the component to indicate impor-
tant operating and maintenance instructions in
the accompanying literature.
Calls attention to a procedure, practice, condi-
tion or the like that, if not correctly performed
or adhered to, could result in injury or death.
Calls attention to a procedure, practice, condi-
tion or the like that, if not correctly performed
or adhered to, could result in damage or
destruction to part or all of the product.
Calls attention to information that is essential to
highlight.
WARNING
CAUTION!
Note:

GX-7 Introduction
iii
Table of Contents
Getting Started
About The GX-7 ........................................................................ 1-2
Highlights ............................................................................. 1-3
Product Registration .................................................................. 1-3
Installation Considerations......................................................... 1-3
Basic Operation
Front Panel Overview ................................................................ 2-2
Rear Panel Overview .............................................................. 2-3
Power Control Connections .................................................. 2-5
Protection Mode ................................................................... 2-6
Troubleshooting & Maintenance
Troubleshooting........................................................................ 3-2
Maintenance ......................................................................... 3-2
Appendix
Specifications ............................................................................A-2
Declaration of Conformity .........................................................A-3

1
Getting Started
About The GX-7 ......................................................................... 1-2
Highlights ................................................................................................ 1-3
Product Registration................................................................... 1-3
Installation Considerations.......................................................... 1-3

Getting Started Lexicon
1-2
ABOUT THE GX-7
Thank you for purchasing a Lexicon Power Amplifier. The GX-7 is a
high-performance power amplifier designed to meet the rigorous
demands of today’s home theater installations. It is designed with
full complementary circuitry from input to output. It includes a
high-current power supply driven by a massive, custom-designed,
toroidal transformer with two separate windings for each channel.
Each channel also features six discrete output devices, vast filter
capacitance and is protected by an advanced protection circuit.
Heat dissipation is accomplished by large heat-sinks mounted to
each channel, enabling the GX-7 to function at full-power without
the need for internal cooling fans.
With seven channels, the GX-7 will be at home in today’s
7.1-channel music and cinema systems as well as for use in
5.1-channel systems with two additional channels that can be used
in bi-wiring configurations, or to power speakers in another room.
The GX-7 delivers 125 Watts/8 ohms per channel.
The GX-7 includes high-quality gold-plated unbalanced (RCA)
input connectors, as well as heavy-duty speaker output connectors.
A trigger input connector allows the GX-7 to be powered on and
off automatically with a preamplifier equipped with a trigger
output. The GX-7 is specially designed for many years of listening
enjoyment. The GX-7's impressive performance and flexibility
ensure it is well equipped for the most sophisticated home theaters.

GX-7 Getting Started
1-3
HIGHLIGHTS
• 125 Watts/8 ohms per channel
• Massive toroidal power transformer with two windings for each
channel
• High-power supply voltage for extra headroom at the outputs
• Stable with mismatched, reactive, or unusual loads
• Compatible with 4 ohm speaker impedances
• Heat-sink mounted to each channel for cooling
• Speaker protection against DC and frequencies below 10Hz
• Protection against short circuits, device failures, miswiring, and
internal faults
• Trigger input for power control from an external device
• RCA inputs
• Gold plated input and output connectors
• Rack-mount option available
PRODUCT REGISTRATION
Please register your new amplifier within 15 days of purchase.
Register online at www.lexicon.com or complete and return the
product registration card attached to the back cover of this user
guide. Retain the sales receipt as proof of warranty coverage.
INSTALLATION CONSIDERATIONS
To ensure optimal performance, pay particular attention to
instructions below and to other precautions that appear
throughout this user guide.
DObe careful when moving the amplifier, as it is quite heavy.
DOinstall the GX-7 on a solid, flat, level surface such as a table or
shelf. The GX-7 can also be installed in a standard 19-inch
equipment rack using an optional rack-mount kit available from an
authorized Lexicon dealer.
DONOT install the GX-7 on a surface that is unstable or unable to
support all four feet.
DOselect a dry, well-ventilated location out of direct sunlight.
DONOT expose the GX-7 to high temperatures, humidity, steam,
smoke, dampness or excessive dust. Avoid installing the GX-7 near
radiators and other heat-producing appliances.
DONOT install the GX-7 near unshielded TV or FM antennas, cable
TV decoders, or other RF-emitting devices that might cause
interference.
DONOT place the GX-7 on a thick rug or carpet, or cover the
ventilation holes in the chassis, as this might prevent proper cooling.
DONOT place the GX-7 on a windowsill or any location exposed
to direct sunlight.
DONOT stack the GX-7 directly above heat-producing equipment
such as another power amplifier.

2
Basic Operation
Front Panel Overview ................................................................ 2-2
Rear Panel Overview .................................................................. 2-3
Power Control Connections ....................................................... 2-5
Protection Mode ....................................................................... 2-6

Basic Operation Lexicon
2-2
FRONT PANEL OVERVIEW
The GX-7 front panel is shown below. The standby/on button is the only front panel control.
STANDBY/ON BUTTON
Activates and deactivates standby mode when the GX-7 amplifier is powered on with the rear panel master power switch. The standby/on
button performs no function when the amplifier is powered off with the rear panel master power switch.
When the unit is on, pressing the standby/on button activates standby mode and deactivates the power amplifier. When in standby mode, the
front panel LED is red. Power is still supplied to the GX-7 when it is in standby mode.
When the unit is in standby, pressing the standby/on button activates the power amplifier. When the GX-7 is activated, the front panel LED is
blue.
Note:
When the status of the GX-7 changes, relay clicks may be audible. This is normal operation.

GX-7 Basic Operation
2-3
REAR PANEL OVERVIEW
The GX-7 rear panel is shown below. The numbers in the rear panel illustrations correspond with the numbered description items.
1. Audio Input Connectors
2. Audio Output Connectors
3. Master Power Switch
4. Remote Trigger Input
5. AC Power Connector
6. Fuse Holder
1 AUDIO INPUT CONNECTORS
Provide audio input for the speakers connected to the corre-
sponding audio outputs.
RIGHT RIGHT SIDE RIGHT REAR CENTER LEFT REAR LEFT SIDE LEFT
LEXICON, INC.
DESIGNED AND
ASSEMBLED IN U.S.A.
SERIAL NO.
GX-7
FUSE 10A 250V 3AB Slo-Blo
TRIGGER INPUT
+
—
+
—
+
—
+
—
+
—
+
—
+
—
12VDC
RIGHT RIGHT SIDE RIGHT REAR CENTER LEFT REAR LEFT SIDE LEFT
ATTENTION
RISQUE DE CHOC ELECTRIQUE
NE PAS OUVRIR
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
~
AC 120V 50-60Hz 1200W
OUTPUTS
INPUTS
2
34
1
6
5

Basic Operation Lexicon
2-4
2 AUDIO OUTPUT CONNECTORS
Provide audio output for the speakers. Output connectors can
accept bare speaker wires, banana plug connectors, or certain
spade connectors. When using bare speaker wires, loosen the
connector, insert the wire into the top of the receptacle, then
tighten the connector. The same procedure should be used for
spade connectors. Banana plugs should be inserted into the
outward-facing receptacle.
Use heavy gauge speaker cable to ensure low-impedance connec-
tions between the amplifier and the speakers. Observe correct
speaker polarity.
CAUTION!
Never make or break connections to the GX-7 unless the
GX-7 and all associated components are powered off.
Do not connect the outputs of one channel to the outputs
of other channels or to other amplifiers.
Note:
The Class 2 Wiring label is required for any unit in which the audio output
power exceeds 10 watts per channel under normal operating conditions
or the unit is intended to be installed or connected by a qualified person.
3 MASTER POWER SWITCH
Connects and disconnects power to the AC Input Connector. When
this switch is on, the front panel standby/on LED illuminates. When
it is off, the front panel standby/on button will not function. Set this
switch to off when making or breaking connections to the amplifier.
To power on the GX-7, press the rear panel master power switch.
When powered on, the front panel LED will light. There will be a
short pause from the time the power is turned on until the output is
sent to the speakers. This is normal operation and protects the
speakers from potential damage while the unit stabilizes. You may
hear a relay click during start-up, this is also normal operation.
CAUTION!
When the GX-7 master power switch is switched off or
there is a power outage, the state of the unit remains the
same when power is returned. If in standby mode (red
LED) and power is disconnected, it will remain in standby
mode when power is returned. If the unit is in active
mode (blue LED) and power is disconnected, it will remain
activated when power is returned. It is recommended that
the GX-7 is set to standby mode before powered off to
prevent potential damage to the unit or your speakers.
If the GX-7 is not trigger connected to a controlling
device, such as the MC-12HD/MC-8, which comes out of
power loss and recovery in standby mode, and/or with a
known volume setting, there is a potential for damage to
the speakers if power is lost and restored with the GX-7 in
active mode.
4 REMOTE TRIGGER INPUT
Enables the GX-7 to be controlled by the MC-12HD/MC-8 or other
external devices with a 12V DC trigger output. Connect the trigger
output of the external device to the TRIGGER INPUT of the GX-7
amplifier. The GX-7 will automatically respond when the external
device is powered on and off. When the controlling device is turned
on, the amplifier will turn on after a short pause. This pause is inten-
tional and serves to protect the speakers from damage while the
unit stabilizes. During start-up, you may hear a relay click. This is
normal operation.
WARNING

GX-7 Basic Operation
2-5
5 AC POWER CONNECTOR
The AC input connector provides power to the unit with the
supplied power cord. Do not use an extension cord.
CAUTION!
Never make or break connections to the GX-7 unless the
GX-7 and all associated components are powered off.
6 FUSE HOLDER
The GX-7 uses internal fuses to protect itself and the speakers from
possible damage. In the event that a replacement fuse is needed, be
sure that a fuse of the original rating is used. If a fuse continues to
fail, the GX-7 may have developed a fault. In this event, contact
Lexicon customer service.
POWER CONTROL CONNECTIONS
The GX-7 features a built-in remote power-on system that will
automatically switch the amplifier on when another device in the
system is switched on.
REMOTE TRIGGER POWER ON
To connect to a 12V trigger jack:
Using an accessory cable with a 3.5mm mono mini-plug on each
end, connect the trigger-output jack on the rear of the source
device to the GX-7 rear panel TRIGGER INPUT.
When these connections are made, the GX-7 will automatically
power on whenever the triggering device is turned on.
REMOTE POWER ON WITH EXTERNAL AC TO DC
POWER CONVERTER
If your preamplifier, processor or receiver does not have a dedicated
trigger jack, it is still possible to activate the unit for automatic
power on when a Switched Outlet is available on the source device
rear panel. To control the GX-7 in this instance, a small AC to DC
power converter capable of delivering a 6 to 12 volt DC signal is
required. The DC voltage should terminate in a standard 3.5mm
type mini plug.
To connect to an external AC to DC Power converter:
1. Plug the AC adapter into a switched outlet that will be activated
when you wish to have the amplifier power on. This may be the
switched outlet at the rear of an AC receiver or other audio
component.
2. Connect the 3.5mm mini-plug from the adapter to the GX-7
rear panel TRIGGER INPUT. The GX-7 will now turn on and off
automatically, depending on the status of the controlling
device.

Basic Operation Lexicon
2-6
POWER CONNECTION SAFETY
After all audio and system connections have been made, connect
the power cord to an AC power source. Be sure that the GX-7 is
powered off and that the device connected to the remote trigger
input is off when connecting the power cord and plugging it in to
an AC outlet.
Do not plug the GX-7 directly into the “Switched
Accessory” outlet of another device! These outlets are
intended for use with low current draw products such as
tuners, CD players or cassette decks. These outlets are not
designed to handle the high current draw of a power
amplifier. Using these outlets for a power amplifier is a
significant safety hazard.
Note:
It is not recommended that you connect other power amplifiers or
products with a high current draw, to the same AC power circuit as the
GX-7, unless they are used with the remote power-on and sequencing
system. The simultaneous power-on of multiple amplifiers on the same
circuit may cause circuit breakers to trip due to the high current draw.
SOURCE COMPONENT CONNECTIONS & OUTPUT
SETTINGS
Make all connections before powering on the GX-7. It is also recom-
mended that you power on the source components and processor
in your system before powering on the GX-7. This avoids the possi-
bility of any pops or transients from other components being
amplified and sent to the speakers. Always start with a low volume
level on the controller or preamplifier to avoid potential damage to
the speakers.
All volume and level adjustments are made on your preamplifier,
controller or surround processor. When using the GX-7 for the first
time, you should re-set the output levels of the channels on your
processor. Experiment to ensure that your system components are
properly matched with the GX-7.
PROTECTION MODE
The GX-7 is equipped to protect itself against potentially damaging
conditions such as overheating, miswiring and electrical failures.
Under such conditions, the GX-7 will enter a protection mode.
When this occurs, the unit will mute to protect itself and speakers
from potential damage.
If the GX-7 enters protection mode (mutes itself):
1. Immediately power off the unit with the rear panel master
power switch and disconnect the AC power cord.
2. Examine all speaker connections to ensure there are no shorts.
3. Power on the GX-7. If the unit continues to mute, contact Lexicon
customer service for assistance.
WARNING

3
Troubleshooting & Maintenance
Troubleshooting..........................................................................3-2
Maintenance...............................................................................3-2

Troubleshooting & Maintenance Lexicon
3-2
TROUBLESHOOTING
The amplifier does not power on.
1. Make sure the rear panel master power switch is set to the I
“on”position.
2. Attempt to activate the amplifier with the front panel
standby/on button.
3. Examine the power cord to ensure a good connection between
the rear panel AC input connector and the wall outlet.
4. Check the electrical circuit.
One or more channels is not passing audio.
1. Reduce system volume level.
2. Power the amplifier off.
3. Check input connections.
4. Check speaker connections. Allow the amplifier to cool before
powering it on again.
Audio sounds out-of-phase
Check to ensure proper speaker wiring.
Audio levels differ.
Check the settings on your preamp, processor or controller.
Audio plays, then cuts off.
Check speaker connections for short circuit at amp and speaker.
A humming sound is present in the audio.
1. If a cable TV connection is present, disconnect the cable from
the wall outlet. If this eliminates the humming sound, a ground
loop isolation device is required. Contact your dealer or the
cable provider for assistance.
2. Disconnect components one at a time to isolate the problem.
Once the problem is identified, make sure the associated
component is properly grounded and connected to the same
electrical circuit as the GX-7.
The TRIGGER INPUT is connected to an external device, but the
amplifier does not power on and off with the external device.
Verify the trigger cable is connected at both ends.
If all else fails. . .
1. Contact an authorized Lexicon dealer.
2. Contact Lexicon Customer Service at 781-280-0300 or send an
email to: [e-mail].
Note:
Visit the knowledgebase at http://www.lexicon.com/kbase for answers to
frequently asked questions and additional troubleshooting information.
MAINTENANCE
Routine maintenance should be performed on a periodic basis.
Clean the exterior surfaces of the unit with a soft, dry, lint-free cloth.
Do not use alcohol, benzene, acetone-based cleaners, or strong
commercial cleaners. Do not use a cloth made with steel wool or
metal polish. If the unit is exposed to a dusty environment, a low-
pressure blower may be used to remove dust from its exterior.

A
Appendix
Specifications ............................................................................. A-2
Declaration of Conformity.......................................................... A-3

Appendix Lexicon
A-2
SPECIFICATIONS
Specifications are subject to change without notice.
Audio Input Connectors
7 RCA
Audio Output Connectors
7 pairs of heavy-duty, gold-plated binding posts
Performance
Output Power 125W RMS per channel into 8 Ohms from 20Hz to 20kHz
188W RMS per channel into 4 Ohms from 20Hz to 20kHz
Minimum
Recommended
Speaker Impedance
4 Ohms
Frequency Response 20Hz to 20kHz +0.1dB/-0.5dB
10Hz to 40kHz +0.1dB/-1.5dB
Total Harmonic
Distortion (THD)
Less than 0.05% at full power ratings
Signal-to-Noise Ratio Greater than 100dB, ref 125W/8 Ohms (30kHz band-
width)
Intermodulation
Distortion (IM)
Less than 0.05% at full power ratings
Crosstalk Greater than -80dB @ 1kHz (30kHz bandwidth)
Damping Factor Greater than 200 @ 20Hz (ref 8 Ohms)
Input Sensitivity 1V for 100W out @ 8 Ohms
Input Impedance Minimum 10kOhms
Gain Minimum 28dB
Other
Trigger Input 5 to 12 Volts DC ± 10%, 3.5mm T/S jack
Power Requirements 120V 60Hz 10 Amp [1200W] (domestic)
230V 50Hz 4 Amp [920W] (export)
Height 5-inches
Width 16.2-inches
Depth 19.5-inches (including handles)
17.12-inches (not including handles)
Weight 51 pounds (23.1 kg)
Rack Mounting Optional brackets are available for mounting the
amplifier in a standard 19-inch equipment rack.