CAUTION: THIS PRODUCT SATISFIES FCC REGULATIONS WHEN SHIELDED CABLES AND
CONNECTORS ARE USED TO CONNECT THE UNIT TO OTHER EQUIPMENT. TO PREVENT
ELECTROMAGNETIC INTERFERENCE WITH ELECTRIC APPLIANCES SUCH AS RADIOS AND
TELEVISIONS, USE SHIELDED CABLES AND CONNECTORS FOR CONNECTIONS.
THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT
THE USER TO THE PRESENCE OF IMPORTANT OPERATING AND MAINTENANCE
(SERVICING) INSTRUCTIONS IN THE LITERATURE ACCOMPANYING THE APPLIANCE.
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 PERSONS.
READ INSTRUCTIONS: All the safety and operating instructions should be read before
the product is operated.
RETAIN INSTRUCTIONS: The safety and operating instructions should be retained for
future reference.
HEED WARNINGS: All warnings on the product and in the operating instructions
should be adhered to.
FOLLOW INSTRUCTIONS: All operating and use instructions should be followed.
CLEANING: The product should be cleaned only with a polishing cloth or a soft dry
cloth. Never clean with furniture wax, benzine, insecticides or other volatile liquids
since they may corrode the cabinet.
ATTACHMENTS: Do not use attachments not recommended by the product
manufacturer as they may cause hazards.
WATER AND MOISTURE: Do not use this product near water, for example, near a
bathtub, wash bowl, kitchen sink, or laundry tub; in a wet basement; or near a
swimming pool; and the like.
ACCESSORIES: Do not place this product on an unstable cart, stand, tripod, bracket,
or table. The product may fall, causing serious injury to a child or adult, and serious
damage to the product. Use only with a cart, stand, tripod, bracket, or table
recommended by the manufacturer, or sold with the product. Any mounting of the
product should follow the manufacturer’s instructions, and should use a mounting
accessory recommended by the manufacturer.
CART: A product and cart combination should be moved with care. Quick stops, excessive
force, and uneven surfaces may cause the product and cart combination to overturn.
See Figure A.
VENTILATION: Slots and openings in the cabinet are provided for ventilation and to
ensure reliable operation of the product and to protect it from overheating, and
these openings must not be blocked or covered. The openings should never be
blocked by placing the product on a bed, sofa, rug, or other similar surface. This product
should not be placed in a built-in installation such as a bookcase or rack unless proper
ventilation is provided or the manufacturer’s instructions have been adhered to.
POWER SOURCES: This product should be operated only from the type of power
source indicated on the marking label. If you are not sure of the type of power
supply to your home, consult your product dealer or local power company.
LOCATION: The appliance should be installed in a stable location.
NON-USE PERIODS: The power cord of the appliance should be unplugged from the
outlet when left unused for a long period of time.
GROUNDING OR POLARIZATION:
• If this product is equipped with a polarized alternating current line plug (a plug
having one blade wider than the other), it will fit into the outlet only one way. This is
a safety feature. If you are unable to insert the plug fully into the outlet, try reversing
the plug. If the plug should still fail to fit, contact your electrician to replace your
obsolete outlet. Do not defeat the safety purpose of the polarized plug.
• If this product is equipped with a three-wire grounding type plug, a plug having a
third (grounding) pin, it will only fit into a grounding type power outlet. This is a
safety feature. If you are unable to insert the plug into the outlet, contact your
electrician to replace your obsolete outlet. Do not defeat the safety purpose of the
grounding type plug.
POWER-CORD PROTECTION: Power-supply cords should be routed so that they are
not likely to be walked on or pinched by items placed upon or against them, paying
particular attention to cords at plugs, convenience receptacles, and the point where
they exit from the product.
OUTDOOR ANTENNA GROUNDING: If an outside antenna or cable system is
connected to the product, be sure the antenna or cable system is grounded so as to
provide some protection against voltage surges and built-up static charges. Article
810 of the National Electrical Code, ANSI/NFPA 70, provides information with
regard to proper grounding of the mast and supporting structure, grounding of the
lead-in wire to an antenna discharge unit, size of grounding conductors, location of
antenna-discharge unit, connection to grounding electrodes, and requirements for
the grounding electrode. See Figure B.
LIGHTNING: For added protection for this product during a lightning storm, or when it
is left unattended and unused for long periods of time, unplug it from the wall outlet
and disconnect the antenna or cable system. This will prevent damage to the
product due to lightning and power-line surges.
POWER LINES: An outside antenna system should not be located in the vicinity of
overhead power lines or other electric light or power circuits, or where it can fall into
such power lines or circuits. When installing an outside antenna system, extreme
care should be taken to keep from touching such power lines or circuits as contact
with them might be fatal.
OVERLOADING: Do not overload wall outlets, extension cords, or integral
convenience receptacles as this can result in a risk of fire or electric shock.
OBJECT AND LIQUID ENTRY: Never push objects of any kind into this product
through openings as they may touch dangerous voltage points or short-out parts
that could result in a fire or electric shock. Never spill liquid of any kind on the product.
SERVICING: Do not attempt to service this product yourself as opening or removing
covers may expose you to dangerous voltage or other hazards. Refer all servicing to
qualified service personnel.
DAMAGE REQUIRING SERVICE: Unplug this product from the wall outlet and refer
servicing to qualified service personnel under the following conditions:
• When the power-supply cord or plug is damaged.
• If liquid has been spilled, or objects have fallen into the product.
• If the product has been exposed to rain or water.
• If the product does not operate normally by following the operating instructions. Adjust only
those controls that are covered by the operating instructions as an improper adjustment of
other controls may result in damage and will often require extensive work by a qualified
technician to restore the product to its normal operation.
• If the product has been dropped or damaged in any way.
• When the product exhibits a distinct change in performance, this indicates a need for service.
REPLACEMENT PARTS: When replacement parts are required, be sure the service
technician has used replacement parts specified by the manufacturer or have the
same characteristics as the original part. Unauthorized substitutions may result in
fire, electric shock, or other hazards.
SAFETY CHECK: Upon completion of any service or repairs to this product, ask the
service technician to perform safety checks to determine that the product is in
proper operating condition.
WALL OR CEILING MOUNTING: The product should not be mounted to a wall or ceiling.
HEAT: The product should be situated away from heat sources such as radiators,
heat registers, stoves, or other products (including amplifiers) that produce heat.
(2)
REAR:REAR:
REAR:
REAR:REAR:
FRONTFRONT
FRONT
FRONTFRONT
PP
ANEL:ANEL:
P
ANEL:
PP
ANEL:ANEL:
GXA 750/1600
STEREO MODE:STEREO MODE:
STEREO MODE:
STEREO MODE:STEREO MODE:
PP
ARALLEL MODE:ARALLEL MODE:
P
ARALLEL MODE:
PP
ARALLEL MODE:ARALLEL MODE:
MONO BRIDGE MODE:MONO BRIDGE MODE:
MONO BRIDGE MODE:
MONO BRIDGE MODE:MONO BRIDGE MODE:
CONNECTIONS:CONNECTIONS:
CONNECTIONS:
CONNECTIONS:CONNECTIONS:
XLR
or
1/4” TRS
XLR
or
1/4” TRS
SPEAKON
SPEAKON
1/4” TRS
(3)
XLR
or
SPEAKON
INTRODUCTION:
Congratulations on purchasing your Gemini GXA power amplifier. This
state of the art power amplifier includes the latest features and is backed
by a three year limited warranty. Prior to use, we suggest that you
carefully read all the instructions.
FEATURES:
• State of the art technology provides exceptional reliability when working with difficult
speakers.
• Stable down to 2 ohm impedence
• Excellent handling of low frequencies as well as clear mids and flawless highs
• High output power to drive professional loudspeakers without distortion
• Oversized toroidal transformer, filter and heatsinks for better low end, transparency and stability
• Comprehensive protection circuitry (short, overheat, DC, subsonic and RF filters, turn-on
delay) with high current speaker protection relays
• Three modes of operation - stereo, parallel mono and mono bridge with mode status
indication LED on front panel
• Flexible input configuration with active balanced inputs; additional input
connectors to chain amps
• True clip LED for better control
• Front-to-Rear airflow with 2 speed dual fan control
• Efficient dual aluminum extrusion heatsink design for thermal stability and reliability
• Turn-on in-rush current limiting circuitry
• Compact 2U well balanced enclosure
• Steel reinforced chassis construction for durability and longevity
CAUTIONS:
Read all operating instructions before using this equipment. To reduce
the risk of electrical shock, do not open the unit. There are NO USERREPLACEABLE P ARTS INSIDE. Please contact the Customer Gemini
Service Department or your authorized dealer to speak to a qualified
service technician. Be sure to allow adequate front and rear ventilation to
avoid possible heat damage to your equipment. Be sure that AC power isOFF and all level controls are set to MINIMUM before making connections.
This will eliminate any chance of unexpected, loud audio transients that
could damage your speaker systems. Be sure that AC power is OFF
when changing modes of operation and when changing the position of the
ground lift switch. DO NOT EXPOSE THIS UNIT TO RAIN ORMOISTURE. Operators of electronic equipment should in no way be in
contact with water . When connecting to AC power line be sure you
haven’t lost the ground connection by using an adapter or extension cord
without a 3 prong plug. DO NOT USE ANY SPRAY CLEANER OR
LUBRICANT ON ANY CONTROLS OR SWITCHES.
CONNECTIONS, CONTROLS AND
INDICATORS:
AC POWER SECTION:
FUSE: Replace FUSE (1) with those of proper type and rating.
SIGNAL GROUND LIFT SWITCH: SIGNAL GROUND LIFT SWITCH (2)
is used to lift the balanced input connectors’ ground/shield from the
amplifier’s ground. When the signal ground lifted, the sound source
disconnects from the amplifier’s ground preventing ground loops which
can generate hum and noise. See the Signal Ground Lift Switch
Instructions for more detail.
AC CORD OUTLET: AC CORD OUTLET (3 ) is used to attach the power
cord to the unit.
REAR PANEL:
INPUT SECTION:
There are two parallel input connectors (one female XLR and one 1/4”
TRS jack) per channel. Either can be used as an input or as a link to chain
inputs accept a standard XLR male connector. Pin 1 = shield/ground, pin
2 = hot or positive (+) and pin 3 = cold or negative (-).
1/4" TRS INPUT JACKS:1/4" TRS INPUT JACKS (6, 7) accept a
balanced as well as an unbalanced line level signal. The unbalanced line
uses a standard tip-sleeve connection. The tip is positive and the sleeve is
negative/ground. The balanced line uses a tip-ring-sleeve connection.
Tip = hot or positive (+), ring = cold or negative (-), and sleeve = shield/ground.
OPERA TION MODE SWITCH:OPERATION MODE SWITCH (8 ) is used
to set the unit for STEREO mode, PARALLEL MONO mode, and
MONO BRIDGE mode.
OUTPUT SECTION:
Disconnect the unit from the AC power source before making any
connections. Pay close attention to polarity (shown on the back of the unit)
when connecting your speakers. Connecting your speaker systems using
the wrong polarity will not damage your speakers, but it will impact the
quality of the sound (lack of bass and incorrect stereo image).
SPEAKER OUTPUTS (9, 10, 11):SPEAKON connectors are provided to
connect speakers to the amplifier quickly and easily. They are high current
rated and provide very stable and durable contacts. A third SPEAKON
connector in the center is provided to be used if the amplifier is in the
MONO BRIDGE mode. Every SPEAKON connector has (PIN 1-) as
negative and (PIN 1+) as positive.
NOTE: TOTAL SPEAKER IMPEDANCE MUST NOT BE LOWER THAN 2 OHM PER CHANNEL FOR
STEREO AND PARALLEL MONO MODES, OR 4 OHM FOR MONO BRIDGE MODE. THE GXA
AMPLIFIER IS DESIGNED TO HANDLE LOW IMPEDENCE LOADS AND WILL OPERA TE
NORMALLY WITH MOST 2 OHM SPEAKERS/P ARALLEL SPEAKER COMBINATIONS. HOWEVER,
FOR OPTIMAL PERFORMANCE AND RELIABILITY WE RECOMMEND USING SPEAKERS WITH
HIGHER IMPEDENCE.
FRONT PANEL:
POWER SWITCH: The POWER SWITCH (12) turns the unit on and off.
POWER LED: The POWER LED (13) lights when the power is on. If the
POWER LED (13) does not light, refer to the trouble shooting guide.MONO LED: The MONO LED (14) will light when you have set the rear panel
OPERATION MODE SWITCH (8) for PARALLEL MONO operation
always make sure that this switch is in the correct position and that all
speaker connections have been made correctly for the mode of operation
you wish to use before powering up the amplifier.
BRIDGE LED: The BRIDGE LED (15) will light when you have set the
rear panel OPERATION MODE SWITCH ( 8) for MONO BRIDGE
operation. Always make sure that this switch is in the correct position and
that all speaker connections have been made correctly for the mode of
operation you wish to use before powering up the amplifier.
SIGNAL LED: The SIGNAL LED (16) for each channel show when a
signal is present. In MONO BRIDGE mode, both the CHANNEL ALED
and the CHANNEL BLED will light in unison.
CLIP LED: The amplifier has true CLIP LED (17) to help you properly
control the amplifier’s output and achieve undistorted sound. The CLIPLED (17) for each channel light when your signal level is so strong that
the distortion reaches 1% THD. The CLIP LED (17) should not remain
constantly on or flash repeatedly during operation. For clean sound
reproduction, the CLIP LED (17) should only light occasionally for an
instant. If the LED remains on or flashes repeatedly , you will hear distorted
sound that can be damaging to your speaker systems. If this occurs,
reduce the signal level by lowering the input level control for the channel
that is clipping or reduce the level at the source. If the CLIP LED (17)
lights when no signal is present, it may indicate a DC level on the output
which may cause damage to speakers (the DC level will not be audible).
Please note that when you are using the amplifier in the MONO BRIDGE
mode, both CLIP LED (17) of the bridged channels will operate simultaneously.
PROTECT LED:PROTECT LED (18) when you first turn on the amplifier,
the PROTECT LED light briefly during a turn-on delay which indicates that
the outputs are disconnected internally. There will be an audible click
when the outputs reconnect and the PROTECT LED (18) will turn off.
Otherwise, the PROTECT LED (18) indicates that there is a problem
either in the amplifier’s external connections, load or temperature
conditions or its internal functions. If one of these situations occur, the
amplifier senses the problem and automatically switches into
PROTECTION mode. The LED will light to warn you of the trouble and
the amplifier will stop working. If this occurs, switch off the amplifier and
refer to the Trouble Shooting Guide. If the PROTECT LED (18) remains lit
when resuming amplifier operation, do not use the amplifier and contact
an authorized service technician.
LEVEL CONTROLS:LEVEL CONTROLS (19, 20) establish the input
levels required for each channel. Only the CHANNEL A LEVEL
CONTROL (19) works in MONO BRIDGE mode.
OPERATING INSTRUCTIONS:
THE AMPLIFIER’S POWER MUST BE TURNED OFF
WHEN CHANGING MODES OF OPERATION.
STEREO OPERA TION:
The unit has two channels for stereo operation. Each channel provides a
separate and discrete signal at the speaker outputs according to the
signal received at the inputs. The following instructions are for applications
with 8 Ohm, 4 Ohm or 2 Ohm speakers of matched power ratings.
1. With the power off, set the OPERATION MODE SWITCH (8) to the
STEREO position. When the power is on, the MONO LED (14) and
BRIDGE LED (15) on the front panel will not light. If these LED illuminate,
you have the switch in the wrong position. Correct before continuing.
2. With the power off, connect your input cables to the CHANNEL A and B inputs
using either the XLR INPUT JACKS (4, 5) or 1/4" TRS INPUT JACKS (6, 7) of
each channel. The other CHANNEL A and CHANNEL B input s can be used to
link to an additional amplifier.
(4)
3. Connect the loudspeakers to the CHANNEL A and CHANNEL B
SPEAKER OUTPUTS (9, 11). THE TOT AL SPEAKER LOAD MUST BE
A T LEAST 2 OHMS PER CHANNEL. If you try to operate at a lower
impedance, the amplifier will go into PROTECTION MODE and stop
operation until you correct the load conditions.
With the LEVEL CONTROLS (19, 20) of both channels set to zero (fully
4.
counterclockwise), turn the POWER SWITCH (12) ON. With the level
controls of your MIXER or other INPUT device turned all the way DOWN,
turn the amplifier level controls all the way up for desired loudness from
your speakers.
present in the amplifier’s output section. If a CLIP LED (17) remains on or
flashes repeatedly, reduce the signal level by lowering the input level control
for the channel that is clipping or reduce the level at the source.
5. Now adjust your MIXER or other INPUT source to your desired listening
level. You also have the choice of keeping the volume of both speakers
equal, or for certain situations you can adjust the volume so one side will
be louder than the other.
Note, when the CLIP LED (17) light, there is distortion
PARALLEL MONO OPERATION:
Follow these instructions for PARALLEL MONO operation using a single
input cable, and you will have the same monophonic signal on both the
CHANNEL A and the CHANNEL B outputs. Each channel’ s output is
controlled independently by that channel’s level control.
1. With the power off, set the OPERATION MODE SWITCH (8) to thePARALLEL MONO position. When the power is on, the MONO LED (14)
on the front panel will light. If the LED does not illuminate, you have the
switch in the wrong position. Correct before continuing.
2. With the power off, connect your input cables to the CHANNEL A input
only using the either the XLR INPUT JACK (5) or 1/4" INPUT JACK (7) of
CHANNEL A. The other CHANNEL A input can be used to link to an
additional amplifier.
3. Connect the loudspeakers to the CHANNEL A and CHANNEL B
SPEAKER OUTPUTS (9, 11). THE TOTAL SPEAKER LOAD MUST BE
A T LEAST 2 OHMS PER CHANNEL. If you try to operate at a lower
impedance, the amplifier will go into PROTECTION MODE and stop
operation until you correct the load conditions.
4. With the LEVEL CONTROLS (19, 20)of both channels set to zero (fully
counterclockwise), turn the POWER SWITCH (12) ON. With the level
controls of your MIXER or other INPUT device turned all the way DOWN,
turn the amplifier level controls all the way up for desired loudness from
your speakers. Note, when the CLIP LED (17) light, there is distortion
present in the amplifier’s output section. If a CLIP LED (17) remains on or
flashes repeatedly, reduce the signal level by lowering the input level
control for the channel that is clipping or reduce the level at the source.
5. Now adjust your MIXER or other INPUT source to your desired listening
level. You also have the choice of keeping the volume of both speakers
equal, or for certain situations you can adjust the volume so one side will
be louder than the other.
MONO BRIDGE OPERATION:
Follow these instructions to bridge the unit’s outputs. Bridging the amplifier
converts the unit to a monophonic or single channel. The amplifier can be
used with 4Ohm or higher loads only in MONO BRIDGE mode. This
mode is used to provide a higher voltage with greater headroom to your
speaker. Before setting your amplifier for MONO BRIDGE operation,
make sure that your speaker can handle the high power level provided by
the amplifier in MONO BRIDGE mode.
CAUTION: VOLTAGE OVER 100 VOLTS MAY BE PRODUCED AT THE BRIDGE OUTPUT
TERMINALS IN THIS MODE.
1. With the power off, set the OPERATION MODE SWITCH (8) to the
BRIDGE position. When the power is on, the BRIDGE LED (15) on the
front panel will light. If the LED does not illuminate, you have the switch in
the wrong position. Correct before continuing.
2. With the power off, connect your input cables to CHANNEL A input only
using either the XLR INPUT JACK (5) or 1/4" INPUT JACK (7) of
CHANNEL A. The other CHANNEL A input can be used to link to an
additional amplifier.
3. Connect the loudspeaker to the BRIDGE SPEAKER OUTPUT (10) only.
The total speaker load must be at least 4 Ohms or above. If you try to
operate at a lower impedance, the amplifier will go into PROTECTIONMODE and stop operation until you correct the load conditions.
4. With the CHANNEL A LEVEL CONTROL (19) set to zero (fully
counterclockwise), turn the POWER SWITCH (12) ON. With the level
controls of your MIXER or other INPUT device turned all the way DOWN,
turn the amplifier level controls all the way up for desired loudness from
your speakers. Note, when the CLIP LED (17) light, there is distortion
present in the amplifier’s output section. If a CLIP LED (17) remains on or
flashes repeatedly, reduce the signal level by lowering the input level
control for CHANNEL A or reduce the level at the source. During MONOBRIDGE operation, the CHANNEL B level is inactive, however, both
channels LED will flash simultaneously and show output conditions.
5. Now adjust your MIXER or other INPUT source to your desired listening
level. You also have the choice of keeping the volume of both speakers
equal, or for certain situations you can adjust the volume so one side will
be louder than the other.
USING THE SIGNAL GROUND LIFT SWITCH:
Depending on your system configuration, sometimes applying the ground
will create a quieter signal path. Sometimes lifting the ground can
eliminate ground loops and hum to create a quieter signal path.
1. With the power amp on, listen to the system in idle mode (no signal
present) with the ground applied (the SIGNAL GROUND LIFTSWITCH (2)
in the left position).
2. Then turn the power off before moving the SIGNAL GROUND LIFT
SWITCH (2). Lift the ground by moving the SIGNAL GROUND LIFT
SWITCH (2) to the right, turn the power back on and listen to determine
which position will provide a signal devoid of background noise and hum.
Keep the SIGNAL GROUND LIFTSWITCH (2) in the ground position if
the noise level remains the same in either position.
CAUTION: DO NOT TERMINATE THE AC GROUND ON THE POWER AMPLIFIER IN ANY WAY.
TERMINATION OF THE AC GROUND CAN BE HAZARDOUS.
SPECIFICA TIONS:
Output Power EIA: 1 kHz @ 1% THD
Single Channel 8Ω190340
Both Channels Driven 8Ω175300
Single Channel 4Ω325600
Both Channels Driven 4Ω275500
Single Channel 2Ω470950
Both Channels Driven 2Ω360800
Mono Bridge 8Ω5501000
Mono Bridge 4Ω7501600
Dynamic Headroom:
8Ω1.31.3
4Ω2.32.1
Frequency Response.................................................................20 Hz - 20 kHz
Total Harmonic Distortion...........................................less than 0.01% @ 1 kHz
Intermodulation Distortion.........................................less than 0.02% (SMPTE)
Signal to Noise Ratio.....................................100 dB below rated power @ 8W
Damping Factor (GXA-750)..........................................greater than 500 @ 8W
Damping Factor (GXA-1600)........................................greater than 800 @ 8W