Constellation audio Hercules II User manual

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CAUTION
To reduce risk of electric shock, do not remove any of the amplifier’s cover plates or screws. There are no
user serviceable parts inside. Contact qualified service personnel.
WARNING
To reduce risk of fire or electric shock, do not expose this amplifier to moisture, rain, or excessive humidity.
The lightning flash with arrowhead, 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 electrical shock to persons.
The exclamation point within an equilateral triangle is intended to alert the user to the
presence of important operating maintenance (servicing) instructions in the literature
accompanying the appliance.

Thank you for purchasing the Constellation Audio Hercules II amplifier. You are about to
experience what we believe is one of the finest amplifiers ever built.
Because of their very high power output, this amplifier demands careful and thoughtful
installation in order to deliver the performance it is designed to achieve. This is especially
true of the Hercules II Mono, which delivers double the power of the Hercules II Stereo. By
reading through this brief manual and following the simple steps outlined within, you can
ensure that your amplifier performs at its very best.
Contents
Page Topic
4 Before you install the amplifier
Unpacking
AC connection
Locations
Speakers
In the event of malfunction
6 Connections
BAL input
Direct input
RCA input
Speaker-cable binding posts
20-amp IEC AC socket
Trigger jack
8 Controls / displays / indicators
Front power switch
LED status indicator
Master power switch
Mute switch
Input select switch
10 Operation
Initial installation and power-up
Normal operation
11 Maintenance
11 Troubleshooting
14 Specifications: Hercules II Mono
15 Specifications: Hercules II Stereo
16 For more information

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Before you install the amplifier
Unpacking
At more than 200 pounds each, the Hercules II amplifier is too heavy for one person to lift safely. Four strong
people are required to lift each amplifier and to move it from place to place.
Likewise, do not place this amplifier on surfaces that cannot safely support their weight. Lightweight furniture
and equipment racks should not be used to support these amplifiers.
Lift the amplifier by hooking your fingers under the side edges, as indicated by the arrows in the photos at
right. It’s a good idea to wear soft gloves to protect your fingers and help avoid fingerprints on the amplifier.
AC connection
Each Hercules II should be plugged into its own dedicated 20-amp AC outlet,
with no other component but the Hercules II connected to that AC circuit. In
the U.S., all 20-amp AC outlets have a T-shaped hole next to an I-shaped hole,
as shown in the photo.
Confirm at your home’s electrical box that the outlet you use to power the
Hercules is connected to a 20-amp circuit breaker. A 15-amp breaker will trip
often due to the Hercules’ high current demands.
Do not use a “cheater” cord to plug the Hercules II into a 15-amp AC socket—
you will significantly reduce the amplifier’s maximum power output. Also, do
not plug two Hercules amplifiers into the same 20-amp AC socket or into the
same AC circuit. If you do, each amp will get only half the AC current it needs
for maximum performance, and you will probably trip your home’s circuit
breaker often. Each amplifier should be connected to its own 20-amp circuit
with its own circuit breaker at the electrical box.
Do not plug the Hercules II into a power strip or AC line conditioner—few such units are designed to handle
the current that the Hercules II can pull.
When you connect or disconnect the AC cord, always grasp it by the plug, not by the cord itself. Pulling the
plug out by the cord can damage the cord, the AC socket, and/or the Hercules.

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Location
The Hercules II must be installed in an area with adequate ventilation. There should be at least 6 in/15 cm of
clearance between the vents on the side of the amplifier(s) and the nearest wall or cabinet. Ensure that no
curtains or shades can be lowered in a way that will block the amplifier’s vents. If the amplifier is installed in
a cabinet or in an equipment closet, ensure that the cabinet/closet has adequate ventilation. Installation in
an unventilated cabinet or closet may cause the amplifier to overheat.
The amplifier requires a room-temperature environment to operation properly. Ambient temperature should
be about 70°F/21°C, plus or minus 10°F/5°C. Never install the amplifier in a place where it may be
exposed to direct sunlight, and do not install it next to a room heater, radiator, air conditioner, etc. Ambient
temperature can rise even more quickly with two Hercules II Monos, so if you place both of them in an
enclosed or tight space, make extra sure to provide plenty of ventilation and air flow.
Make sure that the amplifier will not be exposed to moisture. Do not locate it in an area where it might be
spilled on, and do not place it in a humid location (such as an unfinished basement).
Installing the Hercules II Mono or Stereo in a place where it will be exposed to direct sunlight or moisture, or
where it will not have adequate ventilation, will void your warranty.
Speakers
The Hercules II Mono and Stereo both have sufficient voltage and current to drive practically any loudspeaker
made, regardless of the speaker’s impedance, sensitivity, or “power rating.” However, the Hercules II Stereo
and, especially, the Hercules II Mono have enough power to damage some loudspeakers if used carelessly.
When you turn up the volume on your preamp, do it gradually. If you hear distortion, crackling noises, or
mechanical thumps from the speaker, turn the volume down immediately.
You can best appreciate the amplifier’s performance by connecting it to a large set of full-range
loudspeakers. It will sound excellent with small speakers, too, but if you connect it to a small set of speakers,
avoid turning the volume on your preamp to maximum.
Constellation Audio is not responsible for damage of any speaker connected to the Hercules II amplifiers.
In the event of malfunction
Do not under any circumstances open the cabinet of the amplifier. There are no user-serviceable parts inside.
Opening the cabinet can present a shock hazard even if the AC power is disconnected. Any alteration or
modification of the amplifier’s internal parts or circuit will immediately void your warranty.
If your amplifier does not function correctly, refer to the Troubleshooting section at the end of this manual. If
you are still unable to resolve the problem, contact your Constellation Audio dealer.
If any liquid is spilled on the amp, or if any metal object (such as a staple or a paper clip) is inadvertently
forced in through the vents, immediately disconnect the AC power and contact your Constellation Audio
dealer.

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Connections
1. BAL input
Use this XLR balanced input for connection to balanced-
output preamps of other brands. To select this input, set
the input switch to BAL (left position). To remove the XLR
plug, push on the tab above the jack and pull the plug out.
2. Direct input
Use this XLR balanced input only for connection to the
Constellation Audio Virgo or Altair preamp. This connection
forms the Constellation Direct—an audio interface that is,
in essence, perfectly balanced. The positive- and negative-
going halves of the signal will exhibit near-zero difference
except for their polarity. To select this input, set the input
switch to Direct (middle position). To remove the XLR plug,
push on the tab above the jack and pull the plug out.
3. RCA input
This input is provided as a convenience. You can use it if
you elect to feed the amplifier with an unbalanced signal
source. To select this input, set the input switch to RCA.
However, to get the best performance from the Hercules II
you must use an XLR input.
Hercules II Mono input jack layout
Hercules II Stereo input jack layout

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4. Speaker-cable binding posts
On the Hercules II Mono, two sets of
binding posts are provided for the output.
These can be used for standard cabling
(with a two-conductor cable running from
the amp to the speaker) or in a biwired
arrangement with separate cables going
from one amp to the speaker’s woofer
and midrange/tweeter drivers. Consult
your speaker’s manual for more
information. On the Hercules II Stereo,
one set of binding posts is provided for
each channel. These may also be used for
biwiring--see the discussion of the Biwire
switch on page 9.
For Hercules II Mono, connect the marked
connector or cable conductor for the left
speaker cable to the left positive (+ or
red) binding post and the unmarked
connector to the negative (- or black)
binding post underneath. Repeat with the
right speaker cable on the other amp.
Make sure the speaker cables on both
channels are connected identically—
marked cable conductor or connector to
red, unmarked conductor or connector to
black. For Hercules II Stereo, connect the
left cable to the left binding posts and the
right cable to the right binding posts as
described above.
Hercules II Mono binding post layout
Hercules II Stereo binding post layout
The binding posts accept spade lugs or banana plugs. Make certain that the spade lugs on your cables will fit
the amplifier’s binding posts—do not force the spade lugs onto the posts if they do not fit. Do not use bare
wire connections, because the amplifiers’ high power output might vaporize any stray wires that touch.
The binding posts are designed to be tightened only by hand. Do not use tools to tighten the binding posts.
Before you turn on the power, check at the terminals of the speakers and the amplifier to make sure the
positive and negative leads of the speaker cables are separated and not touching.

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5. 20-amp IEC AC socket
Connect the supplied 20-amp AC cord here. You may also
use an aftermarket power cord if you wish.
6. Trigger input
This 3.5mm jack accepts a 12-volt DC on/off trigger signal
from preamps and third-party control systems. When a 12-
volt DC trigger signal is input to the jack, the Hercules II
will turn on. When the trigger signal stops, the amplifier
will turn off.
Controls / displays / indicators
7. Front power/mute switch
The bar running across the front of the amplifier is the power/mute switch. Press on the left end of the bar
and hold it for 3 seconds to turn the amp on and off. Press and release the left side of the bar to activate and
deactivate mute mode.
8. Status indicator LED
This LED shows if the amp is on or off, and also
indicates mute, warm-up, and cool-down
modes. Here are the LED modes:
SOLID RED: Standby mode. Amp is powered
down but ready to use.
FLASHING RED: Cool-down mode. Amp is
powered off but cooling down. The power
button cannot be used in this mode. This mode
lasts 1 minute.
FLASHING GREEN: Warm-up mode. Amp power
is on but amp is warming up and cannot be
used. This mode lasts 1 minute.
SOLID BLUE: On mode. Amp power is on and
the amplifier is fully functional.
FLASHING BLUE: Mute mode. Amp is powered
but will produce no sound.

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9. Master power switch
This switch disconnects the amplifier from AC power.
If the switch is set to the Off position, the front power
switch will not be active and the status indicator LED will
not be illuminated. If the switch is set to the On position,
the front power switch will become active and the LED will
glow solid red, indicating standby mode.
This switch also resets the amplifier’s internal circuit
breaker. If the circuit breaker trips, flip the switch off and
on again to reset it.
10. Mute switch
This switch puts the amplifier into mute mode. In this
mode, the amplifier is fully powered up, but the sound is
muted. Use this mode if you wish to mute the sound, of
course, but also when you are checking the connections
into and out of the amplifier. In the event of an accidental
disconnection, using the mute mode will prevent
unwanted bursts of sound from coming through the
speakers.
11. Input select switch
Use this switch to select which of the amplifier’s inputs you
wish to use. The BAL setting (left position) selects the
balanced input, which should be used with balanced-
output preamps not manufactured by Constellation Audio.
The Direct setting (middle position) selects the Direct input, which should be used for connections to the
Constellation Audio Virgo or Altair preamp. This setting and input form half of the Constellation Direct—an
audio interface that is, in essence, perfectly balanced. The positive- and negative-going halves of the signal
will exhibit near-zero difference except for their polarity.
The RCA setting (right position) selects the RCA input, used with preamps that do not offer balanced output.
This connection is provided for convenience only; for best performance, use a preamp with balanced output.
12. Biwire switch (Hercules II Stereo only)
This switch, found only on the Hercules II Stereo, allows easy configuration of the amplifier for biwiring—using
one channel of the amp to power the speaker’s woofer and the other channel to power the tweeter and
midrange drivers. (This arrangement is also known as passive biamping.) To use this switch, you must have
speakers that are designed for biwiring, i.e., that have at least two sets of binding posts.
To biwire your speakers, connect one channel of the Hercules II Stereo to the speaker’s lower set of binding
posts, and the other channel to the speakers upper set of binding posts. Set the Biwire switch to on. Use only
the right-channel (lower) input on the Hercules II. Turning Biwire on sends this signal to both channels of the
amp.

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Operation
Initial installation and power-up
STEP 1: Before making any connections, make sure the amplifier’s master power switch is turned off. If the
AC has not been connected, connect the amplifier(s) to the wall AC power socket using the supplied cord.
STEP 2: If you are using Hercules II Monos, connect a high-quality speaker cable from the left speaker to the
left amplifier’s binding posts, and repeat the process for the right speaker/channel. If you are using a
Hercules II Stereo amp, connect the speaker cable from the left channel binding posts to the left speaker,
and repeat for the right channel/speaker. Be sure to connect the marked (often red) connector or cable to
the positive (red or +) binding post on the amplifier, and the unmarked (often black) connector or cable to the
negative (black or -) binding post on the amplifier. If you are using Hercules II Monos, you may use either of
the two positive (red or +) posts and either of the two negative (black or -) posts; just make sure that the
red/+ post is connected to the red/+ cable and that the black/- post is connected to the black/- cable.
Repeat for the right speaker.
If you are biwiring/biamping your speakers using the Hercules II Stereo amp, set the Biwire switch to on,
connect one channel of the Hercules II Stereo to the speaker’s lower pair of binding posts, and the other
channel to the speakers upper pair of binding posts.
Make sure that the conductors of the cables do not touch; that there are no stray wires coming from the
cables that might cause a short circuit; and that the amplifier and speakers do not come into contact with
metal objects that might cause a short circuit. While the amplifier is internally protected against short
circuits, it delivers enough current to vaporize small wires, so a fire hazard can result in the event of a short
circuit.
STEP 3: Connect a high-quality XLR balanced audio interconnect from the left channel of the preamp output
to the left Hercules II Mono’s XLR input or the Hercules II Stereo’s left channel XLR input. Use the Direct input
if you are using a Constellation Audio Virgo or Altair preamp; the BAL input if you are using a balanced XLR
connection from a different brand of preamp, and the RCA input if your preamp offers only unbalanced RCA
output. Repeat for the right channel.
If you are biwiring/biamping your speakers using a pair of Hercules II Stereo amps, connect the signal from
the left-channel output of the preamp to the right-channel (lower) input of the left Hercules II Stereo, and the
right-channel preamp output to the right-channel (lower) input of the right Hercules II Stereo.
STEP 4: Using the input select switch near the amplifier’s input jacks on the back panel, select the input to
which you connected the interconnect cables. Set the switch to BAL (left position) if using the regular
balanced inputs, Direct (middle position) if using the Constellation Direct Direct inputs, or RCA if using the
unbalanced RCA inputs.
STEP 5: Make sure the mute switch is set to Off (on both amps if you are using Hercules II Monos or two
Hercules II Stereo amps.
STEP 6: Turn on the master power switch on the back of the amplifier (both amps if you are using Hercules II
Mono or biwiring with Hercules II Stereos), above the connection for the AC cord. The front LED status
indicator on the amplifier(s) should glow red. If it does not, check your AC connection.
STEP 7: To power up the amp, push the left side of the bar on the front panel for 3 seconds. The LED status
indicator in the middle of the bar will start flashing green, which indicates that the amplifier is warming up.
After 1 minute the indicator will turn solid blue and the amp will be active. If the preamp and a source are
connected and playing, and the volume on the preamp is up, you should hear sound.

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STEP 8: To mute the amplifier, press and release the left side of the bar on the front panel. The LED status
indicator will start flashing blue and the sound will stop. To unmute the amp, press and release the left side
of the bar again.
STEP 9: To turn the amplifier off, press and hold the left side of the bar on the front panel for 3 seconds. The
LED status indicator will start to blink red, indicating that the amp is in cool-down mode. It will remain in this
mode for 1 minute, and during this time, you will not be able to use the front power button. After 1 minute,
the LED will glow solid red and you can power up the amp again.
Normal operation
Once the amplifier is installed and properly set up, it normally requires no user operation except for turning
the amplifier on and off.
Other than the power button on the front panel, the only control that you might want to use on a regular basis
is the mute function, which can be activated from the front power button or the rear mute switch. However,
this function is provided mainly as a convenience—you would normally use the mute function on your preamp
or the pause button on your source device to mute the sound from your audio system.
Maintenance
The Hercules II amplifiers require no regular maintenance.
If the amplifier’s surface becomes dusty, simply wipe it off with a soft dry cloth. Do not spray cleaners on the
surface.
To clean fingerprints from the surface of the amplifier, spray a small amount of mild window cleaner such as
Windex onto a soft dry cloth, then use the cloth to remove the fingerprints. Do not spray the cleaner directly
onto the amplifier.
If dust collects inside any of the amplifier’s vents, vacuum it out with a hand vac or shop vac. Use a brush
attachment if available in order to avoid scratching the surface of the vents. If you do not have a brush
attachment, do not touch the surface of the vent with the nozzle of the vacuum, in order to avoid scratching
the surface.
Troubleshooting
Amplifier will not turn on
1. Check to see if the front status indicator LED is illuminated red. If it is not, try the following steps in order.
If any one of the steps restores the power, there is no need to continue to the next steps.
A. Make sure the master power switch on the rear of the amplifier is turned on.
B. Check to make sure the AC cord is connected to the amplifier and to a wall outlet.
C. Flip the master power switch off and on again. This will reset the amplifier’s internal circuit breaker.
D. Check the circuit breaker in the electrical box to make sure it has not been tripped. If it has, check to
make sure a short circuit does not exist at the amplifier’s speaker terminals or the speaker’s input
terminals. If no short circuit exists, flip the breaker on and off to reset it.

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E. If none of these conditions restores power, it is likely one of the amplifier’s internal fuses is blown. Do
not attempt to change the fuse yourself—the amplifier requires the use of special high-voltage fuses
that are not commonly available. Contact your Constellation Audio dealer for service.
2. If the front status indicator LED is illuminated red, push the left side of the front power switch bar and hold
it for 3 seconds. The LED should begin flashing green. If it does, wait for 1 minute for the amplifier to warm
up. When the LED turns blue, the amplifier is ready to use. If the LED glows red but does not change color
when you push and hold the power switch, contact your Constellation Audio dealer.
Amplifier is on but no sound is produced
1. Make sure the front status indicator LED is glowing blue, indicating that the amp is warmed up and in
active mode. If the LED is glowing red, push it and wait 1 minute for the amp to warm up and the LED to glow
blue. Sound should now be restored.
2. If the LED is flashing blue, the amplifier is in mute mode. Push the left side of the front power switch bar
and release it. The LED should glow solid blue and sound should be restored. If not, check to make sure the
rear mute switch is set to Off.
3. If the switch is glowing blue and you hear no audio, try the following steps in order. If any one of the steps
restores the power, there is no need to continue to the next steps.
A. Check to make sure your preamp and signal source are both turned on, and your preamp is not in
mute mode.
B. Make sure the desired source is selected on your preamp.
C. Make sure the source device is putting out signal—i.e., if it is a CD player, make sure that the CD is
playing and not in pause mode.
D. Check the connections between the amplifier(s) and the preamp, and between the preamp and the
audio source device. If a cable is disconnected, reconnect it. If this does not restore sound, try
substituting a different set of cables in order to make sure the original set was functioning properly.
E. Check the connections between the amplifier(s) and the speakers. Make sure the speaker cables
have not come loose. If it has, turn the power off on the amplifier(s), wait for the front LED to glow red,
then re-install the cable.
F. If you are using two Hercules II Stereo amps for biwiring, make sure the input cables are connected to
the right-channel (lower) inputs of the amplifier.
Sound comes from the wrong speaker
If left-channel sounds are coming from the right or vice-versa (i.e., the violins in an orchestral recording come
from the right speaker, not the left), check the cable connections between the amplifier(s) and the speakers,
between the amplifier(s) and the preamp, and between the preamp and the source device. Make sure left-
channel interconnect cables are connected to the left channels of the source, preamp and amp, and right to
the right channels. Make sure the left speaker is connected to the Hercules II Stereo’s left-channel binding
posts, or to the Hercules II Mono or biwired Hercules II Stereos used for the left channel. Check the right
speaker connection in the same way.
Sound comes from only one speaker
1. If you are using Hercules II Monos or biwired Hercules II Stereo amps, make sure both amps are plugged in
and powered up. If you encounter difficulties, follow the troubleshooting steps under “Amplifier will not turn
on” above. If you are using biwired Hercules II Stereo amps, make sure the Biwire switch is set to on.
2. Switch the preamp to a different input and play music from a different source device. If sound now comes
from both speakers, check the connection between the source device and the preamp.
3. If you get sound from only one speaker no matter which preamp input you select, check the cable(s)
connecting the preamp to the amplifier(s) and the amp(s) to the speakers. Make sure the speaker cables are
firmly connected to the amplifier and the speaker, and that the cables have not been damaged. Then check
to make sure the interconnect cables are connected correctly between the source component and the
preamp, and between the preamp and the amplifier(s), and that all of the interconnect cables are in good
condition.

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4. If these steps do not restore sound to both speakers, turn the rear power switch off on the Hercules II Mono
or biwired Hercules II Stereo connected to the speaker that is not working, or on the single Hercules II Mono
amp. Leave the music playing, and allow it to continue to play until the sound dies out. This will discharge the
power supply to avoid possible electrical shock or amplifier damage. If you are using Hercules II Monos or
biwired Hercules II Stereo amps, connect the left speaker to the amplifier normally used for the right channel,
and vice-versa. If you are using a non-biwired Hercules II Stereo amp, switch the speaker cables, connecting
the left speaker to the amplifier’s right channel and the right speaker to the amplifier’s left channel. If the
same speaker doesn’t work—if, say, the left speaker was silent before and it’s still silent after you switch the
cables—you probably have a malfunction in that speaker. If the sound moves to the other speaker—i.e., if only
the left speaker was playing but now only the right speaker is playing—contact your Constellation Audio
dealer.
Sound seems unfocused
1. Play a CD of typical pop vocals and sit in front of your speakers at an equal distance from both (at least 8
feet away from each speaker). If the vocals seem to come from between the speakers, they are connected
correctly. Alternatively, you can use the “barking dog” test from the Stereophile Test CD or a similar phase
check test from another test CD.
2. If the vocals seem to come from all around you, make sure that the cables on both Hercules II Monos (or
both channels of the Hercules II Stereo amp) are connected properly, with the marked connectors or cables
connected to the positive (red or +) binding post on the amplifier, and the unmarked connectors or cables
connected to the negative (black or -) binding posts.
3. If you need to change the speaker cable connection, turn the amplifier off first. To avoid possible electrical
shock or damage to the amplifier, you must discharge the energy stored in the power supply. To discharge
the power supply, turn the power off with music playing. It may take up to a minute or so for the sound to die
out. After the sound dies out, it is OK to change or adjust the cables.

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Specifications: Hercules II Mono
Inputs 1 Constellation Direct XLR
1 standard balanced XLR
1 unbalanced RCA
Outputs dual metal binding posts
Power output, 8Ω (1 kHz @ 1% THD+N) 1.1 kW
Power output, 4Ω (1 kHz @ 1% THD+N) 1.5 kW
Power output, 2Ω (1 kHz @ 1% THD+N) 2 kW
Frequency response 10 Hz to 100 kHz
+1/-0.5 dB
Gain 14 dB Constellation Direct
26 dB Balanced & RCA
THD+N (1 kHz @ up to 90% of rated power) <0.05%
Output impedance 0.05Ω
Damping factor (8Ω load) 150
Input impedance 20KΩ Constellation Direct
20KΩ XLR balanced
10KΩ RCA unbalanced
Output noise <500 µV, -100 dB @ 250
watts
Weight 220 lbs/100 kg
Dimensions (hwd) 13.00 x 19.00 x 32.00 in
330.2 x 482.6 x 812.8 mm

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Specifications: Hercules II Stereo
Inputs 2 Constellation Direct XLR
2 standard balanced XLR
2 unbalanced RCA
Outputs metal binding posts
Power output per channel, 8Ω (1 kHz @ 1% THD+N) 550 W
Power output per channel, 4Ω (1 kHz @ 1% THD+N) 750 W
Power output per channel, 2Ω (1 kHz @ 1% THD+N) 1 kW
Frequency response 10 Hz to 100 kHz
+1/-0.5 dB
Gain 14 dB Constellation Direct
26 dB Balanced & RCA
THD+N (1 kHz @ up to 90% of rated power) <0.05%
Output impedance 0.05Ω
Damping factor (8Ω load) 150
Input impedance 20KΩ Constellation Direct
20KΩ XLR balanced
10KΩ RCA unbalanced
Output noise <500 µV, -100 dB @ 250
watts
Weight 220 lbs/100 kg
Dimensions (hwd) 13.00 x 19.00 x 32.00 in
330.2 x 482.6 x 812.8 mm

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For more information
Your Hercules II Mono or Hercules II Stereo amplifier should give you many years of trouble-free,
maintenance-free service. If you encounter any problems you cannot solve or have technical questions,
please contact your Constellation Audio dealer.
For more information about Constellation Audio products, please visit our website:
www.constellationaudio.com