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Hercules II Mono Amplifier

Hercules II Mono Amplifier

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Reviews From America's Best

When one of America's best-known audio reviewers described our original Hercules amplifier, along with our Altair preamp, as "the most transparent, detailed, and cleanest electronics I've heard," we knew our "dream team" of top audio engineers and industrial designers had achieved its goal: to create the world's best amplifier.

A Revolutionary Twist

The Hercules II Mono employs a revolutionary twist on the concept of a fully balanced amplifier. In all balanced amplifiers, mirror-imaged amplifier circuits are used, with one part amplifying the positive half of an audio signal, and the other part amplifying the negative half. Yet in other balanced amps, the two halves are not quite equal, because one uses N-type transistors and the other uses P-type transistors. Hercules II achieves an essentially perfect balance by combining two matched single-ended amplifiers using only N-type output transistors. Every element of the musical signal passes through exactly the same types of circuit components, maintaining all the musicality of the original single-ended module.

1,000 Watts of Power into 8 Ohms

With 1 kilowatt of rated power into 8 ohms (and even that is a conservative number), the Hercules II monoblock has more than enough power for any speaker, any space and any listening taste. It handles low-impedance speakers with ease, delivering 1.5 kW into 4 ohms and an incredible 2 kW into 2 ohms.

Balanced Drive Design for Superior Musicality

By using only N-type output transistors, instead of half N-type and half P-type as in other amplifiers, Hercules II achieves an essentially perfect balance between the positive and halves of the audio signal. As in a single-ended amplifier, the entirety of the audio signal passes through exactly the same type of output device.

Modular Circuit Concept

By building Hercules II from numerous 125-watt single-ended modules, we achieve the sound quality of a small amplifier with a full 1,000 watts of power.

Dual 3,000-Watt Power Transformers

These custom-wound toroidal transformers contain several isolated sets of windings to supply independent power feeds to various circuits within the amplifier. Because the windings are isolated, the demands of one circuit do not affect the performance of other circuits, and consistent voltage and current are always supplied.

No Zobel Network Needed

Hercules II's inherently stable circuit design eliminates the need for a Zobel network at the output terminals to ensure stability at high frequencies.

Large Heat Sinks with High-Flow Ventilation Ports

An amplifier of Hercules II's incredible power must have ample and consistent airflow for reliable operation. To ensure that the amplifier runs cool, we equip it with huge heat sinks and hundreds of large ventilation ports that minimize airflow impedance.

Line Stage Gain Module

In order to assure that all incoming signals are perfectly balanced and can thus benefit from Hercules II's balanced drive design, we gave it the same type of input stage we use on all of our line-level components. This fully complementary preamplifier circuit uses hand-selected FETs and servos to achieve an essentially perfect balance between the positive and negative halves of the signal.

Constellation Direct Balanced Interface

Because all Constellation Audio preamplifiers supply a perfectly balanced audio signal at their outputs, Hercules II includes the Constellation Direct input. This input bypasses the amplifier's Line Gain Stage Module, thus simplifying the audio signal chain and achieving maximum musicality.

*All Units are Available in Black at an Additional Cost*

Constellation Hercules II Mono Amplifier User's Manual


Inputs: 2 XLR (1 Constellation Direct), 1 RCA

Outputs: Metal Binding Posts

Power Output:

1.1 kW, 8 ohm (1 kHz @ 1% THD+N)

1.5 kW, 4 ohm (1 kHz @ 1% THD+N)

2 kW, 2 ohm (1 kHz @ 1% THD+N)

Gain: 32 dB

Damping Factor (8Ω load): 150

THD+N: <0.05%, 1 kHz @ rated power

Frequency Response: 10 Hz to 100 kHz, +1/-0.5 dB

Input Impedance (direct): 100K Ω

Input Impedance (balanced): 10K Ω

Input Impedance (single-ended): 10K Ω

Output Impedance: 0.05 ohm

Weight: 220 lbs

Dimensions: (W x H x D)

19 x 13 x 32 in (whd)
48.26 x 33 x 81.3 cm (whd)

Constellation Award 2022