Reference Series
Hercules II / Stereo Power Amplifier
REFERENCE ALTAIR II Line Stage ORION Phono Stage HERCULES II Mono Power Amplifier HERCULES II Stereo Power Amplifier
Hercules II / Stereo Power Amplifier / Overview
Hercules II Monoblock Power Amplifier
The horizontal format of the Hercules II amplifier made it practical to create a stereo version—an amplifier in the same chassis as the Hercules II Mono, with the same effortless, extraordinary sound, but with two 500-watt channels instead of a single 1,000-watt channel.

The Hercules II Stereo uses exactly the same circuit as the Hercules II Mono and the original Hercules. The same circuit that inspired a leading reviewer to describe our original Hercules amplifier and Altair preamp as “the most transparent, detailed, and cleanest electronics I’ve heard.” The Hercules II Stereo cannot quite match the dynamics of the Hercules II Mono, but the fundamental sound quality is the same.

The Stereo benefits from the same upgrades we made to the Mono. The power supply features substantially larger storage capacitors, to deliver cleaner DC power and more headroom on loud peaks. The pure copper bus bars used for the speaker outputs and power supply rails are twice the size of those in the original Hercules. Both of these improvements allow the Hercules II Stereo to perform even better with low-impedance speakers.

The transformers and digital control circuits are now isolated in their own fully shielded and suspended enclosure, to protect the audio circuits from electromagnetic interference and vibration, and to prevent any vibrations from the transformers from being carried into the listening room.

Despite the reconfiguration from vertical format to horizontal, despite the splitting of the monoblock’s resources into two channels, the Hercules II Stereo maintains exactly the same sonic character, the same unprecedented combination of solid-state power and control with the warmth and musicality of a small, single-ended tube amplifier.

All of our Hercules amplifiers have been based on the same circuit: a single-ended, 125-watt amplifier design tuned purely for musicality. Each of these amplifiers forms a module. Rather than bulking up the Hercules amplifiers with more and more components to make the desired power rating, we simply combine multiple 125-watt modules. This is why the 500-watt-per-channel Hercules II Stereo sounds exactly like that original 125-watt amp.

Hercules II Stereo Power Amplifier
The revolutionary Balanced Bridged circuit topology used in all Constellation Audio amplifiers gives the Hercules II Stereo exceptionally low noise and outstanding common-mode rejection ratio. But those are just technical terms. What’s more important is that with an essentially perfect balance between the positive and negative halves of an audio signal, the Hercules II Stereo achieves a level of musicality previously heard only in our other amplifiers. The key element in our topology is the use of only N-type output transistors, instead of a mix of N- and P-type transistors as found in other fully-complementary solid-state amplifiers. Because every element of the musical signal passes through exactly the same types of circuit components, all the musicality of the original single-ended module is preserved.

All this would be for naught if the incoming audio signal were not itself perfectly balanced. For that, we equipped the Hercules II Stereo with the same Line Stage Gain Module used in our Altair II and Virgo line stage preamplifiers. The Line Stage Gain Module uses servo circuits and hand-selected field-effect transistors (FETs) to achieve the same perfect signal balancing found throughout the Constellation Audio line. If a Constellation Audio preamp is used, the amplifier’s Constellation Direct input, which bypasses the Line Stage Gain Module, provides the purest possible audio signal path.

For each of Hercules II’s channels, a custom-wound 3,000-watt toroidal transformer, feeding a capacitor bank with even more farads of capacitance per watt than the one found in the original Hercules, provides a consistent, imperturbable source of DC power. Fully regulated, noise-free DC power supplies feed the low-level circuits.

We do recommend the Hercules II Monoblocks for the very largest systems and the most demanding audiophiles. But for music lovers who don’t need the absolute maximum in power and dynamics, or whose listening room cannot easily accommodate two large monoblocks, the Hercules II Stereo can be the path to musical perfection.

Reference Series Index
Altair II Line Stage
Orion Phono Stage
Hercules II Mono Power Amplifier
Hercules II Stereo Power Amplifier
Overview
Features
Specifications


Inspiration Series Index
Preamp 1.0 Line Stage
Stereo 1.0 Stereo Power Amplifier
Mono 1.0 Monoblock Power Amplifier


Performance Series Index
Argo Integrated Amplifier
Virgo III Line Stage
Cygnus Digital File Player/DAC
Perseus Phono Preamplifier
Centaur II Power Amplifier
Centaur Mono Monoblock Power Amplifier
Centaur Stereo Power Amplifier



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