Hercules II / Monoblock Power Amplifier
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 ...
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.
- Inputs 2 XLR (1 Constellation Direct), 1 RCA
- 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
- Outputs metal binding posts
- Frequency response 10 Hz to 100 kHz, +1/-0.5 dB
- Gain 32 dB
- THD+N (1 kHz @ rated power) <0.05%
- Output impedance 0.05Ω
- Damping factor (8Ω load) 150
- Input impedance 10KΩ unbalanced, 20KΩ balanced
- Output noise <500 µV, -100 dB @ 250 watts
- Weight 220 lbs / 100 kg
- Dimensions 19 x 13 x 32 in (whd)
48.26 x 33 x 81.3 cm (whd)
While no one could ask for more performance, some dealers and customers asked if we could build the tower-shaped Hercules in a more traditional, horizontally oriented enclosure that could fit into equipment racks. This is exactly what we have done with the Hercules II Mono. The amplifier circuitry is the same, merely reconfigured to fit the new enclosure.
The new form factor also gave us space to incorporate significant upgrades. The Hercules II Mono power supply uses larger storage capacitors than the original Hercules, so the DC power is even cleaner and better to respond to extreme peak demands. We also had room to double the size of the copper bus bars used on the power supply rails and the speaker outputs. Both of these changes further enhance performance into low-impedance speakers.
The dual 3,000-watt power transformers are now enclosed in their own shielded, suspended enclosure, along with the control circuitry. The shielding protects the audio circuitry from electromagnetic interference produced by the transformers and control circuits. The suspension prevents vibration from the transformers from leaking into the audio circuitry or into the listening room.
Although the form factor of the Hercules II Mono is more convenient, it still delivers the same incomparable combination of tube-like warmth and limitless dynamics.
We’ve always loved the depth and delicacy that single-ended triode tube amps provide, yet we wanted more: more power, more dynamics, and more compatibility with different types of speakers. Thus, we based the original Hercules design on a single-ended amplifier: a 125-watt design tuned purely for musicality. By building these single-ended amplifiers as modules, and combining multiple modules in a single chassis, we could create a 1,000-watt monoblock that sound exactly like that original 125-watt amp.
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.
Of course, if the incoming audio signal is not perfectly balanced, it does little good for the amplifier to be perfectly balanced. To ensure a pristine incoming signal, we equip Hercules II Mono with our Line Stage Gain Module, the same circuit used in our Altair II line stage. Our Constellation Direct interface allows this gain stage to be bypassed if a Constellation Audio preamp is used.
As with its predecessor, the performance of the Hercules II Mono is not affected by the speaker, nor by the program material, nor by the listening volume. It delivers the same musical intimacy and emotion with any speaker, with any music, at any volume. It is exactly what audiophiles have always wished for... but never really dared to hope for.
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.
Constellation Audio was founded on the premise that one cannot create something extraordinary through slavish adherence to established methods. When tradition is the best path, we embrace it. When new technology is necessary to achieve the performance we want, we invent it. When we find a radical circuit topology that delivers a substantial advance in sound quality, we use it.