Constellation Audio Centaur Monoblock Power Amplifier

In my review of Constellation Audio’s Altair preamplifier and Hercules power amplifiers in Issue 215 I concluded that these electronics “established a benchmark against which all other linestages and power amplifiers can be compared.” Since that review, which was the world premier of the debut electronics from newcomer Constellation Audio, the company’s products have received wide critical acclaim, tremendous commercial success, and are the choice of many loudspeaker manufacturers for show demonstrations.

The name Constellation Audio might have been new when I reviewed the Altair and Hercules, but the people behind the company are anything but new to high-end audio. Constellation was founded by the principals behind the Continuum Caliburn turntable. For Constellation Audio, they assembled a team of the world’s greatest designers to create a new line of reference-grade electronics, a team that included among others John Curl, Bascom King, Demian Martin, and James Bongiorno, all led by industry veteran Peter Madnick. (Sadly, James Bongiorno, the man behind Ampzilla and Great American Sound in the 1970s, passed away January 10, 2013.)

Although the Hercules delivered reference-quality performance, its $140,000-per-pair price put it out of reach for all but the most well-heeled of audiophiles. Plus, who really needs 1100W into 8 ohms (and 2kW into 2 ohms)?

Enter the Centaur monoblock, an amplifier that isn’t a trickle- down version of the Hercules, but rather is the same amplifier with half the output power. The schematic is identical, but the Hercules features cost-no-object parts such as Vishay foil resistors. This $54,000-per-pair Centaur monoblock delivers 500W into 8 ohms, which is more than sufficient to drive all but the lowest- sensitivity loudspeakers.

The Centaur’s form factor is the more conventional rectangular chassis rather than the Hercules’ vertical tower design. A large bar running across the front panel turns the unit on and off; a tri- color LED within the bar indicates the operating status (off, on, warm-up, shut-down, mute). The rear panel offers two pairs of binding posts as well as two balanced inputs and one unbalanced inputs. A toggle switch selects between balanced an unbalanced operation. One of the balanced inputs is marked “Constellation Direct” and is used when driving the Centaur with a Constellation preamplifier. This input bypasses one entire gain stage in the Centaur. The chassis features an unusual surface texture machined into the aluminum along with ventilation holes in the side panels. The heat sinks are completely internal.

I won’t go into a full technical description here (see my Hercules review in Issue 215), but will hit the highlights. The output stage transistors are, unusually, all N-channel devices. Virtually all push- pull amplifiers employ complementary pairs of P-channel and N-channel transistors. These designations refer to the transistors’ polarity; the P-channel transistors handle the audio waveform’s positive polarity and the N-channel transistors handle the waveform’s negative polarity. But it’s impossible to make P-channel and N-channel transistors with identical characteristics; they don’t turn on and off with the same speed, introducing a waveform discontinuity at the zero crossing point where one transistor in the pair “hands off” the signal to the complementary transistor. Constellation’s answer is to use all N-channel transistors. The output stage is modular, and built around 125W elements that can be ganged together for higher output power. The Hercules output stage is built on eight such modules; the Centaur is built around four of these modules. Each module employs eight MOSFET output transistors, for a total of 32 transistors per Centaur monoblock.

Of course, the Centaur’s power supply is smaller than that of the Hercules, and the Centaur lacks the flagship’s cool functions such as the rear-panel readout of the amplifier’s operating parameters including internal temperature, output power at any given moment, and other features.

Listening

I’ve been listening to the Centaur monoblocks driving the Magico Q7 loudspeakers for several months, comparing them to the Rowland 725s, the Lamm ML2.2 single-ended triode, and the Absolare Passion 845 single-ended triode amplifiers. I’ve also heard these amplifiers, and the $26,000 stereo version (reviewed by Jonathan Valin in Issue 223), many times at shows.

The Centaurs sound very much like the Hercules, with tremendous transparency and resolution, a big and open spatial presentation, and a feeling that the amplifier is light on its feet dynamically. The overall balance leans slightly toward the upper- midrange and treble, with very airy and highly resolved midrange and treble. The Centaur’s bottom end is full and satisfying, but not the last word in weight and heft. The bass tends to be quick, agile, and articulate. Resolution and transparency are simply world- class—this is an amplifier that allows you to hear back through the playback chain with every detail highly resolved.

In a lesser amplifier this personality could make the sound analytical and cold, with bleached tonal colors and a threadbare rendering of timbre—resolution for its own sake rather than in the service of musical enjoyment. The Centaur’s somehow manages to combine standard-setting transparency, resolution, and openness with absolutely gorgeous textural density, fully saturated tone color, and a full measure of warmth and body. There are amplifiers one can admire for their sonic achievement but not fully enjoy musically. These amplifiers tend to have massive resolution and spectacular soundstaging, but somehow don’t connect emotionally because of a lack of warmth and richness of timbre. The opposite end of the spectrum is the amplifier that sacrifices resolution and transparency for “musicality” at the expense of a certain intellectual disengagement induced by a diminution of real musical information. The Centaur’s great achievement is delivering the most transparent and resolved midrange and treble presentation I’ve ever heard from an amplifier (except the Hercules) along with an exceptional richness of tone color and density of timbre. Massed strings or solo violin tend to be an acid test that reveals where an amplifier falls on the analytical-warmth spectrum. Getting just the right sheen on the strings without excessive edge and brightness is a tough challenge. But listen, for example, to the LA Philharmonic string section on the outstanding Speaker’s Corner LP reissue of Holst’s The Planets. Through the Centaur the violins have a light and airy rendering with tremendous resolution of inner detail, yet at the same time are richly textured and silky smooth with no trace of edge or whitish character. This is no mean feat, and largely due to the remarkably pristine quality through the treble. The Centaur’s top end is as clean as it gets, but it never crosses the line into the dry or antiseptic.

Just as the Centaur combines resolution with ease, it also portrays transient information with whiplash speed without an unnatural emphasis on transient leading edges. The upper registers of piano are particularly impressive, with a full measure of attack without the glassy hardness of many solid-state amplifiers. The transient speed in the bottom end is phenomenal, with startling impact on bass drum. I also enjoyed the Centaur’s sense of immediacy, presence, and vitality through the midrange and treble. The sense of presence isn’t the result of a forward midrange balance, but rather of the amplifier’s wonderfully realistic rendering of timbre, tremendous purity of instrumental texture, and remarkable sense of nothing between the music and me. Moreover, the jet-black background contributes to the vividness, setting off instruments with greater realism and drama.

Conclusion

Although I auditioned the Centaur monoblocks in a different system than the Hercules, I thought that the Centaur gave up very little to the $140,000 Hercules in sound quality. If you don’t need 1100W the Centaur monoblocks will get you within a hair of the state-of-the-art in solid-state amplification today. Both amplifiers are extremely transparent and resolved, with a light and open character that never crosses the line into the analytical. This combination of rich and saturated tone color with such an open and detailed midrange and treble is unprecedented in my experience (save the Hercules). The Centaurs are also unflappable dynamically, throw a huge and well-defined soundstage, and are beautifully built.

Recommending an amplifier is often accompanied by caveats regarding the amplifier’s particular sonic signature or its technical limitations, such as the ability to drive difficult loads. I have no such reservations about the Centaur monoblocks; these amplifiers are gorgeous sounding without straying from neutrality, and are muscular enough to drive virtually any loudspeaker with ease. They will satisfy those looking for extremely high resolution, but also listeners who value gorgeous tone color, density of texture, and musical ease. The Hercules sets the bar high in solid-state amplification, but the Centuar monoblocks come tantalizingly close for less than half the price.

SPECS & PRICING

Output power: 500W into 8 ohms, 800W into 4 ohms, 1000W into 2 ohms (1kHz, 1% THD+N); Gain: 26dB (14dB in Constellation Direct mode)
Input impedance: 100k ohms unbalanced, 200k ohms balanced
Output impedance: 0.05 ohms
Inputs: Two balanced on XLR, one unbalanced on RCA
Weight: 103 pounds each, net
Dimension: 11″ x 7″ x 20″
Price: $54,000 per pair

Constellation Audio
3533 Old Conejo Road, Suite 107
Newbury Park, CA 91320
constellationaudio.com