Halcro is very likely the most famous Australian hi-fi brand you’ve never heard of. Indeed you’re likely to be more familiar with the name of the company that founded it — Minelab — than you are to be with Halcro, since you can buy a Minelab metal detector almost anywhere in the country… which isn’t true of Halcro, at least not yet. Hi-fi and metal detectors — what could these possibly have in common? The answer is quite simple: inventor and physicist Bruce Halcro Candy, who founded both companies.

Halcro builds the Eclipse in two versions: a monobloc power amplifier (as reviewed here) and a stereo power amplifier. The model name of both amplifiers is the same, so it is important that I differentiate them by referring to the monoblocs as ‘Eclipse Monos’ and the stereo version as an ‘Eclipse Stereo’.

Essentially, other than the obvious fact that you need two monoblocs for stereo, the Eclipse Mono and Eclipse Stereo use similar circuitry, but there are major differences in power output, with the monoblocs being more powerful — 550 watts into 4Ω, versus 350 watts into 4Ω for the stereo version, and the specifications for THD, IMD and TIM are slightly higher than for the Eclipse Mono.

One has to take into account here the word ‘slightly’, along with the fact that Halcro is claiming the Eclipse Mono has lower distortion than the Halcro dm58, an amplifier that was independently proved to have less of these distortions than any other amplifier in the world. To hang some figures on that claim, Halcro says the THD at 1kHz of the Eclipse Stereo is more than 130dB down (0.00003%) while that of the Eclipse Mono is more than 140dB down (0.00001%). It also says that IM products on the Eclipse Stereo are more than –110dB (0.0003%), down, and that they’re more than –126dB (0.00005%) down on the Eclipse Mono.

One significant technical difference between the two amplifiers is that that whereas the Eclipse Monos operate at all mains voltages from 85V through to 270V, there are two versions of the Eclipse Stereo, one optimised for mains frequencies between 90–140V and one optimised for mains frequencies between 200–270V. This means that whereas the Eclipse Monos will work in any country in the world, irrespective of its mains voltage or frequency, you have to order the correct version of the Eclipse Stereo according to the power supply of the country in which you intend to use it.

As for the power supply itself, it’s an unusual ultra-low noise ‘dual’ switch-mode design, where the first switch-mode power supply is used for power factor correction, ensuring that the voltage and current drawn from the mains power socket remain in phase. This first supply generates a high direct-current voltage that feeds a second switch-mode power supply, which creates the final d.c. voltages that power the amplifier’s circuitry. According to Halcro, as well as the advantages delivered by the power factor correction, the other advantages of its design are that its performance is not affected by load conditions, and that it has much lower noise levels compared with other power factor corrected power supplies. All printed circuit boards in the power supplies are quad-layer types to minimise EMI and voltage transients and improve reliability, and all are populated exclusively by industrial-grade semiconductors and capacitors with 105°C temperature ratings.

The Halcro Eclipse Mono’s power supply is not only shielded, it’s also kept physically separate from the amplifier circuitry. In fact there are four heavily shielded and damped compartments integrated into the Eclipse Mono chassis. As for the chassis itself, it’s still basically the vertical winged chassis originally developed for the very first Halcro amplifier, the dm58, but for this new Eclipse Mono (and, as it happens, the Stereo version as well), Halcro has increased the thickness of the casings to eliminate microphonics and resonances, and has improved the connections between the cases and the main heatsink pillars. If you closely compare an early-model Halcro with the new Eclipse Mono and Eclipse Stereo, you will see that the more solid construction has enabled the company to add some extra curves to improve the overall look of the amplifier. However, you certainly won’t have to look hard to see the improvement in the quality of the finish on the metalwork, which is now an aerospace-grade wet-sprayed coating. This not only looks fantastic, but is also very tough.

The circuit boards in the audio power amplifier section of the Eclipse Mono have six layers and, like the power supply section, are populated exclusively by industrial-grade semiconductors. All the electrolytic capacitors have 105°C temperature ratings and only low-impedance polypropylene capacitors and highly linear resistors are employed in the critical audio path.

The rear of the Halcro Eclipse Mono has four different inputs: one is a standard unbalanced input (with an impedance of 100kΩ) via a gold-plated RCA terminal, one is a standard balanced input (with an impedance of 100kΩ+100kΩ) via a female XLR socket, then there is a ‘minimal path’ unbalanced input (with an impedance of 600Ω), again via a gold-plated RCA terminal.

According to Dr. Peter Foster, of Halcro, the minimal path input bypasses one of the internal amplifier gain stages, so whereas the total amplifier gain for the unbalanced input is around 35.6dB, that for the minimal path input is only around 29.5dB. According to Mike Kirkham of Halcro, the minimal path setting “produces great results with higher-efficiency loudspeakers”.

The fourth input is a decidedly non-standard ‘current mode’ input (with an impedance of 60Ω).

The three first-mentioned inputs are all ‘voltage mode’ inputs, meaning that when a voltage is applied to any of them, the Halcro amplifies the voltage of the signal to send to the speakers. The fourth ‘current mode’ input requires you to connect a device with a current output to it, and the Halcro then amplifies the signal current rather than the signal voltage. In current mode, I would expect the amplifier’s bandwidth to be more extended, the slew rate to be faster, and even-lower levels of transient intermodulation distortion. According to Bruce Candy, the current mode input is “most desirable for minimising earth-loop-generated mains hum and ripple, high frequency interference” as well as to minimise “cable, plug and socket-generated interference.”

The problem with having a current input is that so few audio components have the necessary ‘current output’ required to drive the Halcro’s ‘current input’ that almost all audiophiles will end up having to use one or the other of the voltage mode inputs. As to the suitability of using these, Candy says the balanced connection is to be preferred over the unbalanced connection, but that “the unbalanced voltage [input] is quite satisfactory as long as earth loop generated
mains hum and ripple are not a problem…  and they should not be a problem unless the source equipment is poorly designed.”

(At the time of going to press, Halcro had  not signed off on the circuit topology of its new Eclipse Preamplifier, and a final decision had not even been made about whether it will even have a current output… though it seemed likely that it would.)

Switching between inputs is done via a single rotary control which means that you could have up to three different source components connected to the Halcro Eclipse Mono, and select between them, so if all three had their own volume controls, you could eliminate the need for a pre-amplifier or a control amplifier.

The number of inputs is another difference between the Eclipse Mono and the Eclipse Stereo. Whereas the Eclipse Mono has these four inputs, as described, the Eclipse Stereo has only three, with the one missing being the ‘minimal path’ input.

Halcro very cleverly does not have any publicity photographs of the Halcro Eclipse Mono amplifier ‘in situ’ or even with other audio components in the same shot, so it might come as a surprise when you see a pair for the first time and realise how large they are, because the Halcro Eclipse Mono is 790mm high, 400mm wide and 400 deep. And it weighs 55kg. Very obviously the Halcro Eclipse Mono amplifiers
are intended to be floor-standing!

As befits an amplifier with a rated output of 550 watts into 4Ω, the Halcro Eclipse Mono incorporates comprehensive protection circuitry for both the amplifier itself and its power-factor-corrected power supply. Halcro says the Eclipse Mono amplifier circuit has thermal protection against overheating, will shut it down if the output current exceeds an average of 12 amps continuously, or in the event of a short-circuit or a continuous d.c. offset, plus it has over-current limiting as well as short-circuit protection.

Halcro says that the Eclipse Mono’s power supply is “protected against most mains transients”, and “will cut out if most common faults are detected in the power supply (e.g. overvoltage, master clock at incorrect frequency, excessive temperatures etc)”.

In Use and Listening Sessions
The design of the Halcros — which you can see for yourself from the photographs — is such that they’re very easy to move around… provided that two strong people are doing it. Once they’re in place, hook-up is simple, thanks to the huge, rubber-covered gold-plated speaker terminals (two pairs per amp, to allow bi-wiring). The main 240V power switch is underneath the amplifier, alongside a 3-pin IEC socket and a huge gold-plated, rubber covered earth terminal. The standby power switch is located underneath the uppermost case, in the centre. It has a very odd ‘feel’ when it’s pressed, but it switches reliably every single time. Power status is indicated by two LEDs low down on the front panel of the power supply unit: a large red LED for stand-by and a smaller blue one for ‘on’. Oddly enough, these LEDs are replicated on the rear of the amplifier as well. Presumably some audiophiles install their Halcros with the speaker terminals facing the listening position. And I wouldn’t blame them — the Eclipse amplifiers look
stunningly beautiful from all angles.

The words ‘stunningly beautiful’ can also be used to describe the sound of the Halcro Eclipses, because it is simply gorgeous. Effortlessly gorgeous and staggeringly real. Listening
to Sarah Vaughan singing Ain’t No Use (from her album ‘The Divine One’) you can hear instantly why her nickname was ‘The Divine One’! (though she’s equally well known by her other nickname — ‘Sassy’.) But it isn’t only Vaughan’s voice that the Eclipses illuminate. Listen to the double bass, particularly the differences in tone between high and low-stopped notes. Listen, too, to the haunting sound of Sweets Edison’s muted trumpet. Then there’s the tinkling but clear sound of Jimmy Jones’ piano, chiming in only as necessary but oh-so-effectively. But while you’re hearing all these things, what you don’t hear is the Halcro Eclipse. The sound just exists in your room, like magic.

A few tracks on in the same album, Every Time I See You has Vaughan demonstrating just some of the vocal gymnastics at her disposal, and at the same time also giving an inkling of where that ‘Sassy’ nickname came from! And once again the Halcro Eclipse Monos laid bare her talent like no other amplification I have ever experienced. And I use the word ‘experienced’ rather than ‘heard’ deliberately… because the sound of the Halcro Eclipse Monos is truly a unique experience.

An unexpected delight was the precision of the stereo image created by these two monoblocs. The downfall of many monoblocs is imbalances in gain between the two completely different amplifiers, which results in image shifts. Not here! The central image is perfectly stage-centre, and all players are perfectly positioned in their places on the stage. Furthermore the sound-staging itself is also always perfect — never wider than it needs to be, but always exactly as wide as it should be. The soundstage seemed almost to be dynamic in its ability to accommodate the music being played. The ability of the Halcros to be sonically invisible was a constant joy. For example the guitar intro during Gloomy Sunday snapped me upright, even though I knew it was coming, because the illusion of there being a guitarist in the room, just in front of me and to the left, was palpable.

Guitar sound continued to captivate on Elliot Maginot’s ‘Young Old Everything In Between’, but on the second track, Monsters of War, I marvelled not only at the tone of Maginot’s acoustic guitar, but also at the sonic impact of Mathieu Leguerrier’s kick drum and the way the tonal quality remained identical irrespective of the volume at which I was listening. Here I confess that I ended up listening at much higher levels than I normally would, because the Halcro Eclipse Monos had that curious ability to play loud without actually sounding loud… an attribute that benefits all music genres, but most particularly full-scale orchestral works. At the same time, the silences are amazing, ably demonstrated by the shockingly short silence between Monsters of War and the track that follows, Djibril.

While I could hardly say I was surprised that the separation between the two channels of the Eclipse Monos was total — they are monoblocs, after all! — the sonic effect of such total channel separation is always mind-blowing, as was amply demonstrated by the percussion at 2:47 in Bell. But it definitely pays dividends when reproducing complex sound fields. For example I always thought that the sonic maelstrom that is Koi Child could never be cleanly (and clearly) reproduced by any hi-fi system, but the combination of the Halcro Eclipse Monos and Vivid Audio Kaya 90s proved me wrong. During the rap of Cruzy I could hear Cruz’s vocal perfectly, while Van’s bass guitar remained super-solid and Christian’s tenor sax just sounded superior. The PRAT the Halcro Eclipses Monos exhibited throughout this album — and all of my sessions — was exceptional.

It was also exceptional on the Miles Davis track Blow (or, as I like to call it, Hello, you have no messages) from his last studio album ‘doo-bop’. The frenetic percussion is faultlessly reproduced, the depthiness of the bass is luminary and the ‘fullness’ of the sound-field exemplary. I have never heard this track sounding as good before. Listening to Miles’ Australian connection (the soundtrack to the film ‘Dingo’), the echoed trumpet lines are achingly soulful and, with the bird and cricket noises, the Halcro Eclipse Monos delivered the true sound of the Australian outback. The ‘coo-ee’ calls that both trumpeters (the other being Chuck Findley) extract from their instruments are so realistic it’s almost impossible to believe they’re issuing from a trumpet.

The Halcro Eclipse Mono is a superb amplifier, one whose visual presentation captures the imagination like no other amplifier I have ever seen. Its sound quality is so breathtakingly good that I had to pinch myself through my listening sessions to remind myself I was awake, and
not in some blissful audiophile dream. But to describe the performance of the Halcro Eclipse Monos, I can do no better than echo the praise of Paul Bolin, who in turn paraphrased Shakespeare to say: ‘feed them the best, and the Halcros will give you an experience that is such stuff as dreams are made on.’

Halcro Eclipse Mono power amplifiers
Price: $135,000 (per pair)
Output power: 4Ω (resistive): 550 watts; 8Ω (resistive): 300 watts
THD @ 1kHz: <–140dB (<100 parts per billion) at 550-watts (4Ω)
THD @ 0–20kHz: <–126dB (< 500 parts per billion) at 550W (4Ω)
IMD (CCIF): <–126dB
IMD (SMPTE): <–126dB
Equivalent input noise: 5nV/sqrt(Hz) for the voltage modes; 6pA/sqrt(Hz) for the current mode.
Slew rate: 100V/μs
Inputs: Unbalanced voltage mode input with an impedance of 100kΩ, a balanced voltage mode input with an impedance of 100kΩ+100kΩ, a current-mode input with a 60Ω input impedance to minimise cable reflections (driven by current source), a minimal path voltage mode with an input impedance of 660Ω.
Gain: Balanced and unbalanced inputs 60V/V; Minimal path input 30V/V, Current mode input 9V/mA
Dimensions (HWD): 790 × 400 × 400mm
Weight: 55kg (each)