Hephaestus Audio’s Harpocratus Monoblock Amplifiers (Special Edition)

by Martin Appel on January 15, 2014 · 2 comments

in Amplifiers, Star Components

For the last several years my reference amplifiers have been the Hephaestus HMA 1000 mono-blocks (now simply called the Hephaestus — see my review August 2010) and have performed absolutely flawlessly. I am always chagrined at the looks of incredulity on many an audiophiles’ face after listening to these audio giant killers. How can these diminutive Class D amplifiers sound so good?

Joey White, the designer and company president has an Electrical Engineering background and is passionately involved in amplifier design, primarily, Class D. He eschews the use of off the shelf power supplies and OEM amplifier modules. His designs reflect original thinking and an understanding of how we perceive music. He produces several models or versions of the Hephaestus amplifier. His latest model is the Harpocratus, and is appropriately named after the Greek God of Silence. White loves his Greek mythology. His intent was to take his successful design of the Hephaestus model and do everything he could to reduce the already infinitesimal noise floor. The goal was to produce the quietest, smoothest sounding and most musically accurate amplifier that his fertile mind could imagine. Since I was already a convert, I had to get a hold of these babies and see how successful he was at achieving these goals.

Before the amps were shipped White upgraded the standard version (not requested by me) by replacing the standard fare with silver binding posts (WBT-0705Ag), silver IEC inlets (Oyaide IEC-CM 174-R) and silver mains fuses ( Hi-Fi Tuning Silverstar ).

The standard Harpocratus amps were going for $5,900USD per pair. The silver upgrades bring the MSRP to $7,000USD. When asked, Joey suggested that the silver upgrades give even greater clarity and resolution.

I appreciated the extra goodies and this review will be of that on the upgraded, Special Edition (SE). It would be interesting to compare this to a standard pair of Harpocratus amplifiers to see what extent the performance was affected by the upgrades and/or is it worth the extra cost.

First I want to say the appearance of the Harpocratus has taken a leap forward versus the utilitarian aesthetic of the Hephaestus. These new amps have a much more sophisticated aesthetic with brushed anodized aluminum and the construction feels more robust.

As usual with White’s kit, the amps have no footers, no on/off switch, no indicator lights and no power cords. As discussed before he believes that any audiophile will experiment with after market power cords and the many choices of footers to optimize the sound. I do wish he could have included an indicator light and on/off switch.

I used about 100 hours of burn-in and that seemed to do the trick. Prior to burn-in, the amps were cold, edgy and thin sounding. After about a day they started to warm up and open up. At the 100 hour point they were ready.

Before I start I must mention that our colleague, Mike Levy, has formed a speaker company called Alta Audio and lent me a pair of his stand mounted two way speakers called the FRM-2’s (Full Range Monitor) for Beta testing and they were used extensively during this review. I will be doing a formal review in the near future [unless I sneak a pair first -Ed].

My first impression was the distinct clarity and separation these new amps offered. The key thing was that it achieved this without resorting to hyper edginess that some equipment exhibit but by pouring forth detail in a natural, easy, uncluttered way making the music more accessible. The ‘lifting of veils’ or the ‘removal of grundge’ are expressions we’ve all used and experienced in the description of this phenomena of increased openness and resolution. In this case, it was wonderfully true. I’m sure the reduced noise floor of the new amps from the 70uVrms unweighted of the Hephaestus to the 40uVrms unweighted of the Harpocratus was a major factor in achieving such high levels of resolution.

In addition to the improvements of greater resolution, the Harp’s dynamic capabilities have improved as well. Going from 119db, unweighted, of dynamic range to 124db, unweighted, proved eye opening. These amps had the ability to reproduce crescendos with explosive power, without any strain and with complete musical clarity. These amps took life as people making music.

These accomplishments alone were very impressive and worthwhile but what I didn’t expect were the improvements in the soundstage as well. It seemed wider and deeper then the Hephaestus produced and its image specificity and three dimensionality, already excellent, improved even further.

White gives a 90 day 100% money returned policy which makes it very attractive to try these little ‘killers’ in your system. Once you have them in the ‘Gods of Silence’ will take over and music will reign throughout the Democracy.

I recommend these amps unequivocally and the only ‘nit to pick’ would be the lack of an on/off switch with indicator light.

[It is with great pleasure that we award The Audiophilia Star Component Award to Hephaestus Audio's Harpocratus Monoblock Amplifiers (Special Edition). Congratulations! - Ed]


1000 Wrms into 4Ω / 600 Wrms into 8Ω
20 Hz – 20 kHz +0.0/-0.5 dB (any load)
124 dB dynamic range (unweighted)
40 uVrms noise floor (unweighted)
26 dB gain / 10 kΩ input impedance
9.0” x 6.75” x 2.25” / 3.5 pounds each
90 day return policy with 100% refund
7 year parts and workmanship warranty

Reference System

Amplifiers: Hephaestus HMA-1000 Monoblocks

Speakers: Levy Acoustics FRM-1, Alta Audio FRM-2

Phono Preamplifier: AVID Pulsare updated to II

Digital: MSB DATA CD IV Transport w/
Preamplifier/Processor: The DEQX HDP-4
Analogue: Avid SEQUEL SP/SME IV arm/Cartridge: Shelter 7000

Speaker Cables: Acoustic Zen’s Absolute, Kaplan GS Mk III
Power Cords: Kaplan GS Mk II

Interconnects: Antipodes Audio KOKIRI, KOMAKO and REFERENCE, Acoustic Zen’s Absolute, Morrow Audio MA-7

Accessories: Redpoint BLAKHOLE’s, Herbie’s Audio Lab Tenderfeet, Soundcare products, Acme Audio Labs wall outlets

Power Conditioning: Kaplan Alchemist


Hephaestus Audio’s Harpocratus Monoblock Amplifiers (Special Edition)

Manufactured by Hephaestus Audio

940 Little Bardfield Road
Webster, NY 14580, USA

Price: $7000/pair
Source: Manufacturer loan

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Merrill Audio visits with their Veritas Monoblock amplifiers — Audiophilia
10.27.14 at 10:10 am

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Karl Sigman 01.15.14 at 5:28 pm

When I upgraded my system a while back and replaced my 50 pound stereo amp with a pair of 8 pound (each) mono block Class D amps (not made by Hephaestus, and considerably less expensive; a real bargain), I was amazed by the quality of sound. How could such tiny/light boxes perform like this? I became hooked on Class D.
Marty then lent me, about 2 months ago, a pair of his older model, the Hephaestus HMA 1000, for about 8 days to try on my system.
That was an eye opener. It is then, for example, when I came to understand and appreciate what Marty says in his review here about the handling of crescendos.Then, after listening to Marty’s new pair of the Harpocratus on his system and hearing how spectacular they sounded, I was completely hooked: I acquired a pair myself to try out—they are now my reference amps. Joey White sent me a note, “I hope you enjoy your upgraded Harpocrates amplifiers for years to come.” (Upgraded means Special Edition (SE).) I plan to. And they only weigh 3.5 pounds each; less that half the weight of my previous Class D amps….I still can’t believe it.

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