H&S EXCEPTIONAL

1/17/2022

Author: Karsten Hein

Category: Gear & Review

Tag(s): Power Amplifiers

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The H&S Exceptional is an ultra-linear MOSFET power amplifier that is capable of pumping 200 watts per channel into 8 Ohm loads and double this amount into 4 Ohms. Usually, doubling the power-rating as impedance halves works in theory, but here it also does in practice. At the heart of the amplifier is a large toroidal transformer able to extract a maximum of 1000 VA from your household grid. The amp’s sturdy body is constructed out of 2 mm steel sheets, and an additional inner steel cage serves to protect the delicate audio signals from harmful EMF that are generated by the power section. The outer cover is chromed. This mirrored-surface helps to accentuate the amp’s modest size of just 36cm in width and 16.6 cm in height. When I first chanced upon it, I had been sitting in the same room for a while and had hardly noticed the amp in the rack. However, the modest first impression was quickly forgotten, when I carried the amp for the first time. Its body felt ultra-solid, as if the unit was cut from a single block of metal. This effect was supported by the use of high-quality materials, right down to the stainless steel screws that were perfectly integrated with the chassis.

There was no popping, traceable vibration, or humming when the H&S Exceptional was switched on. Even with our periphery attached, there was no hissing or noise in the absence of signal. And, yes, even with my ear held to the speakers, the amp remained dead-silent. This did take me by surprise, because both our B&K ST-140 and Hafler XL280 amplifiers produced at least a faint amount of hissing, despite being well-made and excellent-sounding devices. My first impression therefore was that the H&S was an exceptionally well-behaved amplifier. Could this have been the reason for its ‘Exceptional’ name?

The H&S brand was originally created by the German Ortofon service technician Eugen Stöckl and his partner, first as a side-project next to their jobs and then as their main occupation. Over a period spanning more than 20 years, H&S developed and built a range of small-series Hi-Fi components for audiophile listeners. Among these products were the phono preamp H&S ‘Exact’, the ‘Iceblue’ phono cartridge, and three consecutive versions of the amplifier that is presented here. The main difference between the amp versions rested in the designs of the housing with the heaviest specimen weighing up to 38kg. Through the increase in sales of their products to audiophile customers, H&S was beginning to get noticed. When, in 2011, the leading international Hi-Fi magazine “The Absolute Sound” listed the H&S Iceblue among the world’s best phono cartridges of all time, Eugen Stöckl was able to receive this considerable honour in person, before his untimely death from a heart attack in the following year.

When reading about his sad demise on Markus Kannewischer’s website, I was reminded of the tragic fate of Peter Snell who had similarly died of a heart attack shortly after the launch of his popular C-Series loudspeakers. And, while men dying of heart failure was not unheard of, the idea of them dropping dead at the height of success did feel rather tragic to me. Hi-Fi had once again lost one of the industry’s humble contributors. Eugen Stöckl had been a staunch believer in the synergy of measuring and listening and spent lots of time doing both. His investment and stubborn diligence had paid off, and H&S was able to offer some true highlights to the audiophile community. The phono-preamp H&S Exact, for example, is considered to rank among the best of its kind until this day.

As the H&S Exceptional was a heavy amplifier, it took some 30-40 minutes warming up before displaying its full potential. With the original cost of the amp having been well in the five digits, Mr. Stöckl could be certain that the original amp owners would neither mind nor notice the increase in their electric bill while waiting for their amps to reach operating temperature, especially, as they were anticipating to experience a musical performance that would make them feel as the amp’s name suggested.

From one Solid State to another:

I began my exploration of the H&S Exceptional by hooking it up to our main system. This consisted of our Restek V1 preamplifier (previously upgraded by Restek and featuring a quality power supply by Mr. Kassel) and Martin Logan SL3 electrostatic loudspeakers. A Sansui SR-525 turntable with AT-VM95 ML cartridge and a Rega Planet 2000 CD player served as music sources. All units were interconnected with solid-core silver cables with copper-mesh shielding. I had a choice of loudspeaker cables and decided to start with our trusty Belden 9497 in bi-wiring (and connected to a single point of contact on the side of the amp for improved response). I chose a range of music and styles to focus on various aspects of performance, but will use just a few examples to highlight my findings.

Transitioning to the Exceptional from our trusty B&K ST-140 workhorse, I measured a 6 dB increase in effective volume when driving the H&S at the usual setting on the stepped Restek dial. I attributed this difference to the fact that the Exceptional had close to twice the power of our B&K but nearly the same input sensitivity. To avoid the criticism of comparing apples with pears, I made sure to set the volume at our usual listening level. Yet, even with the volume dialled back, the Exceptional sounded more focused and cleaner whilst playing stronger and more determined than our ST-140. In combination with our Martin Logan electrostatic speakers, the H&S achieved superb spatial and tonal separation of music events. The amp’s agile power output was driven by a total of 120,000 mF in supply capacitors which facilitated a rise speed of 300 V/μS. And, in combination with its formidable damping factor of 800:1, this resulted in an ultra-hard grip on the speakers. Amps like this are a valuable asset when listening to classical music and other scenarios in which many instruments play at once with multi-layered spatial and tonal character.

The Exceptional was capable of superb bass-punch and ultra-abrupt decay while holding simmering high hats suspended for eternity. In an all-solid-state setup (CD, Restek, H&S) this much command could at times sound overly dry and tight-fisted, stressing accuracy over musicality, but even exchanging one part of this signal chain could result in magic. Switching from our Planet 2000 CD player to the Sansui turntable, for instance, highlighted the amp's more musical side. Vinyl could easily benefit from a highly accurate amplifier by receiving a bit more transparency, drive, and punch than usual. Due to the relative absence of overlapping frequencies, of the kind that came from time-lag issues on the part of the loudspeaker drivers, the H&S Exceptional would not on its own be deemed as a 'warm' and soulful amplifier. It is relatively free of such effects. But, when paired with a turntable and tube preamplifier, it could well contribute to a superb mixture of musicality and detail, in addition to offering the welcome flexibility of being able to drive even the most difficult loads.

From exceptional amps to exceptional cables:

On 19 January 2022, just two days after writing the previous chapters of this review, I exchanged our standard Belden 9497 speaker cables (which work excellent on tube amps, etc.) for a pair of monsterous Madrigal Mark Levinson flat solid-core copper cables. The result was truly magical with the H&S Exceptional amplifier sounding perfectly balanced. It seems that the increase in capacitance and the uniquely crafted solid-core design of the Madrigal cable served well to bring out the amp's true merits. After all, the H&S Exceptional was targeted at owners of Krell or Mark Levinson amplifiers who were seeking to move upward. More information on this subject can be found in my Madrigal cable review.

Specifications

  • Power output (RMS, 8 ohms): 2 x 200 watts
  • Maximum power consumption: 1,000 watts
  • Transistor Type: Power MOSFET
  • Frequency response: 4 - 150,000 Hz
  • Total harmonic distortion: 0,03%
  • Signal to noise ratio: >100 dB
  • Channel separation: 105 dB
  • Input sensitivity: 1.3 Volts, max.
  • Input resistance: 27 kOhm
  • Damping factor: 800:1
  • Rise speed: 300 V/uS
  • Rise time: 0,5 uS
  • Dimensions: (W)360mm; (H)165 mm; (D)310 mm
  • Body: 2 mm steel casing + 2.2 mm steel shielding
  • Finish: polished chrome, silver-matt faceplate
  • Weight: 19,5 Kg
  • Years: 1990 - 2011 (Series 1-3)