Unison Research are expanding on their class-leading range of valve-based hi-fi electronics to produce their first ever dedicated headphone amplifier solution. The SH is a single-ended, two-stage full-valve headphone amplifier designed to accommodate traditional analogue and modern computer-based audio sources.
The SH began with the same basic remit as the coveted Simply Italy integrated amplifier; to produce a world-class sound from a specialised device using the best technology available. The result was a fairly simple, linear circuit that produces an output voltage which is more than capable of driving a wide range of headphones, while keeping distortion low throughout the frequency range. This allows the SH to deliver a consistent, coherent sound character when in use.
The input stage uses ECC83 valves, while the output stage uses one EL84 valve (both operating in triode mode). The benefits to using this specific combination of valves are in the reduced power requirements for how the valves are usually employed, resulting in extended life, and the EL84’s ability to drive an output transformer with optimal electrical and sound qualities.
The SH comes equipped with two headphone outputs, connected in parallel for easy switching between headphones, or to accommodate multiple listeners. There is also a “Sensitivity” switch, to ensure the widest possible range of headphones can be comfortably driven by this amplifier. When set to “High Sensitivity”, the output voltage from the amplifier is reduced, and at “Low Sensitivity” it is at its maximum. The added advantage of this switch is for maintaining optimal sound quality while listening to music at lower volumes.
In addition to a standard un-balanced RCA input for connecting any traditional analogue source, the SH is also equipped with a class-leading USB DAC. The asynchronous USB 2.0 technology is the same as found on the recent Triode 25 amplifier, and supports audio formats up to 384kHz PCM and DSD 128. The patented jitter-elimination circuit ensures a great sonic performance, assisted by the galvanic isolation employed between the power areas of the USB interface and the conversion IC. This additional input option brings SH up-to-date with the latest requirements of computer-based audiophiles.
With the use of an Apple lightning to USB connector (not included) you can plug your iPhone/iPod/iPad directly into the SH's DAC and play your hi-res music files straight from your device.
The reason for choosing a headphone-based product was so Unison Research could cater for the growing world of headphone audiophiles, offering them the best valve-based amplifier to enjoy. It’s very difficult for solid-state solutions to compete with the un-rivalled influence valves can have on audio performance, making the SH a must-audition for anyone who takes their sound seriously.
A more sophisticated, more mature version of the award-winning NightHawk, NightHawk Carbon boasts several acoustic, ergonomic, and cosmetic refinements, adds a second pair of earpads, and includes a more versatile, durable cable—all while retaining its predecessor’s exceedingly low distortion, unsurpassed comfort, and naturally beautiful sound.
Compared to the drive-units commonly used in most headphones, NightHawk Carbon’s 50mm dynamic driver much more closely resembles the high-quality drive-units found in today’s most sophisticated loudspeakers—not simply in appearance, but, more importantly, in terms of function and performance. It employs a carefully constructed bio-cellulose diaphragm, voice-coil former, and compliant rubber surround, resulting in quality that is as easily seen as it is heard.
Designed for exceedingly low distortion and high excursion with true pistonic motion, NightHawk Carbon’s driver contributes significantly to the headphones’ well-controlled bass, rich midrange, and naturally extended highs. Its combination of effortless clarity and outstanding representation of space produces meaningful, emotionally compelling listening experiences. More than merely capable of providing short-term pleasure, NightHawk Carbon is designed to deliver satisfaction that endures.
The open-back design of NightHawk Carbon’s speaker enclosures—its earcups—enables an expanded, three-dimensional soundstage with natural dynamics and smooth, coherent performance that extends into the lowest and highest octaves.
As with any open-back headphone, the open area had to be protected by a grille to prevent damage to the headphone’s precision-made internal parts. Traditionally, this has almost always been accomplished with perforated metal/plastic, wire cloth, or some other effectively two-dimensional material. While more or less successful at protecting the headphone’s internal parts, these materials also tend to compromise the headphone’s performance, reflecting sound back toward the driver, creating standing waves and resonant colorations.
But what if this grille could be three-dimensional and promote a random scattering of sound—diffusion—to successfully prevent those destructive standing waves?
Hi-Fi World, August 2016
|Reviewed By:||Martin Pipe|
EXCELLENT - Extremely Capable
Comments of Note:
Playing: Garett Brennan - ‘Alta Powder Day’ (DSD64)
“Such simplicity makes for a very natural sound, to which the SH did full justice with an intricately-detailed and open, yet intimate presentation.”
Playing: Man – ‘Slow Motion’ (FLAC)
“There’s a lot going on in tracks like ‘Hard Way To Die’ and ‘Day And Night’ and these multiple musical layers were all definable. The guitars, deliciously warm bass, tight percussion and keyboards swirling beneath could be picked out and positioned, yet at the same time they gelled together as a whole.”
Playing: Kiasmos – ‘Thrown’
“Electronic percussion also fared well and the bells also forming a part of ‘Thrown’ were rich in timbre.”
“What this track revealed above all, though, was the SH’s ability to cope with what must rank among the meatiest basslines yet committed to record.”
Playing: Ligeti – ‘Kammerkonzert’
“…a complex work involving strings, woodwinds and keyboard instruments. This was delivered with the depth, texture and urgency it merited.”
Playing: Sibelius – ‘Second Symphony’
“…demonstrated the benefits of headphone listening – an expansive soundstage and balanced tonality, freed from the deleterious effects of room acoustics and speaker colouration.”
“…an engaging and musical experience…”
“…a great headphone listening experience.”
“FOR – musically-engaging – plenty of body and depth – two headphone outputs”
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