2014 Buyer's Guide: Power Amplifiers Under $8,000

Equipment report
Solid-state power amplifiers,
Tubed power amplifiers
Bob Carver VTA-27S Black Magic,
Nuforce Reference 18 V3,
Sanders Sound Magtech,
Van Alstine FET Valve 600R,
Van Alstine UltraValve
2014 Buyer's Guide: Power Amplifiers Under $8,000

AVA Ultravalve
According to Frank Van Alstine, the Ultravalve’s lineage is traceable to the Dynaco Stereo 70, which he denotes as its “great grandmother.” Although not as romantic sounding as the original, it is far better focused, and in general sounds like a higher-resolution device. It handles bass lines with superb control and good impact and is capable of dishing out plenty of boogie factor. Its ability to retrieve microdynamic nuances allows for the full scope of the music’s dynamic intensity and interaction between musicians to shine right through. avahifi.com

Carver VTA-27S Black Magic Amplifier
This 20Wpc stereo amplifier reflects Bob Carver’s love for the EL84/6BQ5 pentode—historically, the most popular power tube of all time. Circuit topology is fairly simple. The input signal passes through a 250kOhm pot and is then amplified by one half of a 12AX7. The second half of the 12AX7 is configured as a cathodyne phase-splitter. The push-pull output stage is pentode connected and uses a pair of self-biased EL84M per channel. Its sonic signature is more rhythmically convincing than that of many KT88- and EL34- based amps, meaning that it boogies far better than much of its more expensive and powerful competition. Notable sonic attributes are a clear midrange tone, plenty of low-level resolution, excellent soundstage transparency, and a well-controlled treble range. A sonic gem in its price range, but be sure that matching speakers are 90dB+ sensitive. bobcarver.com

AVA FET Valve 600R
Frank Van Alstine’s 300Wpc hybrid amp is based on AVA’s patented forward-transimpedance design. A 12AT7 triode front end is coupled to a fully complementary power MOSFET output stage. The stock JJ Electronic tubes are quite musical, so there’s no compelling reason to tube roll. No, it doesn’t sound like a tube amplifier, but what sets it apart from a host of solid-state designs is its soulful midrange and ability to retrieve music’s drama and tension. Tack on decent spatial delineation and you have the making of a successful hybrid design. It’s a complete package featuring low distortion, superior speed, killer bass, and superb dynamics. The treble is somewhat closed in, and tonally, harmonic colors are on the dark side of reality, requiring careful system matching. At its best, the 600R can sound much like a $20k power amplifier. World-class power amplification at an affordable price. avahifi.com

Sanders Sound Magtech
This no-nonsense amplifier was designed to drive any loudspeaker impedance, particularly full-range electrostatics which can have an impedance of less than 1 ohm in the top octave. The Magtech “sounds as if it had infinite power into anything with total stability,” said REG. The fully regulated power supply is unusual. Delivering 500W into 8 ohms and 900W into 4, and fully stable driving capacitive loads, it is the perfect choice for electrostatics. sanderssoundsystems.com

NuForce Reference 18 V3
We have reviewed successive generations of NuForce Reference 9-series Class D amplifiers, noting that each has offered worthwhile (albeit subtle) incremental improvements. With the Reference 18 V3, though, NuForce has taken a much more substantial sonic leap forward. Internally, the Ref 18 has a larger, more elaborate power supply than those used in past NuForce amps, necessitating a new full-width chassis. Sonically, the benefits are dramatic, including a more detailed, three-dimensional, and dynamically expressive sound than we’ve heard from past NuForce monoblocks. Although the Ref 18 has the same published output specifications as the Ref 9, it sounds noticeably more powerful and expressive. Similarly, low-level details and, especially, spatial/ soundstaging cues flow more freely and effortlessly from the new amp. The upshot is that the Ref 18 is a forthright truth-teller that keeps faith with recordings, though it refuses to sweeten or embellish their sound in any way. nuforce.com

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