It’s no secret that I’m in possession of a considerable tube amplifier collection, but there’s only one push-pull triode design in the lot. And that would be the Radio Craftsman C500A monoblock which is based on the Williamson circuit as tweaked by the legendary Sid Smith circa 1953. It operates with a pair of triode-connected KT66 output tubes to deliver a magnificent 15 watts. It has served as a model of what push-pull triode sound should be all about. It typifies a naturally sweet, clear, and transparent tone delivery, and the Luxman fits perfectly into that mold. It was capable of depicting subtlety and purity of tone that made reproduction of female voice a joy to hear. Microdynamic expressiveness was also a strong suit, and this became a key factor in nudging me over the line from “liking” this amp to “loving” it.
When it comes to purity of tone, it’s mainly about a benign distortion spectrum that is at play, one that does not emphasize odd-order harmonics. Triode amps have the edge in this regard, and as a consequence, the Luxman could never be characterized as a bright-sounding amp. Upper midrange glare was absent. That would be the sort of brightness that I typically associate with pentode designs, hence the moniker “pentode glare.” It tends to add false detail and drive to the music. And that’s not a good thing in my book, though some folks seem enamored with such a sonic “caffeine rush.”
Luxman recommends a break-in period of 80 hours, and that’s no exaggeration. Textures continued to smooth out during this period so that eventually the Luxman’s twin sonic virtues of clarity and control came into sharp focus. Transients were reproduced with a sense of speed and finesse that pentode amps would be hard pressed to match. There was plenty of detail to behold, though that was a function of the front end and matching loudspeakers. It was superbly resolving of changes introduced by digital source components, to the point that I decided to use it as a reference during DAC evaluations. It was quite happy when matched with a high-sensitivity speaker—no surprise here. And even in this context it proved to possess an extremely low noise floor. My educated guess is that it should also be compatible with most moderately sensitive loudspeakers in small to medium-sized listening rooms.
The Luxman performed extremely well driving my Quad-57 ESLs (refurbished and upgraded by Electrostatic Solutions), and that’s something worth writing home about. The Quad is all about midrange satisfaction, and even after all these years, it still holds its own against all comers. Granted, there are problems at the frequency extremes. There’s not much that can be done about the recessed upper treble, other than adding a super tweeter. But the upper bass, when controlled by a suitable amp, can sound phenomenal. My favorite performance and recording of the Bach suites for solo cello is Jean-Guihen Queyras on the Harmonia Mundi label, and it never sounded any better—no doubt a function of the Luxman’s excellent damping factor and bandwidth extension. The majesty of the cello was on full display with superb harmonic bloom and image focus. However, in the context of orchestral recordings, the one soundstaging aspect I would have to downgrade the Luxman on was its reproduction of a recording’s depth perspective. Relative to Linear Tube Audio’s ZOTL Ultralinear amp, orchestral soundstage depth was somewhat compressed front-to-back and lacked the layering afforded by the Berning design.
The Luxman MQ-88uC is nothing short of a musical treasure. It represents a nearly perfect introduction to the joys of triode sound and is highly recommended for those in search of a closer approach to the real thing, and is a mandatory audition for all Quad-57 ESL owners.
Specs & Pricing
Power output: 25Wpc (into 4, 8, and 16 ohms)
Input sensitivity: 890mV
Input impedance: 32k ohms
Frequency response: 20Hz–20kHz (+0, -0.5dB); 10Hz–100kHz (+0, -3.0 dB)
Total harmonic distortion: 0.1% (1kHz,1W); 0.5% (20Hz–20kHz,1W)
Signal-to-noise (IHF-A): 105dB
Vacuum tube complement: 2x ECC83S, 2x ECC82, 4x KT88
Dimensions: 440mm x 184mm x 230mm
Net weight: 16.1 kg
LUXMAN AMERICA INC. (North American Distributor)
27 Kent Street, Suite 105A
Ballston Spa, NY 12020
Loudspeakers: Quad ESL 57, Basszilla Platinum Edition DIY
Preamplifiers: Lamm Audio Industries L2.1 Reference, Supratek Chardonnay
Digital front end: Apple Mac BookPro running Audirvana 3.5 software, Schiit Audio Yggdrasil DAC, Ayon Audio CD-10 CD-SACD player
Analog front end: Kuzma Reference turntable; Kuzma Stogi Reference 313 VTA tonearm; Koetsu Rosewood Signature and Clearaudio da Vinci V2 phono cartridges; Merrill Audio Jens phonostage
Cables: Acrotec 6N, Kimber KCAG Select interconnects; Acoustic Zen Hologram II and Museatex Crypton speaker cable
Accessories: Sound Application power line conditioners