TAS 188: Vincent Audio SA-T8 Preamplifier & SP-T800 Monoblock Amplifier

Equipment report
Categories:
Tubed power amplifiers
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Products:
Vincent Audio SA-T8
TAS 188: Vincent Audio SA-T8 Preamplifier & SP-T800 Monoblock Amplifier

The German company Vincent was established in 1995 with the goal of placing high-end sound within reach of the common man. The question of how to make the high end affordable was answered by its founder, Uwe Bartel, using a business model, which while innovative for its time, has become common-place today: Design products in the West and have them built in China. This marriage of German engineering and Chinese manufacturing proved quite successful. Mr. Bartel, an electronics engineer, had no problem designing interesting audio gear, and Vincent’s attractive mix of good sound and value slowly gained momentum and global marketshare. The SA-T8 line preamp and SP-T800 monoblock power amp represent Vincent’s top-of the-line Premium line. Even though these products’ fit, finish, and elegant aluminum chassis exude a distinct high-end feel and look, the price is quite affordable by high-end standards and well below the onset level of sticker shock.

Vincent’s quality is more than skin deep, as a glimpse under the hood will reveal. In addition, there’s quite a technical story to tell. Let’s start with the line preamp. The SA-T8 is an all-tube balanced design, meaning that both the positive and negative legs of a balanced signal are amplified separately. What happens to a single-ended (RCA) input? Well, it’s converted to a balanced signal by being routed through a split-load (also known as a concertina) phase-splitter, using one section of a 12AU7 preamp tube per channel. This type of phase-splitter creates two balanced outputs of opposite phase from an unbalanced input. However, both balanced and single-ended preamp outputs are provided—just in case your power amp lacks balanced inputs. The gain stage consists of a cascade of two 12AX7 triode sections. The output stage features a cathode follower based on a single 12AU7 section. Note that Russian (rather than Chinese) tubes are used exclusively. The power supply uses two power transformers and is quite sophisticated. It features shunt-regulated high-voltage rails. The filament supplies are DC and are also fully regulated. A total of four RCA and two Neutrik XLR inputs are provided. A heavy-duty aluminum-cased remote control is included, which controls the input selector and a motorized volume control. My only quibble is with the motorized volume control. It takes some getting used to, as anything beyond a light tap on the “up” and “down” remote buttons results in too large a level change. As with many other modern line preamps, there is no balance control. Too bad, as this is a feature I find handy on occasion in adjusting for interchannel sensitivity differences.

The SP-T800 power amplifier is also a fully balanced design, and a hybrid in that it consists of a vacuum-tube front end and a solid-state output stage. The amp does accept either a single-ended or a balanced input, selectable on the rear panel. As with the SA-T8, a 12AU7-based split-load phase-splitter is used to convert the single-ended input to a balanced signal. The first voltage amplification stage uses a Russian 6922, which feeds a 6CG7 dual triode connected as a series-regulated push-pull driver stage. The output stage uses a total of eight high-power transistors to meet its power rating. Much of this amp’s bulk and weight are the result of an impressively large 500W-rated power transformer and a total capacitor reservoir of 80,000 microfarads, all of which are isolated in a separate compartment. The power supply is fully regulated, including the DC tube-filament supplies. Passive parts used in the signal path are audiophile-grade, and include Wima and Solen caps.

My strategy in evaluating these products was to audition each component separately in several contexts and then, for the grand finale, combine both units in the signal chain. The preamp sounded pretty good out of the box even after only an hour break-in period. The monoblocks, on the other hand, required a significantly longer break-in before reaching peak performance levels. Since the Vincent gear was evaluated in parallel with the TEAC Esoteric A-100 power amplifier, comparisons of the sound of the SP-T800 to that of the A-100 were inevitable. Keep in mind, however, that the A-100 is not only four times more expensive but is also an all-tube, KT88-based, power amplifier.

The ultimate goal of a hybrid power amplifier is to combine the best of both worlds—the magic of tubes with the bandwidth and bass crunch of solid-state. The SP-T800’s solid-state genes were definitely in evidence while driving the Esoteric MG-20 speakers. There was more treble energy and enhanced treble detail relative to most all-tube power amps. And bass definition was quite convincing. A power amp with a fairly low source impedance (e.g., the SP-T800) not only provides superior bass damping but also generates minimal interaction with a speaker’s impedance magnitude and hence produces a more predictable tonal balance. Most tube amps, especially the low or no-feedback designs, are stuck with a source impedance of several ohms and thus generate a significant load dependence. On the flip side, the Vincent gave up some ground in microdynamic intensity and soundstage transparency.

While driving the Final Sound 1000i electrostatics, plenty of tube magic shone through. The midrange displayed a warm and smooth tone, and in particular, a robust lower midrange that did justice to male voice. The soundstage spatial impression was expansive, especially with regard to width. There were losses in depth perspective and image focus relative to the A-100, but image focus was the area most affected by continued break-in and showed considerable improvement over time. There was plenty of speed in evidence. Transient attack was cobra-like in its quickness, while transient decay was well behaved. The Vincent displayed a healthy dose of kinetic energy as it propelled musical lines along. Bass output was nothing short of spectacular. I had never heard the 1000i sound so punchy, and it’s far from being the easiest load on the planet. The SP-T800 made the 1000i sing on large-scale orchestral music, revving up from soft to loud with the greatest of ease. Though, as it left its sweet spot of 20Wpc Class A operation, the midrange started to sound a tad more electronic than the real thing.

Enter the Venture Audio Excellence III loudspeakers, and more or less the same story to tell. Tremendous bass punch, pitch definition, and drive, with no upper-octave brightness. Excellent timbre fidelity, especially good with male vocals. A slightly warm tonal balance, this prized tube warmth being a big plus in my book. Slight losses were observed in image focus, soundstage depth, and transparency, all of which made it a bit difficult to fully resolve massed voices.

The inescapable conclusion is that the Vincent SP-T800 is a remarkable performer blending some traditional tube virtues with solid-state power reserve and bass punch. Its tube signature shines through clearly in the midrange, though it is slightly diluted by the solid-state output stage. Its imaging style is certainly transitional. By that I mean that it isn’t as good as many tube amplifiers in fleshing out a soundstage, but it is head and shoulders in this department relative to the average all-transistor design. If you’re an imaging fanatic, I suspect that you’ll be a bit disappointed with this amplifier, while solid-state fans will probably rejoice.

And the story gets even better with the SA-T8 line preamp. It made a very positive first impression with its precise and speedy transient reproduction, pure midrange textures, and rhythmic drive. I did initially note a bit of grain and assertive brightness through the upper registers, but as the preamp settled in after several hours of break-in the rough edges essentially disappeared. The lower treble, however, remained a bit coarser texturally relative to the midrange. Despite the fact that this is an all-tube preamp, its presentation was both direct and broadband in nature. No deficiencies were noted as far as treble roll-off or bass extension. And most remarkable of all, it evinced a velvety black background, which allowed the music’s harmonic tapestry to unfold with crystalline purity.

I decided to compare the sound of the SA-T8 head on with James Bongiorno’s Ambrosia—a full-function solid-state preamp. The contrasts, as expected, turned out to be tube-versus-transistor characteristics. The Ambrosia clearly won the battle at the frequency extremes with purer highs and better bass definition. But the SA-T8 erected a more spacious soundstage with exceptional depth of field and palpable image outlines. Microdynamic nuances, the 1 to 2dB volume variations that imprint feelings onto the music, were reproduced with greater conviction, though not as well as with my much more expensive reference line preamp—the Concert Fidelity CF-080.

Mating the SA-T8 with the SP-T800 monoblocks gave me the opportunity to take full advantage of the SA-T8’s balanced output. In fact, I made it a point to compare the sound of the preamp-amp combo using both unbalanced (RCA) and balanced (XLR) connections between the two. Even with an unbalanced connection, it was clear that the SA-T8 nudged the voicing of the SP-T800 closer to tubeland. Image focus improved but I also noted a slight reduction in the hall’s reverberant signature. The latter became a non-issue when I switched to balanced connections. There was significantly more immediacy to the presentation and I was easily able to follow reverberant decay down to the noise floor of a recording. Bass lines were tightly defined. In particular, kick drum was reproduced with satisfying punch and weight. Percussion, brass, violin overtones, and soprano voice were all nicely controlled with plenty of resolved low-level detail. Harmonic colors were generally neutral without noxious tube brightness. Midrange textures were creamy smooth without being overly liquid and soft.

It’s fair to say that when aided by the SA-T8, the SP-T800 closely fulfils the promise of a hybrid design: tube magic with plenty of bass crunch and power drive in one nicely “gift-wrapped” chassis. Both units represent sensational value, but the SA-T8 is an absolute steal at its asking price. In my estimation, nothing else at this price point comes close to equaling its primary twin virtues of crystalline clarity and ample boogie factor. Kudos to the Vincent team for shifting the economics of high-end audio within reach of the working man.

SPECS & PRICING

Vincent SP-T800 Hybrid Power Amp

Tubes: One 12AU7, one 6922, two 6CG7
Frequency response: 10Hz–50kHz, +/- 0.5dB
Power output: 200W into 8 ohms; 320W into 4 ohms (20W Class A into 8 ohms) 
THD: < 0.1 % (1kHz, 1W)
Input sensitivity: 1.1V
Signal-noise ratio: > 90dB
Input impedance: 47k Ohm
Inputs: One unbalanced on RCA jacks, one balanced on XLR jacks
Outputs: A&B speaker terminals
Control: Two 12V triggers
Dimensions: 8.3" x 10.4" x 15.75"
Weight: 39.6 lbs.
Price: $4500/pr.

Vincent SA-T8 Tube Preamp

Tube complement: Four 12AX7, three 12AU7
Frequency response: 20Hz–50kHz, +/- 0.5dB
Output voltage: 2V
THD: < 0.1 % (1 kHz, 1 Watt)
Input sensitivity: 240mV
Signal/noise ratio: > 90dB
Input impedance: 47k Ohm
Inputs: Four unbalanced on RCA jacks, two balanced on XLR jacks
Outputs: Two unbalanced on RCA jacks, one balanced on XLR jacks, one unbalanced record-out on RCA jacks   
Control: Two 12V trigger outputs
Dimensions: 16.9" x 5.3" x 14.6"
Weight: 22 lbs.
Price: $2500 (w/remote)

WS Distributing (U.S. Distributor)
3427 Kraft SE
Grand Rapids, MI 49512
www.wsdistributing.com

(616) 885-9809

Associated Equipment

Final Sound 1000i electrostatic speakers, Esoteric MG-20 and Venture Audio Excellence III Signature speakers; Kuzma Reference turntable outfitted with Graham Engineering model 2.5 tonearm and Grado Reference cartridge; Air Tight ATE-2 phono preamplifier; PrimaLuna Eight CD player, AcousticPlan Vadi CD player; Altmann Micro Machines Attraction DAC; Concert Fidelity CF-080 line preamplifier, Spread Spectrum Technologies Ambrosia preamplifier; Silicon Arts Design ZL-120 mono block amplifiers, TEAC Esoteric A-100 tube amplifier; Bybee Speaker Bullets; FMS Nexus-2, Acrotec 6N and 8N copper, Kimber Select KS-1030, Kimber KCAG interconnects; FMS Nexus speaker cable.