VTL TL-5.5 Series II Signature Preamplifier and ST-150 Power Amplifier

While recently listening to András Schiff’s remarkable 2012 recording of Bach’s Das Wohltemperierte Clavier [ECM]—in which Schiff, rather unusually, and to enchanting effect, employs no sustain pedals—I was struck by how this great Hungarian artist seems to inhabit the very soul of Bach’s music, so beautifully and directly does he convey the essence of these intricate preludes and fugues.

Having now spent a great deal of time with VTL’s TL-5.5 Series II Signature preamp and ST-150 power amp, I’ve started to think of them as being rather András Schiff-like, as the crux of the pleasure they deliver lies in their ability to convey the essence of whatever music you play. Like a lip-smacking bottle of wine that leaves you anticipating the next glass, this VTL tandem will have you excitedly pulling out record after record.

VTL’s goal in designing the ST-150 was to create a relatively compact yet powerful stereo power amplifier employing 6550 tubes capable of driving a wide range of speaker loads, “as opposed,” VTL’s head Luke Manley explained, “to the EL34s that we use in other products in the Performance range.” Compared to EL34s, Luke says the 6550s offer the ability to operate in either tetrode or triode modes, and provide better bass wallop and linearity, and an extended well-defined treble. Manley described the $6000 ST-150 as a classic all-tube push/pull power amp delivering 150Wpc in tetrode mode, and, via the flick of a rear panel toggle, 70Wpc in triode operation, with a parallel 12AT7 input stage and 12BH7 long-tailed phase-splitter driving the push-pull output stage. “A fairly standard, simple circuit,” said Luke.

While I wouldn’t like to get in the habit of comparing the two tube operating modes every time I play a piece of music, I did find that, generally speaking, the more powerful tetrode state was the obvious choice for rock, large orchestral and opera, and hard-driving jazz, while the triode circuit, with its extra sense of bloom and the third dimension, was preferable for chamber music, folk, and generally lighter, more intimate forms of music.

The ST-150’s manual bias adjustment is fairly straightforward, even for a decidedly non-technical type such as myself. It does require removing the cage and a few tools such as a good voltage meter—that VTL was kind enough to provide—and I found that checking bias every three months or so is the best way to keep the ST-150 in top operating condition.

Finally I must say that, living in a small San Francisco house, I grew to appreciate the ST-150’s notably compact footprint (19″ x 10″ x 9″). This is a high-performance amp that can find a home in pretty much any size listening room.

As for the ST-150’s companion preamp, the TL-5.5 Series II Signature preamp was initially introduced in 1997 and has been seriously improved using technologies found in the flagship TL-7.5 Reference Series III ($20,000) and TL-6.5 Signature Series II ($13,500). These are, respectively, well over and nearly double the TL-5.5 Series II’s price. That said, the 5.5 II ’t’aint exactly chump change, selling for $8000 as a linestage only, and $10,500 with its optional internal phonostage, which is how I elected to review it.

Another difference between these three top VTL models is that the 6.5 and 7.5 are hybrid designs employing FET buffers, whereas the 5.5 shares their basic circuit, but uses tube buffers, which makes the 5.5 Signature II VTL’s top all-tube model.

The optional phonostage is derived from VTL’s standalone TP-6.5 phono preamp, and Luke Manley believes the performance of the 5.5 version comes close to that of the pricier separate unit. Indeed, during a visit from Manley and his wife, Bea, Luke popped the top on the TL-5.5 Series II in order to adjust (via jumpers) the load of the phonostage, revealing just how much space the phono section occupies within the chassis. It’s a surprising chunk of real estate, but as Manley said, “We felt it was important to have as much of the TP-6.5’s sound as possible.”

This topless view also gave me an appreciation for the overall build and layout quality of the design. Keeping with the fully balanced idea, the phono section delivers a balanced signal to the balanced linestage, which creates a balanced output from the single-ended input.

As Luke explained it, the volume control is largely responsible for delivering the linestage’s high-resolution performance. A chip-based control designed specifically for audio use, it has no crossing detection or internal op-amp buffers, which Luke tells me would degrade the sound. Instead VTL employs its own JFET buffer design, the same one used in its stand-alone phonostages. The volume chip operates at an unusually high 15 volts, which Luke explained allows for optimum signal headroom. Moreover, it’s a dual-chip design, operating in differential mode—one chip per channel—that controls both volume and balance, thus avoiding running the signal through the more commonly used, lossy, wiper-type volume control.

Via an e-mail exchange Luke added, “In designing the Series II version of the TL-5.5 we wanted to keep as much of the user interface and sonic capabilities of the more expensive TL-6.5 and 7.5, but offer a full-function preamp for people who require phono. We designed in the precision regulated power supplies in both the linestage and the phonostage that we use in the more expensive models, and I feel this gives the preamp its sonic precision and refinement.”

His point is that VTL worked hard to pack a lot of price-to-performance value into the TL-5.5 Series II. In my experience it has succeeded marvelously.

I also appreciate the 5.5 II’s features set, which, via either the front-panel buttons or remote control, allows users to select from among eight inputs, engage an external processor, select a mono mode, control absolute polarity as well as balance, and (of course) set volume. As noted earlier, you have to crack the lid to adjust phono loading, and once inside you can also tweak the gain for phono, as well as for high-level sources.

I was rather bummed recently to miss a series of local 50^th Anniversary concerts that Ravi Coltrane had planned in celebration of his father’s A Love Supreme. But it did trigger me to immerse myself in the superb sounding Acoustic Sounds 45rpm reissue of this extraordinary musical offering. Here is another fine testament to the VTL duo’s musical soul. And indeed, I can think of no finer compliment to these designs than to tell you that, except when taking the necessary notes for this review, contemplating the “sound” of this gear was pretty much the furthest thing from my mind. After all, who wants to listen to gear? The gear is merely a conduit for the music. Right? Well, that’s like, my opinion, man….             

But you want to know what it sounds like, so let’s get back to A Love Supreme. First, harmony. By that I refer to the harmonious interplay of Coltrane’s great quartet. Their collectively raw yet beautiful power, energy, and brilliance as a group is the key to this ecstatic, near-hypnotic gift to Coltrane’s God, as well as to us, the listeners. From the start of “Acknowledgement,” with Jimmy Garrison’s four-note bass recitation of “a love supreme,” Coltrane’s lengthy, unfolding, gospel-like tenor, McCoy Tyner’s insistent chord progressions, Elvin Jones’ syncopated rhythm and delicately shimmering ride cymbal, the music, no matter one’s religious bent (or none, for that matter), is as powerfully spiritual as it gets. And through this VTL pair there was a strong degree of transparency back to the session, an immediacy that makes one feel transported via time capsule to Rudy Van Gelder’s studio on a December day in 1964.

But beyond this sensation of the musicians’ presence is another kind of harmony created by these designs, the kind that, taken altogether, creates a seamless sense of bottom-to-top tonal coherence, dynamic push, and resolution to create a thrilling sense of aliveness and of the music-making process. These things are hard to articulate, but most of you reading this magazine have most certainly experienced that sense of being transported while listening to great music over great gear.

Natural instrumental textures, for me, are another important key to surrendering to reproduced music. Here, Coltrane’s tenor sounds big and meaty, airy and brassy—you can practically feel the wind blowing though the bell. It’s intense, but warm of tone and never hard or unpleasantly brash. And this from one of the hardest blowing, least inhibited of all horn players. Garrison’s bass sounds man-sized and cavernous of body, with softly textured strings and a warmth reminiscent of fine Kentucky bourbon. Tyner’s piano is a percussive force to compete with Elvin Jones’s kit, but with great harmonic richness. And via VTL, Jones, surely one of the most distinctive voices to ever sit behind a drum kit, conveys a kind of contained frenetic motion—always highly articulate, passionate, driving, attention-grabbing but never less than supportive, with a palate of tones and textures as richly painted as one can imagine from stretched skins, brass cymbals, sticks, and mallets.

By the end of this four-movement suite, pushing it to levels right at the edge of my Magnepan 1.7s’ comfort zone, the ST-150 never lost its composure or sounded as if it was running on fumes. Indeed, I’m sure this music left me feeling more breathless than the amplifier was.

Of course, the personality traits described above translate across all musical genres. And part of the pleasure and value of gear like this is that it regularly leads to crazy-fun listening sprees wherein many neglected or perhaps forgotten sides gain temporary freedom from their place on the record shelf. For example, one night after playing Dylan’s Blood on the Tracks followed by Desire [Columbia LPs]—great music, hardly state-of-the-art recordings, but immediate and communicative in their own ways, and thoroughly engaging with this VTL pair—something compelled me to pull out the original Reference Recordings LP, Ravel, with Stanislaw Skrowaczewski and the Minnesota Orchestra.

Perhaps it’s because I, like so many audiophiles, have fond memories of the Turnabout box of Ravel’s music from the same orchestral team. Regardless, there I was at midnight listening to, of all things, Bolero. This has never been a favorite of mine and indeed it often baffles me that the man who wrote my beloved Gaspard de la nuit also composed many a slutty cheeseburger. Regardless, there I was, at midnight, ahem, enjoying Bolero. And Keith Johnson’s excellent recording certainly allowed the VTL gear to shine. My Maggie 1.7s performed a pretty impressive disappearing act, with a stage as wide as the room and a depth that seemingly stretched far outside its rear wall. The hall’s ambience was quite apparent, with a finely delineated sense of air around the players. Of course, Bolero is all about the slow simmer, and Johnson’s recording is a study in subtle dynamic shading, building, like a Burgundian vineyard, layer upon layer of dynamic gradation as well as orchestral texture as the orchestra swells in ranks and volume to its final, roaring, cymbal-crashing climax.

This actually strikes me as one of Johnson’s most natural-sounding efforts, without what I sometimes feel are exaggerated dynamic swings and deep bass power shots. Indeed, the sheer sonic thrill of it all made me feel like a budding audiophile again, as I submitted to the waves of gorgeously natural instrumental tones and textures, to the three-dimensionality, and precise sense of imaging.

So I continued with the Pavane, another guilty pleasure of shimmering, silver-laced strings, weightless-as-cobweb harp strings, winds as delicate as an angel’s breath…. Goodness, look what happens to a jaded audiophile like me when the equipment is capable of sweeping us so completely into the music—and yes, ravishing sound.

At Luke’s urging I also played the TL-5.5 Series II Signature through a solid-state amp, in this case Primare’s A34.2 (review forthcoming). The results were impressive, showing that the preamp can bring many of the qualities described above to music lovers who may shy away from the all-tube route, and reminding  a potential buyer that, if he loves the warmth, air, and texture of the best tube designs (without, allow me to add, the overly colored timbres and poorly controlled bass of some models( and is willing to futz with biasing and occasional tube failures, then there is greater pleasure yet to be had pairing up these units, as I was lucky enough to do for the duration of this review process.

Circling back to Schiff’s recording of Das Wohltemperierte Clavier actually left me feeling that my old favorite, Glenn Gould’s on Columbia, seemed mechanical by comparison (and this on LP vs. Schiff’s ECM CD). While Schiff’s pedal-less account won’t be for all ears, I find it compellingly convincing as well as poetically beautiful. The VTL pair delivered Schiff’s thoughtfully artful and highly articulate account with precision as well as an almost golden, lit-from-within sound to the piano.

As is obvious, for these ears (and this heart) VTL’s TL-5.5 Series II Signature preamp and ST-150 power amp are remarkably successful at delivering on all fronts—thrilling in the ways that can arouse the latent audiophile within while drawing him deeply into all spectra of music. And what more, I ask, can we ask from our systems?

SPECS & PRICING

TL-5.5 Series II Signature Preamplifier
Inputs: Two pairs balanced XLR or single-ended RCA (optional mm/mc phono cards); six pairs single-ended RCA
Outputs: One pair single-ended RCA, one pair buffered RCA (tape)
Tube complement: Two 12AU7, four 12AT7 (line stage), two 12X7, two 12AX7 (mm), two 12AU7 (mc)
Dimensions: 17.33″ x 3″ x 15.5″
Weight: 30 lbs.
Price: $8000 (linestage only), $10,500 (with internal phonostage)

ST-150 Power Amplifier
Power output: 150Wpc into 5 ohms (tetrode); 70Wpc into 5 ohms (triode)
Inputs: One pair single-ended RCA
Tube complement: Eight 6550, two 12AT7, two 12BH7
Dimensions: 19″ x 10″ x 9″
Weight: 100 lbs.
Price: $6000

VTL
4774 Murrieta Street, Unit 10
Chino, California 91710
(909) 627-5944
vtl.com

Associated Equipment
Rega RP10 turntable and Apheta MC cartridge; Pro-Ject Xtension 10 turntable with Sumiko Palo Santos cartridge; Sutherland Engineering N1 preamp; Primare A34.2 power amplifier; TEAC HC-501CD/SACD Player; Magnepan MG 1.7 loudspeakers, Tara Labs Zero interconnects, Omega speaker cables, The One power cords, and BP-10 Power Screen; Finite Elemente Spider equipment racks.