Tube Power Amp Reviews

When you can hear the originally designed balance of your reference speaker shifted because of the interface with the test amplifier, then life becomes significantly more difficult. Even the Wilson WITT II, whose impedance variation with frequency is remarkably small, was influenced by the Bel Canto SET 80 on its 8 ohm setting. For the record, with the WITT II driven from the ST 80's 8 ohm output, the resulting sound was a little heavy in the midbass, thickened and rounded in the mids, dulled through the presence range, and then tipped-up and glazed in the upper treble. Vocals lost some articulation, percussive transients their speed and attack. It would be so easy to get the wrong idea about this special kind of amplifier.

However, the SET 80's 4 ohm setting, which in theory reduces the output impedance by a factor of root 2, satisfactorily tames the wayward frequency response. When I sifted through the observed variations, a common thread emerged that conveyed the impression that this Bel Canto is both well balanced and intrinsically tonally neutral—paradoxically, it is more neutral than the big Cary.

It was surprising just how little the SE tube technology affected what I felt to be the SET 80's true sound, for the Bel Canto had relatively powerful and evenly weighted bass; a level, even midrange; and a generally unobtrusive, integrated treble. Coloration in the usual sense of the word was absent. Indeed, in true SE triode tradition, its midrange approached a revelatory quality, free from the ubiquitous and generally (if grudgingly) accepted glare and hardness of typical power amplification.

What the SET 80 does is unusual for the genre. It could kick hard in the bass and would also play loud, leaving its 8–18W brethren far behind. This amplifier wasn't frightened of the volume control, and while it needed more than a few volts to get cooking, it held on to its fundamental character over a wide dynamic range. I got sound levels closer to a perceived 150W than the claimed 70Wpc, so benign was the SET 80's soft-clipping behavior. In fact, it went nearly as loud (within about 2dB) on the 4 ohm setting—which for many, will be the setting of choice.

So, this Bel Canto could play louder than the big Cary, is less expensive, and its sound was essentially constant from low to high levels. But what did it really sound like? The bottom line: Here is an undoubtedly fine amplifier with several qualities that I enjoyed, but which didn't quite hit the spot, for me at least.

Where the Krell FPB 300—and, to a significantly greater extent, the Krell FPB 600—can gather you up and deliver you into the spaciousness and majesty of great musical experiences, and where the Cary 805C can beguile with an extraordinary tactile impression of reality, pure harmony, and lifelike vitality, the Bel Canto SET 80 was somehow more distanced from the listener. The Bel Canto sounded quite dynamic, and retained some of the surprise and attack in good music program, but it was neither particularly rhythmic nor well timed.

Interestingly, both the Krells and the Cary can inform the listener about timing and rhythm, even if their language and accent differ. But with speakers that have good timing discrimination—from a Wilson WATT 3 to an Epos 12, a budget Mordaunt-Short MS 10i Classic, and the WITT itself—the SET 80 did not sound as surefooted as these reference amplifiers. It didn't quite succeed in marrying bass with mid or mid with treble in a fast-moving transient percussive context. I don't want to exaggerate the importance of this aspect, as perception of its magnitude will be so dependent on the rest of the audio chain and the acuity of individual listeners. What I'm saying is that it matters to me.

The shortfall in rhythm was accompanied by some deficiencies in the presentation of low-level detail, which prevented stereo perspectives from developing fully. The soundstage didn't extend as far back, and the resolution of space and air was not in the top class. Consequently, the sound had a rather staid, laid-back character.

If this sounds like bad news, remember that the Bel Canto is eminently listenable too: sweet and singularly low in aural fatigue; most obviously a zero-feedback, class-A, triode design. Considered with the fine stereo focus, this indicates a middle ranking among audiophile amplifiers for the SET 80. It offers a perfectly reasonable alternative to a number of rather mechanical-sounding, old-fashioned solid-state and high-feedback designs.

I obtained genuinely good results from the Bel Canto, even if the afterglow from the Cary 805C was something that even a dedicated reviewer found it hard to resist. The SET 80 remained tuneful throughout the frequency range. Its bass was tolerably good, especially by SE tubed standards, but it wasn't as grippy or extended as, say, an Audio Research VT100, never mind a Krell FPB 300. It sounded tidy in the treble: uneventful, and not particularly clear or revealing, but low in apparent grain or false "edge."

I found the amplifier more convincing on folk and classical material, and ended up revisiting some old material from the '60s and '70s, including some Joan Baez records I hadn't played for years. Early Decca SXLs were great fun; for example, Sibelius' Karelia, with Maazel/VPO, coupled with his Symphony 1 (SXLL6084).

For those who follow my idiosyncratic attempts to provide a continuity of merit scoring in UK audio magazine HFN/RR, the SET 80 gets 23 points—interesting, certainly on the audiophile ladder, and worthy of closer attention.

Conclusions
You can't turn the clock back. Prior to the likes of the Audio Research 150SE, the Conrad-Johnson Premier Eight A, the Krell FPB 600, or the Cary CAD-805C, Bel Canto's SET 80 would have enjoyed a clear run, especially in the higher-power SE stakes. This horse does sing well, and offers an archetypal tube SE midrange; it was fluent, naturally sweet, and well balanced. It also packs a substantial kick in the bass, unexpectedly so for the genre. Remarkably, its designer has succeeded in achieving genuinely high powers from a SET amplifier that did not disappoint in audition. These superior merits must stand with the judgment of moderate transparency and rather average rhythmic expression leading a laid-back character that was less involving than had been hoped for, despite above-average rendition of dynamics and a quite good sense of space.

The SET 80 acquitted itself well in the lab, showing exceptional power, bandwidth, and linearity for its type. Noise levels could have been a bit better in view of higher-sensitivity speakers, though the healthy power rating offers compatibility with normal speakers too.

Bel Canto's SET 80 is one of the better-sounding SE amplifiers, and is probably one of the loudest. Its innate tonality is a notable success and, while it's not my first choice, I do recommend that people try it for themselves in their systems. It might well work out.