VAC Phi 70
For lovers of tube sound, the push pull triode configuration offers a wonderful middle ground in a power amp. It can have much of the golden glow musicality that many people like in single ended triode amps, but with considerably better sound in many aspects, since it can have much lower distortion, wider bandwidth, lower coloration thanks to lower source impedance, and much higher power. We're surprised that this topology isn't far more populous in the marketplace, instead of the far more limiting single ended triode topology. In previous articles (see IAR issues 76-79) we've written extensively about golden glow sound (vs. white light sound), and about other push pull triode power amps. The vonGaylord (formerly known as Legend) monoblock LM Triode, now available in MkII form, remains a superb push pull triode amp for its midlevel price of $5495 per pair. For those of you on a budget, the $2500 stereo Cary Rocket 88 is a great choice. But if want the best push pull triode amp, and have some extra change in your pocket, there's a new kid on the block who will steal your heart away.
VAC (Valve Amplification Company) has made tube amps in many formats over the years. Their Renaissance line, well established for many years and now in its Mk III state of ever improving development, has employed the renowned 300B output tube in a push pull class A configuration, and gets very good sound from the 300B. VAC's new Phi line is a deluxe further development of their Renaissance line, with a new deluxe preamp and several power amps (including a stereo 30/30 and a monoblock that uses beam power output tubes, not triodes). We evaluated the new Phi 70, which is a 70 watt monoblock.
The VAC Phi 70 is a spectacular power amp, intensely engaging and musical. The chassis alone already testifies to the perfectionism lavished on this $20,000 per pair amp. Each monoblock channel boasts two large chassis, including a monster outboard power supply on one chassis and the audio circuitry on another, connected by a fat six foot umbilical cord. This long length keeps the power supply fields far away from the audio circuitry, yielding lower noise and purer sound, and also allows the power supply chassis to be hidden away while you show off the other chassis with the audio circuitry. This widely separated power supply, together with other design features (including new exotic shielding techniques), yield very low noise figures for the entire new Phi lineup, including the Phi 70. The residual noise at the output of this power amp measures a mere .3 mV (less than the output of many phono cartridges)!
The new low noise design of the Phi series also has benefits in sonic transparency and purity. You might think that low noise design wouldn't matter, especially in a power amp where the signal level is very high, so you'd hardly ever even hear the noise in the background. But it does matter. That's because noise is any audio system is always riding on the music waveform. True, you might only be able to hear this noise sounding like noise per se when the music is very quiet. But when the music starts playing (louder) that same noise is still there. You might not hear it sounding like noise per se, but it is still there. This noise, riding on the music waveform, fuzzes the outline of what should sound pristinely clean and pure, and it creates a slight haze that veils subtle musical inner detail (detail which would otherwise be audible if the background between musical transients were a quiet black instead of noise). Thus, noise can degrade clean purity, and can degrade transparency by veiling subtle musical detail. In a high resolution system, you can hear the improvements in musical purity and transparency when noise is lowered. This is the state of the art frontier that VAC's Phi series works at, and the benefits you can hear translate into better musical realism.
The Phi 70 sound is like nothing you've ever heard before from 300B tubes. As you might expect from the 300B, the midranges are bold, making the music jump to life before your ears. The Phi 70 raises the 300B sound to new heights, with a wealth of subtle inner musical detail that you can't hear from most other 300B amps. And then, to complete the sonic portrait of music coming vividly to life, the Phi 70 brings you more power than other brands of 300B amps (certainly far more than the puny single digit wattage you get from single ended 300B amps), and wide open dynamics that even VAC's own 70 watt Renaissance amps don't deliver (and the Phi 70's dynamics seem to deliver more power than other brands of 70 watt amps). The sound is also very clean and pure, amazingly so for a 300B amp, and will be a revelation to you if you've only heard single ended 300B amps, which usually have highly audible grundge problems. The Phi 70 is also very rewarding toward the frequency extremes, with natural (but not exaggerated) bass and trebles (most other 300B amps are notably weak at the bass and treble extremes).
The Phi 70's audio circuitry chassis has to be one of the most beautifully executed package designs in all audio, showing off its glowing tubes basking behind a protective clear cover, and featuring gorgeous champagne metalwork with a look clearly inspired by Marantz' fabled Model 9 monoblock amps.
The stunning 300B sound of the Phi 70 validates its perfectionist, no compromise design, which costs an arm and a leg to execute. This amp might have a high price, but you're getting what you pay for in spades. Actually, its price is only marginally more than VAC's own dual mono Renaissance 70/70 (at $14,000) and Signature 70/70 (at $19,000). But the Phi 70 gives you a heck of a lot more amplifier, with significantly better sound. The mere fact that the perfectionist Phi 70 requires four chassis instead of the single chassis of VAC's dual mono 70/70 amps makes the Phi 70 much more expensive to produce. So the Phi 70 is actually a very reasonable bargain, in terms of both the better sound you get and the sheer amount of hardware you get (not to mention the stunning good looks of the Phi 70).
If you already know and love the special musical qualities that triodes can deliver, and if you can afford it, you can safely order the Phi 70 sight unseen (actually, you can catch a peek at VAC's website, www.vac-amps.com). You'll thank us. If you don't yet know triode sound firsthand, then get yourself to a VAC dealer and have a listen.
VAC Avatar & Avatar Super
When we first heard it, the original Avatar immediately became our favorite tube integrated amp. Its most striking feature was its unique sound.
The original Avatar employed EL34 output tubes, which we have always enjoyed, and which have been a mainstay of some of the best classic tube amps, from the Marantz series (Models 2 to 9) to the Eico HF-89 kit. Though the EL34 sound varies from brand to brand (reportedly even more than other tube types), all the samples we have heard have been wonderfully musical. The EL34 sound we know featured rich warmth, liquid midranges, and sweet, delicate, extended trebles. But the EL34 sound also had some downsides. The trebles were defocused and soft, not individually articulated. And there was a slight sense of soft veiling and grundge throughout the spectrum.
The original Avatar changed all this. Somehow, with his wizardly skills, designer Kevin Hayes managed in the Avatar to keep all the good musical qualities of the EL34, while banishing its downsides. The Avatar gave us, for the first time, the musical strengths of the classic EL34 sound, without its traditional attendant weaknesses. In the Avatar, the EL34 sound is much cleaner, purer, and more transparent throughout the spectrum. And the trebles are delineated very well, instead of being defocused and soft. The sound of the original Avatar was at once very neutral and also very beautifully musical. That's one reason why the original Avatar has been kept in the VAC lineup, even after the introduction of the new Avatar Super. Other good reasons include the lower price ($4000, vs. $5500 for the new Super), and the fact that the original Avatar can be switched into triode mode (just like the classic Marantz amps), to give you about 28 watts per channel of pure triode sound, instead of the 65 watts per channel when you use the EL34s in pentode mode.
The new Avatar Super is whole new animal. It is not merely an upgraded version of the original Avatar. Rather, the new Super is an entirely fresh new design, which draws upon the new high end preamp and power amp products in the VAC lineup. These newest VAC high end separates incorporate new technologies and new circuit tricks, which can be beneficially applied (perhaps in scaled down form) to an integrated amp. The new Avatar Super reaps the benefits of trickle down technology, to give you better performance in virtually all aspects.
The Super's sound is even cleaner and more transparent than the original Avatar, revealing even more of music's subtle inner details. The Super puts out 80 watts per channel (instead of 65), and sounds even more dynamic. The frequency extremes are covered with even better extension. There can be even more harmonic richness and warmth (this aspect will depend somewhat upon your speaker's impedance curve, as it does for most tube amps). And the Super has even quieter background noise, which also further enhances musical transparency. The Super also includes an extra set of line level output jacks, with a corresponding set of input jacks directly to the power amp section, so you can easily interface it with a cinema processor (there is also the usual complement of jacks for a tape loop, which brings the signal back in at an earlier point, before the volume control and final preamp stage).
To obtain its higher power, the Super uses a different output tube, the KT88 beam power tetrode. So the Super is not switchable to triode mode, as the original Avatar is. And, since the output tube is different (not to mention the rest of the circuitry), the overall sonic personality of the Super is somewhat different than that of the original Avatar. Sonic personality differences like this are a matter of personal taste, so it would be best for you to compare the two Avatars before settling on your final choice.
No discussion of the Avatar would be complete without mention of the package design aesthetics. Both Avatars are stunningly beautiful, and, like some other recent premium products in the VAC line, draw their inspiration from the styling of the classic Marantz Model 9 power amp. The package designer doing ths work for VAC is in our opinion a genius. He draws just enough inspiration from the timeless Marantz 9 styling to pay homage, and then departs in original directions with subtle styling touches that enrich the tradition and create a new individualistic stamp for the new VAC product. Since integrated amps are prominently displayed in your system, and cannot be hidden away as power amps can be, eye pleasing aesthetics like the Avatars' is an important further feather in the cap for many of you.
The Avatars' stunningly beautiful sound and stunningly beautiful looks make an irresistible combination for anyone seeking a tube integrated amp, and the price is very reasonable for the quality you get.
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