VAS Citation One Preamp & Citation Two Power Amplifier

Equipment report
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Tubed power amplifiers
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VAS Citation One
VAS Citation One Preamp & Citation Two Power Amplifier

It will be more than a passing irony if the LP outlives the CD. Yet, if sonic merit is the issue, the LP should be the survivor. Both mediums have their plusses, but I still turn to my LP collection for most of my serious listening—and to SACD for much of the rest. SACD and DVD-A may not have captured the market, but they clearly show that CD is an outdated technology with sonic limits that the very best players— such as the Meitner—can ameliorate but not overcome.

The future of technology also favors the survival of the LP over the CD. Digital servers and downloads are only part of the story. My first experiments with Dolby TrueHD (I have not heard DTS-HD, the DTS equivalent) also indicate that even a home receiver like the new Onkyo TX-NR905 can produce musical sound with HD DVD and Blu-ray discs that has better upper-octave definition and deep bass than all but the best (and most expensive) CD players. If Dolby TrueHD and DTS-HD make the major breakthrough into music they seem destined to make in video, CD is likely to deservedly go the way of the 78-rpm record. And, if downloadable lossless digital becomes widely available, the day may well come when records are the only discs left.

As many audiophiles are discovering, LP is also more fun to collect. I have yet to read articles about anyone collecting older or esoteric CDs, in part because many older CDs reveal all of the faults in digital and few of the merits. Collecting mono and stereo LPs (and even 78s), as well as high-quality new LPs, is a different story. You can find Web site after Web site devoted to how to collect and reproduce them. Exploring the history of recording and exploring the history of musical performance are both rewarding and fun.

This brings me to the VAS Citation One preamp and Citation Two amplifier. For those of you who are not familiar with the Citation name—and it has been quite a while—the Citation line originated as Harman-Kardon’s “high-end” products back in the tube era. The Citation One and Citation Two were designed by Stewart Hegeman, one of the greatest designers of tube equipment of any era. They were highly innovative components at the time, and provided a sound quality that had only one rival—Dynaco—at anything like their price. The original Citation One and Citation Two were sharply cost-constrained in parts-quality however, and designed and sold before designers fully discovered just how different given capacitors and resistors could sound.

The VAS Citation One: The Last True Analog Preamp?

The Citation One preamp was a particularly outstanding fullfeatured preamp back in the days before it became fashionable to omit the phonostage and virtually every other preamp control feature. It had adjustable turnover and roll-off for virtually every LP ever made. It had separate tone controls for each channel, a blend control, a moderately useful loudness control, and low-frequency filters for rumble. Unlike far too many preamps today, it also had a balance control. Preamps did a lot before they became reduced to linestages, in a process of high-end evolution that seems to charge more and more for less and less.

Unlike many of its competitors at the time, the Citation One was not forgiving or warm, but it did have a truly exceptional midrange with excellent upper-bass-to-lower-midrange timbre and detail. It also had very good life and air in the upper midrange without a touch of hardness. In fact, the design proved to be so good that—like the Marantz 7C and other great tube preamps of the day—some audiophiles still use it in its original version, although listenable survivors survivors must have their power-supply filter capacitors replaced, and resistors and caps in the signal path should be updated. The same, incidentally, is true of the Citation Two amplifier and virtually all older tube equipment.

The VAS version of the Citation One is very similar to the original unit, but makes some important improvements in components and features, adding a much bigger power supply with a transformer four times larger than the original transformer. It also uses polypropylene capacitors, audiophilegrade resistors, ceramic sockets, and Teflon wire. Given the fact that the original design dates back to the 1950s, there is good reason for most of these updates and they make the new version of the Citation One into a real high-end product.

Another area where the VAS Citation One is a major advance over the original is that it not only comes with the original moving-magnet phono circuit but also with a stepup transformer for moving-coil cartridges. This moving-coil transformer proved to be of exceptionally high sonic quality. No device is perfectly neutral, but in comparing the sound of the same model of high- and low-output Dynavector cartridges, I heard virtually the same sound quality through the moving-magnet and moving-coil inputs. The transformer was transparent enough so that the sonic differences were largely the result of the slight differences in sound of the two cartridges rather than colorations introduced by the transformer. (High- and low-output cartridges of the same model never sound exactly alike.) The transformer’s loading and gain are also well chosen—100 ohms for its higher-output moving-coil input with 12dB gain, and 47 ohms for its loweroutput moving-coil input with 18dB gain. The loading of the VAS Citation One’s own moving-magnet circuit is 47k ohms and 250pf. This range of inputs allows the Citation One to handle cartridges with outputs from 0.1mV to 5mV.

The Citation One retains some features that are of unique value to the analog addict and record collector. VAS has kept all the original adjustments for record roll-off and turnover. This will not matter to anyone who does not collect older LPs, but it is a critical feature for the serious record collector. The RIAA equalization standard was not adopted until 1954, and it took some time for U.S. and especially foreign-made recording companies to more or less comply. There were more than 90 different 78 and LP equalization curves before the adoption of the RIAA curve, although the NAB curve did become something of an earlier standard.

The differences between LP-equalization curves were anything but minor. For example, the turnover settings on the Citation One compensate for the reduced bass response necessary to cut a record with reasonable groove excursions. Depending on the label, this turnover began at frequencies ranging from 250Hz to 629Hz, and the rate of turnover varied by record manufacturer by at least several dB. (Record manufacturers were not always consistent in equalizing below their turnover point, and some rise or cut in bass may still be necessary, even with the right turnover frequency.) The rolloff settings of the Citation are also needed because different manufacturers used different equalization curves above 10kHz, and the rate of roll-off between different labels varied by at least 4dB, and some times by as much as 8dB.

While there are a number of specialty EQ products for the serious recordist, and for digital archiving, I don’t know of any other contemporary preamp that offers the ability to set turnover and roll-off for virtually every LP a collector can find. I can tell you that the Citation One does an excellent job of reproducing older LPs. I lost many of my mono and early stereo LPs during a rushed exit from Iran sometime back, but I have enough surviving mono LPs from U.S. and European companies to assure you that if you are seeking really good analog sound, and you want to go back to the future with a minimum of technical complexity and agony, the Citation One is the way to go.

At the risk of starting a religious war with today’s audio Puritans, I found that some of the other features in the Citation One that most contemporary preamps now omit also helped in getting the most realistic sound. The balance control is something I feel should be in every high-end preamp; it should be called the “soundstage” or “imaging” control. Minor adjustments in balance are needed to compensate for the minor balance differences between channels in all too many recordings, as well as to help compensate for the impact of room effects and speaker placement. Getting balance exactly right for a given recording and setup helps lock in the centerfill of the soundstage, extend the stage symmetrically on both sides, and reveal a touch of added depth. Only sheer luck can produce the same effect without a balance control with many recordings and in many listening rooms. In fact, of all the recent trends in charging more and more for less and less in a preamp, the omission of the balance control is the one I find most irritating and most likely to cheat the audiophile out of a key aspect of sound quality.

The Citation One has three other features that are now unusual to very unusual. One is a loudness control. Having heard some technically accurate efforts to provide this kind of compensation in digital equipment, like the Tact 2.2XP, I’m not going to praise the Citation’s version for accuracy. It may not come close to compensating for the ear’s very different frequency response at low sound levels, but it can help improve low-level and late-night listening.

The Citation One’s tone controls are now stepped switches rather than the continuously variable ones in the original design. VAS states that the stepped switches are more accurate, better balanced, and have a real out-of-the-circuit zero-position. I prefer the continuously variable kind, but the tone controls on the VAS Citation One are still flexible enough to help touch up the occasional recording that needs just a touch of boost or cut at the frequency extremes. In an ideal world, I would prefer a “tilt” with a broad shelving effect in the treble and variable roll-off (as in the old Quad preamps), and bass tone controls with adjustable turnover points, but those vanished into Puritan oblivion long before the balance control became unfashionable. Once again, this is a feature that should have been improved in modern preamp designs rather than omitted, and a case where the Citation One scores points over the lessfeatures/ more-cost school of design.

Finally, the Citation One also has a blend control and a middle-channel output. The blend control—used with discretion—can reduce hole-in-the-middle effects in twochannel setups where the speakers have to be too far apart (screen size, room features/acoustics, etc.) Excessive use will affect dynamic life and depth, but a touch can sometimes help.

The third channel output allows you to use three amplifiers and speakers with stereo with an absolute minimum of processing. As such, it comes close to the original designs for “stereo,” which called for three channels instead of two. A center speaker was intended to anchor the soundstage and the others could handle the left and right. Décor, cost, and just getting stereo to work at all prevented such steps from becoming popular, and the third speaker never caught on. A pity! I tried out such a setup with a third Citation Two amp and three Snell XA90 speakers. The sonic result of adding the center channel output was scarcely the state of the art in discrete surround sound, but it made an impressive improvement in stereo listening with stereo and mono LPs, CDs, and SACDs. Mono LPs and tapes become more centered and stable with the third channel.

While today’s stereo recordings and advances in stereo speaker setups largely compensate for the lack of a third speaker—and two great amps and speakers are better than three merely good ones—the use of a third channel and speaker sometimes made a surprising improvement in the soundstage. It allowed exceptional soundstage width, while providing stable centerfill and more natural image size. (The effect was especially good with older RCA and Mercury recordings.) Again, an argument against audio Puritanism and the paying-more-and-more-forless- and-less school of audio design.

As for overall sound quality, the Citation One is a slightly warm or romantic-sounding design compared to most purist tube linestages of the last half-decade or so, although your choice of tubes will make a difference. I opted for the slightly warmer sound of Sovtek 12AX7LP long-plate and Electro Harmonix 12AT7 in the case of my review sample. Steve Leung of VAS tells me, however, that I could have gotten a leaner and more contemporary sound by using the Sino- Shughang tubes.

I did not make this choice of tubes casually. I’m not into “warm.” My reference preamp is the Pass O.2 and Xono phono preamp. These are some of the most accurate and neutral designs available in either tube or solid-state equipment, and I don’t seek out a warm and fuzzy sound. At the same time, I see no reason to try to make tube preamps sound leaner simply because this has become the fashion.

I want woodwinds to have the full midrange and bass energy of woodwinds; brass should bite but not harden, and the timbre of pianos and harpsichords should have the warmth of the original as well as the higher-frequency detail. I never want to hear the sound of a violin harden to the point of shrillness in a way that simply cannot occur in live performances. My ideal in terms of detail remains what you can hear live with acoustic instruments and from voice in a natural unamplified recital. I simply don’t share the present high-end desire for levels of information that I never hear in live listening and which are generally more irritating than pleasing.

Auditioned from this perspective, the Citation One did a remarkable job of reproducing voice, acoustic jazz, and classical music in timbre, micro-dynamics, massive musical changes, and natural instrumental detail. In addition to excellent performance with a wide range of new and old LPs, it did equally well with demanding SACD recordings like the relatively close-miked Frost recording of Brahms Clarinet Sonatas and Trios [BIS SACD], providing natural clarinet tone without the hardness of many leaner preamps, and had excellent imaging and depth perspective within the limits of the recording.

At the same time, it did not romanticize recordings that have audible flaws. Excessively lean and bright recordings like the Kanka recording of the Haydn Cello Concertos [Praga], and Kuijen String Quartet recordings of Mozart chamber music [Challenge] were still slightly shrill and had too little bass and lower midrange energy and somewhat steely strings. In contrast, a far better balanced version of the same music cello music by Haydn (the Viersen recording on Etcetera) had all of the sweetness and natural bass energy that it should.

Operatic and solo voice recordings were accurate in timbre, dynamics, detail, and soundstage with exceptional midrange life. Difficult recordings, including voices with more breath than usual like some of the Judy Collins LPs and CDs, were very natural, and sibilants were real rather than hard or muted. On the other hand, some of the problems with Denon and early Telarc digital-to-LP transfers came through quiet accurately— again without romance or the kind of “forgiveness” that can affect the upper register of strings and piano and alter the character of instruments like the flute.

I should, however, add a caution for those audiophiles who have never ventured into tube preamps. Today’s best and most expensive tube preamps do virtually remove all audible hiss and hum, and ease gain and grounding problems with some modern amplifiers that I’ll discuss shortly. There will, however, be some audible hiss form all tube preamps if you put your ear near the speaker, As with all tube preamps, I also recommend you insert grounded phono plugs into each unused input to remove any noise as you shift from one input to another. The Citation One also uses mechanical switches and not solid-state switching or relays. You should turnoff or mute unused frontend equipment to eliminate any hint of low-level signal or “breakthrough” from an unused input into the input that is active. (This is basic good sense with any preamp that does not have full relay or digital muting).

The VAS Citation Two Power Amplifier

Reviewing the Citation Two power amplifier seems a bit mundane by comparison. The VAS version also differs more from the original Hegeman design of the Citation Two amplifier. The VAS Citation Two is a nominal 50-watt mono amp where the original Citation Two was a 50-watt-perchannel stereo unit. The built-in biasing meter and switches on the original Citation Two are gone. The new Citation Two also uses a tube rectifier (a full-wave, high-current 5AR4), rather than solid-state rectification, and has two tubes in the drive stage (one 12AX7 and one 12AU7), rather than three 12BY7As. Mine also came with EL-34s (6550EHs or 6CA7s are optional), where the original came with KT-88s or EL-34s. I’m not a fan of tube rectifiers on reliability grounds, but many experts do feel they sound better.

Steve Leung of VAS explains the differences between the original Citation Two and the VAS Citation Two as follows:

• There are now two power supply transformers instead of one, allowing greater isolation and more instantaneous power.
• The new transformers run cooler. Each one is hand-wound and potted for low noise and high efficiency. Hence the added 10 watts of power.
• There is tube regulation for a smoother midrange and better overall transient reproduction.
• There are ceramic tube sockets for long life and great gripping power.
• IEC power cord socket are provided, so the customer can experiment with different cords.
• Output and input sockets are CE rated.

Another difference is that there is no longer a 16-ohm output tap (but then I haven’t seen a 16-ohm speaker in decades). What may be more important is that no 2-ohm output was added. In some setups, the mismatch between a complex speaker load and the output transformer’s relatively high impedance relative to the speaker load can affect power, distortion, and frequency response. It can be useful to have the ability to use a lower impedance output on the output transformer to ease the mismatch between the amp and speaker.

I did, however, find that the audible power transfer from the Citation Two was as good at driving TAD-1s, Eggleston Nines, Snell XA90s, and Thiel 7.2s as the nominally more powerful PrimaLuna ProLogue Seven. The Citation also seemed less speaker-load-sensitive than the PrimaLuna. This was true even when I used using the lower-impedance taps on the PrimaLuna. As a result, I can only theorize as to whether the lack of a 2-ohm tap will ever matter.

There also were some additional advantages to the new design features of the VAS Citation One that Steve did not mention. Construction is excellent, and component and chassis parts are higher quality. The power and output transformers also seem to be better made. The fact that each amplifier is now a completely separate mono unit ensures cooler running and more stable performance, as well as no crosstalk and improved dynamics. You can now switch easily between pentode and triode operation. The triode operation cuts power from a nominal 50 watts to around 25 watts, but can produce a slightly sweeter, cleaner, and faster response with some relatively efficient speakers. The older Citation Two had to be modified by altering the internal wiring, and this was a “mod” that, as far as I know, was never authorized by the manufacturer.

As for sound, the Citation Two made a natural partner for the Citation One. Regardless of any design changes, the basic sound of the amplifier is remarkably close in character to that of the preamp, and it has just the right gain and grounding arrangements to ensure the cleanest signal-to-noise ratio with a minimum risk of hum, noise, and ground loops.

The combination of the Citation Two and Citation One does produce some low hiss and just a faint trace of hum if you put your ear to the speaker. I didn’t find this to be audible with the gain set at anything approaching real-world listening levels; however, listening in a dead quiet room, some may. In this regard, there were real sonic advantages in having a matched amp and preamp. The Citation One and Two combination, for example, had slightly lower noise than a Citation One and the PrimaLuna ProLogue Seven combination.

Gain-matching to some modern solid-state amplifiers did prove to be a bit of a problem. If the combination of a tube preamp output level and the power amplifier has too much gain, the end result will be audible noise. The hum and hiss that is part of the noise floor of the preamp will be amplified far more than it should be, given the high signal level coming from the preamp. I discussed this problem with VAS, and it will modify the Citation One to have both a high- and low-gain output that will make it suitable for use with both older tube and newer power amps. (A service technician can modify the output of existing Citation One’s to have a gain suitable to a given amplifier.)

The overall level of detail and transparency of the Citation One and Two did not equal the demanding standard set by the very best Audio Research, BAT, Conrad-Johnson, and other top-of-the-line high-end tube designs, but it was still very good, and competitive with any other combination of tube preamp and amps I have heard at anything approaching the same price range.

As for the other aspects of sound quality, the Citation Two had the same high-quality midrange as the Citation One preamp. The upper treble was a bit softer in detail than most high-end transistor designs, but was still extended and natural rather than romantic. As might be expected, the Citation Twos preserved the best features of the soundstage of the Citation One: medium rather than exaggerated width, good to very good depth, natural musical detail, and as natural an image size for voice and instruments as the recording permits. Not the ultimate for soundstage freaks, but very musical.

Micro- and low-level dynamics were very good, and provided exceptional midrange life and transient energy. However, really demanding dynamics were a different story. A 50-watt amplifier is a 50-watt amplifier. Some audiophiles feel tube amps sound more powerful than transistor amps, but the reality is that few of us really listen to high power levels most of the time. Moreover, when we do raise the gain setting, most of the power goes to the deep bass. The lack of damping in a tube amp can produce more midbass energy with less wattage but it will do so at the cost of less low bass and less detail, and driving a tube amp hard pushes its peak output into very high distortion levels. Like all other low- and medium-powered tube amplifiers, the Citation Two does not provide the deep bass and lower midbass sound quality of a high-power solidstate design with a high damping factor or of a tube amp in the 100-watt to 200-watt range.

The Citation Two did, however, perform very well for a 50- watt amplifier, and its apparent power was surprisingly close to that of the 70-watt PrimaLuna ProLogue Seven. This superior dynamic and power performance may be because the Citation Two’s output transformer is wound to present a relatively low output impedance to the speaker. This reduces the interaction among the amplifier, speaker cable, and speaker that can cause both output and dynamic frequency response to vary, making it difficult to predict the sonic nuances you will actually hear with a given cable and speaker, particularly when moderatepowered tube amps are driving drive complex crossovers and relatively low-sensitivity speakers.
 

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