BAT VK-55 końcówka mocy klasy High End oparta na Triodach. Moc 55W W pełni zbalansowana konstrukcja - wejścia tylko XLR . Zero pogłosów sieciowych.
W komplecie 8 lamp mocy (4 nowe) i 8 lamp sterujących (4 nowe RCA NOS , mam rachunek na zakup lamp) Rachunek,Karton, Instrukcja. Stan idealny. Napędzam nimi Wilson Audio WP
Wzmacniacz z lekko osłodzoną średnica, bardzo szybki jak na lampę, grający zwartym basem (kontrola basu jak w tranzystorze) . Bardzo szeroka , głęboka scena. Czarne tło , brak pogłosów jak lampy nie zbalansowane. Sprzedaje to wspaniałą lampę z uwagi na zakup monobloków lampowych. Lampa BAT-VK55 zluzowała u mnie w systemie monobloków Jeffa Rowlanda / Gamuta D200. BAT vk-55 zdeklasował VTL na EL34 (oczywiście w moim systemie). Najważniejszą wadą lamp jest ustawianie BIASu , w przypadku VTL MB-450 które rozważałem do zakupu musiałbym każdą lampę ustawiać prądowo - BAT VK-55 ma autobias tzn że sam ustawia prąd - to oznacza że wsadzam nowe lampy a BAT sam ustawia sobie prąd.
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zamieszczam recenzje z stereophila
It's been 10 years since Balanced Audio Technology (BAT) introduced their first products: the VK-5 line-stage preamplifier and the VK-60 power amplifier. (I reviewed both in the December 1995 Stereophile, Vol.18 No.12.) The success of these and other BAT products has allowed designer Victor Khomenko (the "VK" of the model designations) and partner Steve Bednarski to quit their day jobs at Hewlett-Packard; they were joined by Geoff Poor as a partner to handle the sales end of the enterprise. BAT's current lineup includes several preamps, phono stages, a CD player, and tube as well as solid-state amplifiers. The top of BAT's preamp range is theVK-51SE, which costs $9000; their top tube power amp is the VK-150SE monoblock($17,000/pair); if you want their best phono stage, the VK-P10 will set you back $8000.
While I know that many Stereophile readers can afford to buy products in that price range, I'm more interested in the type of product that delivers topnotch performance at a relatively modest price. The new BAT VK-3iX preamp and the VK-55 power amp have a combined price of $6490—not cheap by any means, but a long way from cost-no-object, and listening to a system featuring these components at Home Entertainment 2004 made me think that these products could be exactly my cup of tea.
Description and design The original VK-5 and VK-60 had looks that were more no-nonsense functional than audio jewelry. I have no problem with that—I'd rather see a manufacturer spend money on parts quality than cosmetics—but I have no objection to improved appearance if the increase in cost is relatively minor. In fact, the VK-3iX and the VK-55, while maintaining the general industrial design of their predecessors, are definitely more attractive, with a more classy fit'n'finish. The VK-3iX's front panel is uncluttered, having only a power switch, a couple of large knobs for source selection and volume, a mute switch, and a numerical volume display. There is no balance control or channel trim—a cost-cutting measure that may in fact have a benefit by enhancing the simplicity of the circuit path.
In keeping with the company name and design approach, the original VK-5 had only balanced XLR inputs and outputs; single-ended input/output connections had to be made with optional XLR-to-RCA adapters. The VK-3iX takes greater cognizance of the fact that some components connected to it may not be configured for balanced operation: there are four RCA as well as two XLR inputs, an RCA tape output, and one RCA and one XLR output. If the optional phono board is installed ($500), one of the Aux RCA inputs becomes a phono input.
Remote control is another option ($500), and features Volume Up/Down, Mute, Fade, and pushbutton selection of five user-defined preset volume settings and a sixth, Unity Gain setting (for feeding a surround processor). Its remote is the only feature of the VK-3iX that I'm not fond of. It's heavy and obviously well made, but has the common design fault of having buttons that are all the same size (small); it's hard to find the important Volume Up/Down and Mute buttons by feel. I found the Fade function to be only marginally useful, and five user-defined preset volume settings are five too many, in my opinion. My advice: Save $500 and enjoy the enhanced fitness you'll experience as a result of those long walks from listening chair to preamp.
To those familiar with BAT tube amplifiers, the most immediately noticeable thing about the VK-55 is its size: not quite diminutive, but much smaller than the VK-60 and its direct descendant, the VK-75. The amp is missing that industrial-strength handle at the back, and power on/off is now handled by two pushbuttons located front and center, more convenient than the previous toggle switch at the back. The power transformer is now inside the chassis, so only the output transformers are on top. The VK-55 has balanced XLR inputs only; driving it by an unbalanced preamp requires RCA-to-XLR adapters. Like the VK-3iX, the VK-55 has benefited from a refinement of its industrial design, and is more attractive than earlier BAT amps.
BAT's stated audio design approach is to have true balanced circuits from input to output, high-energy power supplies, simple signal paths, and little or no global negative feedback. (For the VK-3iX, the global negative feedback is zero; for the VK-55, it's 6dB.) According to Victor Khomenko, the VK-3iX continues the tube-based differential circuits first implemented in the VK-5, with massive power supplies and symmetrical high-voltage rails. Like BAT's reference VK-51SE preamp, the VK-3iX has a single gain stage with no buffer or cathode follower circuits, and a shunt volume control using high-quality Vishay resistors. The gain stage uses 6922 tubes in the standard configuration, and 6H30 SuperTubes in the VK-3iXSE (which costs $1000 more than the standard version). Also available are the SIX-PAK ($600) output-capacitor and SUPER PAK ($500) power-supply upgrades, which are also included in the SE version.
The review sample was the standard version, sans upgrades. The optional phono card ($500)—which was installed in the review sample—is solid-state, and has its own onboard power supply and transformer. It employs two gain stages with a passive RIAA circuit. The card has two gain settings, 45dB and 60dB, and sockets for resistive loading of cartridges.
In talking about these two new products, Victor Khomenko seems especially proud of the value represented by the VK-55. He points out that the VK-60 cost $3995 when it was introduced in 1995, that price rising shortly thereafter to $4495. He suggests that with 10 years of inflation, the VK-60 would cost around $8000 today, and yet the VK-55, with similar power output and numerous refinements, is only $3995. He credits Plitron, manufacturer of the toroidal transformers used in the VK-55, with allowing the amp to have a bandwidth extending from 7Hz to 200kHz—rare for a transformer-based tube design.
The VK-55's power transformer is inside the chassis, in close proximity to circuits, so it required extra care in design to avoid hum and noise. Like BAT's other tube amps, the VK-55 uses Russian 6C33 tubes in the output stage, as well as an auto-bias circuit, refined in previous generations of BAT amplifiers, to compensate for tube mismatch, aging, and power-line fluctuations. One cost-cutting measure in the design of the VK-55 was a reduction of the number of power supplies: three rather than the 10 found in the VK-75. Khomenko admits that this presented a particular challenge, given that he considers low noise an important design objective, and a smaller number of power supplies means that an amplifier is less likely to produce ground loops and their associated buzzes.
Tube matters The VK-55 had a couple of initial tube-related problems, perhaps as a result of some rougher-than-usual handling the equipment might have received in shipping. Two of the smaller 6H80 tubes (one in each channel) were microphonic; even moderate tapping of the amplifier chassis resulted in a fairly loud sound being produced by the speakers. Replacing these tubes solved the problem; I could then tap the chassis quite hard, with no sound coming from the speakers.
The second problem involved one of the 6C33 output tubes. This happened after having used the amp for a few weeks: one channel simply went dead, and the bias LEDs in that channel were not lit. I replaced the fuse in that channel (easily accessible from the top of the chassis), and when I turned on the amp the sound came back on, but I could see some arcing in one of the 6C33s. I quickly turned off the amp, replaced the tube with a spare, and everything was fine from then on. The VK-3iX was trouble-free throughout the review period.
Sound I first listened to the VK-3iX and VK-55 in combination, with balanced XLR connections between preamp and amp, and the CD input fed from an unbalanced RCA source using XLR-to-RCA adapters. (It occurred to me later that I could have used the input labeled Tuner, which has RCA jacks.) With my Avantgarde Uno 3.0 loudspeakers, my first concern with any new amplifier is noise: with a sensitivity of +100dB, the Unos are merciless in exposing any noise in the system. As it turned out, the Avantgardes driven by the VK-3iX and VK-55 produced less noise than I'd heard with any other combination of preamp and power amp. With nothing playing but the volume control set at a fairly high level, I had to go right up to the midrange or tweeter horn to hear a very slight hiss, and when I put the VK-3iX on mute even that disappeared. Most impressive!
Over the years, listening to audio systems and trying to come up with descriptions of the sounds and the contributions of various components, it has become increasingly clear to me that this critical enterprise is quite different from, and is in some ways antithetical to, listening to music for pleasure. In "critical" listening we're always trying to analyze the sound, paying attention to details, picking apart different aspects of the sound-reproduction process. Listening for pleasure is much more holistic, more dependent on the overall effect. In this type of listening, details of musical reproduction become important only when they draw undue attention to themselves, like a part of the frequency range that's overemphasized (eg, boomy bass or screechy highs), or when some things that we know should be there seem to be absent (eg, imaging and a sense of depth). Increasingly, my approach to reviewing equipment has moved more toward this holistic approach, which I believe comes closer to the way most people listen to music.
With this in mind, the best description that I can give of the sound of my system with the VK-3iX and VK-55 installed is that it just seemed right, with no specific aspect of the sound drawing undue attention to itself, and no indication that anything important was being omitted. The sound was...well, balanced, with the various parts of the frequency range all there in the right proportions, a good sense of rhythmic ebb and flow, and imaging that was convincing in its depiction of depth and the positions of voices and instruments in space. To a very large extent, the sound of the system with the BATs doing the preamplification and amplification chores was the sound of the source materials, the components doing their best to get out of the way of the music. It certainly helped that, with the BATs, my system had such a vanishingly low noise level, but there was more to it than that; a lack of noise is of little importance if the sound itself is not convincingly real. With the VK-3iX and VK-55, it was convincingly real. If it were not for the fact that I had to write a review of these components—which inevitably involves making some comparisons—I would have been quite content to ignore the equipment and enjoy the music.
Comparisons It was obvious in listening to the VK-3iX and VK-55 that these components worked very well together, but I wanted to check out how they worked—and compared—with other components.
First on the list of comparison components was my reference preamp, the Convergent Audio Technology SL-1 Ultimate. The CAT has been around for many years in various guises, and is generally recognized as being in the front rank of preamps. The CAT is a single-ended rather than a balanced design, so to connect it to the VK-55 I ran RCA-terminated versions of the same brand and model of cable (Nordost Quattro Fils), with RCA-to-XLR adapters at the amplifier end. The CAT has a switched-resistor type of volume control with quite rough gradations, so in making the comparisons I tried to match the CAT's volume setting with the VK-55's, measuring voltage at the speaker terminals. This was still not within the ideal ±0.1dB, so I used the "bracketing" method, listening with the VK-3iX's volume control slightly above and slightly below the CAT's. With the CAT driving the VK-55, the noise level was not as low as with the VK-3iX and VK-55, but it was quite good: with everything on but no CD playing, I could tell that the system was on, but this noise was masked by music played even at a low level.
The most obvious difference between the CAT and the VK-3iX in this comparison was at the frequency extremes. The bass with the CAT was more prominent and seemingly more extended, and the highs had greater sparkle. The CAT also had the edge in dynamic flow, with a greater sense of rhythm. Soundstage depth was excellent with both preamps, but the CAT had even greater definition of images in the soundstage. The gimmicky-but-fun "General Image and Resolution Test"—track 47 on the Best of Chesky Jazz and More Audiophile Tests/Volume 2 (Chesky JD68), in which people march around the room in an uncanny simulation of multiple-speaker surround sound—was very effective with both preamps, but through the CAT the individual percussive sounds and voices were more startling.
So, is the CAT, which costs more than three times as much as the VK-3iX, simply a better-sounding preamp? Well, not exactly. In fact, comparing the CAT with the VK-3iX on a wide range of recordings made me realize that the CAT tends toward brightness, which translates to harshness with some recordings. The VK-3iX, in comparison, is smoother and more forgiving, and I preferred its sound to the CAT's on some recordings.
One of these was The New Moon (Ghostlight 4403-2), one of my latest "Records To Die For" picks. When I'd selected this recording for R2D4, I was listening to it through the VK-3iX and VK-55, and I thought it sounded very fine. However, with the CAT in the system, Christiane Noll's silvery soprano in "One Kiss" took on a somewhat steely edge—one that, having heard her live several times, I know it does not have. On other recordings, primarily of the purist audiophile sort, my preference was for the CAT's greater immediacy and transparency, but even with these recordings I felt the sound would have benefited from a tonal balance a bit closer to the VK-3iX's. My CAT is an SL-1 Ultimate, which has been superseded by the paradoxically named SL-1 Ultimate Mk.II (perhaps the Ultimate should have been renamed the Penultimate); if nothing else, my experience with the VK-3iX convinced me that it's time to get my CAT preamp upgraded.
To compare with the VK-55, the amplifier I had on hand was the Audiopax Model Eighty Eight SE (which I reviewed in May 2003, Vol.26 No.5), a $10,000/pair monoblock that is probably my overall favorite of all amps I've had in my system. The Audiopax is single-ended, so I used the VK-3iX's RCA outputs and, again, the "bracketing" method to match levels with the VK-55 in listening comparisons. The Audiopax has lower gain, so its volume control had to be turned up much higher to get the same output as from the VK-55, but that was no problem. The noise level was almost as low as with the VK-3iX and VK-55, and lower than when pairing the CAT SL-1 preamp with the BAT VK-55. The Audiopax inverts absolute polarity; I reversed the speaker-cable connections to compensate for this.
In evaluating audio components, a characteristic I value most highly is a component's ability to communicate the sound of the recording with the minimum of electronic artifacts. The Audiopax Eighty-Eight SE does this better than any other amp of my experience; with the Audiopax's Timbre Lock settings optimally adjusted, recordings that sound harsh and artificial (dare I saydigital?) with other amps suddenly seem much more natural and musical. A CD I play quite often when I want to impress people with how good an old recording can sound is Frank Sinatra's Come Fly With Me (CD, Capitol CDP 7 48469 2). The recording was made in 1957, and the CD transfer has no special audiophile pedigree, but "On the Road to Mandalay" can have a presence in the room that is almost spooky. The Avantgarde Unos have much to do with this effect, but it also depends on the amplifier (and, of course, the rest of the system). With some amplifiers, the voice and the instruments may be all there, but I'm too aware of the fact that the recording was made 50 years ago, with microphones that were peaky in the upper midrange, and the hardness added by the transfer to digital.
With the VK-3iX and the Audiopax, my attention focused more on what Sinatra was singing and Billy May's swinging brass arrangement. Substituting the VK-55 (balanced XLR connection) resulted in some diminution of this effect, so that the recording seemed to sound more artificial than before, but the difference wasn't great. The general tonal balance of the two amplifiers was quite similar, but the VK-55 had bass that sounded a bit more firm and extended, as well as the edge in the ability to present high-level dynamics. Considering the $6000 price difference, this is excellent showing for the VK-55.
Phono stage This may be, as Michael Fremer said in "Analog Corner" in January 2005, "a great time to be into vinyl." In that column he reviewed BAT's VK-P10SE phono stage ($8000) and concluded that it was one of the top three phono stages he'd heard, coming in No.2 after the Boulder 2008 ($29,000) and ahead of the Manley Steelhead ($7300).
Sorry, Mikey, those are all too expensive for me! I listen to LPs not so much because of their sound quality—which, I will concede, with the best equipment may still beat CDs—but for the repertoire; I have many old records that I'm fond of, and which have not been released on CD. For this, I would be satisfied with a preamp that has a phono stage that's of good quality without being absolutely cutting-edge, and at a reasonable price. That, it seems to me, is exactly what the VK-3iX's phono card provides. The phono card's selectable low and high gains provide matching for a wide range of cartridges, and the ability to plug in load resistors provides for further tweaking potential.
There was no question that the high-gain setting would be more appropriate with my AudioQuest 7000nsx low-output moving-coil cartridge, but what about a load resistor? The VK-3iX phono stage comes with a standard 47k ohm load, and when I first tried it, I heard nothing that would suggest a cartridge/load incompatibility. Still, the recommended load for this cartridge is 100 ohms (that's what I use with the CAT SL-1 preamp), so I thought I should try it. Adding a load resistor to the VK-3iX phono stage is not all that easy; you have to provide your own, and the resistor lead wire has to be just the right diameter to fit the socket. BAT's service department sent me the appropriate resistors, and they were a little loose in the sockets. However, as it turned out, I heard no benefit from using the 100 ohm resistors; if anything, I preferred the sound with the standard loading, so that's how I listened to it.
And it sounded just fine! In a fit of vinyl nostalgia, I put on Depth of Image (LP, Opus 3 79-00), one of my standard test records in the days when I would fiddle with various cartridges and phono stages, tweaking VTA, etc. I quite like the first track, a Swedish pop song that may or may not be about a woman waiting for a phone call. (I know she sings "telephone ringen.") The sound was characterized by a huge soundstage, crisp percussion transients, and the voice having just the right amount of hardness on the sibilants. (I remember from my days of tweaking that the sibilants on this cut were quite sensitive to various setup parameters.) I have no reason to doubt that BAT's $8000 VK-P10SE would be better still, but the VK-3iX phono stage performs far better than anyone can expect for $500, and is likely to satisfy all but the most devoted fans of cost-no-object vinyl playback.
Paradigm shift The Avantgarde Uno 3.0 is a wonderful speaker, and quite revealing of differences among system components, but its design—horn midrange and tweeter combined with a powered subwoofer, sensitivity about 15dB higher than the typical box speaker—puts it in the category of exotica. To check out how the VK-55 would perform with more conventional, lower-sensitivity speakers, I got hold of a pair of Paradigm Reference Studio/100 v.3s. John Atkinson followed-up on this speaker in the January 2005 issue, and I was pleased (and relieved!) that his response to them was as positive as mine had been to the v.2 (June 2000). The Paradigm's relatively small footprint meant that I was able to place them in the room next to the Avantgardes rather than having to take the Avantgardes out of the room. (Finding storage space in our fairly modestly sized house for the Avantgardes, then trying to put them back intoexactly the same spots afterward, are chores I like to avoid if at all possible.)
The Reference Studio/100 v.3 was measured by JA to have an above-average 88.5dB sensitivity but to present quite a demanding impedance load. Nevertheless, the VK-55 was able to drive these speakers very effectively in my 14' by 16' by 7.5' listening room, with no indication of strain up to levels that I would describe as fairly loud—my RadioShack SPL meter (C weighting, Fast response) indicated peaks of 95dB, and this meter is known to underestimate actual peaks by several dB. The sound was wide-ranging, smooth, neutral in tonality, and engaging. I compared the performance with the speakers connected to the VK-55's low- and medium-impedance output terminals, expecting the low-impedance connection to be more optimal, but I actually found the medium-impedance connection preferable, with better dynamics.
When I reviewed the Studio/100 v.2, one of the amps I tried with it was the BAT VK-60, and I found that amp to be not as well-matched to the speaker as the high-powered, solid-stateBryston 9B-THX. I did not have that amp around this time for comparison, so I can't say whether it would have provided a better match with the v.3 as well, but the pairing of Paradigm Reference Studio/100 v.3 with the BAT VK-55 was a very good one, and, if memory serves, superior to the Studio/100 v.2 with VK-60.
Conclusions Considered as individual components or in combination with each other, the Balanced Audio Technology VK-3iX and VK-55 are exemplars of the best that specialist home audio has to offer. Both are compatible with a wide range of associated equipment, and neither is fussy or quirky in use. Best of all, with the right sources and associated equipment, they're capable of producing sound that bears a striking resemblance to real music.
At $6490, the VK-3iX and VK-55 combo is not inexpensive, but it represents excellent value in today's audiophile market, and stands up well in comparison to some much-higher-priced references. A most welcome feature of these products is BAT's well-developed upgrade path. The VK-3iX is good enough that upgrades are not imperative, but for those who wish for more low-end oomph and greater dynamics, two capacitor upgrades are available. I've never heard of a situation where increased capacitance in the power supply was not of some benefit, however marginal, so if you have the money, these capacitor upgrades are probably worthwhile.
There is also the Special Edition upgrade, which incorporates not only the capacitor upgrades but a change from the 6922 to the 6H30 SuperTube. I would think more carefully about this one. A change in tube type tends to have a more dramatic effect on sound, and while the results may be technically superior, if you're pleased with the sound of the VK-3iX as is, you may find that the sound with the SuperTube upgrade not as much to your liking. I would certainly want to listen to an SE version of the preamp before going ahead with that upgrade.
For the VK-55, the upgrade consists of conversion from a 55Wpc stereo amp to a 110W mono amp, which would be worthwhile if your speakers are particularly power-hungry and/or if you have a large room.
Or you can get the basic combo of VK-3iX and VK-55, forget about upgrades for a while, and just listen to the music.
