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Following article appeared in

Volume 6, Number 4, Positive Feedback Magazine.

Reproduced here with permission. Summer 1996



Tube Fest, Part IV:

The Quest For The Holy Grail!

Stu McCreary

Trudging through the tangled tundra of tubes, breaching steep chasms of consonance, climbing the peaks of amplifier ecstasy only to see a higher peak appear on the horizon, beckoning me onward in my Tube Fest quest -- the search for the Holy Grail of amplifiers. For two long years and through more than eighteen amplifiers, Sir Stuart the Stalwart has searched earnestly for the Grail, hoping against hope that it truly existed, that it was more than a myth, more than wishful thinking. Many fine chalices have been found. A select few might have made this gentle Knight forsake the quest. Ah yes, the Manley SE/PP 300B, Golden Tube 300B and most recently the BAT VK-60, may well have ended it. Each in their own way having the semblance of form and bejeweled glisten of the true Grail. But he trudged on, drawn by an aching desire to uncover the myth, all the while hearing more clearly in his mind the beauteous sounds the Grail would produce. It would have a fine, grain free resolution and would eschew the bleached tonality of solid state in favor of the harmonic truth of the best SE 300B amps. It would present an absolutely transparent window to the musical performance, neither overly dark and romantic, nor hyper-detailed with clinical coldness. It would reproduce the bottom octave like thunder rolling down from the gates of Valhalla and mid-bass that would rattle dry bones ---all without a trace of overhang or bloat. The treble would soar effortlessly to the sky suspended on a small, billowy cloud of air just large enough to float without obscuring a single detail of the ascent. It would conjure up breathtaking life-sized images that would float like pulsating cylinders between the speakers - each in a clearly defined space with the blackest of voids between them. It would be equally adept at communicating the intent of the quietest whisper and the shock of a raw trumpet blast while preserving all the subtle gradations in the micro to macro-dynamic continuum. ...and last, but certainly not least, a Knight must be able to acquire it without swearing an absolute oath of poverty. You see, the Holy Grail must possess ALL the amplifier virtues and these must not be in meager portions. No, the Grail is chock - full, pressed down, running over with its abundance. There should be no question of its authenticity when it is experienced. Its abundance should nearly overwhelm anyone who hears it. Well roll up the gates and flood the moat, I finally found it! My personal Grail is the BC-2 monoblocks painstakingly crafted by Gilbert Yeung of Blue Circle Audio, Innerkip, Ontario Canada. By all rights the Tube Fest should end right here. When I set out on this adventure, I clearly stated that it was enlightened self-interest that motivated me, not a sense of audio altruism, so having found the right amplifier for my system, I could call it quits with impunity. Heck, would anybody blame me after more than 18 tube amps have come and gone (some still haven't gone and I'm expecting a menacing phone call any day now). Well, to be fair, I really should continue with Tube Fest. I've listened to a few great amps lately, like the BAT VK-60s, and they deserve some commentary. I should also emphasize, once again, that this was a personal, system dependent quest and I'm not about to suggest that my conclusions have universal application. Yet, I can speak boldly on this subject knowing that my opinion is unimpeachable. I am the world authority on this subject. ..and that is-- what sounds best to Stu in Stu's room with Stu's equipment. I'd better rattle off what that equipment is right now. My current system consists of a modified CEC TL2 transport on the Black Diamond shelf and cones perched on a Bright Star big foot, Audient Tactic, DTI-Pro 32, Audient Reference digital cable, Audient Audit, Electronic Visionary Systems DAC-1, Reference Line Preeminence II, Blue Circle BC-2 monoblocks, Von Schweikert Research VR-4.5s (silver wire, Hovland caps and Solo CFAC inductors),Tice IC-1 interconnects, Tice 416 bi-wired cables, Tice Powerblock III, all Tice power cords with High Wire Power Wraps, Yamamura sleeves, large ferrite chokes, a plethora of Black Diamond cones and Shakti Stones. ......OK, so maybe I'll talk just a little bit more about the technical features. The BC-2s are a unique design, the first of its kind as far as I know. They are hybrids, utilizing a single 6SN7 tube in the front end for voltage gain, two interstage bipolar transistors and ten bipolar transistors for the output. Not so unique you're thinking - after all, didn't counterpoint do something like this?---well hold on there....try single-ended with zero global or local feedback with five of the bipolars used as current valves and the other five as current "mirrors," providing a constant current source... now we're talking unique! Jennifer Crock, the US distributor and design collaborator, calls the amp "a fairly low impedance perfect voltage generator (swinging +/- 80 volts) that can sink and source current more or less simultaneously in different frequency domains." Oh, but I hear someone else thinking, I'll bet they sound a lot like the Pass Aleph amps, since they're using single ended solid state output devices. I thought that too....until Rich Brkich brought up the Aleph 3 for a head-to-head comparison. I'll make this short. The Pass amps sound nothing like SE triode amps (and not all that much like conventional solid state amps either). They don't capture the whole harmonic envelope, lacking the bloom and decay that I like. Nor do they float pulsating spherical images like the SE triodes do. But yes, they are very transparent and they do have excellent transients. We had substituted the pre-warmed Pass amp for the Blue Circles for several hours and then popped the Blue Circles back in. Within minutes I said, "Ahhhhhhhh.....thank you Lord!" Now we had the transparency and the transients, plus the timbre, the bass, the depth, the layering, and oh yes, the BC-2s bloomed like an early spring flower. The Pass Aleph 3 is a geat little amplifier, but it paled in comparison to the BC-2. I should mention that my commentary is based on the use of NOS Sylvania 6SN7 tubes in place of the stock Sovteks. With the stock tubes the BC-2s are great amps, but not quite Grail status. The quality of the 6SN7 tube makes a huge difference in the performance. The Sylvanias have a richer midrange and far better depth delineation than the Sovteks. Come to think of it, I haven't heard an amp yet that uses the Sovtek 6SN7 that couldn't be improved by a better tube. If I have my way, by the time you're reading this, Blue Circle will be offering a tastier tube in the stock amp. Angela Instruments has an excellent JAN Phillips 6SN7 in quantity for only $8.00 a pop and it would be a crime not to try it. I've come to realize that 9-18 watt SE triodes can't cut it on the 88db sensitive VR-4.5s. They sound wonderful at lower levels, but just can't handle an orchestra at full gallop. Thirty watts is about the bare minimum. These speakers also reveal another shortcoming of the SE or differential SE triodes. With in-room bass that is nearly flat to 20Hz, there is nowhere for the amplifier's bottom octave performance to hide. You can plainly hear if the bass rolls off and where an amplifier loses its grip. With the extremely low output impedance of bipolars, 75 watts and plenty of current, the Blue Circles have bass performance that rivals any conventional solid state amp I've heard. They easily bested the mighty Meitners, which I have always felt to be a David among Goliaths in bass performance. But what they do that the Meitners, and every other SS amp I've heard (even the Pass) can't, is to accurately reproduce the "whole harmonic envelope." I describe this, as many others have, as being comprised of three stages: (1) the transient pluck of a string, (2) the balanced harmonic development of the fundamental and overtones, and (3) the ambient decay. The SS amps can pluck like crazy, but it's straight down hill from there. On the other hand, in my system, most of the SE triodes (and nearly all other tube amps I've auditioned) are weaker pluckers, but much better with the harmonic bloom and decay. To my amazement, the BC-2s have all three of these stages nailed!... and what I mean by this is that each stage is done as well as I have ever heard. Hmmm...all the virtues in great abundance. Kinda' makes you think of....oh, gee, I don't know, uhmmm... a Holy Grail? If you simply must test this for yourself in a scientifically repeatable manor (yeah, right), I have the perfect track to use for your analysis. It's the Adagio from Mozart's Flute Quartet No. 1 in D. KV 285 that you'll find at track 2 on Chesky's recording of Gary Schocker, flutist, and the Chester String Quartet. This is a superlative performance and recording that delivers in spades the three stages of the harmonic envelope. The staccato plucking of the strings have a wonderfully fleshy quality through the BC-2s, the harmonic bloom of the cello is to die for and all the while the lilting tone of Schocker's flute fills St. Peter's Church and defines its boundaries. This is music worthy of a Holy Grail. The Blue Circle has an extraordinary ability to lift detail out of the noise floor. During my listening sessions, it was a common experience for me to detect a new sound and have to back track to confirm that it wasn't my imagination. It was as if I were sitting on a hill gazing out over a familiar lake, when slowly the water was drained and mysterious rocks, stumps and branches began to poke up through the placid surface. It was all very natural without surreal, in-your-face detail. I could go on for pages with titillating audio pornography, but what's the point. I wouldn't call the Blue Circles my personal Holy Grail if they didn't do it all, and do it exceedingly well. I suggest you fantasize about your own perfect amplifier and then see if the Blue Circle BC-2s fulfill your fantasy as well as they have mine.

Positive Feedback Magazine

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