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Authorized reproduction from:

Ultimate Audio

Vol.2, No.1, January/February 1998

One New York Plaza, Suite 214

New York, NY 10004

Tel/Fax: (718) 796-2825

Blue Circle BC-2

Single-Ended Hybrid

Amplifiers

No Ordinary Amps by Richard E. Jenson The Blue Circle BC-2 monoblock amplifiers stand dramatically apart from other conventional attempts to create the ultimate amplifier. While they distinguish themselves in many ways, the first indicator of the BC-2s' originality is their apprearnce. These are large amplifiers whose signature is wood. The combination of their deep and vertical aspet with the characteristic Blue Circle "look" of stainless steel and wood hints immediately at the possibility that these are no ordinary amps.

That look is not a random style choice. Gilbert Yeung, Blue Circle's designer, says that the materials were chosen for their complementary (low) resonant properties. The narrow, elegant faceplate is made of smooth stainless steel interrupted only by a toggle switch and an indicator light; the rest of the chassis is made entirely of superbly finished wood. Mine was a red cherry; other woods are also available. While these amplifiers by no means recede visually into the background, they are at once soft and striking to the eye.

SILENCE, THANK YOU

While I have seen wood in many components (although not often in the past 30 years), this is the first wooden chassis I have ever noted. Yeung tried other materials but wood offered the best sound. Indeed, one of the amps' major strengths is their nearly silent background; whether the wood is at all responsible for this I do not know, but there is a deep black silence behind the beautiful music that comes from them.

The BC-2s are uncannily quiet. The silence and blackness of the background gave me the ability to crawl inside and inhabit, as it were, the body of the music. Musical tones seemed to have more substance than I had perceived before. Not that they were richer in any conventional sense (although that argument could be made as well), but I could flesh out the tone itself and imagine the texture of the instrument that produced it.

Listening to a superb recording of Mozart's Clarinet Concerto by the little-known Solistes EuropÈens de Luxembourg (own label, SEL 1991/1), I was struck by the soulful stateliness of the Adagio. Each note from Olivier Dartevelle's clarient occupied an extraordinary moment where it filled the air, serious and sad but never losing the pace of the lightness of the opening movement. Again, the richness of tone never came at the expense of dynamism or liveliness; it was merely the music as seen from the inside.

The silence of the BC-2s is very much akin to Myles Astor's description of the Sonic Frontiers Line 3 in Issue 4 of Ultimate Audio. As I listened more and more to get the measure of the BC-2s, the image of "blackness," an absence of background-seemed less accurate, in that it conveys,. The sense of a real space – a space that is inhabited but almost dead quiet – is always there when warranted. So, "blackness" does not quite suffice as a description of this special capability of the BC-2s. Rather a lowering of the noise floor, as Myles said, creates an impression of silence in comparison to my normal references.

HEART

Even more satisfying a journey to the heart of the musical tone is the sound of the contrabass on Gary Karr's recording of the Adagio d'Albinoni (King K33Y 236). The rich, resiny sound of the instrument, full against its nearly silent backdrop, has an analog-like quality I've rarely if ever heard on CD. In that sense, the ability of the BC-2s to allow me to see "inside" the string and the body of the contrabass recovers for CD's a palpable quality which so often seems missing. The Karr disc, through the BC-2s, has a sad grandeur, which is only promised through other amplifiers in my system.

A happy by-product of this clear view into the heart of the music is a sense of ease, which is one of the great stengths of the BC-2s. While I cannot say what component problems or failings normally cause a lack of ease in presentation, for me the unforced arrival of the notes is one of the hallmarks of live music. There are probably few serious listeners who have not wondered why live music in the concert hall, even when one is seated up front, is so unstrained and "natural" in comparison to even superb systems in the home. A particularly fine example of the relative strength of the BC-2s in this area is the "Matilda" cut from the Belafonte at Carnegie Hall (Classic Records LSO-6006). Part chat with the audience, part sing-along, "Matilda" is the song I imagine Belafonte might have sung in a small local hall. The utter lack of excess chestiness or resonance in his voice – speaking or singing, it matters not – is a joy (not) to hear. The BC-2s communicate a real person singing real music and, by the way, talking to the crowd, at ease and without apparent effort.

I cannot speak of the unforced transparency of the BC-2s without citing my pleasant surprise at the Keith Jarrett recording Live at the Blue Note (ECM 1575-1580). As an analogophile, I must admit that this great six-CD set starts off for me with two "demerits": (1) they're CDs, and (2) they're ECM CDs, meaning they might tend toward the cool, analytical and precise, No flaws, No spurious artifacts. No soul. But, surprise – listen to "On Green Dolphin Street" from disc 5, which is the cut of choice in recent months for me; at about 12:00 it shifts into overdrive, becoming a driving and joyous celebration of the song's melodic line. The sense of ease, of a Lexus quiet, combines with the timbral truth to create not just the warmth, but the heat, of the real thing. On ECM, no less!

THE NOTES YOU WANT TO HEAR

I shuld underline that the just-right timbral quality that one can reach out and touch is for me the BC-2's signature. There is a consistency to the sound throughout the musical spectrum: From the upper bass through the highs, the BC-2s (as was said of George Harrison, another understated performer) "play the notes you want to hear." I cannot accurately comment on the deepest bass, as my Genesis VIs cross over to their dedicated subwoofer amp for the lowest notes. However, the BC-2s exhibited a consistency and coherency of timbre well down into the bass. They never hinted at any wooliness or softness, and never began to run out of steam.

The amps are rated – conservatively, according to Gilbert Yeung – at 75 watts per channel. My Genesis VIs are fairly efficient speakers, at about 89-90 db/1w at 1 meter, and all the more so without requiring the region below 50 Hz of the main amp. I might hesitate to sue the BC-2s with grossly power-hungry speakers in a large room, but I never even got them to breathe hard in my modest room, even at ear-splitting volumes for Nirvana and Chumbawmba.

TECHNICAL HIGHLIGHTS Gilbert Yeung's design for the Blue Circle BC-2s evolved over a long period of time. At the age of 10, distressed by the sound of his Sony cassette player, he wondered what could make better sound. Not long after, he chanced to see and hear a David Berning preamp. The contrast between the cassette player and the high-end preamp gave Yeung the impetus to try his hand at designing audio components.

The approach started with something close to the proverbial "clean sheet of paper," with simplicity a major design criterion. The BC-2 is pure single-ended Class A. Single-ended because the signal is handled by only one component in each stage; Class A because, among other things, of the constant load presented to the input stage. In each case, Yeung concluded simpler is better.

The amplifier is a hybrid, with a tubed input (one 6SN7) and a transistor output. Blue Circle's engineering white paper (easy to read even for the technically challenged) outlines the reasons for selecting transistor outputs – among them wide response, speed and lack of phase error. An advantage for tinkerers is that one can experiment with tubes for the input without spending a fortune. An NOS Philips is used, but Yeung has also had good results with the Sylvania Chrome Dome, and less positive outcomes with the Sovtek.

While the amplifiers get very hot during operating (single-ended being here less efficient than push-pull), the heat sinks draw off the heat very quickly from the output transistors. Yeung states that the orientation of the heat sinks and the space for air "intake" allows for air to be drawn in through the bottom to cool the transistors. The transistors' casings will often be cooler than the heat sinks, with the resulting constant temperature ensuring stability and long life.

I asked Yeung why he thought the amplifier is so quiet. He replied, "Background noise or mechanical quiet? The reasons are different." For the former, he claims it is the high input sensitivity. Again, a simple answer, although if that were the sole reason, all one would need to do to design a quiet amp is to ratchet up the sensitivity. Mechanically, the BC-2s have a tuned spring support for the tube and predriver subsystems, but Yeung says that the transformer, which has three layers of insulation (padding, a resin/epoxy that expands with temperature, and a metallic inner layer), is largely responsible for the silent operation. It might just be that rich red cherry chassis, though.

ON A HIGH

On the other end of the spectrum, high-frequency performance is often cited as a weakness of amplifiers with transistor outputs. It is clear form the start that the BC-2s do not have either the stridency or the dullness afflict other amplifiers of the type. The sound of the Scottish whistle on the "Whistle Theme" from the Local Hero soundtrack LP (British Vertigo 811038) was delicate and airy. At the same time, the whistle had a body and heft to its tone that sounded entirely natural. The "Whistle Theme" can sound somewhat cool and clinical with certain solid-state amplifiers, especially through speakers with very extended high-frequency response. The BC-2s' rendering is both more euphonic and closer to a real whistle.

Longer-term listening produced a vague impression of roundness – a characteristic I would use to describe the entire sound of the BC-2s and one not inconsistent with live music – which caused me to wonder if some of the top-end sparkle is missing. It is possible that the BC-2s are just on the soft side of complete and utter neutrality in the high frequencies. My impressions of this varied somewhat by recording. I listened to the London Super Analogue recording of the "Spring" concerto of Vivaldi's Four Seasons (Marriner, Academy of St. Martin-in-the-Fields): The strings were light as a feather, yet they maintained the body and resonance so characteristic of these amps. The harpsichord came through the strings without any heaviness and was able to occupy its own space in the overall sonic picture. At the same time, I was not fully won over by Joni Mitchell's voice in "A Case of You" from Blue (Reprise M 2038), or "Refuge of the Roads" from Hejira (Asylum 7E-1087). My listening notes read "smooth on top, curved rather than sharp." Still, it was only at the edges of her voice, where the voice ends and silence beings, that I could perceive any possible softening.

One other characteristic of the BC-2s is their very focused presentation of the soundstage. They consistently depicted a soundstage that had great (and not exaggerated) depth, with space for each of the instruments occupying the stage. In my small listening room, the sense of depth and focus, combined with the palpable tonal quality, produced a synergy that was altogether pleasing. On the other hand, compared to my reference, the width of the stage was somewhat narrower. Not once did it extend much beyond the middle of the speakers. That may be a function of room interactions; I would cite is as less important to the overall quality of the amps than the depth, which is a real strength. Referring once more to Blue, Mitchell is properly placed in both depth and width; in general, the BC-2s did a fine job in this regard.

Interestingly, I also had the chance to listen briefly to the BC-3 line stage preamp. While the BC-3 is not the subject of this review and merits much more extended listening, it exhibits the same general sonic qualities of the BC-2s. Like the BC-2s, the BC-3 is built like a tank. Like the amplifiers, it is a hybrid design in stainless steel and wood. And likewise, the BC-3 has a very low noise floor and a rich presentation of the source material. I also found that the soundstage was similar – deep and precise in its ability to locate instruments and voices, with ample space for the instruments, but a bit narrower than what I am accustomed to.

My initial reaction is that the BC-3 would mate very well with a digital source that tends to the analytical, since the fullness of the sound tends to tame some of the digititis one often hears from CDs. In that respect as well as others, it sounds like the BC-2s, but perhaps more so. By a small margin I preferred the sound of my system with either of the Blue Circle units to that with both of them. The window upon the music that the amps delivered is marvelous; I felt closer to that elusive sense of musical truth with the BC-2 alone.

FURTHER THOUGHTS

The low noise floor of the BC-2s became all the more obvious after they departed my house. Upon reconnecting my RM-9 II, I was surprised at the audibility of the noise in the amp, whose sound I thought I knew well. While the Music Reference yields little to the best amplifiers in terms of transparency and articulation, I found myself wishing also to have the silent backgrounds of the BC-2s. Playing "one Green Dolphin Street" anew confirmed the higher noise floor. I might easily have ascribed the background noise to the live setting in the club (the Blue Note), complete with ambient rustling and Jarrett's singing, had I not listened to the cut 10 times with the BC-2s. The Blue Circle amps gave me all the low-level club noise and a window into Jarrett's voice (which I had not wished for), but against a very dark (if not completely black!) background. The distinctions are fine, but the small advantage here contributes to the overall quality of the amps.

...AND SOUL

The Blue Circle BC-2s are more than the sum of their strengths. The "ledger" approach to evaluation – "this is good, that is not as good" – fails to account for the essence or the excellence of these units. They may have heated my listening room on cold December days and, yes, the sonic image may be a hair short of perfect, but the Blue Circles capture the heart and soul of the music. Whether they very tangible, almost physical tonal honesty is due to the unique design (i.e. single-ended hybrid in wood) or to the careful execution and bombproof build matters little. It is almost a cliché to say that a fine component lets you forget it is there and allows you to just enjoy the music, but the cliché holds for the BC-2s. I could live happily (and warmly!) with the Blue Circle amplifiers for a long time and easily forget about new toys; they play exactly the notes I want to hear.

REFERENCE EQUIPMENT Front End: Linn Lingo / Cirkus / Trampolin, Ittok arm, Monster Sigma 2000 II cartridge, Proceed PCD3 II (modified a la francaise);

Electronics: Music Reference RM-9II amplifier, conrad-johnson Motif MC-8 preamplifier; Seapkers: Genesis VI;

Cables: Transparent Reference, Tara Temporal Continuum II, Monster M1000;

Accessories: Target stands, Tice MBF-4 PLC, VersaBlock power cord, VPI bricks, Gryphon Exorcist, AudioPrism CD Stoplight and Blacklight, Tiptoes, Hunt EDA brush, Stylast, Record Doctor cleaner.

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Contact:  bcircle@bluecircle.com  /  519-469-3215