July 2005

Blue Circle Audio BC204 Stereo Amplifier

by Marc Mickelson

Sometimes things just happen in bunches. On July 1 we published a review of Blue Circle Audio's BC202 power amp, and now a little over two weeks later we publish a review of another amp in the same series, the BC204. Here's the story. I lugged the BC202 home with me from CES, so that I could hear it before we sent it to Bascom King for measurements. I was immediately impressed with its sound, so much so that it seemed a pity to write a mere sidebar to Jason Thorpe's BC202 review, which was the plan. There was no way I could pull the amp from Jason and write about it myself; the easiest way to alienate an audio writer is to yank a product he's anticipating. Instead, I talked to Gilbert Yeung, the head of Blue Circle, about reviewing another of his new BC200-series amps. He had a BC204 on hand, he shipped it to me, and I get to tell you about it.

This sort of informality underscores the fact that no one in the audio biz is quite like Gilbert Yeung. He's zany and fun-loving, yet as serious and knowledgeable as any designer of audio equipment I've met. He loves to act all gruff and bothered, especially when you visit him at CES, but deep down he's exceedingly good-natured and really wants people to know the salient features of the products he makes. And he does make them, building almost every product himself. "I've been working 12 or 16 hours a day this summer, just to keep up with orders," he told me. "If people aren't willing to wait for me to make what they order, I tell them to buy something else." That's Gilbert.

The BC200 series of amplifiers was introduced a little over a year ago and currently comprises three stereo models, with a monoblock coming. The $7795 USD BC204 is the middle child, fitting between the $5295 BC202 and $10,295 BC206. The rated power outputs of the three amps are not all that different from each other: 125Wpc for the BC202, 150Wpc for the BC204, and 180Wpc for the BC206. "I'm not selling watts," Gilbert explained. "The differences are in refinement."

All three amps use a quad of 6922 tubes for the input stage along with power op-amps in the place of more traditional solid-state output devices. The op-amps that Yeung uses are designed for industrial and aerospace applications to drive very complex loads, which makes them perfect in Gilbert's mind for driving loudspeakers. The BC204 uses three output modules, which consist of two op-amps and a circuit board mounted on their own heatsink, per channel, versus two for the BC202, and has a larger power supply as well, 850VA instead of 600VA.

All of the BC200-series amps are fully balanced designs, with a twist. The tube input stage is wired such that when you use the RCA jacks, it is a true single-ended circuit, and when you use the XLR jacks, it acts as a balanced circuit. As you can imagine, this has some effect on the BC204's sound, something I'll comment on below.

The BC204 measures 17 1/2"W x 9 7/8"H x 21 1/2"D and weighs an unwieldy 85 pounds. Like many Blue Circle products, much of the BC204 is component-to-component wired, which is one of the reasons Gilbert builds his equipment himself: It's painstaking work. On the front of the amp is the power switch and Blue Circle logo, which dimly glows when the amp is on. Around back are the RCA and XLR inputs, two pairs of speaker binding posts, and a 20A Neutrik twist-lock connector for the BC61 power cord that comes with the amp. There is also a feature that I wish other manufacturers would include: a ground-lift switch that disconnects only the signal ground for safety.

As Jason Thorpe explained about the BC202, the BC204 is available in a seemingly unlimited array of color combinations -- any in which you can purchase paint. In my opinion, none of these looks as good as Blue Circle's stainless-steel duds, a $650 premium, or a combination that includes one of the purpleheart-and-walnut faceplates from Blue Circle's AG line, which will cost you an extra $400. In standard form, the BC204's faceplate and bottom platform are made of MDF, and its outer case is 12-gauge steel. Gilbert feels that these materials increase "mechanical integrity."

System and setup

I used the BC204 with two different pairs of speakers and three digital sources. Speakers were Wilson Audio MAXX 2s or Alexandria X-2s, while an Audio Research CD3 Mk II, Esoteric X-01, or Zanden Model 5000 Signature/Model 2000 Premium combo spun CDs or SACDs. The preamp was a VTL TL7.5 Reference. Interconnects and speaker cables were from Siltech (SQ-110 Classic Mk 2 and LS-188 Classic Mk 2), Nordost (Valhalla), or Shunyata Research (Antares and Orion), and power cords were Shunyata Research Anaconda Vx and Alpha, Taipan, and Python. Everything was plugged into a Shunyata Research Hydra Model-8, which itself was plugged into one of Shunyata Research's Venom outlets.

Amps for comparison were Lamm ML2.1 or M1.2 Reference monoblocks. The ML2.1s sat on Silent Running VR 3.0 isoBases, the M1.2s on 5/8"-thick slabs of Corian. The BC204 rested on the carpeted floor of my listening room. As I noted in my review earlier this year, the VTL TL7.5 preamp has very high voltage gain, which can create hiss with certain amps, like the Lamm M1.2s, which have very high voltage gain themselves. Luckily, the BC204 has only 21.5dB of voltage gain, so it worked well with the VTL preamp. Gilbert Yeung designs his amps this way deliberately, so buyers will have to turn up their preamps and thereby get into the volume control's rotation where the sound is best.

A few in-use considerations. First, you will want to pair the BC204 (and BC202 for that matter) with cables that sound fast and open, even a bit lean. Nordost Valhalla and Shunyata Antares and Orion worked very well here. With the wrong cables, ones that are on the mellow side of the spectrum, the BC204 may sound overly subdued in the upper midrange. I found this out by pairing the amp with Siltech SQ-110 Classic Mk 2 and LS-188 Classic Mk 2, which were definitely the wrong cables for the amp. Second, the BC204 sounds best through its balanced inputs, where its full resolving power and dynamic capabilities are on display. Single ended, the BC204 sounds sweeter and more intimate, but also slower, less dynamic and a touch distant. Perhaps this was a system-dependent thing, but even Gilbert Yeung recognizes that the two inputs do sound different, which naturally implies that one is better. Luckily, experimentation is easy. Finally, Bascom King found that the BC202 inverts polarity through its balanced inputs but doesn't through the single-ended inputs. The same is true of the BC204. You'll want to compensate accordingly.

Listenin'

Because I had heard the BC202, I had some idea of what to expect from the BC204: a natural presentation that's never harsh or merciless in the way it conveys detail, the sort of sound I personally seek. However, the BC204 added a couple of things, including a slightly more incisive character that greatly enhanced the reproduction of brass instruments and piano, better large-scale dynamics, and slightly more presence in the bass region. What that extra $2500 buys is a better amp, not simply a more powerful one.

One of the best CDs I've bought recently is of a double-length recording from 1967 that has only recently made it to CD: Bill Evans's California Here I Come [Verve B0002681-02]. Of course, Evans's classic trio featured Paul Motian on drums and Scott LaFaro on bass accompanying Evans on piano. California Here I Come, which was recorded live at the Village Vanguard, where Evans laid down the classic Sunday at the Village Vanguard and Waltz for Debby, features the hard-playing Philly Joe Jones on drums and Eddie Gomez on bass, an interesting musical amalgam. For some reason "Available until 2007" is marked on the outside of the CD's packaging. I'd still rush to get a copy. Mine cost less than $10 -- for 75 minutes of great-sounding music from a legend. This is the definition of a bargain.

Verve has done a wonderful job remastering California Here I Come -- it has a JVC XRCD's warmth and resolution. Via the BC204, the music is detailed but not electronically influenced, the entire soundstage taking on a physicality that's thrilling. "Utterly grainless" say my listening notes. I wasn't referring here to a warm, syrupy, forgiving presentation, but rather a basic characteristic of what we hear from live music: the lack of reproduction artifacts. There is no upper-midrange highlighting or electronic grunge, no embellishment of the leading edge of notes. With music, grainlessness translates to an organic, flowing character that is the antithesis of the aggressive, overly airy presentation that some well-regarded amps exhibit. It's no small accomplishment. If you're used to amplifiers whose sound has a mechanical glaze, the BC204 will be a revelation.

The BC204 was easy to like -- and love -- with so much music. To test the amp's ability to portray space, I pulled out James Taylor's New Moon Shine [Columbia CK 46038] and played "The Frozen Man," a cut I know well. I was curious to hear whether the BC204 would diminish the sound of the shaker in the opening or the sense of space captured on the recording. It didn't, preserving the fine details that make this song so poignant. While the BC204 doesn't exactly sound like tubes, its performance does embrace a few tube traits -- ease and sweetness -- without overdoing them. Balance is key to the overall quality of the BC204's sound. In its quest for naturalness, the BC204 doesn't reach beyond the music's own grasp.

To test the BC204's bass, I put on Ani DiFranco's Evolve [Righteous Babe RBR030-D] and cranked the title track with its athletic bass guitar. The bass was very good -- bouncy and sinewy -- though not quite up to the crushing standards of solid-state powerhouses from Simaudio, Mark Levinson and Krell. It does soften a bit at its very lowest reaches, as one would expect, whereas these other amps just keep pounding away. This begs the question, "Which is correct?" I can say that during my listening, I would only ponder the BC204's low frequencies in relation to those of other amps, and then always in an inquisitive way. Nothing about the BC204's bass raises concern. The upper bass has suppleness that preserves quick starts and stops and gives the entire region a lively quality. This, along with the BC204's complete lack of grain, makes the amp ready for those who like to hear rowdy music turned up to 11.

There is a touch of sweetness in the mids, enough that you won't characterize voices as sounding dry or lean, but not so much that they exhibit excessive warmth or bloat. Again, grain, even of the finest variety, is gone, and this gives the BC204 an unforced character, but one that never tips over into opacity or veiling. Martha Wainwright's singing on "There Ain't No Sweet Man That's Worth the Salt of My Tears," from Geoff Muldaur's Private Astronomy [edge music B0000907-02], was finely rendered, projecting into the soundstage, and my listening room, in delicate blats. The BC204 preserved the transparency of the recording, Wainwright's challenging vocals sounding smooth and pure. I've burned this cut on my CES demo CD-R in the past, but I've never heard it reproduced better than with the BC204 driving the Wilson Audio Alexandria X-2s.

Another phrase from my listening notes, "musical truth," sums up the BC204's sound well. Because of its purity, its absolute lack of grain, the BC204 lets the music through without destroying its beauty, which is the only kind of truth that matters when it comes to reproduction. The BC204 is defined by this, and is significant because of it.

Hybrid vs. hybrid

Hybrid circuits make a lot of sense to someone with audiophile sensibilities, yet amplifiers that employ them are relatively rare. Perhaps the best-known hybrid amplifiers come from Lamm Industries; one version or another of Vladimir Lamm's hybrid design has been in production for over a decade. I owned a pair of original M1.1 monoblocks, and I've used a pair of M1.2 Reference monoblocks ($21,690 per pair due to a recent price increase) off and on for a while, swapping them with Lamm ML2.1 single-ended amps. Therefore, I am very familiar with Lamm's oldest and most successful amplifier design, and I was anxious to compare it to the BC204.

The strengths of the M1.2 Reference amps are many, including the same sort of naturalness that I have attributed to the BC204. The M1.2 Reference amps are incredibly easy to listen to, but they can supply solid-state-like fireworks, especially in the bass, when called on to do so. The BC204's bass, though very good, doesn't have quite the weight and slam of the M1.2 Reference's. In turn, neither amp offers the sheer impact and power that some solid-state behemoths do, but the low frequencies of these amps often draw attention to themselves as well. The bass of both the Lamm and Blue Circle amps is expertly integrated into the music they make, sounding neither anemic nor attention-grabbing. You should expect no less from a great amplifier.

If the BC204 has an "utterly grainless" sonic character, does that mean that the Lamm M1.2 Reference has at least a touch of grain? Nope. Both amps are below the threshold of discrimination in this respect, but the BC204's presentation is smoother than that of the M1.2 Reference. With California Here I Come, the BC204 displayed image density and tonal color that the M1.2 Reference couldn't quite match, but images cast by the Lamm amps had greater edge definition, which led to more distinct image outlines. The BC204 was better at portraying a sense of body, and the M1.2 Reference, the image outline.

Neither amp approaches coarseness or harshness, but the M1.2 Reference is certainly the more resolute and incisive of the two. It also captures the air on recordings better -- when it is there to begin with. Where the BC204 surpasses the M1.2 Reference is in the liquidity of its presentation, which doesn't come at any sonic cost. It's the sort of trait that you could transpose on the performance of just about any amp and consider it an improvement.

Maybe the BC204's greatest achievement is that it does surpass the mighty M1.2 Reference in some ways -- very few amps do in any respect -- and at roughly one-third the price.

Choices

Let's say you lust for one of the great amplifiers on the market -- the Lamm M1.2 Reference or even the Atma-Sphere MA-2 Mk II.3, both of which I have reviewed and admire greatly. You've heard one of these amps and loved it, believing that it would be the perfect mate for your speakers, which sound detailed and refined but need some juice. You've realized that you have two choices: take out a home-equity loan to buy the amp of your dreams, or give up on the idea of owning such an amp but know that you'll always wish for it.

Now you have a third option: the Blue Circle BC204, one of the most satisfying amps I've heard, and well under five figures in price. While I can’t say that the BC204 equals the Lamm and Atma-Sphere amps in every way, I can say that during my many weeks of listening to the BC204, I only had the desire to reinsert my reference amps to determine if what I was hearing from the BC204 was as good as it seemed -- to suspend any disbelief, so to speak.

In terms of our Reviewers' Choice designation, the BC204 is a 'tweener product: too expensive to be considered a screaming bargain, and behind other Blue Circle amps in the same series, so difficult to consider as state of the art. However, as with the Wilson Audio Sophia (which would be a great match for this amp), more than a smidgen of the best attainable sound is available at less-than-stratospheric pricing.

Blue Circle products do get their share of reviews, but based on my experience with the BC204, Gilbert Yeung's amps in particular don't get nearly the credit they deserve. Don't let the scarcity of near-mystical praise for Blue Circle products deter you from seeking out the BC204. It's a honey.

...Marc Mickelson
marc@soundstage.com

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