Blue Circle Audio BC3 Preamplifier and BC3 Power Amplifiers

      Date posted: February 11, 1997

Blue Circle BC3 Preamp
Preamp Sugg. Retail: $3995 (CAN)
Power Amps Sugg. Retail: $7499 to $7999 pr (CAN)
depending on finish
Manufacturer: Blue Circle Audio Inc. R.R.#1,
Box A-O, Innerkip, Ontario N0J 1M0
(519) 4369-3215 FAX 469-3782

(Reprinted from the Winter 97 Audio Ideas Guide)

      There is no question that high end audio is usually a labour of love for the designer, this being a given where technology and art meet. What kind of love is another question altogether: sometimes love is blind, sometimes it’s tough, and as often as not, simply perverse. I guess that’s what makes for the remarkable diversity we find in components with such an emotional content. It is perhaps useful to view this pair from Blue Circle Audio in this light.

     This company’s designer, Gilbert Yeung, definitely has his own ideas, these embodied in both preamp and amplifier. The BC3 preamplifier is a minimalist design with high gain in a single- ended dual triode configuration. It is also dual mono, with a twist, which I’ll outline below.

     A line stage, the BC3 has 4 knobs on its brushed stainless steel front panel (the rest of the case is also shiny stainless steel, reminding me of the DeLorean sports car) which fulfil 2 functions. The outside pair select inputs (there are 5), while the inner 2 are resistor ladder volume controls precisely calibrated using “Holco 0.5% metal film resistors” connected to a “Shallco military grade” control “with silver coin contacts and stainless steel shaft.” With this preamp you select inputs and level settings separately for each channel, which puts this product definitely into what Quad’s Ross Walker called the “hair shirt audio” category. A more Canadian view might be that this is a preamplifier for Jacob Two-Two, since you have to do everything twice. However, that touch is suitably luxurious, the 4 knobs coming in a standard solid black oak, with red cherry, golden oak and other woods available; I guess it’s the equivalent of the burled walnut dashboard trim.

     The input jacks at rear, also dual-mono configured, are so widely separated that you can’t use a normal stereo cord because the RCA plugs have to be close to a foot apart to plug in. Dual mono, indeed! The irony, the twist alluded to above, is that after all this, the stereo signals, separated at input, switched and level- set separately, then go into two tubes, not separately, but sequentially for gain. That’s right, the stereo signal goes through one tube, and then another, each signal separated now by only a vacuum in the dual filaments of the triode tube (both are 6922s). All this seemed to make perfect sense to Gilbert, who noted that it made sure that tube aging would be equal for both channels, and channel balance would be maintained through the life of the tubes.

     The power supply for these gain stages is outboard, connected via a Neutrik 4-pin XLR plug and jack. The preamp has 2 sets of outputs for bi-amping, and a single tape out. With Kimber Kaps, Jena Labs wiring, Cardas Eutectic solder and RCA jacks, andSolen Fast Caps, the BC3 puts a strong emphasis on parts, and its wiring is all point-to-point.

     If the preamplifier leans to the hair-shirt high end side of things, “tough love” if you like, the dual mono amplifiers could be said to be a labour of both love and perversity. Larger than some speakers at 10 1/4″ wide by 16″ high by 25 1/2″ long, the BC2 pair will tend to dominate a listening room, and seem fated for floor positioning, as they were in my room between the speakers. Each weighs 55 pounds, with very nicely finished wood side and end panels. Black oak is standard, with red cherry, walnut and other woods available at higher cost. The top of each amplifier is a matrix of angled heatsinks, inside of which are the output transistors.

     For the BC2 is a Class A, single-ended solid state design, using a tube (a single 6SN7) as driver. This may be perverse in the face of triode orthodoxy, but it actually makes more sense than tubes and transformers, with their inherent current and saturation limitations, and high harmonic distortion. Solid state single-ended amplifiers are said to offer the magical midrange without the woolly bass and overly harmonic high end.

      Unfortunately, this approach is both very expensive to design and build, and ultimately, to operate. By virtue of being Class A, the constant current draw is large, and a dedicated amplifier AC circuit is highly recommended. We used just such a circuit for auditioning (one of 3 in my listening room); the BC2 has relays to control the initial current draw (no, lights do not dim when you turn the amps on), and to turn on the speaker outputs only after thermal stabilization of the circuit, which takes 30 seconds or so. The speaker binding posts are large gold-plated 5-way types.

     As in the preamp, wiring in the BC2 is all point-to-point, and the tube driver circuit is mechanically isolated to eliminate microphonics. Here’s how Gilbert Leung describes this unusual amplifier he’s designed in his spec sheet: “The BC2 is a pure single-ended Class A monoblock amplifier delivering 75 watts into 8 ohms. We feel that simplicity of design, topology & execution are critical to the extraction of the subtlest details from the musical source. With this in mind, the BC2 employs only three stages, and when used with the BC3 preamplifier, there are only five stages from the input of the preamplifier to the output of the power amplifier. In this case, fewer and simpler is better. There are no circuit boards. [italics theirs] The BC2 is totally hand assembled and hard-wired.”

     Gilbert tells me it takes him about 40 hours to build each matched amplifier pair. As in the preamplifier, the best parts are employed, the amplifier having two separate power supplies, “one for the pre-drivers, one for the output stage.” “Multiple small value filter capacitor networks” are used to combine excellent transient response with large current capability.

     And this latter ability is one thing that distinguishes this single-ended design from tube types; it can deliver more current to the speakers. However, it will not drive low impedances with full output, having its greatest power capability of 75 watts at 8 ohms, and only half that power at 4 ohms.

     The BC2s run quite hot, and work quite nicely as space heaters, so a fairly large room is recommended. Most of this heat comes directly off the heat sinks for the bipolar transistors for each amplifier. If these were literally “hair-shirt audio” they’d probably catch fire. Boy, that wouldn’t smell too good!

     I did most of my initial listening to the BC3 pair without the matching preamp, driving it directly with our Monarchy M-33 DAC/preamp. I was impressed by a sound that was very warm, clean, and precise, without the exaggerated harmonic energy heard from many tube single-ended designs. It was a little compressed at high levels, the bass a little fat and fuzzy compared to a Brsyton 3B ST, but extension and power were well maintained to the deepest notes.

     One of my favourite jazz reissues is Art Pepper +Eleven (Analogue Productions APJ 017), and it’s also an excellent LP for assessing harmonic delicacy, a certain subtlety of tonal balance among the brass and reeds beautifully captured in the 1959 recording. Listening to side 2, starting with Bernie’s Tune, I could hear both the strengths and weaknesses of this amplifier technology: the musical textures were very immediate and natural, but the brass overtones were just a bit edgy, moreso than I think they should be. Perhaps my Veritas, with their 4-to-5-ohm impedance over much of the bass range stressed the BC2’s power capabilities, but at very high levels the sound of the amplifier tended to unravel into graininess.

     Within its limitations, however, it was a very sweet, detailed and seductive sound, with superb imaging, underlining a particular strength of the v1.8. If these qualities are a little to the left of accuracy, so be it. The Blue Circle BC2 is the best single-ended amplifier I’ve listened to at any length, and rather more practical in terms of dynamics and realistic sound levels than any other such design I’ve heard.

     I listened to it almost exclusively for about a week to all kinds of music from FM, LPs, CDs, and DAT master tapes. In an overall sense, I think an amplifier like this tends to bring out the sound rather than allowing you to listen into it. That distinction is an important one, and takes us back to the delicate tonal interplay of + Eleven: for me, it’s just not quite there in this amplifier; maybe the best way to put it is that the BC3 puts sugar in its coffee, and I don’t, because I want to taste the real flavour of the brew. If you’re a sugar person, then you might like this amplifier a lot.

     The preamplifier seemed more neutral, a little bright, but with a very nicely transparent midrange, with good speed on percussion and good articulation on voices. I did note a slight sharpness on female voice, but this was nicely balanced by the open quality of the sound. There was lots of gain, accompanied by very good dynamics, though I missed a little bass slam and weight. It’s a good preamp sonically, and the unusual tube-sharing triode approach should maintain channel balance (both tonal and level) through even tube aging.

     That said, this component is just a bit too much hair-shirt hi-fi for me. Though I can appreciate the beauty of the internal wiring and expensive parts (see the picture with top off), I think an even simpler approach can sound better, and resistor-ladder level controls are ideally suited for remote control, and thus greater convenience of operation. Also, if the cops ever wanted a complete set of my fingerprints, all they would have had to do was arrive just after I lifted this preamp out of the box;the DeLorean got complaints for the same reason, and, being a pretty sexy car, got touched and stroked a lot. The BC3 is a hands-on product too: one hand for the left-channel knobs, and one hand for the right-channel knobs.

     What are the upsides of spending $10,000 or more on this combination? Well, you get a pair of hand-crafted audio products that are unique works of art and craft, and together their sound is extremely musical if not entirely neutral. The midrange transparency and slight sharpness of the preamp are compensated for pretty much in the softer focus of the amplifier’s midrange, and if you value liquidity over transparency, you may find this sound very attractive. You will always find both visually very handsome, high end statements in wood and steel.

      Andrew Marshall

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