June 2000Blue Circle Audio BC21 Preamplifier
by Ken Micallef
Do you have a favorite tube? I do.
For some reason, call it fate, happenstance, serendipity, I began my happy trek through audio funland when the tube goblin set upon my ears and showed me a glimpse of sonic nirvana. The Audio Note M2 preamplifier became an essential part of my rig in 1997, in no small part because it responded very differently to the various NOS 6SN7 tubes I sunk into its delicate chassis. Tube rolling, I believe, is what they call it, and soon I was experimenting with all the brands I could afford: Tungsol, RCA, Raytheon, Ken Rad, Sylvania. Yeah, I got 'em all, and I'm still looking and hoarding! Call me narrow-minded, or just plain ignorant, but there is something about the sound of the 6SN7 tube in a preamp that, to my ears, betters the more commonly used 6922 or 6DJ8. I've been told that the 6SN7 is easier to work with and get a good sound out of than a 6922, due to that tube's microphonics and other issues, and, well, I believe it. A good 6SN7, due to its dual triode capability, can handle a stereo signal all on its own, though I have seen several preamps, such as the BC21 in question here, use two (one per channel), and the Wyetech Jade, which uses three. The Audio Note M2 has remained my reference for a while (though I loved the $5000 Legend preamp I reviewed a few months back, another 6SN7 unit) since it performs well with various types of music, uses that single signal tube and also features tube rectification in its power supply. The Audio Note M2 with mods retails for $3400, the Blue Circle BC21 for $1500, and they both use 6SN7s. But I'm getting ahead of myself.
Regular readers of SoundStage! (and aren't you all?) know that Blue Circle Audio is a favorite of the staff, currently in regular use by at least two of our illustrious ranks. But that doesn't mean that when I was assigned this review that I was simply going to fall in line with SoundStage! conventional wisdom. I am a firm believer that no matter how well reviewed a piece of equipment is, the fact remains that everyone's listening environments differ greatly, from power sources to room resonances to the gear to the actual ability to hear different things. Hence, many factors come into play when evaluating a piece of gear and the final sound it will make in your home. We might all agree that a top-of-the-line product from Theta or Audio Physic will outperform any plastic geehaw from Circuit City, but there is so much excellent, extremely well-built high-end audio equipment available now that, really, building a system is about which flavor of audio you prefer rather than finding drastic flaws in any one piece of gear.
The entry-level preamp in the Blue Circle Audio range, the BC21 would have to cut some serious corners, or so you would think, to compare to its pricier siblings. Its closest cousin, the BC3 Despina, which goes for $3300, is built on dual-triode class-A topology; is totally dual mono in the signal path, including volume controls; features point-to-point wiring; has an acrylic signal board mounted on a pre-compressed spring assembly; and uses an external power supply. But the BC21 is no slack and is quite gorgeously built. Its gleaming soft steel case (17.5"W x 3.625"H x 8.625"D) features a stainless-steel front panel with three trademark Blue Circle wooden knobs for volume, balance and source selection. The look resembles a Scandinavian art piece built by a high-tech tradesman.
Inside, the BC21 is a little maze of wires and components and resembles a jet-engine layout. It features all Cardas point-to-point wiring with Cardas Gold connectors, two Phillips 6SN7 tubes (self-biasing), each on its own blue acrylic mounting board, large Polypropylene capacitors, and a high-current power supply. The entire chassis is also affixed on an internal polymide washer system. Other specs/features include three line-level inputs, one tape output, one tape input, and one preamp output. Maximum output is 20 volts, weight is 15 pounds, and the warranty is three years parts and labor, 90 days on tubes. (Specs, apart from the warranty, are not mentioned in the manual, only on the website.) Unlike my Audio Note M2, the BC21 uses a separate tube per channel, which makes for greater gain and allows you to run longer lengths of interconnect to the power amps if needed. I played the BC21 uncritically for a couple months, with NOS Sylvanias (available for $10 to $15) in place of the stock Phillips tubes, so the unit was well broken-in.
Movin' on up
Having recently moved to the top floor of my Manhattan tenement, my listening room acoustics have changed considerably from the dungeon flat I previously rented from our often MIA landlord. Welcome to Manhattan, kids. Anyway, I now have a much nicer apartment, but one with more sonic bugaboos as well. An original tin ceiling is lovely to look at but it reflects sound horribly, and though I love all the light in my new space, the 360-degree windows bounce treble like a banshee. So after strategically fixing three slabs of RPG foam on the ceiling with 3M Spray Adhesive (this stuff works even when the ceiling fans are running 24/7), doing the same on the adjacent walls as well as hanging some heavy curtains on the windows and installing some new rugs, I got down to assembling my rig. Anybody seen that Bel Canto DAC1?
Looks ain't everything
Now, unlike some, I am not a fan of the wood and metal look of the Blue Circle line, as I think the two materials as implemented only clash. Gimme all wood or all metal, or like my Audio Note, mix the gorge-osity of the piano black front plate with gold knobs and a black metal case. But Gilbert Yeung of Blue Circle does offer stainless-steel knobs for an extra charge. What I do like, though heck, I love it -- is the gorgeous blue light that emanates from the circular Blue Circle logo. With those additional stainless-steel knobs, the wider-than-it-is-deep BC21 would look perfect alongside my Theta transport and the big tanker-sized Carys. I plugged the Shunyata Sidewinder power cord into the butt of BC21, got hyp-no-tized by the Blue Circle light for a minute, then got down to work.
Time out of mind
Ever get transported by the audio experience? And I don't mean high end; I mean when some old song brings back memories long forgotten? Well, the BC21 transported me instantly and with a new record, tenor saxophonist Mark Shim's Turbulent Flow [Blue Note 23392]. With his mellow, Coltrane-meets-Mobley tone and his supporting musicians' expertly relaxed and deep-barreled swing, the BC21 said one thing to me, out loud: beautiful. Where the Legend L2 I reviewed a few months back was a powerhouse of deep-ass response and treble lushness, and my own Audio Note M2 the model of button-downed, British-correct audio, the sound of the BC21 is simply beautiful. Another thing is apparent pretty fast: The BC21 likes to be played loud. Not that it wimps out at low volumes, but when you want to crank it, the BC21 is right there, prodding you on. Mostly, around nine o'clock seemed the best room-filling setting with my 100-watt a side amps.
The stage on the Shim record is wide and smooth, the BC21 enabling me to hear easily every snare ruff and cymbal ring of Eric Harland's intense drumming. That was a constant with recordings of all stripes through the BC21. With drums, I could hear not only the stick bead on cymbal but the ambient spread that should come off the cymbal like a sound halo. This owes to perhaps the BC21's strongest suit, treble extension, which made vocals, drums, strings and especially guitars, really soar, being very pronounced and detailed no matter what the record or style of music. I always felt that I was hearing every last bit of detail in the music, but not at the cost of smoothness. This is one smooth puppy, producing a vivid, brilliant, sunny presentation at all times that helped to give the music a real jump and sparkle. But never did I feel that it was etched or hard. Coming from the more straight-laced Audio Note, I wasn't prepared to hear every last nuance in a recording at first, but when I removed the BC21, I soon missed that last cell of detail. On Steely Dan's Two Against Nature [Giant 24719], that sparkle and jump enabled me to finally understand every last word in "Gaslighting Abbie," and it gave the guitars and brass throughout the record real slam. Ditto for the chorus vocals.
The BC21 stages well, and with that exceptional treble extension, it's a real champ at imaging and focus. Pat Metheny's Imaginary Day (Warner Bros. 46791) is a vast, dense production of modern jazz quintet augmented by three percussionists and occasional strings, with traces of world music and even techno. The BC21 reproduced it all with large-scale immediacy and accuracy. I have to say that for $1500 you won't get the definitive word in transient refinement, but the BC21 does do an excellent job at delivering long, leading-edge transients. This preamp has plenty of air to spare, giving instruments plenty of space within the soundfield, while allowing a lustrous gleam to the music. Dynamically, the BC21 also holds it own with more expensive units. I love track 7 on the Living Stereo CD of Mussorgsky's "Pictures At An Exhibition" [RCA 09026-61958]. Here, a forlorn French horn cries over strings that circle in the background like mourners. Slowly, the music builds and increases in volume as snare drums roll and thunder. The BC21 reproduced the snare drums as airy yet driving, and re-created the hall ambience with excellent depth and space. The musicians were stretched across the stage, snares popping up front, triangle above that, and strings right behind with brass off to the right.
For bass response, the BC21 goes as low as the Legend L2, but is nowhere near as room filling or potent. As another SS!er said somewhere, "good bass costs money." On The David Arnold 007 Project, Shaken & Stirred [Sire 31011], all the stops are pulled out on "Diamonds are Forever," with humongous production of a full orchestra with the focus on looming brass, tympani, bubbling techno bass doubled by subterranean strings and the feline voice of David McAlmont in the role of Shirley Bassey. When the techno bass rhythm kicks in on the verses, most speakers, much less amps or preamps, just can't handle the sheer tonnage of low-end bombast. The BC21 did a good job of relaying the timing and sheen of the recording, but the bass, while hefty and with decent slam, lacked ultimate kick-ass power. On jazz recordings like the Shim, the bass was dead-on accurate and quite deep, but somehow undefined. I didn't get that last bit of grip and resolution that tells me this is real bass or perhaps acoustic and not electric bass. The BC21 goes damn low, but at the price of some absolute definition. Still, for 1500 smackers, the bass of the BC21 is pretty impressive.
Switching the Carys from the ProAc minimonitors to the more full-range Audio Physic Virgos sweetened the bass spread and depth of field, but also showed up the BC21's bass weaknesses. Again, we are talking lack of ultimate resolution, yet with very low tonality. The midrange was much more fleshed out through the Virgos, which probably owes more to the speakers than the BC21, but overall, the amps sounded better through the big boys, and made the bass problems less noticeable.
I have been comparing the BC21 to my Audio Note pre as I've gone along here, usually to the detriment of the Audio Note, but one area the M2 excels over the BC21 is midrange bloom, body and warmth. Perhaps it's the Black Gate caps or the Audio Note silver wiring but the M2's sound is just better fleshed out in the midrange, making some music more informative and organic-sounding. The BC21 kicks the AN's butt in treble extension and bass slam, potency and quantity, but that last touch of midrange makes the Audio Note preamp at times more natural-sounding. That is the only real fault I can lay at the Blue Circle's blue logo, though, but it is a characteristic that robs of it sounding absolutely natural and real.
The Blue Circle Audio BC21 line-stage preamplifier is a beautiful-sounding unit, imparting a lustrous, vivid sound to jazz and classical, and its slam-a-bility factor makes it a good choice for rock and techno as well. Treble extension is stellar, and decent bass wallop is coupled with liquidity and warmth. Sometimes low bass can be a mite undefined (though this is very dependent on the recording), and midrange texture isn't quite up to the BC21's other high standards of treble extension and sweetness. But for $1500, this has to be a serious contender for one of the best tube preamp bargains around, and its price point makes it one to consider even if you can afford one of Gilbert Yeung's other creations. I forget to mention that when I tried different NOS tubes, the BC21 was very responsive and revealing, a sure sign of solid engineering and design. The BC21 is built like a tank, glows in the dark and makes very sweet music. How many relationships can you say that about?
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