Blue Circle does not specify gain for the BC21 or BC22. In fact, other than maximum output, it specifies no performance…
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Finally and most curious, the BC22, like the BC21, sits on three round wooden feet that I found strangely out of sync with Blue Circle's otherwise no-nonsense style. The company says it uses wooden feet for reasons of acoustics, but each foot is about 2" in diameter—they can't truly offer the stability of a tripod stance, and seem to have no significant compliance to provide isolation. On the other hand, I can't see that this curiosity in any way compromises the amp.
Lately, I've been enjoying David Johansen and the Harry Smiths (Chesky JD196). On each track, Johansen tones his voice to match the material, and the BD-21/22 revealed it all. In addition, the varied accompaniments on guitar, bass, and drums all had the requisite kick and impetus. And as good as the Blue Circle electronics were with the Revel Studios, my experience with the Paradigms suggests that there might be other, more apt matches for the Blue Circles—Revel's Performa F30 and the Soliloquy 5.3 speakers come immediately to mind. Boy, would I love to hear those with the Blue Circles!
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Sidebar 1: Specifications
BC21 line preamplifier: Tube complement: two 6SN7. Three line-level RCA inputs, 1 pair tape inputs/outputs, 1 pair line outputs. Maximum output: 20V RMS. No other specifications published. Power requirements: 120V AC, 50/60Hz, 38W.
Dimensions: 17.5" W by 3.625" H by 8.625" D. Weight: 15 lbs net.
Serial number of unit reviewed: 21PPPVXXCP.
Price: $1500 (2001); $1650 with Alps pot, $1900 with Shallco stepped-ladder attenuator or with a motorized Alps pot and a wireless remote control. For an additional $75, any version can also be ordered with the…
Sidebar 2: Associated Equipment
Sources: Meridian 508.24 CD player, Meridian Reference 800 DVD transport, Mark Levinson No.360 D/A converter.
Preamplifier: Sonic Frontiers Line-3.
Power amplifiers: Bel Canto Evo 200.2, McCormack DNA-1 (with Rev.A modifications), Sonic Frontiers Power-3 monoblocks.
Loudspeakers: Revel Ultima Studio, Paradigm Reference Studio/60 and Studio/20.
Cables: Digital: Apogee Wyde-Eye Illuminations D-60. Interconnects: Cardas Cross, Cardas Golden Cross, Straight Wire Maestro II, JPS Balanced Super-Conductor 2. Speaker: AudioQuest Granite.—Kalman…
Sidebar 3: Measurements
BC21: I first looked at the performance of the Blue Circle BC21 on the test bench. Its maximum voltage gain was a moderate 18.7dB and its input impedance was high at around 50k ohms, the exact figure varying slightly with the position of the volume control. The output impedance was quite low at 453 ohms at 1kHz and 20kHz, this increasing slightly to 727 ohms at 20Hz. The BC21 inverted absolute signal polarity.
The Blue Circle's frequency response at 1V output (fig.1) was flat within the audioband, but there was a greater degree of ultrasonic rolloff with…
The unweighted, wideband S/N ratio (ref. 1W into 8 ohms) was only fair at 58.5dB, due to the presence of some 60Hz hum and some ultrasonic noise. This improved to 83.3dB when A-weighted, but I would have preferred a lower noise floor. Distortion levels were also generally low, at around 0.03% in the midrange and bass (fig.9), but the THD rose precipitously in the treble, due to a low level of negative feedback, that lack of proper compensation, or both.
Fig.9 Blue Circle BC22, THD+noise (%) vs frequency at (from top to bottom at 4kHz): 4W into 2 ohms, 2W into 4 ohms, 2.83V into…
Kalman Rubinson wrote about the BC21.1 in September 2003 (Vol.26 No.9):
More than two years have passed since I reviewed the Blue Circle BC21 preamplifier and its stablemate, the BC22 power amplifier, for the February 2001 Stereophile. Having jogged my memory by re-reading those reviews and my original notes, I now recall enjoying the Blue Circles' performance, singly and mated, despite finding the BC21 to have rather more forceful a personality than was ideal. I was less impressed by their construction and cosmetics. When Blue Circle's Gilbert Yeung offered me the new BC21.1 for a…
When no one's watching, it's easy to express your opinion. When tens of thousands of people are reading over your shoulder, it becomes more difficult. In fact, it can be downright creepy—especially when what you're thinking sounds like one of those grand, all-encompassing (over)statements you yourself tend to distrust. You don't want to be wrong; on the other hand, if you're too much of a wuss to express what you reallythink just because someone might take it as grandiose, then it's time to give up.
Having watched other audio writers descend into hyperbole hell when…
Sidebar 1: Specifications
Description: Optical-fiber active line-level interconnects.
Prices: CyberLight Wave (source to preamp) and P2A (preamp to power amplifier) interconnects: 1.5m, RCA, $1499; 1.5m, XLR, $1899; 3m, RCA, $1699; 3m, XLR, $2099; 5m, RCA, $1799; 5m, XLR, $2199; 10m, RCA, $2299; 10m, XLR, $2699. Custom lengths available. Cyber Power Pack, $399.
Manufacturer: Harmonic Technology, 13200 Kirkham Way, Unit 100, Poway, CA 92064. Tel: (858) 486-8386. Fax: (858) 486-6633. Web: www.harmonictech.com.
Sidebar 2: Associated Equipment
Analog Sources: Simon Yorke S7, Nottingham Audio Deco turntables; Immedia RPM-2, Graham 2.2, Nottingham Audio Ace-Anna tonearms; Lyra Titan, Lyra Helikon mono, London Reference cartridges.
Digital Sources: Musical Fidelity Tri-Vista SACD/CD player, Alesis Masterlink CD-R recorder.
Preamplification: Aesthetix Saturn Rhea, Whest PhonoStage .20, Musical Fidelity kW, Manley Steelhead phono preamplifiers; Aesthetix Saturn Calypso, Musical Fidelity kWP preamplifiers.
Power Amplifiers: Yamaha MX-D1; Musical Fidelity kW monoblocks; Kora Explorer 150SB…