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Last summer, John Atkinson and I were playing a jazz gig poolside at my local club, and during a break we began discussing equipment. As JA adjusted his microphones and I became increasingly nervous about the running, jumping kids splashing chlorinated water on his Nagra digital recorder, he asked me if I'd like to review the Z1 loudspeaker from BG Corp. "It's an interesting little bookshelf speaker featuring a ribbon tweeter." Hmm—an affordable bookshelf speaker matching a ribbon tweeter to a dynamic woofer? Very interesting. "Sounds good," said I, and resumed my ivory duties.
Sidebar 1: Specifications
Description: Two-way shielded bookshelf loudspeaker. Drive-units: Neo3 PDR ribbon tweeter with a neodymium magnet, 5.25" aluminum-cone woofer. Frequency range: 55Hz–30kHz. Sensitivity: 88dB/2.83V/m. Impedance: 8 ohms. Power handling: 100W.
Dimensions: 13" (330mm) by 7.1" (180mm) by 9.5" (240mm). Weight: 13 lbs (5.9kg).
Finishes: "Hardwood" veneer.
Serial Numbers Of Units Reviewed: 001001/2.
Price: $499/pair. Approximate number of dealers: 125.
Manufacturer: BG Corp., 1780 Forrest Way, Carson City, NV 89706. Tel: (775) 884-1900. Fax: (775) 884-1276…
Sidebar 2: Associated Equipment
Analog Sources: VPI TNT IV turntable, Immedia RPM tonearm, Koetsu Urushi cartridge; Rega Planar 3 turntable, Syrinx PU-3 tonearm, Clearaudio Virtuoso Wood & Aurum Beta S cartridges.
Digital Sources: Lector CDP-7T, California Audio Labs Icon Mk.II Power Boss, Creek CD53 Mk.II CD players; Pioneer DV-333 DVD player.
Preamplification: Vendetta Research SCP-2D phono stage, Audio Valve Eklipse line stage.
Power Amplifier: Audio Research VT100 Mk.II.
Integrated Amplifier: Creek 5350SE.
Loudspeakers: Epos M5, NHT SB-3, Nola Mini.
Cables:…
Sidebar 3: Measurements
My estimate of the BG Z1's voltage sensitivity was 88.5dB(B)/2.83V/m, which is within experimental error of the specified 88dB figure. This speaker will go surprisingly loud with relatively low-powered amplification, but it is fair to point out that for a speaker this small to have this high a sensitivity, it invariably will have restricted low-frequency performance. The Z1's impedance is higher than normal, with a minimum midrange magnitude of 6.4 ohms at 244Hz and a value that drops below 6 ohms only in the top audio octave (fig.1). This speaker will work well…
When a loudspeaker designer produces a world-class product, it is usually the result of years, perhaps decades, of experience gained from designing less ambitious products. To review a particular designer's product history is to witness the learning curve in action as both his skill and technology advance. Successfully battling the laws of physics to produce a truly exceptional loudspeaker is thus thought of as the domain of the seasoned veteran whose vast knowledge and experience culminate in the pinnacle of his career—a world-class loudspeaker. Moreover, it is just these designers, working…
These aspects of loudspeaker design are not trivial. To achieve low-frequency extension, the enclosure needs to have a large internal volume. A big enclosure means large panels which are prone to resonances, not to mention higher cost. The designer is thus forced to accept either reduced LF extension or cabinet resonances. The Hales System Two Signature solves this dilemma by lavishing a substantial portion of the build cost on making a large enclosure that is relatively resonant-free. I would speculate that the Signature's cabinet-to-drivers cost ratio is higher than that of nearly any…
Sidebar 1: Specifications
Description: Two-way sealed-box dynamic loudspeaker with two 7" bass-midrange drivers and one 1" titanium-dome tweeter. Crossover frequency: 2kHz. Impedance: 4 ohms nominal, 2.9 ohms minimum. Frequency response: 40–26kHz ±3dB anechoic (in-room –—dB point will be lower). Sensitivity: 87dB (distance and input power not specified, but assumed to be 1W/1m).
Dimensions: 11" W by 48" H by 21" D. Weight: 181 lbs. net, 194 lbs. shipping, 24 lbs. external crossover, 440 lbs system.
Price: $4850/pair (1991); no longer available (2006). Approximate number of…
Sidebar 2: System Context
The playback system used with the Signatures included a Classé Audio DR-5 preamplifier, Electronic Visionary Systems Stepped Attenuator passive control unit, and VTL 225W Deluxe monoblocks. The analog front end was a VPI HW-19 Jr. turntable fitted with an AudioQuest PT-5 tonearm and Sumiko Boron vdH cartridge. Digital sources were decoded by the Wadia 2000 digital processor driven by either a Marantz CD-94 or the Esoteric P-2 transport. Speaker cable was bi-wired AudioQuest Green Hyperlitz and interconnects included Music Meter, van den Hul D-102 Mk.II, and…
Sidebar 3: Measurements
Starting with the Listening Room Diagnostic Recording (LEDR) test on the Chesky Test CD (JD37), I heard the most accurate spatial positioning of any speakers I've had in my listening room. The "Up," "Over," and "Lateral" tests produced contiguous, stable images throughout their apparent travel beyond the loudspeaker boundaries.
Next, the Signatures were driven with a variable-frequency sinewave with my hand and ear on the cabinet walls to detect enclosure resonances. A loudspeaker will typically have several low-frequency modes that set the cabinet to…
Flip flip flip]...Where the heck is it?...[flip flip flip]...Got it!" What am I looking for? There, in black and white, on p.634 of J. Gordon Holt's Really Reliable Rules for Rookie Reviewers (footnote 1), is the Prime Directive On Loudspeaker Setup: "Never, ever, choose a loudspeaker that has too much bass extension for your room!"
Time and time again I get letters from readers who have relatively small rooms asking why they can't get an even tonal balance from their [insert brand-name of massive, flat-to-20Hz behemoth here] speakers.
The answer is a no-brainer: If you have only…