Description: Three-way floorstanding loudspeaker with woofer amplifier. Driver complement: Two servo-driven 12" woofers, one 4' ribbon midrange, four 1" planar tweeters. Impedance: 4 ohms. Sensitivity: 90dB/1W/1m. Frequency response: 20Hz–20kHz ±3dB.
Dimensions: 28½" W by 6' H by 2½" D. Weight: 1250 lbs/pair shipping, 1000 lbs/pair net.
Finish: Brazilian rosewood.
Serial numbers of speakers reviewed: 251006/7.
Woofer amplifier power output: 400W RMS/channel (into 2 ohm load presented by the II.5 woofers).
Amplifier dimensions: 19" W by 41/2" H by…

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At the time of writing, I've been using II.5s for the past five months, auditioning them with a variety of equipment. Without question, the best amplifiers for the II.5s were the superb Audio Research VT150 tubed monoblocks (reviewed in Vol.17 No.8). When relieved of driving the woofers, the VT150s could really sing. It was almost as if these products were made for each other: the II.5s were particularly adept at resolving things the VT150s do so well—eg, depth, space, truth in timbre, and layering. After trying solid-state amplifiers, I recommend tubes for the II.5.…
John Atkinson measured the II.5s in my new listening room—a much easier proposition, given the system's weight, than trucking it to the test lab in Santa Fe—and was therefore only able to perform a limited set of measurements. The II.5's impedance magnitude and phase angle are shown in fig.1. Note that this plot is of the midrange and tweeter section only—not the woofers. The minimum impedance is 3 ohms through the top octave, with a slightly higher 3.8 ohms or greater through the rest of the band. The combination of the phase-angle and the impedance magnitude in…
That's how my long, peculiar relationship with J. Gordon Holt began, back in 1978. Born on April 19, 1930, Gordon died Monday July 20, 2009 after a long struggle with emphysema. He leaves behind his son Charles and daughter Alicia, both featured in old issues of Stereophile, his great Colorado friends Bob O'Neill and Steven Stone, both former Stereophile contributors, and legions of grieving audiophiles. We are all struck down by his passing.
Gordon had moved to Santa Fe that year and was yearning for audiophile companionship (…
J. Gordon Holt
Editor: My father passed away July 20, shortly after noon Colorado time. He had suffered a long fight with COPD-emphysema, and he died in his home with his family around him. If you are so inclined, you can pay him your respects by having a good martini and complaining about the weather.—J. Charles Holt, Boulder, CO
Cheers, Gordon
Editor: To the man who discovered, defined, and truly verbalized audiophilia—cheers! Thank you, J. Gordon Holt, for the many years of enjoyment, and—oh, it's hot, humid, and sunny today—darn!
Be with God,…
Sire 519396-2 (CD). 2009. Mike Elizondo, Jeff Lynne, Jacknife Lee, David Kahne, prods.; Adam Hawkins, Marc Mann, Steve Jay, Tom McFall, engs. AAD? TT: 47:21
Performance ****
Sonics ****½
Sounding adorable and singing in a little-girl voice while aspiring to be taken seriously as a confident, capricious pop artist is a singular blend in the vast expanse of popular music, one that singer-pianist-songwriter Regina Spektor has nearly perfected on her third album, Far.
Nowhere is the range of Spektor's woman-child vision more apparent than in Far's best…
The rules have changed today
What makes the QB-9 different? I'll just hit the high points here. (For the full particulars, see Ayre's white paper.)
To achieve the maximum resolution, a D/A converter must use a high-precision clock circuit running at a fixed frequency to control the timing of the…
I might get burned up by the sun
The obvious question, I reckon, is that if using a computer as a source component for music isn't brain-dead easy, why bother? Well, spinning LPs isn't brain-dead easy either—people put up with the aggravation because they like the sound. Now, for the first time ever,…
Playing the 24-bit/44.1kHz version of Rhapsody, I was hard-pressed to hear a great amount of difference between the QB-9 and the Bel Canto combination. Perhaps the Ayre let me hear deeper into the acoustic of the…
Description: Asynchronous transfer mode, USB-input, oversampling (16x) digital-to-analog converter with minimum-phase digital filter. Input: USB 1.1–compliant. Sample rates supported: 44.1, 48, 88.2, 96kHz. Word lengths supported: up to 24 bits. Maximum output levels: 2.05V RMS (unbalanced outputs), 4.10V RMS (balanced outputs). Frequency ranges: DC–20kHz (at 44.1kHz), DC–22kHz (at 48kHz), DC–40kHz (at 88.2kHz), DC–44kHz (at 96kHz). Signal/noise: 110dB (unweighted, no reference level given).
Dimensions: 8.5" (216mm) W by 3" (76mm) H by 11.5" (290mm) D. Weight…