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Sugden A21ai Series 2 integrated amplifier Measurements

Sidebar 3: Measurements

I primarily used Stereophile's loaner sample of the top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and www.ap.com) to examine the measured behavior of the Sugden A21ai Series 2; for some tests, I also used my vintage Audio Precision System One Dual Domain.

My first test of an amplifier is to run it for 60 minutes at one-third its specified power into 8 ohms, which is thermally the worst case for an amplifier with a class-B or -AB output stage. But a class-A amplifier is at its most efficient when delivering maximum…

Jamo Reference R 907 loudspeaker

It was love at first sight when I saw a Jamo Reference R 909 loudspeaker in sparkling red lacquer on the floor of the 2007 Consumer Electronics Show. It made no sound, but it was beautiful, and I wanted it. It summoned up all my latent predilections for snazzy colors, striking shapes, and dipole speakers. But, as with many passing encounters in life, nothing came of it.

At the 2008 CES, another Jamo, the more modest Studio S 606, caught my eye, and I contacted Jamo USA. While I had Klipsch's then PR contact, Keith Claytor, on the line, I recalled the R 909 and thought, Hey, why…

Jamo Reference R 907 loudspeaker Page 2

3) The effects of a dipole's rear radiation on the speaker's frequency response and the size of its soundstage are at the mercy of room dimensions, room surface treatments, and speaker positions. This is the responsibility of the user, and accounts for the poor showing of the R 907s in that Manhattan hotel room. Normal listening rooms such as mine will be much more hospitable. It should be noted, though, that the R 907's tweeter has a sophisticated rear enclosure; only the woofer and midrange function as dipole drive-units.

Now that I've got the two of you alone . . .
The Reference…

Jamo Reference R 907 loudspeaker Specifications

Sidebar 1: Specifications

Description: Three-way, floorstanding dipole loudspeaker. Drive-units: 1" (25mm) fabric-dome tweeter, 5.5" (140mm) midrange unit, two 12" (305mm) woofers. Crossover frequencies: 250Hz, 2.5kHz. Frequency range: 35Hz–30kHz. Low-frequency extension: –6dB at 29Hz. Impedance: 4 ohms. Sensitivity: 89dB/2.83V/m.
Dimensions: 46.8" (1189mm) H by 17.3" (440mm) W by 19.2" (487mm) D, including base. Weight: 115.5 lbs (52.4kg) each, including base.
Finish: Piano black, high-gloss red.
Serial Numbers Of Units Reviewed: 0007, 0016.
Price: $10,000/pair. Approximate…

Jamo Reference R 907 loudspeaker Associated Equipment

Sidebar 2: Associated Equipment

Digital Sources: Sony SCD-XA9000ES, APL-modified Philips SACD1000 SACD/CD players; modified Oppo DV-980H universal player.
Preamplifiers: Parasound Halo P7, Meridian Reference 861.
Power Amplifiers: Bel Canto REF1000 monoblocks, Classé CA-3200.
Subwoofer: JL Audio Fathom f113.
Cables: Interconnect: Crystal Cable Cinemax multichannel, AudioQuest Cheetah balanced. Speaker: AudioQuest Mont Blanc biwire. AC: JPS Aluminata.
Accessories: APC S-15, Environmental Potentials EP-2450 power conditioners; Echo Buster room treatments.—Kalman Rubinson

Jamo Reference R 907 loudspeaker Measurements

Sidebar 3: Measurements

The Jamo Reference R 907's voltage sensitivity is specified as 89dB/2.83V/m. My B-weighted estimate on the speaker's tweeter axis, with the grille removed, came in close to this, at 88dB(B)/2.83V/m. The speaker's impedance magnitude and electrical phase are shown in fig.1. Other than a dip to 3 ohms in the midbass, with a rather severe capacitive phase angle just below that region, the speaker is an easy load for the partnering amplifier to drive, with an impedance that remains greater than 7 ohms above 200Hz. (The shape of this trace will give a somewhat tilted-…

PS Audio Quintet Power Center

PS Audio's Power Plant Premier is a high-end product that takes the regeneration approach in providing audio/video gear with the cleanest AC possible. But not everyone can afford to spend $2195 on such a product, and although the new amplifier design that forms the basis of the Premier is relatively efficient, it does use power, and concern about conservation of the planet's energy resources might lead one to prefer a passive approach to power-line treatment. PS Audio's line of Power Centers provides such an alternative. The model I had for review was the Quintet Power Center, which differs…

PS Audio Quintet Power Center Specifications

Sidebar: Specifications

Description: Microprocessor-controlled AC filter with 5 pairs of AC outlets, surge and spike protection, electrical isolation of each pair of receptacles, 12V trigger.
Price: $495. Approximate number of dealers: 147.
Manufacturer: PS Audio, 4826 Sterling Drive, Boulder, CO 80301. Tel: (720) 406-8946. Fax: (720) 406-8967. Web: www.psaudio.com.

Home Theater <I>vs</I> High-End Audio

A hot topic for discussion in recent issues of Stereophile has been the impact Home Theater has had on the High End. Some of the magazine's contributors—J. Gordon Holt and Corey Greenberg, for example—have written that the advent of Home Theater means that we should expand the audio context of the magazine to include reviews of video components (footnote 1). Others, including Bob Harley, Tom Norton, and myself, feel that we should stick to what we know and love—audio—and enter the new field only to advise Stereophile's readers on how to achieve the best sound from a Home Theater system.…

Home Theater <I>vs</I> High-End Audio Corey Greenberg Responds

Corey Greenberg Responds

After reading Ken Gould's anti–Home Theater "As We See It" in August (Vol.16 No.8, p.7), I feel I must clarify my position regarding Home Theater coverage in the pages of Stereophile.

With all due respect, JA mischaracterizes my position in his introduction to Mr. Gould's essay. In fact, I have never stated—privately or publicly, as JA implied that I had on the CEFORUM section of Compuserve—that I felt Stereophile should be reviewing video components. Never have, never will. Because, like JA, I think Stereophile should stick to covering what it knows…