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B&W Nautilus 805 loudspeaker Measurements

Sidebar 3: Measurements

My estimate of the Nautilus 805's B-weighted voltage sensitivity was a little below specification at 85.5dB/2.83V/m. However, its impedance plot (fig.1) revealed it as being very easy to drive, with a minimum value of 4.8 ohms at 200Hz and a generally low phase angle, other than in the upper bass. The midbass "saddle" in the magnitude trace indicates the tuning of the unique dimpled port to lie at 42Hz, implying only moderate bass extension.

Fig.1 B&W Nautilus 805, electrical impedance (solid) and phase (dashed). (2 ohms/vertical div.)

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B&W Nautilus 805 loudspeaker Measurements part 2

Fig.4 shows the B&W's overall response, averaged across a 30-degree lateral window on the tweeter axis, spliced to the complex sum (amplitude and phase) of the nearfield woofer and port outputs. The shape of the curve is astonishingly similar to that of the $8000/pair B&W Silver Signature I reviewed back in June 1994: a flat midrange and treble, with a slight boost in the upper bass. Although this will be mainly due to the nearfield measurement technique, it will satisfyingly add to the illusion of the speaker being larger than it really is. The useful bass output extends down to…

B&W Nautilus 805 loudspeaker Measurements part 3

Despite the setback of the tweeter, the Nautilus 805 is not time-aligned, as can be seen from its step response on the HF axis (fig.7). The tweeter output leads that of the woofer by an inconsequential fraction of a millisecond. Finally, apart from the resonant ridge associated with the tweeter's "oil-can" resonance just below 26kHz, the 805's waterfall plot (fig.8) is superbly clean, implying freedom from grain (as long as it is not driven too hard).

Fig.7 B&W Nautilus 805, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).

Fig.8 B…

HeadRoom Traveler Bag

"Cool bag! Can I see it?"

"No problem. Here ya go."

Thud. "What have you got in this thing?"

I'm so glad you asked: HeadRoom Supreme amplifier, Optimus CD-3400, Etymotic 4S in-the-ear headphones, CaseLogic 12-CD Wallet (filled with cool tunes, natch), four D-cell power supplies for both the CD-3400 and the Supreme, and four extra D cells—my bare minimum for travel, about 10 lbs' worth. And the bag that holds it all, HeadRoom's Traveler Bag, is pretty cool. At $129, it ain't cheap—but it's designed to cosset your portable CD player between layers of foam and to hold…

HeadRoom Traveler Bag Page 2

I still haven't mentioned the pen pockets or the cool slide pockets on the battery holder pockets (as in "just slide even more stuff in them"), or the comfortable 2" shoulder strap with a rubber shoulder piece. Everything, as they say, has a place, and there are a couple of places that I couldn't even find an everything to put into.

Flummoxing the editor
When I told JA that I intended to review this bag, he hastily admonished me not to consider it the equal to, say, a Class A amplifier in terms of the attention I lavished on it. I see his point: it's a bag, dammit—you put stuff in…

HeadRoom Traveler Bag Specifications

Sidebar: Specifications

Description: Accessory bag designed to hold a portable, headphone-based sound system and associated components.
Dimensions: 10" W by 5" D by 10.5" H.
Price: $129.

Four D-cell Battery Holder
Dimensions: 3" W by 5.75" D by 1.5" H.
Price: $24.95, HeadRoom Supreme; $29.95, Optimus CD-3400.

Common to both: Approximate number of dealers: factory-direct only.
Manufacturer: HeadRoom Corp., 521 Peach St., Bozeman, MT 59715. Tel: (800) 828-8184, (406) 587-9466. Fax: (406) 587-9484. Web: www.headphone.com.

Dan D'Agostino of Krell: Power Is As Power Does

Maybe Dan D'Agostino was destined to develop and build a line of products distinguished by their sheer might. After all, he grew up just blocks from a natural phenomenon synonymous with power: Niagara Falls. Even today, when the 56-year-old D'Agostino returns to his boyhood home to visit his parents, he enjoys pulling on a pair of shorts and going for a long run in the adjacent park, which resounds with the Falls' unrelenting thunder.

D'Agostino's father, Frank, a machinist by training, owned and operated an appliance store, where Dan worked as a boy, repairing the electric timers in…

Dan D'Agostino of Krell: Power Is As Power Does Page 2

Lander: You've also become known for current-mode designs.

D'Agostino: All of our products for the last 10 years have been really serious current-mode designs. Other companies have it, but we specialize in it. It allows us to get wider bandwidth through the signal path, even though the circuits themselves are a little more complicated and require more parts. Current mode is a domain of current gain as opposed to voltage gain. Obviously, you have to go to voltage gain at some point, but we have as much current gain as we possibly can before we get into voltage-gain stages, which reduces…

Balanced Audio Technology VK-5 preamplifier & VK-60/75 power amplifiers VK-60 amplifier in April 2000

Sidebar 3: Robert Deutsch wrote again about the VK-60 amplifier in April 2000 (Vol.23 No.4):

Time sure flies when you're having fun. Seems like yesterday, but it was actually more than four years ago (December 1995, to be precise) that I reviewed a preamplifier and power amplifier—the VK-5 and VK-60, respectively—from a promising new manufacturer, Balanced Audio Technology. But the design and manufacture of high-end audio equipment is not a guaranteed path to fame and fortune, and, looking at the table of contents of the December 1995 Stereophile, I note that four of the companies whose…

Balanced Audio Technology VK-5 preamplifier & VK-60/75 power amplifiers 2000 Associated Equipment

Sidebar 4: 2000 Associated Equipment

Analog source: Linn LP12 turntable (fully updated), Ittok tonearm, AudioQuest AQ-7000nsx cartridge.
Digital source: PS Audio Lambda II transport, Muse Two Ninety-Six digital processor.
Preamplifier: Convergent Audio Technology SL-1 Ultimate.
Loudspeakers: Dunlavy SC-IV/A.
Cables: Digital link: Illuminati Orchid. Interconnects: Nordost Quattro Fil, TARA Labs The Two. Speaker cables: Nordost S.P.M. Reference, TARA Labs The Two. AC cords: TARA Labs Decade.
Accessories: Argent RoomLenses (5), PS Audio P300 AC synthesizer (used with…