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Another way of looking at a speaker's time coherence is to examine not its phase response as such, but the phase deviation left over when that due to the speaker's departure from a flat amplitude response is removed. In a minimum-phase system—one that has just the right amount of phase deviation for its frequency response—the phase and amplitude responses are related mathematically by the Hilbert Transform. Subtracting the Hilbert-transformed amplitude response from the measured phase response will leave what is called the "excess phase"; ie, the speaker's departure from a true minimum-phase…
Brian Damkroger wrote about the CS6 in October 2003 (Vol.26 No.10):
Over the course of the year that Trish and I have lived in our new home, I've been rebuilding my reference system a piece at a time. I've been more or less methodically working through different cable packages and combinations of electronics, experimenting with various racks and isolation systems, even tearing down and rearranging the room layout and treatments a number of times. But the heart of the search was always figuring out what to use as a reference speaker.
On paper, it was easy. I needed something simple, to…
Sidebar: Brian Damkroger's Associated Equipment
Analog source: VPI TNT Mk.V-HR turntable-tonearm, Grado Statement cartridge.
Digital sources: Burmester 001, Simaudio Moon Eclipse CD players.
Preamplifier: VAC CPA1 Mk.III.
Power amplifiers: VTL Ichiban & Mark Levinson No.20.6 monoblocks.
Cables: Speaker and interconnect: Nirvana S-X Ltd., Audience Au24, Nordost Valhalla, Monster Cable Sigma Retro. AC: Audience PowerChord.
Accessories: Finite Elemente Pagoda equipment rack, String Suspension Concepts equipment & loudspeaker feed, Immedia SSC footers; Nordost ECO3 and…
One day last year, my friend Larry and I were talking about our college-fraternity days and loudspeakers. Those were four of the best years of my life. Strong friendships were formed, and ever since, we've kept in touch with most of our fraternity's brothers-in-heart. Ours was not a jock house, nor was it the last bastion of rampant male sexuality—it was, after all, an MIT frat house. But it was full of music lovers who fell neatly into three camps: the California School owned JBL Decades, the New England School had Smaller Advents, and the Renegades boasted bootlegged Bose 901s (footnote 1…
First, inner detail in the midrange was excellent, and as good as any under-$500/pair speaker I have reviewed. The Advent's articulation of transients, and its ability to render wide dynamic swings, were extraordinary—also in the league of the most impressive bookshelf speakers I've reviewed in the last few years. The Advent's bass extension, too, was surprising—more akin to what I'd expect from a floorstander, and accomplished without any of the modern design tricks of judiciously placed reflex ports.
Classical music brought out the Advent's best. Listening to Tomiko Kohjiba's The…
Sidebar 1: Specifications
Description: Two-way acoustic-suspension bookshelf loudspeaker. Drive-units: 2" paper-cone tweeter with central dome, 9.5" paper-cone woofer. Frequency response: 33Hz–17kHz ±3dB (measured by 1975 High Fidelity Buyer's Guide). Nominal impedance: 4 ohms. Recommended minimum power: 15W.
Dimensions: 20 1/8" (515mm) H by 11 5/8" (300mm) W by 9 3/8" (240mm) D. Weight: not noted.
Serial Numbers Of Units Reviewed: S 47877, S 47106.
Price: $139.90/pair in 1972 ($668/pair in 2006 dollars).
Manufacturer: Advent Corporation, (then of) 195 Albany Street,…
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, AudioValve Eklipse line stage.
Power Amplifier: Audio Research VT100 Mk.II.
Integrated Amplifier: Creek 5350SE.
Loudspeakers: Amphion Helium2, Epos M5, Infinity Primus 150.
…
Sidebar 3: Measurements
I performed a complete set of measurements on the two samples of the Smaller Advent, serial nos. 47877 and 47106, the latter manufactured on October 30, 1972, according to the tweeter chassis. They were very similar, though 47106 was slightly less sensitive than 47877 as measured on the tweeter axis: 84.5dB(B)/2.83V/m vs 85.5dB(B)/2.83V/m. Both figures are 2–3dB below the average for modern speaker designs. The Advent's impedance, however, was not too demanding of current, as can be seen from the impedance graphs for 47877 (fig.1) and 47106 (fig.2). Despite the…
About three weeks ago, while perusing the gear in a local audio retail establishment, I overheard a salesman, who could well have been selling used cars, giving a classic spiel to an obviously confused customer. "You see, sir, all preamplifiers basically sound alike, especially with line-level inputs. The only differences are in the number of features." He went on to tell his prey that spending big bucks for high-end products such as Krell or Mark Levinson (neither of which he sold) would be a big mistake. I choked back my automatic response of a certain bovine term, but thought it better to…
Setup
Unlike the problems I experienced with the first Krell KSA-250 power amplifier review sample, installation of the KBL went without a hitch. Although I preferred to place the KBL atop the stereo cabinetry, Puffin the Pouncer (a very large domestic longhair cat) seemed to enjoy sleeping on the KBL; my visions of exploding preamps in the night forced a move to a lower, less cat-able location (footnote 1). Unlike many preamps that I have owned or auditioned, the KBL's rear panel is very clearly labeled; connections can be easily accomplished with an angled dentist's mirror. The "blind…
Unlike the problems I experienced with the first Krell KSA-250 power amplifier review sample, installation of the KBL went without a hitch. Although I preferred to place the KBL atop the stereo cabinetry, Puffin the Pouncer (a very large domestic longhair cat) seemed to enjoy sleeping on the KBL; my visions of exploding preamps in the night forced a move to a lower, less cat-able location (footnote 1). Unlike many preamps that I have owned or auditioned, the KBL's rear panel is very clearly labeled; connections can be easily accomplished with an angled dentist's mirror. The "blind…