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Krell LAT-1 loudspeaker A Visit to the Krell Factory

Sidebar 1: A Visit to the Krell Factory

As I turned my Porsche Boxster S into the Krell Industries parking lot, I felt right at home. Sitting by the entrance were two new 392hp BMW M-5 sedans. One was the property of Krell's CEO, Dan D'Agostino, the other the pride of COO Dean Roumanis. But I'd been invited to the factory to see a LAT-1 loudspeaker being assembled, not to ogle cars.

Inside, I was given a tour of the 40,000-square-foot factory by Bill McKiegan, Krell's director of North American sales and marketing. McKiegan explained that each Krell product is made by a "cell" of…

Krell LAT-1 loudspeaker Specifications

Sidebar 2: Specifications

Description: Six-driver, three-way, floorstanding moving-coil loudspeaker. Drive-units: 1" (25.4mm) ring-radiator tweeter with central waveguide, two 5.25" (150mm) midrange cone drivers, three 8" (21cm) long-excursion, reflex-loaded, composite carbon-fiber-cone woofers. Crossover frequencies: 300Hz, 2.9kHz. Crossover type: first-order at 300Hz, third-order Butterworth network at 2.9kHz. Frequency response: 38Hz-22kHz, ±3dB. Sensitivity: 91dB/2.83V/m. Nominal impedance: 4 ohms. Minimum load impedance: 3.9 ohms. Recommended amplifier power: 100-800W. Cabinet:…

Krell LAT-1 loudspeaker Associated Equipment

Sidebar 3: Associated Equipment

Analog source: Linn Sondek LP12 turntable with Lingo power supply, Linn Ittok tonearm, Spectral moving-coil cartridge.
Digital sources: Krell KPS-28C CD transport, Sony SCD-C555ES SACD player.
FM tuners: Day-Sequerra FM Reference Classic, Rotel RH-10, Magnum Dynalab MD-102 and Model 205 Sleuth RF amplifier.
Preamplification: Krell KCT CAST preamplifier, Mark Levinson ML-7A with L-2 phono section, Margulis and Duntech MX-10 moving-coil preamplifiers.
Power amplifiers: Mark Levinson No.334, Krell FPB-600C.
Loudspeakers: Revel Ultima Salon,…

Krell LAT-1 loudspeaker Measurements

Sidebar 4: Measurements

As befit the Krell LAT-1's heroic construction, I could find no significant vibrational modes in its cabinet. The Krell is a very sensitive loudspeaker—my estimate of its B-weighted sensitivity came in at 92dB(B)/2.83V/m. However, as shown by its impedance plot (fig.1), it is a 4 ohm design, drawing 2W rather than 1W from the partnering amplifier to reach this measured sensitivity. The minimum impedance is 3 ohms at 1.5kHz, and the phase angle in the midrange and treble is generally low. However, the combination of 5 ohms magnitude and 45 degrees capacitive phase…

Krell LAT-1 loudspeaker Measurements part 2

How audible will this behavior be? The reflections themselves fall within the time window where the ear-brain integrates sounds as all being part of the first arrival, and so will not be heard as separate arrivals. In addition, the measured peaks and dips above 10kHz occur in a region where the ear's sensitivity is reduced—technically, they are all in just one "critical band"—meaning that the measured comb-filtering's audibility will be minimized. As LG was impressed by the Krell speaker's natural tonal quality in the treble, I must assume that the grille plays an essential role in the LAT-1…

Perpetual Technologies P-1A D/D & P-3A D/A processors

At the Consumer Electronics show in Las Vegas in January 1999, Mark Schifter, erstwhile president of Audio Alchemy, was handing out a press release announcing what seemed like a groundbreaking product from his new company, Perpetual Technologies. The product was the P-1A, a digital-to-digital processor that would do resolution enhancement, loudspeaker correction (amplitude and phase), and room correction—all for less than $1k. It sounded too good to be true.

Four months later, at HI-FI '99, PT actually had a working prototype of the P-1A, and gave an impressive demonstration of its…

Perpetual Technologies P-1A D/D & P-3A D/A processors Page 2

Not so for the P-1A/P-3A combination. The basic layout of buttons and indicator lights is economical in the extreme. A button pushed briefly may perform a different function than when it's held for more than two seconds, and when you press it the second time the function is different again. You must read the operating instructions and note the illustrations very carefully.

The operating instructions are in the process of being revised, and I must say they need it. I have some experience with the type of operational logic that Audio Alchemy used, and it's similar to that of the Perpetual…

Perpetual Technologies P-1A D/D & P-3A D/A processors Page 3

The sound was dynamic, with good timbral and transient accuracy, and the sort of natural high-frequency detail that I have come to associate with upsampling D/A processors. I actually preferred the sound of the P-3A to that of the Bel Canto DAC 1 ($1295), which, while smooth and unfatiguing to listen to, sounded a bit bland and soft in comparison. The fully optioned MSB Link III is the recipient of Stereophile's Budget Component of 2000 award, and may well be the best D/A processor in its price range. The P-3A came very close to the standard established by the Link III, matching it in…

Perpetual Technologies P-1A D/D & P-3A D/A processors Specifications

Sidebar 1: Specifications

P-1A D/D processor: Inputs: I2S, AES/EBU, coaxial S/PDIF. Input impedance: 75 ohms. Outputs: I2S, AES/EBU, coaxial S/PDIF. Output impedance: 75 ohms. Output voltage: 0.5V. PC interface: USB-, Microsoft-, and USB subcommittee-compatible. Software update: via USB or EEPROM replacement (optional). Input resolution: 16-24 bits. Output resolution: 16, 18, 20, 24 bits (optional). Input sample rate: 8kHz-108kHz (optional 192kHz via I2S input). Output sample rates: 44.1kHz, 48kHz, 96kHz (optional 192kHz via I2S output).
Dimensions: 5.5" by 8.25" by 1.75". Weight: 4…

Perpetual Technologies P-1A D/D & P-3A D/A processors Upgrades

Sidebar 2: Upgrades

It's generally acknowledged by designers of audio equipment that the most reliable way to improve a product's performance without changing its basic circuitry is to improve the power supply. However, good power supplies are costly and not terribly glamorous, so manufacturers building products to meet certain price points often compromise in this area. Audio Alchemy's early digital processors were notorious for this, and the same seems to be true of the Perpetual Technologies products.

The P-3A's power supply is just a small transformer in a box; the P-1A has a…