Powered-woofer integration can be problematic. You hear assertive bass, so you turn it down. Then it's anemic…
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Usually with new speakers there's an adjustment period: It takes time to acclimate to the different timbral and spatial perspective. But jumping into the Ultra 55s' sonics was easy. I immediately liked what they did, especially timbrally, thanks partly to flawless, seamless driver integration: The drivers sang as one, producing an agreeable picture that was rich and supple in the middle, extended, sweet, and airy on top, and assertive and full-bodied on bottom but never obtrusive.
Sidebar 1: Specifications
Description: Three-way, reflex-loaded, floorstanding loudspeaker with 525W powered-woofer option. Drive-units: 1" (25mm) beryllium-dome tweeter, 6" (168mm) ceramic–dome midrange, two 8" (220mm) ceramic/honeycomb sandwich woofers. Crossover frequencies: 200Hz, 2kHz. Frequency range: 20Hz–40kHz. Nominal impedance: 4 ohms. Minimum impedance: Not specified. Sensitivity: 89dB/W/m.
Dimensions: 42" (1066mm) H × 13" (330mm) W × 24" (609mm) D. Weight: 190lb (86kg) each.
Finish: "Any automotive polyester color."
Serial number of units reviewed: 004. Made in…
Sidebar 2: Associated Equipment
Analog sources: Continuum Audio Labs Caliburn with Castellon stand; SAT CF1-09 and Kuzma 4Point tonearms; Haniwa HCTR-CO, Lyra Atlas Lambda SL, Ortofon MC Century, Anna Diamond, A95, and A90, Grado Epoch3, Miyajima Labs Infinity (mono), Grado Epoch (mono), Ortofon MC A (mono).
Digital sources: dCS Vivaldi One SACD player/DAC, Lynx Hilo AD/DA converter, Roon Nucleus server; Pure Vinyl and Vinyl Studio software.
Preamplification: darTZeel NHB-18S, Ypsilon MC-10L, MC-16L step-up transformers; Haniwa HDV01 current-to-voltage converter; Ypsilon VPS-100…
Sidebar 3: Measurements
Because of the Von Schweikert Ultra 55's bulk and weight, I drove my measurement gear to Michael Fremer's place in deepest, darkest New Jersey to perform the measurements. I chose a day that was forecast to be sunny with minimal wind, because I was going to measure the speaker in his driveway, so that the only source of reflections would be the ground. (Even so, the proximity of the ground necessarily led to aggressive windowing of the time-domain data, which reduced the measurements' midrange resolution.)
I first measured the speaker's spatially…
Jazz collecting has an archaeological aspect to it; it's one of my favorite aspects of the hobby. Far more than most other genres, jazz evolved over its first several decades, and it did so on record. Every musician was distinctive, changed from session to session, and interacted with other musicians in ways specific to the ensemble, the time, the place, and the mood. Every record, live or from a studio, is a snapshot of where jazz was precisely then and there. You can get to know musicians' styles, and with practice, you can really hear what's going on.
I called it "archaeological," but…
Canadian audio manufacturer Classé Audio was founded in 1980 by engineer Dave Reich and entrepreneur/audiophile Mike Viglas. The name "Classé" was a pun on the fact that Reich was a firm believer in an amplifier's output stage operating in class-A, where the output devices never turn off (see sidebar). Though the brand was established with the 25Wpc DR-2, the first review of a Classé amplifier to appear in Stereophile, by Larry Greenhill, was of the later DR-3, in December 1985. No fewer than 22 reviews of Classé products are available in our free online archive. These include the CAM-350…
The first surprise using the Delta Monos was that the meters showed that I almost never used an average level greater than 6W to drive the Vimberg Mino loudspeakers that I reviewed in April. (The meters actually maxed out at "3W," but as they are calibrated in 8 ohm watts and the Mino is a 4 ohm speaker, the indicated power needed to be doubled.) A power of 6W into 4 ohms is equivalent to a voltage of 4.9V RMS. If the music I typically listen to has a high crest factor of 10dB, that means the instantaneous peak voltage would be 15.5V. This is just below the amplifier's maximum voltage…
Sidebar 1: A Class-A Icy Tunnel
Up to their continuous-current limit, a class-A amplifier's output transistors are fully turned on all the time. As well as the devices thus being in thermal equilibrium and therefore relatively immune from having their transfer function thermally modulated by the signal current, the nonlinearities that result from switching the devices on and off during every cycle of the signal—generally referred to as crossover distortion—are sidestepped. Electronically, this is an elegant solution; practically, it is the opposite, in that two-thirds of the power drawn…
Sidebar 2: Specifications
Description: Solid-state monoblock power amplifier. Inputs: 1 single-ended (RCA), 1 balanced (XLR). Outputs: 2 pairs Furutech Torque Guard binding posts. Power output: 300W into 8 ohms (24.8dBW), 600W into 4 ohms (24.8dBW), 1kW into 2 ohms (24.0dBW), with AC line held constant. Class-A output power: 35W (15.44dBW). Maximum output voltage: 113V p–p, 40V RMS, into 8 ohms. Frequency response: 1Hz–650kHz, –3dB. Voltage gain: 29dB at 1kHz, balanced and single-ended. Input impedance: 82k ohms, single-ended and balanced. Input sensitivity (for nominal output): 1.74V.…
Sidebar 3: Associated Equipment
Analog source: Linn Sondek LP12 turntable with Lingo power supply, Linn Ekos tonearm, Linn Arkiv B cartridge, Channel D Seta L phono preamplifier.
Digital sources: Roon Nucleus+ music server; Ayre Acoustics C-5xeMP universal player; PS Audio PerfectWave DirectStream and Weiss DAC502 D/A processors, Ayre Acoustics QA-9 A/D converter.
Power amplifiers: Parasound Halo JC 1+ and Lamm Industries M1.2 Reference (both monoblocks).
Loudspeakers: Vimberg Mino.
Cables: Digital: AudioQuest Vodka (Ethernet), AudioQuest Coffee (USB), DH Labs (1m, AES/…