Although setting up a pair of monoblocks seldom requires instructions, I enjoyed reading Theta Digital's well-written and detailed manual. It revealed that the small rear-panel switch that controls the AC mains supply must be…
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I listened to the Thetas for seven months, alternating them with a Mark Levinson No.334 and a pair of MBL Corona C15s, the latter supplied by JA, who has them on long-term loan. The amplifiers drove my Quad ESL-989 and Revel Ultima Salon2 speakers full range, and were reconfigured to reproduced frequencies above 80Hz when Revel's Rhythm2 subwoofer was in circuit.
Sidebar 1: Specifications
Description: Solid-state monoblock power amplifier. Inputs: single-ended (RCA), balanced (XLR). Outputs: 2 pairs Cardas binding posts. Output power (20Hz–20kHz, 0.01% THD+N): 250W into 8 ohms (24dBW), 500W into 4 ohms (24dBW), 850W into 2 ohms (23.24dBW). Frequency response: 20Hz–20kHz at 300Wpc, +0/–0.5dB. Input impedance: 47k ohms. Output impedance: 0.05 ohm, 20Hz–20kHz. Damping factor: 2500 (minimum), 20Hz–20kHz. Input sensitivity: 130mV for 2.83V output, 1.825V for full output. Signal/noise: 124dB, A-weighted. Voltage gain: 27.8dB. Power consumption: 1W at…
Sidebar 2: Associated Equipment
Analog Sources: Linn Sondek turntable & Lingo power supply & Ittok tonearm, Spectral moving-coil cartridge; Day-Sequerra 25th Anniversary FM Reference tuner.
Digital Sources: Bryston BCD-1 CD player & BDP-2 media player & BDA-1 DAC.
Preamplifier: Bryston BP26.
Power Amplifiers: Mark Levinson No.334 (stereo), MBL Corona C15 (monoblocks).
Loudspeakers: Quad ESL-989, Revel Ultima Salon2; Revel Ultima Rhythm2 subwoofer.
Cables: Digital: WireWorld Starlight Coaxial. Interconnect: Mark Levinson Silver, Red Rose Silver One,…
Sidebar 3: Measurements
I performed a full set of measurements using Audio Precision SYS2722 system (see www.ap.com and the January 2008 "As We See It"). As the Theta Prometheus has a switching output stage that produces ultrasonic noise that would overload the Audio Precision's input circuitry, I carried out most of the tests using, ahead of the analyzer, an Audio Precision AUX-0025 passive low-pass filter. Usually, before measuring an amplifier, I run it for an hour at one-third power into 8 ohms—the most thermally stressful condition for a class-B output stage. But as the Prometheus…
Looking back at our September 2014 issue, I think my review of the Triangle Signature Delta loudspeaker marked something of a watershed in the evolution of my taste in loudspeaker sound quality. For decades I have been a devotee of what might be called "British" sound: low coloration and, overall, a rather polite presentation, coupled with low sensitivity. The Triangle speaker opened my ears to what could be achieved with a very different approach: still-low coloration but high sensitivity, impressive clarity, and a hefty dose of what the late J. Gordon Holt called "jump factor," in which the…
Disc 1 of the Hollies' 50 at Fifty (3 CDs, Parlophone/Rhino RP222354) has most of the British band's hits, and while the midrange quality on these recordings is gritty, the DALI's clarity in the bottom octaves allowed to me to appreciate again, after five decades, what a great player Eric Haydock, the original bassist, was. Even on a harmonically simple song like Maurice Williams's "Stay," Haydock's bass lines, rendered with clarity and weight by the Rubicon 8s, are more complex than you might expect.
Was the Rubicon 8's treble balance being unkind to the vintage Hollies recordings?…
Sidebar 1: Specifications
Description: "2½+½+½-way," five-driver, floorstanding loudspeaker with vented enclosure. Drive-units: 1.8" by 0.67" (45 by 17mm) ribbon supertweeter; 1.15" (29mm) soft-dome tweeter; three 6.5" (165mm) wood fiber-cone woofers. Crossover frequencies: 500Hz, 800Hz, 2.5kHz, 14kHz. Port tuning frequency: 33Hz. Frequency range: 38Hz–34kHz. Sensitivity: 90.5dB/2.83V/m. Nominal impedance: 4 ohms. Recommended amplifier power: 40–250W.
Dimensions: 43.5" (1100mm) H by 8.7" (220mm) W by 17.6" (444mm) D. Weight: 60.3 lbs (27.3kg).
Finishes: Walnut, Rosso, Gloss…
Sidebar 2: Associated Equipment
Analog Sources: Linn Sondek LP12 turntable with Lingo power supply, Linn Ekos tonearm, Linn Arkiv B cartridge.
Digital Sources: Ayre Acoustics C-5xeMP universal player; Apple 2.7GHz i7 Mac mini running OS10.10.1, iTunes 11, Pure Music 2.0, Audirvana Plus 1.5.10; PS Audio PerfectWave DirectStream, Ayre Acoustics QB-9 D/A processors; dCS Vivaldi upsampling D/A system; Ayre Acoustics QA-9 USB A/D converter.
Preamplification: Channel D Seta L phono preamplifier; Pass Labs XP-30, Ayre Acoustics KX-R Twenty line preamplifiers.
Power Amplifiers: Pass…
Sidebar 3: Measurements
I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the DALI Rubicon 8's frequency response in the farfield, and an Earthworks QTC-40 for the nearfield and spatially averaged room responses. My estimate of the Rubicon 8's voltage sensitivity was 89.8dB(B)/2.83V/m, which is both within experimental error of the specified 90.5dB and significantly higher than average. Though this is 2dB lower than the Triangle Delta Signature's sensitivity, the Rubicon 8 will still play loudly with low-powered amplifiers. Those amplifiers, however, should be…
Given his catalog of original tunes, Steve Earle never has to prove that he’s a genius songwriter. Or that he can single-handedly create a new genre; or be a fresh, creative gale blowing through someplace as hidebound as 1980s Nashville. To say nothing of his inestimable talents in raising hell, marrying women or today, being the latest, ummm, folk singing sage to haunt Greenwich Village.
In fact, like all successful songwriters—and make no mistake, before anything else, artistic or personal, good or bad, the man can write songs—Earle is now fighting age (not so hungry), ideas (running…