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To put this problem into perspective, the spl of the hum measured about 56dB unweighted at the listening position, lower than the background noise on the Dorian Pictures recording, but in the very quiet listening conditions I have available, any level of hum is audible except when masked by the music. I assumed that either my controller or subwoofer were faulty or needed an internal modification. I therefore ignored the background hum for the purposes of this review. If you are interested in the full-range Infinity Modulus system, however, it would be worth checking that you do not get any…
Sidebar 1: Specifications
Infinity Modulus: two-way, sealed-box, stand-mounted loudspeaker. Drive-units: 2.125" by 0.5" EMIT-k ribbon tweeter, 5.5" (140mm) IMG (Injection-Molded Graphite) cone woofer. Crossover frequency: 4kHz. Crossover slopes: 4th-order, 24dB/octave, Linkwitz-Reilly. Frequency response: 80Hz–45kHz ±2dB. Sensitivity: 84dB/W/m (2.83V). Nominal impedance: 5 ohms. Amplifier requirements: 50–200W.
Dimensions: 12" (305mm) H by 7" (178mm) W by 10.625" (270mm) D. Weight: 12 lbs (5.5kg) each.
Finishes available: gloss black and white.
Price: $1000/pair (matching…
Sidebar 2: Review context
The speakers were positioned for the best sound (with only one pair of loudspeakers in the 21' by 16' by 9' listening room at a time), some 4' from the longer rear wall (which is faced with books and LPs) and approximately 5' from the shorter side walls (which also have bookshelves covering some of their surfaces). Source components consisted of a Revox A77 to play my own and others' 15ips master tapes, a Linn Sondek/Ekos/Troika setup sitting on an ArchiDee table to play LPs, and Kinergetics KCD-40 and Meridian 208 (Bitstream) CD players. (The latter also saw…
Sidebar 3: Measurements
I use a mixture of nearfield, in-room, and quasi-anechoic FFT measurement techniques (using primarily DRA Labs' MLSSA system with a B&K 4006 microphone, but also an Audio Control Industrial SA-3050A 1/3-octave spectrum analyzer with its calibrated microphone) to investigate objective factors that might explain the sound heard. The speakers' nearfield low-frequency responses and impedance phase and amplitude were measured using the magazine's Audio Precision System One.
There are no surprises in the Infinity's measured impedance (fig.1). The sealed-box…
Reviewing a vacuum-tube power amplifier is like having your pants pulled down in front of a large crowd of people. I don't know how else to describe the feeling of spending a month or two luxuriating in fabulous sound, then writing a glowing review, then receiving a copy of the review as it will appear in the magazine, complete with John Atkinson's assessment of the amp's test-bench performance, which is usually miserable.
Based on my reviewing track record and my addiction to vinyl, it would not be unfair for some readers to conclude that my preferences are for noise, high…
Modjeski claims more than 100Wpc from each pair of tubes, and says that, unlike other tube designs, as the load impedance drops, the RM-200's output actually increases. The manual claims that, from its 8 ohm taps, the amplifier will deliver 112W into 8 ohms, 145W into 4 ohms, and 125W into 2 ohms. According to Modjeski, "typical" tube amps yield 100W, 65W, and 40W into those loads. However, the manual also states that the claimed power represents the amplifier's "True Music Power, not the typical RMS rating." As I write, how the RM-200's True Music Power numbers will translate on JA's test…
Within the instrumental groupings, the individual players also appeared unusually well-converged and placed in space, especially from front to back. Only Belafonte and his audience—most of whom have since probably gone to that great banana boat in the sky—know how accurate was the placement I heard, but it was impressive. The RM-200's rendering of space and dimensionality was therefore exceptional—similar to what the Kora Cosmos delivered, but with more bottom-end weight, and perhaps somewhat less in the way of air and shimmer to cymbals and brass.
The overall tonal picture was "classic…
Changes
As the RM-200 came set up for them, I did most of my listening with the Chinese KT88s—or, as Modjeski described them to me in an e-mail, "the much-maligned KT88s." I also used my reference Harmonic Technology Pro-Silway II interconnect and Magic Woofer speaker cable, as well as Synergistic Research's ultra-detailed Designer's Reference Coupler AC cord. Before trying the more expensive 6550s, I experimented with some cables.
As the RM-200 came set up for them, I did most of my listening with the Chinese KT88s—or, as Modjeski described them to me in an e-mail, "the much-maligned KT88s." I also used my reference Harmonic Technology Pro-Silway II interconnect and Magic Woofer speaker cable, as well as Synergistic Research's ultra-detailed Designer's Reference Coupler AC cord. Before trying the more expensive 6550s, I experimented with some cables.
I need to digress for a minute. Recently, a press liaison for a mainstream speaker manufacturer paid a visit, bringing with him a new $1500/pair full-…
Sidebar 1: Specifications
Description: Hybrid solid-state/tube stereo power amplifier. Tube complement: two 6BQ7, four KT88 or 6550. Output transformer taps: 8 ohms, 4 ohms, 1 ohm. Output power: 100Wpc (20dBW). Frequency response: 6Hz-20kHz, ±0.5dB; -3dB at 2Hz and 60kHz. Half-power bandwidth: 13Hz-65kHz. Full-power bandwidth: 20Hz-35kHz. Harmonic distortion: <0.5% at 1kHz/100W. Signal/noise ratio: not specified. Input sensitivity: 1.1V for full output. Input impedance: 15k ohms, one leg driven; 30k ohms, balanced.
Dimensions: 17¼" W by 7" H by 14½" D. Shipping weight: 52 lbs.
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Sidebar 2: Associated Equipment
Analog sources: Simon Yorke, VPI Aries Extended turntables; Graham 2.2, Immedia RPM2, VPI JMW 12.5 tonearms; Lyra Helikon, Helikon LE, Helikon mono, Benz Micro Glider L2, ZYX R-100FS phono cartridges.
Digital sources: Musical Fidelity Nu-Vista 3D CD player, Marantz SA-14 SACD player.
Preamplification: Hovland HP-100 preamplifier, Manley Steelhead and Zanden 1200 phono sections.
Power amplifier: Musical Fidelity Nu-Vista 300.
Loudspeakers: Audio Physic Avanti III.
Cables: Hovland Music Groove DIN/RCA, RCA/RCA phono. Interconnect: Discovery…