The Classic 60 measured as having a flat response across the audio band (fig.1), apart from a slight rolloff above 10kHz, reaching -0.32dB at 20kHz. This will be just audible as a very slightly soft top octave, but is otherwise inconsequential. Crosstalk was also inconsequential: fig.2 shows the leakage from Channel 1 into Channel 2 with the Channel 2 input shorted, below -120dB across the band, which is effectively buried in the amplifier's noise floor. Looking at the amplifier's response with an input signal consisting of a 200µs, positive-going, rectangular…
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John Atkinson compared the Classic 60 with the Mark Levinson No.23.5 in September 1991 (Vol.14 No.9):
The final set of comparisons was with the Audio Research Classic 60. Now it's true that the significantly lower-powered and less expensive tubed amplifier doesn't necessarily compete with the No.23.5 in the market, a more relevant comparison perhaps being between the solid-state amplifier and a pair of ARC Classic 120 monoblocks. But I'm very familiar with the Classic 60, and felt that as long as I didn't fall into the trap of describing differences that are purely due to the tube…
Robert J. Reina compared the Classic 60 with the Cary SLM-100 in May 1996 (Vol.19 No.5):
I spent a great deal of time comparing the Cary Audio Design SLM-100 Revised monoblock to the Audio Research Classic 60 on both sets of speakers. The results were fascinating: both amplifiers were clearly impressive performers with totally different sonic presentations. They shared a wide and deep soundstage presentation, but it was difficult to determine which was more realistic.
The ARC excelled in image specificity, detail resolution, and transparency, but the images on the stage with the…
Robert J. Reina wrote again about the Classic 60 in May 1997 (Vol.20 No.5):
When compared with my reference, the long-discontinued Audio Research Classic 60, the Sonic Frontiers Power 2 presented an interesting tradeoff of strengths and weaknesses. The Classic 60 had the more neutral midrange and midbass presentation, but the Power 2's high frequencies were much more convincing. The ARC did not, however, approach either the low-level or high-level dynamic capabilities of the Power 2. And, although one of the Classic 60's strengths is its resolution of inner detail, the Power 2 exceeded…
It was almost five years ago that I first spent some serious auditioning time with an omnidirectional two-piece speaker from German manufacturer MBL: the four-way MBL 111. When I reviewed the 111 in the April 1998 Stereophile, I had been extremely impressed with the speaker's stereo imaging, which was superbly stable and well-defined, with images that floated completely free of the speaker positions. The tonal balance was also excellent, with a rich midrange, superbly clean highs, and extended lows. "This Radialstrahler is one of the best tweeters I have experienced," I wrote. In fact, the…
Once I'd got the speakers optimally positioned in my room, the most immediately obvious difference between the MBLs and the Wilson Audio Sophias that had preceded them (review in last month's issue) was how insensitive they were. The volume control of my Mark Levinson No.380S preamplifier had to be set around 10dB higher than it had with the Wilsons to get the same listening level. I wouldn't use less than a 100Wpc amplifier with the 111Bs.
Bass was obviously well-extended, but without the spikes, the 111B's low frequencies again lagged a bit behind the music's pulse. On piano, for…
Sidebar 1: Specifications
Description: Four-way, omnidirectional, floorstanding loudspeaker. Drive-units: 24-segment carbon-fiber omnidirectional bending-mode tweeter; 12-segment carbon-fiber omnidirectional bending-mode upper-midrange unit; two 5" (130mm) alloy-cone lower-midrange units; 12" (300mm) metal-cone woofer in separate bandpass enclosure. Crossover frequencies: 105Hz, 600Hz, 3.5kHz. Crossover slopes: fourth-order Linkwitz-Riley. Acoustic center: 43" (1090mm) from floor. Frequency range: 20Hz-40kHz. Sensitivity: 81dB/W/m. Nominal impedance: 4 ohms. Maximum power handling: 320W…
Sidebar 2: Associated Equipment
Digital sources: Mark Levinson No.31.5 CD transport; Mark Levinson No.30.6, Chord DAC64 D/A processors; dCS 972 upsampler; Meridian 800 DVD-Video/CD/CD-R player; Technics DVD-A10 DVD-Audio player; Musical Fidelity Nu-Vista 3D CD player; Macintosh 8100/80 fitted with two Sonic Solutions SSP-3 digital audio workstation cards; Dell 866MHz Pentium III fitted with RME Digi96/8 Pro and Digital Audio Labs CardDeluxe soundcards, running Windows Me, WinAmp 2.5, SoundForge 5.0, Acid 2.0, and CoolEdit 2000.
Preamplification: Mark Levinson No.380S preamplifier, Z-…
Sidebar 3: Measurements
Other than impedance, for which I used an Audio Precision System One, all acoustic measurements were made with the DRA Labs MLSSA system and a calibrated B&K 4006 microphone. To minimize reflections from the test setup, the measuring microphone is flush-mounted inside the end of a long tube. Reflections of the speaker sound from the mike stand and its hardware will be sufficiently delayed not to affect the measurement.
Confirming what I'd experienced in my listening room, the 111B was not very sensitive. My estimate for the B-weighted figure was 80.7dB…
In the vertical plane (fig.6), the balance doesn't change significantly as long as the listener's ears are between the bottom of the larger Radialstrahler unit and the top of the smaller one. A suckout at the upper crossover frequency does appear 15 degrees below the optimal axis, but this is an impracticably low listening position for anyone other than a hobbit.
Fig.6 MBL 111B, vertical response family at 50", normalized to response on 43"-high listening axis, from back to front: differences in response 15 degrees-5 degrees above axis, reference response, differences in…