Sidebar 3: Measurements
I used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and www.ap.com) to examine the Einstein The Tube Mk.II's measured behavior; for some tests, I also used my vintage Audio Precision System One Dual Domain. Not having seen Michael's review when I performed the measurements, I used the CD input with the stock tubes. (All the inputs are nominally identical.)
Assessed at its balanced outputs, the Einstein offered the same maximum gain—a sensibly moderate 12dB—for both balanced and single-…
It's been a while since I've had a classic amplifier in my system, and McIntosh Laboratory's MC275 is as classic as they come. Introduced in 1961 as the "powerhouse" of that era's newfangled stereo tube amps (two 75W amplifiers in one chassis!), the MC275 retained its position as the amplifier to own—challenged only, perhaps, by Marantz and a few others—until 1970, when it fell prey to the widespread wisdom that transistors were king and tubes were dead, and the model was discontinued. The MC275 briefly returned in 1993, in a limited "Commemorative" edition to honor the late Gordon Gow,…
Although my doctorate is in political science, and my training—in physics and engineering—is at best scanty, these design changes, all told, didn't strike me as quite transformational. As I watched those 11 tubes begin to glow, I wondered: Would this new MC275 sound like a just-slightly-revved-up version of a half-century-old tube amp, oozing midrange magic but rolled off at the top and bottom—or like a warm but zippy modern music-making machine?
Setup
I did all my listening through Revel's Ultima Studio2 speakers. The digital source was a Krell Evolution 505 SACD/CD player; for…
The MC275 was not without weaknesses. In general, very low frequencies tended to sound a little more like bass tones than like notes played on an instrument. The big bass drum at the beginning of "Nuages," on the James Carter CD, didn't have quite the oomph in the attack, or quite the persistence in the decay, that it should. On 88 Basie Street, the notes from Cleveland Eaton's bass were distinct, but the plucking was too soft. Similarly, on Dolphy's Out to Lunch, Richard Davis' bass, though once again its notes were very clear, lacked the wood that this album, and especially this reissue,…
Sidebar 1: Specifications
Description: Two-channel, tubed stereo (switchable to parallel mono operation) power amplifier. Tube complement: four KT88, three 12AX7A, four 12AT7. Inputs: 1 pair single-ended (RCA), 1 pair balanced (XLR). Loudspeaker outputs: separate gold-plated, 5-way binding posts for 4, 8, and 16 ohms. Preamp output: 1 pair single-ended (RCA). Inputs: 1 pair balanced (XLR), 1 pair single-ended (RCA). Output power: 75Wpc (18.8dBW) into 4, 8, or 16 ohms (stereo), 150W into (21.8dBW) 2, 4, or 8 ohms (mono). Frequency response: 20Hz–20kHz, +0/–0.5dB; 10Hz–70kHz, +0/–3dB.…
Sidebar 2: Associated Equipment
Analog Source: VPI Classic turntable & JMW Memorial tonearm, Lyra Delos cartridge.
Digital Source: Krell Evolution 505 SACD/CD player.
Phono Preamplifier: Nagra BPS (battery-powered).
Integrated Amplifier: Krell FBI (mainly used as line stage).
Loudspeakers: Revel Ultima Studio2.
Cables: Nirvana interconnects & speaker cables, Nordost CAST interconnect (between Krell components).
Accessories: Bybee Technologies Signature Model Power Purifier (not power amp), Black Diamond Mk.4 Racing Cones, Mapleshade pucks, VPI HW-19 record-cleaning…
Sidebar 3: Measurements
To perform the measurements on the McIntosh MC275, I mostly used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and www.ap.com); for some tests, I also used my vintage Audio Precision System One Dual Domain. The MC275 has four output terminals for each channel, one labeled "Common," the others "4," "8," and "16." I performed a complete set of measurements from each output transformer tap using the balanced inputs, and repeated some of the tests using the unbalanced input jacks.
With…
Even Mikey Fremer is surprised at vinyl's current popularity. Some pundits postulate that eventually CDs will die out, and we'll be faced with the choice of LPs or downloads. (I hope not. I'm just getting used to CDs.) With abundant sources of new pop releases and a wide range of reissues on vinyl, and a variety of used LPs, every audiophile should own a turntable. And with the availability of affordable turntables such as the Pro-Ject Debut III, which I reviewed in the February 2010 Stereophile, the cost of entry to VinylLand is not very dear. The problem is that so few entry-level…
Finally, with cranked-up rock tunes, the PP 3 exhibited a strong sense of coherence, pacing, and rhythmic consistency, whether reproducing such simple arrangements as Ten Years After's "Love Like a Man," from Greatest Hits (LP, London LC 50008), or more elaborate, densely packed tracks such as Genesis' "Dance on a Volcano," from A Trick of the Tail (LP, ATCO SD-36-129). Listening to either of these tunes, I found it hard to sit still—I itched to twitch, grab a partner, and dance around the room. But my wife wasn't home, and neither of the dogs was interested.
Comparisons
I compared…
Sidebar 1: Specifications
Description: Moving-magnet/moving-coil phono preamplifier with line-level inputs and outputs and an A/D converter feeding audio data to a USB output. Input impedance: 47k ohms + 200pF (MM), 100 ohms + 180pF (MC). Voltage gain: 35dB (MM), 58dB (MC). Input sensitivity at 300mV output: 5mV (MM), 0.38mV (MC). Signal/noise ratio: 76dB, A-weighted (MM); 78dB (MC). Input overload, 20Hz/1kHz/20kHz): 10/100/900mV (MM), 0.65/6.5/60mV (MC). THD: <0.03%, 20Hz–20kHz at 3V output. Digital output (USB): 16-bit linear PCM. Sampling frequency: 48kHz. Dynamic range: 89dB (MM…
