MBL 6010 D Preamplifier

Since I plan to compare the MBL 6010 D linestage preamplifier—the big brother to the 5011 that Wayne just extolled—with the best tube preamplifier I’ve heard, the Audio Research Corporation Reference 3 (reviewed in TAS 159), I want to start by talking a bit about tubes and transistors.

In our next issue, reviewer Jacob Heilbrunn notes that the twain shall never meet, and he’s right. The trouble is he’s also wrong. The two don’t sound more alike in important specific ways, but they do sound more alike in important general ones.

Let me explain. If you were to map the anatomy of a musical note, it would divide neatly into three sequential parts or phases: the attack or transient phase, the steady-state tone phase, and the decay phase. All three are essential to creating a lifelike semblance of the real thing, but all three are more or less fudged by both the recording and playback process.

What typically goes wrong, to my ear, is something that might be called “timing errors”—that is, errors in the realistic reproduction of the duration of each event (and each event has a different duration). As jitter does in digital recording and playback, timing errors in analog recording and playback tend to distort—to artificially expand or condense—the little slices of time (and the dynamic/harmonic information that is contained in them) that constitute each phase of a note’s sound.

Typically tube playback makes everything sound “longer,” like the sostenuto pedal on a piano— i.e., it expands a note’s duration, enriching its colors and textures but softening its impact. Harmonics seem to linger in the air longer with tubes; the air itself seems to be more present; instruments seem larger and more forward on the soundstage. At the same time the sharpness of instrumental attacks seems slightly dulled—too spread out over time. Consequently, instrumental outlines are more splayed out and fuzzier, bigger and less focused.

Typically solid-state playback makes these same events sound “shorter,” like the damping pedal on a piano—i.e., it condenses a note’s duration, slightly desaturating tone color and abbreviating slow-developing textures, but increasing clarity and focus in the way that the clean sharp lines of a penand- ink drawing do compared with the thicker, softer lines of a pencil sketch. Harmonics don’t seem to be as richly developed as they are with tubes; the sense of air around each note (and of air expanding and collapsing with the building up and decaying of dynamics and tone—what I call “action” or “bloom”) is lessened; instruments seem slightly smaller, more focused, and less forward on the soundstage. At the same time the sharpness of both starting and stopping transients is enhanced; consequently, instrumental outlines are sharper and more distinct, and large-scale dynamics have greater and more lifelike speed and impact.

To put this difference more positively, transistors are faster on the uptake, and better at reproducing that part of the note where speed and concision matter most—the attack or transient phase. Tubes are slower to start, and better at reproducing those parts of the note that develop more gradually over time— the steady-state tone and decay phases. Both gain strategies have trouble shifting speeds, and even at their best both only approximate the actual durations of real-life musical notes.

This is the way things stood until fairly recently. Yeah, some solid-state had begun to slow down enough to let you smell the roses; and some tubes had gained significantly in transient speed and clarity. But, as Jacob correctly notes, the fundamental virtues (and vices) of tubes and solid-state have remained more or less the same.

The arrival of the MBL 6010 D preamp and MBL 9011 amplifier, followed shortly thereafter by the Audio Research Reference 3 preamp and Reference 210 amplifier, shook my faith in this paradigm. Not that you would mistake the sound of MBL for ARC; they both still shine where transistors and tubes customarily shine. The thing of it is they also shine where transistors and tubes customarily don’t.

Although I’ve already used this musical example in my review of the ARC Reference 3 and Reference 210, it is worth repeating because it so clearly points up the difference between the MBL 6010 D and every other preamp I’ve heard.

Towards the end of the first movement cadenza in Montsalvatge’s Concerto Breve for piano and orchestra [London], pianist Alicia de Larrocha plays a loud chord sforzando (i.e., suddenly and forcefully) and then uses the sostenuto pedal to sustain the harmonics. The note goes on for several seconds, and at its finish, after each of the piano’s tone colors has died away, a single very-low-level enharmonic overtone continues to sound for a time before it finally and unmistakably stops, and the note ends.