MBl’s corona series electronics made a cameo appearance in my review in issue 228 of the MBL 120 Radialstrahler, the breathtaking three-way compact. Regretfully, because I was running short on space, I could only touch on the general strengths of the C11 preamp, C21 stereo amplifier, and C31 CD player (the CD31 was a 2013 golden ear recipient, issue 235). Nonetheless I was mightily impressed with how well corona performed under the ultra-high-resolution scrutiny of the Radialstrahler—a speaker that doesn’t suffer fools lightly and has been known to un-ceremoniously show the door to any component it finds lacking. (And sadly I have to report my health insurance doesn’t cover the withdrawal symptoms I’ve endured since the MBL 120s departed.) Long story short, when I was offered a second opportunity with a corona amp—in this instance the newly released C51 integrated—I grabbed it.
A quick refresher: corona is, technically speaking, MBL’s entry-level series. “Entry level” is an expression I use guardedly since every product by this berlin-based firm is built to a level that most components only aspire to in their electronic dreams. Corona was also much more than a replacement for the aging classic line (circa 2006). MBL began with a clean sheet of paper in visual design, software implementation, and technical innovation. With the release of the $11,100 C51, Corona is now a complete six-component range that also includes the C31 CD transport/DAC, C61 tuner, C11 preamp, C21 stereo amplifier, and C15 monoblock (500W into 4 ohms).
To my eye, Corona screams elegance—almost Japanese in its graceful, uncluttered simplicity. The top-panel roofline inclines slightly toward its center, merging in a heavy plated panel that waterfalls into the C15’s polished front-panel display, which is lit in a brilliant fluorescent blue. On top, the MBL’s crest nests in a soft “corona” of light that doubles as a top-mounted dimmer for the front-panel display. There are no saw-tooth heatsinks, protrusions, or hard edges to mar the flowing, symmetrical lines of its chassis. So singular is the Corona profile that my own friends, comfortable in the presence of fancy electronics, would invariably cast their approving eyes on the Corona gear and ask, “Wow, what is that?” And tactilely the C51 immerses you in the experience of owning a fine audio instrument. It may not matter to everyone how a knob turns or a button releases, or how deep the luster of a chrome accent appears, but it does to me. The C51 may not be ultra-expensive, but it makes you feel rich with every look and touch.
Corona amplifiers, like the C51, are solid-state, and designed around LASA technology (for Linear Analog Switching Amplifier), an advanced implementation of switch-mode Class D topology and the brainchild of chief designer Jürgen Reis (see Sidebar). The C51 outputs a healthy 180Wpc into 8 ohms and 300Wpc into 4 ohms—specs that are identical to those of the C21 stereo amplifier I’d encountered previously. The C51’s preamp stage uses a sophisticated analog volume control operable via a motorized potentiometer. Front-panel functions are reserved for small soft-touch buttons; the only resident knob is the volume control. All other functions are shuttled off to the remote control. Connectivity is excellent. The back panel is roomy and well laid out; its RCA and XLR jacks are widely spaced. An optional phonostage is available at extra cost ($1710). Firmware updating is accessible via a standard SD slot on the back panel.
In my first go-round with the C11 preamp, I complained that the front-panel volume indicator was too small, virtually useless for fine volume adjustments from any real distance. I’d like to think that MBL took to heart my earlier criticism because that issue has been solved on the C51. Now when a volume change is requested, the software boldly increases the size of the numerical display for a few seconds. MBL, my eyeballs thank you.
Over the years I’ve heard all the elitist pro and con arguments about the integrated amplifier. That they are ho-hum, one-chassis compromises, with average parts-quality and puffed-up power specs, while separates, on the other hand, are technological showcases and super-sexy. Or, that integrated amps should be considered only in the interests of saving space and saving money—a recipe for sissies, not real audiophiles—while only dedicated separates take you down the true path to sonic nirvana. Fiddlesticks. Modern integrated amps are models of the efficient use of space. Plus, by combining preamp and amp sections, an entire bank of circuitry is eliminated along with the need for a pair of interconnects and the sonic influence that brings to bear. While it’s true that the tighter packaging can lead to thermal issues and EMI/RFI concerns, cutting-edge designs like the C51 have answered these Old School reservations.
MBL’s Reis is a die-hard analog guy (and an all-around nice guy, at that), but he’s never ducked a challenge. His stated goal for Corona was for it to match the qualities of the fine, traditional linear amplifiers MBL has been producing for years. In sonics, you can throw away every concern you might have harbored about Class D. Most particularly, the C51 takes the frequency extremes and makes them its playground.