Monitor Audio Platinum Series PL500 II Loudspeaker

Big Time

Equipment report
Monitor Audio Platinum Series PL500 II
Monitor Audio Platinum Series PL500 II Loudspeaker

If you entered my living room (aka my listening room) right now, you might think, “What’s a nice gal like Julie doing with these enormous speakers?” Yes, up to now I’ve been charged with reviewing, shall we say, relatively small-scale equipment. Oh, it’s still serious hi-fi gear, but we’re talking midsized transducers along with a couple of components some might even call “cute,” female-friendly stuff. But for now, every time I enter that room and see the PL500 II towers—that tower over me by at least a foot—I get excited about this hobby all over again. (I even feel a little giddy!)

It’s been said that big loudspeakers mean big problems—and bigger bucks. Happily, neither claim rings true about Monitor Audio’s state-of-the-art flagship, the Platinum Series PL500 II. Tall, dark, and handsome, these boys impressed me from the very first time I heard them—at this year’s CES. (They also caught the attention of JV, who commented on them favorably in his Vegas show report.) The reason why I was impressed was simple: The PL500 IIs didn’t sound like any other Monitor Audio speaker I’d heard. In fact, in some ways—in their warm, rich musicality and overall driving energy—they reminded me of classic Raidho Acoustics speakers (minus the diamond drivers and nearly another zero on the price tag).

Happily, what wowed me (and JV) at the CES show proved equally wow-worthy in my home. With their layers of depth and detail, delightful musicality, and overall coherence the PL500 IIs have been immensely enjoyable companions. They are not only high-energy, high-    resolution transducers that boast beautiful sound; they also offer superb build-quality, advanced technologies, and value far exceeding their price.

Tech Talk
UK-based Monitor Audio is a 40-plus-year-old company that’s well respected overseas for many pioneering acoustical advances; yet the marque has flown largely under the consumer radar in the U.S. But the times are a-changin’. The brand has increased its market presence in the States, while continuing its longtime tradition of technological development. To this very end, the manufacturer brought designer Dean Hartley (see my sidebar interview with Mr. Hartley) on board a handful of years ago—the brains behind the newly evolved flagship Platinum Series, where the PL500 II holds the top spot. (Seven other models round out the line, ranging from the PL100 II stand-mounted two-way and two more floorstanders to two center-channel speakers, an in-wall design, and the PLW215 II subwoofer.)

In keeping with Monitor tradition, the PL500 II contains a wealth of innovative technologies—specifically in its drivers and crossovers. According to the manufacturer’s white paper on the Platinum II line, these new tech developments are the fruit of extensive FEA modeling and measurement (prior to extensive listening testing, naturally). In addition, Monitor Audio builds all of its drivers and crossovers in-house.

The PL500 II is a three-way, seven-driver floorstander in a D’Appolito configuration. The tweeter, a micro-pleated diaphragm (MPD), was created by Monitor Audio as an improved version of Dr. Oskar Heil’s Air Motion Transformer (AMT). Typical AMTs have a null in frequency response at around 40kHz, but with the help of FEA modeling Monitor engineers figured a way around this issue. As explained in the white paper, the larger rolls (or pleats) in the AMT diaphragm were causing phase cancellations at progressively higher frequencies. The resulting null, which reached a –3dB point at roughly 28kHz, could be eliminated by reducing pleat height and increasing the number of pleats. Incorporated for the very first time in a Monitor speaker, this new MPD driver reportedly functions with uniform output to over 100kHz. (In my listening, the treble did, indeed, prove to be quite silky-smooth and sweet-sounding, with desirable detail and no etch or beaminess.)

Another advantage of this advanced transducer is its low mass, lower inertia, and larger radiating surface area (eight times the area of a typical dome tweeter), which together produce transient response that’s more similar to an electrostatic driver than to a dynamic design. Indeed, I found the speaker possessed a satisfying sense of speed of attack as well as snappy overall energy and pacing (traits which of course are also linked to the electronics in the chain powering the speaker, more on which later). The MPD has a pair of neodymium/iron/boron magnets front and rear to reduce distortion, provide greater uniformity of response, and increase efficiency; the micro-pleated diaphragm only needs to move one-eighth of the distance of your average dome tweeter to produce the same output. These factors contribute to the PL500 II’s power handling and high sensitivity of 91dB @ 1W. (This surprising sensitivity allowed me to drive the PL500s with a relatively low-powered Air Tight tube amp—to very ear-pleasing effect.)

Monitor’s newly upgraded Platinum II technologies have also resolved the coherence issues that plague large-scale multiways. For starters, the crossover networks have been redesigned using air core inductors for the tweeter and midrange, and laminated steel cores for the woofer. All cone drivers in the Platinum II line also use underhung voice coils for lower distortion. For more efficient driver and voice-coil coupling, the speaker’s drivers feature Monitor’s new patented Dynamic Coupling Filter (or DCF) mechanism, which is a pliable nylon ring that is calibrated to stay rigid up to the crossover frequency, but above that wavelength to act like a spring to dampen excess HF energy.

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