Monitor Audio Platinum PL300 Speaker System By Thomas J. Norton   •   September, 2009 Price: $25,650 (including stands) At A Glance: Pristine highs, uncolored mids, tight bass • Great dynamic range • Subwoofer lacks wallop in the deepest, loudest bass

Better Than Golden

Founded in 1972, U.K.-based Monitor Audio has long produced speakers that offer good value. Until recently, it topped out at $4,500 per pair for the Gold Signature model. So when I heard about the new Platinum range, priced at $10,000 per pair for just the front left and right flagship PL300, it came as a surprise.

The Platinum range is manufactured in China but engineered and designed in the U.K. Although it isn’t exactly priced for supermarket coupon clippers (particularly when you purchase them as a complete home theater package), it is clearly a design, engineering, and sonic tour de force.

Light and Rigid
The woofer and midrange cones in all of the Platinum models start with a core of honeycombed Nomex material in a shape that’s refined by Finite Element Analysis (FEA). Using a process developed by Monitor Audio—called Rigid Diaphragm Technology (RDT)—this core is layered with an ultra-thin skin of C-CAM. This material is half the thickness of a human hair, and it consists of an aluminum-magnesium alloy with a ceramic coating.

The resulting structure is said to be about 150 times more rigid than a single-layer C-CAM cone and a fraction of the weight. It is seamlessly concave, it eliminates the need for a dust cap, and it’s combined with a voice coil and magnet system designed for very low distortion. The 8-inch woofers employ long-throw voice coils, and their cones are stabilized by dual spiders.

However, the biggest leap here is Monitor Audio’s departure from the dome tweeters it’s used in all of its other past and present models. Instead, Monitor has designed a new ribbon tweeter specifically for use in the Platinum line. It’s a pure ribbon configuration with a thin diaphragm of C-CAM alloy that has a mass of 18 milligrams. Its suspended in a magnetic field produced by rare-earth magnets. Its specified upper response is 100 kilohertz—not that our tests can verify this!

The Platinum cabinets’ front baffles, bases, and tapered internal midrange housings are fabricated from ARC, a thermoset, mineral-loaded polymer that’s said to be inert and highly damped. Cabinet vibrations are additionally suppressed by a combination of internal bracing, bituminous material, and steel bolts that tie the front and back panels to the internal braces. The PL300’s crossover is encased in the ARC base for better isolation from cabinet vibrations.

Monitor’s commitment to quality is also visible in the Platinum line’s finishing touches. The laminated side and back panels are gently curved, and the cabinets are finished with 11 layers of clear gloss polyester. The front baffles are upholstered in Strathspey leather (except for the PLW-15 subwoofer). I’m no authority on leather, but that sounds impressive, and it certainly looks and feels like it came from a high-end cow.

The backs of the full-range Platinum models are fitted with two pairs of biwireable, platinum-coated input terminals. Monitor provides heavy-duty adjustable spikes, and you can fit them to the PL300’s base (and the optional stands for the PLC350 center and PL100—the latter used here as surrounds). You can remove the spikes from the feet, which also have rubberized inserts for use on wood or tile floors. The speakers have removable grilles, which are held in place by invisible, imbedded magnets.

The PLW-15 subwoofer’s 15-inch RDT C-CAM driver, with its 4-inch voice coil, is triple-suspended in a die-cast chassis and driven by a 1,000-watt Class D amplifier. It offers a wide range of adjustments, including a 10-band, one-third-octave graphic equalizer (at 20, 25, 31, 40, 50, 63, 80, 100, 125, and 160 hertz, with +/–6-decibel adjustability in 0.5-dB steps). The sub also has a remote control, but you have to hear, and not see, what it’s doing from your seating position. The small indicator window that provides feedback on your adjustments is on the top of the cabinet, so you can only see it if you’re standing over the sub. Even if it were mounted on the front, the window is too small to read from across the room.

Setup
I set up the Platinum system in my 26-by-15.5-by-8-foot home theater space. I positioned the PL300s to the left and right of my projection screen, which was well away from any nearby walls (and retracted when the listening was music only). The speakers were roughly 9 feet apart and toed in toward the main listening seat. I removed the grilles and didn’t use the spikes (to avoid marring the vintage oak flooring under my room’s large area rug). I didn’t use biwiring. I used a Parasound Halo A 51 power amp and an Integra DTC-9.8 surround processor to drive the speakers. Sources included a Pioneer Elite DV-79AVi DVD player and a Panasonic DMP-BD35 Blu-ray player.