Monitor Audio Platinum Surround Speaker System

Founded in 1972, UK-based Monitor Audio has long produced speakers that offered good value, from its low-end Bronze line, starting at around $325 for a pair of two-way bookshelf models and extending up to $4500/pair for the company's priciest Gold Signature model. Even that is not an outrageous price for an upscale design in today's speaker market. The number of current speaker lines topping out at over $20k/pair, however, would be alarming if it weren't counterbalanced by excellent speakers selling for a fraction of that price.

So when Monitor Audio decided to produce a new flagship line, it were almost conservative in aiming at a price that barely breaks five figures. The new Platinum range, topped by the PL300 at $10,000/pair, hasn't exactly been designed for supermarket coupon clippers, and the full surround array will set you back by 2.5 times that figure, but it is an engineering and sonic tour de force.

The Platinums are manufactured in China, as with many speakers today, but they were engineered in the UK. That keeps the cost down in two ways: first in manufacturing, and second (for consumers in the US) in shipment directly here from the Far East. The latter avoids the currently unfavorable dollar-to-pound exchange rate.

Good speakers begin with great drivers, and the Platinum line definitely qualifies on that count. All the drivers use C-CAM, an aluminum-magnesium alloy overlaid with a ceramic coating. This material, originally developed for the company's Silver S models, is extremely light yet rigid. The woofer and midrange cones start with a core of honeycombed Nomex material in a shape refined by Finite Element Analysis (FEA). This is overlaid with an ultra-thin skin of C-CAM (40µm, or half the thickness of a human hair).

These cones are seamlessly concave with no dust caps. They are attached to a voice coil/magnet system designed for very low distortion. The 8-inch woofers employ long-throw voice coils, and their cones are stabilized by dual spiders.

The biggest design leap is a departure from the dome tweeters used in all of Monitor Audio's other models. Instead, a new ribbon tweeter has been specifically designed for the Platinum line. It's a pure ribbon configuration, with a thin diaphragm of C-CAM (mass = 18mg) suspended in a magnetic field produced by rare-earth magnets. Its specified upper response is 100kHz, but with no stated tolerances—not that any of us at UAV can measure or hear anything quite that high!

The design of the cabinet is also a major factor in speaker performance—just one reason why it's so difficult to produce a great in-wall speaker. In the Platinums, the front baffle, bases, and tapered midrange housings are fabricated from ARC, a thermoset, mineral-loaded polymer 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 caps of these bracing bolts are visible on the back of the cabinets and have been tightened to a specific torque. Owners should definitely avoid the audiophile urge to cinch everything down nice and tight—leave these bolts alone. The crossover for the big PL300 floorstander is encased in the ARC base for better isolation from cabinet vibrations.

Apart from the fully sealed PLW-15 subwoofer, all speakers in the line employ one or two "high velocity" reflex ports (HiVE II, as Monitor Audio calls them). These ports are said to be specifically designed to optimize and accelerate airflow and reduce port turbulence.

The commitment to quality in the Platinum line is also visible in the finishing touches. The laminated side and back panels are gently curved, which is said to help reduce internal standing waves, but it clearly serves cosmetic reasons as well. The cabinets are finished with 11 layers of high-gloss piano lacquer, and the front panels are upholstered in Strathspey leather (except for the PLW-15 subwoofer). I'm no leather expert, but that sounds impressive, and it certainly looks and feels like it came from an ultra high-end cow. Optional stands are available for the PL100 stand-mounter and the PLC350 center channel.

The backs of the full-range Platinum models are fitted with two pairs of bi-wireable, platinum-coated WBT input terminals. Heavy-duty adjustable spikes are fitted to the base of the PL300 and the optional stands for the PLC350 center and PL100, which I used to serve the surround channels. The spikes may be removed from the feet, which also have rubberized inserts for use on wood or tile floors. The speakers have removable grilles, held in place by invisible, imbedded magnets.

The PLW-15 subwoofer's 15-inch C-CAM driver, with its 4-inch voice coil, is triple-suspended in a die-cast chassis and driven by a 1000W class D amplifier. It offers a wide range of adjustments, including a 9-band, one-third octave graphic equalizer (at 20, 25, 31, 40, 50, 63, 80, 100, 125, and 160Hz, with ±6dB adjustability in 0.5dB steps). The sub also has a remote control, but it's of limited use. The small indicator window is at the top rear of the cabinet and can only be seen if you are standing next to the sub. And even if it were mounted in front, the window is too small to be read from across the room.