Shane’s article struck a chord with me.  I couldn’t agree more!  The same edition of Home Theater features a review of Monitor Audio’s Platinum 5.1 Surround system for a mere $25,650.  Check your pocket change to be sure, should this price tag be more than your budget allows!  Still, it is precisely because Monitor Audio can build a high-end speaker system that excels when compared with other esoteric brands that the company is able to manufacturer products at more modest price ranges that are equally exceptional in their performance and value.

Let’s compare Monitor Audio’s Platinum range with the much less expensive Silver RX range in just one (there are many) important area of loudspeaker performance – minimizing unwanted resonance problems.  The “Audio Dictionary” by Glenn White and Gary Louie defines ‘resonance’ as the “tendency of a mechanical or electrical system to vibrate at a certain frequency when excited by an external force and to keep vibrating after the excitation is removed”.  One might also consider resonance as ‘uncontrolled energy’, the effect of which in a loudspeaker is to interfere with and color the desired sound the artist intended to be reproduced.

Not all resonance is bad however.  Resonance in the body of an instrument such as a violin, guitar, or piano is responsible for the richness of timbre and adds to our enjoyment of music.  My father used to lay on the floor under his mother’s piano when she played to hear the rich resonance of tone coming from the strings and the encompassing enclosure.  Dad would say that he knew stereo before it was ever reproduced on a music system!

 

PLATINUM

The ribbon tweeters used in the Platinum models are made of an unusual alloy called C-CAM (Ceramic-coated Aluminum /Magnesium) rather than conventional mylar or aluminum materials. This alloy of aluminum and magnesium has different resonance frequencies so that any adverse resonances are dissipated over a wider spectrum with diminished amplitude.  The powder coating of ceramic further damps and strengthens the ribbon diaphragm to the degree that any subtle resonance remaining is pushed well beyond the audible range. The Platinum C-CAM ribbon is lighter, stronger and faster so as to extend high frequency response to 100kHz.

The Platinum midrange and woofers use a thin skin of C-CAM stretched over a honeycomb of Nomex, a technology called RDT (Rigid Diaphragm Technology).  These drivers are 150 times more rigid than had the cones been made of solid aluminum.  Due to their structure of dissimilar materials rather than sheer mass, these RDT drivers exhibit exceptional self-damping characteristics.  Once again, any resonance issues appear several octaves above the crossover filters and are thus rendered inaudible.

Cabinets in the Platinum range are comprised of multi-layered plywood and an essentially inert ARC (Anti-Resonant Composite) thermo-set polymer which is loaded with minerals.  This ARC material offers strength and exceptional resonance damping qualities, and is used for the front baffle, midrange and crossover enclosures, and the plinth.  Thru-bolts couple the front baffle, the internal brace, and the rear of the cabinet, enabling engineers to further tune out any remaining resonance problems.

 

Silver RX Range

 

SILVER RX

The new Silver RX range exhibits the best of trickle-down technology near the other end of Monitor Audio’s pricing spectrum.  The C-CAM dome tweeter diaphragms are extremely rigid, lightweight and self-damped and in this new Silver series.   Each tweeter’s back chamber has been enlarged to allow for more complete damping of rear waves from the tweeter diaphragm.  The result is high-frequency response extending out to 35kHz.  Highs are smooth and clear with no signs of harshness.

The Silver RX woofers now offer the C-CAM ‘dimpled cones’ once only found in the more expensive Gold Series range of Monitor Audio speakers.  The dimples are bends in the metal so as to strengthen the cone.  This process enables Monitor engineers to reduce the weight and mass of the driver while simultaneously extending the midrange drivers upper range response. The result is solid extended bass and no resonance issues up to 8kHz, a frequency well above the crossover typical 3kHz filter action.  The result is remarkable midrange clarity and low distortion.

Cabinets are constructed of solid ¾” MDF and are heavily braced for greater cabinet rigidity and minimized box resonance.  The drivers are fixed in the cabinet with ‘thru-bolts’ similar to those used in the Platinum series for improved cabinet bracing.  This method of attaching the drivers to the front baffle by pulling them to the front of the speaker from bolts attached to the rear of the cabinet effectively decouples the drivers from the cabinet.  This decoupling eliminates another source of unwanted resonance or coloration and allows for more fluid communication of the critical midrange frequencies.

 

TRICKLE-DOWN?

Engineers juggle a host of parameters when designing a loudspeaker.  Resonance issues are only one consideration along with numerous others such as frequency response, integration of drivers, dispersion characteristics, heat dissipation, sensitivity, power handling, dynamic range, distortion, and the desired price point. 

 

PL300

Consider the goals and design integrity when comparing these two widely divergent price ranges within Monitor Audio’s lineup.  The Platinum PL300 is a three-way speaker whose suggested retail price is $10,000 for the pair and is touted as one of the best values in high-end audio.  The new Silver RX8 is a three-way model retailing for $1750 the pair for an amazing price/performance value.  Bookshelf models from each range start at $4800 and $675 per pair respectively. 

The next time you might be inclined to chuckle over a product whose technology is evident but whose price is over your budget, be sure to check out the company’s lower priced products.  I’ll bet they reflect much of the technology, design integrity and quality of the more expensive products and might be just right for you!