© 2009, Mark Fielder, BG Radia
First conceptualized in the 1930’s, ribbon speakers have been around for many years. But are ribbon speakers just for eccentric audiophiles or have they moved into the main stream? To decide, you need to understand where the ribbon technology has been, and where it is today.
In the earlier days of ribbons, they were unreliable, inefficient, and sounded shrill to many listeners. Their diaphragms would melt or just plain tear apart. Today’s ribbon drivers use space age materials and have highly refined manufacturing processes. The latest ribbon drivers are efficient and reliable, and offer the listener an extremely clear, detailed, and accurate experience.
The mechanics behind a planar magnetic ribbon is straight forward. A thin membrane, with an etched circuit on it, is directly and uniformly driven between two opposing series of magnets. There is no voice coil attached to the edge. An electromagnetic force acts on the conductor and is evenly distributed over the entire diaphragm surface. This eliminates the tendency to generate distributed resonance vibrations.
Ribbons are also phase coherent over their entire operational band while cones and domes have an inherent phase “smear” due to their depth (or profile). Another important aspect in performance is the difference in the mass of the moving system. The thin diaphragm of a planar ribbon driver is ten times lighter than any compression driver diaphragm or dome tweeter and even hundreds of times lighter than a woofer cone. This allows for an instantaneous response to the arriving signal as well as to the smallest changes in that signal. The low mass of the moving system also allows for rapid decay after the impulse. This results in superior transparency and low-level resolution not available in a conventional transducer.
So, are ribbons ready for mainstream?
Yes. When you start looking at the awards and accolades garnered by ribbon speakers, you too will realize just how far planar ribbon technology has come.