The GoldenEar HVFR (pictured above in its Reference version) is a type of driver originally known as an Air Velocity Transformer (AVT), Air Motion Transformer (AMT) or JET transducer. The inventor of this type of driver was Dr. Oskar Heil, who introduced it to production in 1972 (see pic, below).
The first speaker system to use the Heil driver in (C. 1972)
It operates in a very different manner than other, more typical loudspeaker drivers. In the case of the GoldenEar
HVFR driver, the diaphragm is a very thin, flexible resin based film with a conductive circuit printed on its surface and folded into a pleated shape, similar to a bellows (think accordion). The diaphragm is positioned within a powerful magnetic field created by rare-earth Neodymium magnets. (See the illustration below.)
When the audio amplifier's output current flows through the laminated conductor (2) it causes the flexible diaphragm to move left and right within the magnetic field (6), squeezing air molecules in and out in the direction indicated by the arrows (8). The walls surrounding the diaphragm (4) prevent the pressure waves from moving in unintended directions.
The diaphragm creates positive and negative pressure waves by moving in a similar motion to the pleats of an accordion as it's pushed in and pulled out. The alternating pressure waves are interpreted as sound by our ears and brain, like the output of any other acoustic driver. The driver is essentially dipole in nature with an equal amount of sound produced forward and backward. Our HVFR driver's rear output is absorbed by special absorbent material placed behind the pleats.
Since the diaphragm is made of very light material and the pleats move such a small amount, the driver's response to input is exceedingly fast, especially as compared to a typical dome or cone driver. In this characteristic the HVFR most resembles an electrostatic driver.
Although the squeezing motion of the diaphragm is very small, because there are a lot of folds, substantially stronger pressure pulses are created than those produced by a typical dome, cone or electrostatic driver of the same surface area. As a matter of surface comparison our diaphragm has a functional driver area comparable to a 4.5-inch-diameter circular dynamic cone. The folded driver design, combined with the small motion range, means the HVFR performs as a "point source" version of a larger driver. The result is high output with exceedingly low distortion. This is a major reason that GoldenEar speakers sound so clean and open in the upper midrange and high frequencies.
A good analogy to describe the HVFR driver's dynamic motion is to imagine that it "spits" pressure pulses out in a similar manner to shooting a wet watermelon seed from your hand by squeezing it between your thumb and forefinger. This method of pulsing the air molecules results in significantly higher speed as the pressure waves leave the diaphragm. In fact, the pressure waves leave the diaphragm approximately five times faster than the speed of the diaphragm's motion, hence the name,
Air Motion Transformer.
Over the past few years several companies have embraced this type of driver technology. Like everything else, there are differences in the quality of the drivers and their implementation within the system. The GoldenEar HVFR is built completely to our specific design specifications using the finest materials available and incorporates exceedingly powerful magnet assemblies. Although it outperforms every dome tweeter ever made, there is no Diamond or Unobtanium used in its manufacture. So, unlike the super-expensive dome tweeters found in other very expensive high-end brands' speakers, it is not obscenely expensive. This, combined with our advanced balanced crossover designs and state of the art implementation, the HVFR is an excellent example of our high quality and superb engineering delivering exceptional performance at surprisingly affordable prices.