Evolution Acoustics has long understood that conventional soft dome tweeters exhibit non-piston motion, whereby the material bends and flexes at amplitude, causing distortion and limiting high frequency extension. However, the textile material can often possess a very smooth and natural sound across the frequency spectrum. Higher tech rigid diaphragm materials like titanium, beryllium, and even diamond, which certainly solve distortion issues and extend upper frequency response, can often sound hard and somewhat artificial in reproducing certain types of textures.  For many years we employed pure aluminum ribbons in our speakers, which have amazing ultrasonic capabilities as well as extremely delicate and nuanced execution during soft passages. However, the issue with the pure ribbon was that it was both very fragile and delicate and had difficulties holding up sonically during very loud dynamic passages, exhibiting compression at the extremes.  The aluminum ribbon would also slightly “etch” a metallic sound into everything, and once you noticed that characteristic it became difficult to unhear. With both dome tweeters and pure ribbon tweeters, surface area played a big role in evaluating what we would want to achieve moving forward. There are many extraordinary dome and ribbon tweeters available, but the smaller size is simply not capable of matching the scale of the other drivers in SYSTEM. During grand dynamic swings, the tweeter needs to output with the same authority as the rest of speaker, otherwise the presentation will not be believable, like a mosquito on top of a wall of sound.  Considering all these factors we turned to a large 6-inch by 10-inch diaphragm silk-textile Air Motion Transformer tweeter. 

The SYSTEM AMT tweeter uses a folded pleated silk-textile diaphragm of a mere 0.0005-inch thickness. Its “voice coil” is a serpentine pattern of precision-etched aluminum, selected for minimal weight and high-power handling. Unlike a normal piston loudspeaker that excites the air by alternately pushing and pulling a cone or dome, the AMT Air Motion Transformer linearly squeezes and expands diaphragm pleats, moving the air load at a very high velocity. Because the moving mass of the Air Motion Transformer is extremely low and the magnetic structure very powerful, this combination results in extraordinarily high acceleration that yields amazing transients. The Air Motion Transformer diaphragm’s low mass and high output also allow for an unusually high combination of efficiency and wide frequency bandwidth attained in a single loudspeaker. The AMT is a dipolar transducer, making it act just like a live musical instrument, in many cases propagating as much sound to the front as it does to the rear. Therefore, we constructed an extremely sophisticated tuned rear chamber to ensure a perfectly balanced environment optimizing the tweeter’s performance. The diaphragm’s shape delivers wide dispersion in the horizontal axis but tightly controlled vertical coverage. This creates a wide soundstage while simultaneously minimizing unwanted reflections from floor and ceiling. Coupled with the EXACT crossover which completely flattens the frequency response while further lowering distortion, the SYSTEM AMT is the smoothest, most accurate, most dynamic, and transient capable tweeter in the market.