The Privia is a line of digital pianos and stage pianos manufactured by Casio. They have 4-layer stereo piano samples and up to 256 notes of polyphony, depending on model. All Privia models feature some kind of weighted keyboard action which simulates the action on an acoustic piano. First introduced in 2003, the Privia was originally designed to be a new competitor to other brands like Yamaha, Roland, and Kawai in budget digital piano products, but since then more exclusive pianos has been added to the line as well. Overview The original Privia was introduced by Casio in 2003, as a new concept within budget digital pianos, and is widely known for offering more advanced features and high-quality sound at affordable prices, being able to keep up with more expensive instruments. The first Privia was the PX-100. Like any other compact digital pianos, it was able to be played on a table or optional stand, and was equipped with a digital sound source created by independent sampling of various piano timbres. The first generation Privia was produced from 2003 to 2006, and utilizes the Zygotech Polynomial Interpolation (ZPI) synthesis sound engine, as used in Casio's numerous former flagship keyboards. Second generation follows from 2006 to 2009, using similar sound engine. The third generation was introduced in 2009, featuring an all new Linear Morphing AiF (Acoustic and Intelligent Filtering) sound engine with 4-level dynamic stereo piano sampling and 128-note polyphony. The fourth generation is the current version of the Privia, first introduced in 2012 . It uses the improved rendition of Linear Morphing AiF engine, called Multi-Dimensional Acoustic and Intelligent Resonator (AiR) sound engine, featuring a revamped 4-layer sampling and new features such as simulated sympathetic resonance, adjustable key sensor response (referred to as "Hammer Response"), half-damper effect, pedal noises and key-off simulation. Minor update of fourth generation is introduced in 2015, with some models included color touchscreen and improved built-in speaker system, as well as updated various features with few models has up to 256-note polyphony. Keyboard action As with other digital pianos, the Privia features a fully weighted keyboard action to simulate the action on an acoustic piano. This key action consist of a mechanical system of small "hammers" and weights attached to each keys that will lift up when the key is pressed, while the keys trigger the sensors to generate sound. The sensors are located in the