The APX Series of acoustic/electric instruments was introduced in the late 1980s, and they were the first acoustics with cutaways to be offered by Yamaha. They also featured thinner bodies with arched backs, multiple piezo pickups, and several mono and stereo electronic configurations. The APX Series is still available from Yamaha, but the line has undergone several changes throughout the years and most models were changed all at once. The first series of APX guitars was produced until 1993 and they can be distinguished by pop-up control knobs in the side of the body. 1994 was a transition year with the introduction of the C APX Series where all models featured a C suffix. These models have an actual control plate for the electronics, but they only lasted around a year. In 1995, Yamaha introduced the A APX Series that slowly evolved to include all APX models by 1997, when an A suffix was attached to each model. In 2000, the third series of APX models was introduced. In mid-2006, the fourth series of APX models was introduced that featured a three digit number in the model name. Yamaha also offers nylon-string APX models that have overlapped most of the aforementioned series.