PPG, based in Hamburg, Germany, developed the first digital 'wavetable' synthesizers. The earliest model was the Wave - a hybrid of digital oscillators feeding into analogue filters and VCAs (Voltage Controlled Amplifiers). The Wave's most interesting feature was its ability to sweep through 64 waveforms in what PPG termed a 'wavetable' - a group of waveforms held in memory that can be strung together in any order you like, and then played in sequence as the basis of a sound. The result of this technology is that the instrument has a much broader palette and more dynamic timbral sound than that offered by the typical sawtooth, pulse and sine waves of analogue synthesizers, which relied on a filter to animate them. There were later examples of other similar types of 'transitional' synthesis, such as the Sequential Circuits Prophet VS' 'Vector Synthesis' (which later appeared in Yamaha's SY22 synthesizer, after Yamaha bought the company), and Korg's own wavetable synthesis which uses full samples for each stage of the wavetable rather than a single-cycle looped oscillator, and which has survived commercially, as has the Waldorf range through various incarnations, which originally rose from the ashes of PPG.