OP-1 Field Synthesizer10OP1 field is teenage engineering's all in one, battery powered synthesizer, sampler, and drum machine. OP1 field is the evolution of their original OP1 synthesizer, injected with more than a decade of ideas, refinements and improvements. OP1 field is packed with features including: a built in speaker, microphone, multiple effects, vocoder, FM radio, Bluetooth, MIDI, and even a velocity sensitive keyboard. It's the most powerful portable synthesizer