Elektron Analog Four can generate sounds without using traditional oscillators or note sequencing. In this example, all the sounds are created only by internal feedback paths and resonating filters together with intricate lfo modulations. The amplifier section is triggered by a note-on and that is why the sequencer is running. Note, at 19:33 the sequencer is being stopped and the release phase of the amplifier envelope was still active while uploading this video. It may look like one of the external inputs are being used but it is not, only Out Left and Out Right are connected.