The modulator replacement replaces the original circuit, with the original responsible for boosting the output from the VIC-chip and generating composite video, S-Video and the RF-signal. The replacement removes the old RF-signal output as well as the noise it provides, also added to it is options for bypassing some of the more problematic signals and a connector for adding stereo audio output. S-Video picture quality can be further improved upon by not installing the components for composite video.
Given differences in pinouts and voltages found on various Commodore 64 revisions, this variant is only meant for installation on Commodore 64s with so-called "longboards" only!