The built in filter allows you to adjust the cutoff frequency of any voices on your RD-8 unit. As it is part of the FX Bus on the unit, you must assign each voice using the SEND setting. To do this, follow the steps below:

1. Press SEND in the FX section.
2. Use SELECT to assign which voices go to the bus (solid red LED is bus send on).
3. Press SEND in the FX section to return to playback.

Ensure the ON button is illuminated, to show the filter circuit is active. By default, the filter acts as a Low Pass filter where the cutoff dial reduces the high frequencies as its turned anti-clockwise. When HPF is enabled, the filter acts as a High pass filter, where low frequencies are cut as the dial is turned Clockwise.