Roland SP-404MK Reference Manual page 43

Using the Effects Adding Effects to a Sample (BUS FX)
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Assigning Effects to BUS 1 and BUS 2
Hereʼs how to assign the built-in effects of this unit to BUS 1 or BUS 2. You can use two types of effects separately.
1
Press the [BUS FX] button to select the bus to configure.
When the button is lit orange, BUS 1 is selected; and when the button is blinking orange, BUS 2 is
selected.
2
Press the [FILTER+DRIVE]‒[MFX] buttons to select the effect to assign to the bus.
You can assign the built-in effects of this unit to BUS 3 or BUS 4. Up to four effects are available.
To assign an effect to BUS 3 or BUS 4, change the settings in the effect setting screen.
→ "Configuring the Effect Settings (EFX SET)"