If you wish to use the TAP/CTL switch for a third Delay preset in a DD-500 preset Bank instead of Tap Tempo, you can use an external footswitch to control Tap Tempo.
To do this:
1. Press EDIT.
2. Use the Up/Down Arrow buttons to select CONTROL.
3. Press EDIT.
4. Press Down Arrow to select CTL1 FUNC:
5. Turn the TIME/VALUE knob to select the TAP option.
6. To determine whether this will be a a global footswitch assignment, or
patch-based, press Down Arrow until CTL1 PREF: is selected.
7a. If you want the assignment to be Patch based, so it only applies to the patch
you configured, leave this preference set to PATCH and WRITE the changes
you've made to the Preset by pressing EXIT and EDIT together, then press EDIT
once.
7b. If you desire it to affect all patches equally, turn the TIME/VALUE knob to select
the SYSTEM option, then press EXIT twice.