“Tap Tempo” feature is available for both the Spark app and the Spark amp. To access this feature in Spark app, please see How to use Tap Tempo in Spark app.
As soon as you turn on your Spark amp, the “TAP” button will always be flashing, indicating the tempo that is read by delay and modulation effects.
To modify it, simply tap on the “TAP” button a few times at the tempo you desire. You should see the blinking speed change to whatever speed you just tapped.