This Max for Live plugin allows you to control Echo's time knob by tapping out a tempo separate from the global Ableton tempo. This is a light version of EchoControl, my full-featured plugin that optimizes 8 hardware controls to control many additional features in a way that allows for live manipulation.
Effectively, EchoTap measures the time of your tapping (after three taps) and then finds the nearest value in a table of 127 values that correspond to a macro controlling Echo's time knob. It's not a perfect match, but you can expect it to be accurate within about 20ms.
If you like it, please consider purchasing EchoControl, which allows you to control dry/wet mix, input mute, feedback, feedback slam, signal clearing, single-knob LP/HP, repitch, and more with only 8 hardware controls, or just four knobs on a Midifighter twister.