Downloading ADT 1.0.8 for Mac from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this app available. This free Mac app was originally developed by Olaf Matthes. The program belongs to Lifestyle Tools. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe.
From the developer:
The ADT technique was developed at Abbey Road Studios by engineers recording the Beatles in the 1960s. To free John Lennon from having to sing everything twice for real double tracking they came up with an artificial replacement: they sent the original signal to another tape machine and re-recorded it. Due to the physical distance between record and playback heads the new signal was delayed.
You may want to check out more Mac applications, such as AdTat, Art Directors Toolkit 5i or Sound Studio, which might be similar to ADT.