Choose what should sound old
A videotape-style treatment can make a clean recording feel softer, less steady and more lived-in. It is a creative effect rather than a repair process: you are adding coloration, not recovering missing detail from damaged audio. Before changing a control, decide what you want the listener to notice. A spoken memory may need only a little hiss and a darker tone. A dreamlike instrumental can tolerate much more pitch movement. Keeping that intention clear makes it easier to stop before the treatment hides the words or melody you wanted to keep.
Start with a recording you have permission to use. Choose a local audio file in the tool at the top of this page, or use the recording option if you want to capture a new sound. The file limit is 50 MB and the duration limit is 15 minutes; browser decoding support still determines whether a particular file can open. If you are experimenting with a long song, a short passage containing both quiet and loud moments is a useful first test. Preserve the original recording separately so you can return to it later.