SALM TONES can sometimes be tricky. Mode VIII is much easier than, for example, Mode III—but even Mode VIII can be ticklish. One reason is that several are related to each other, such as the example I gave of 1 and 6 in a recent post. Here’s an incredibly useful PDF I just came across from 1949:
* * PDF Download • The Eight Gregorian Psalm Tones (29 pages)
It shows all the “difficult cases” and their solutions:
This chart is even nicer:
* * PDF Chart • The Eight Gregorian Psalm Tones