I've come to rely upon the "9v battery" test to identify preexisting speaker runs for standard speakers, and also realized recently that a tone generator works quite, too.

Is there an equivalent '9v baterry' test for identifying 70v speakers, however? Or, is it safe (and will it work?) to use a tone generator on a 70v speaker?

A toner will work fine for 70v. I have not usd the battery as a testor in over 15 years, as I always have at least 2 toner's with me.

You would want to connect a battery directly to the speaker. If you need to tone them from the head end and can't access the speakers directly, the tone generator will work. A battery sending current to a 70V transformer won't produce much sound.

Toner should be fine. I use it all the time.

great, will try the toner, thank you.