Serge Fiori (lead guitar, vocals) met Michel Normandeau (guitar, vocals) in November 1972 and Harmonium was formed when they added Louis Valois on bass in 1973.
The band put out 3 studio albums from 1974 through 1976: Harmonium, Si On Avait Besoin D'une Cinquième Saison and L’Eptade as well as a live album (En Tournee in 1980).
Below is Pour Un Instant - a short sweet track which was a hit from their first album:
This is paired with a long one - the 17 minute Histoires Sans Paroles which is just so goddamn beautiful:
Fwiw, all 3 of their studio albums made it onto wikipedia’s list of top 100 Canadian albums - they were huge in Quebec and for good reason.
In 2016 a great 2-LP re-issue of their last album (L’Eptade XL) was made available and there are re-issues of everything on CD.
Here is the venerable Peter Gzoski introducing Harmonium on CBC’s 90 Minutes Live.