Real name: Ilse Ella Gertrud Reichel

Effective period / Period of releases: 1970 - 1974

Gertrud "Katja" Loos (born on January 20, 1916 in Hamburg as Ilse Ella Gertrud Reichel, died on August 30, 2000 in Stuttgart) was a German organist, sound engineer and music therapist. She was a co-founder of the German Music Therapeutic Society (Deutsche Musiktherapeutische Gesellschaft) and for many years the first chairman.
Credited also as liner notes author and for conception (e.g. Für Die Jugend).