Fri Feb 17, 2023 4:32 pm
Nancy has some neobaroque mods, so its easier to talk about original C-C organs from 1850 onward.
A book from 1917 available from Wayne Leupold, Wallace Goodrich's "The Organ in France", gives some useful views of the tonal differences between 19th C French and American organs and how to adjust registrations. See also the two Rollin Smith books on interpreting Cesar Franck.
C-C organs, until near the end of the century, tended to have a nicer balance between the foundation flues (fonds) than we're used to, both between families and across divisions. Instead of loud Diapasons and Clarabellas with a dominating Great, C-C had the four flue families closer in level to each other, blending into a characteristic warm sound where no single voice stands out much, though the Bourdon does tend to vanish below the Gambe, Montre, and Flute Harmonique. You can hear this blend on Caen, St. Omer, and Oloron-St-Marie by drawing all the 8' fonds (no celestes) and coupling the manuals together.
The Positif fonds in Franck's St. Clotilde C-C organ were almost as loud as the GO. The Positif was expected to hold its own as a complete second chorus, both plein jeu and grand jeu. Later in the century, toward 1890 - 1900, the Positif weakens more toward an accompanying manual like our Choir division in some organs, but much French symphonic music still expected the Positif to be a complete second GO, not overwhelmed by the Recit. By 1902-3, you can hear a weak, Choir-like Positif on Notre Dame de Metz original without extension stops, by Mutin, C-C's successor firm.
When you add the Pos Anches (trumpets and sometimes upperwork) after the Recit Anches, the expectation was a considerable boost in sound and excitement, short of the GO Anches, but not just a faint reinforcement of the Recit. I don't really think later composers like Widor, Gigout, Guilmant, and Vierne asked for a weak Positif as mainly an accompaniment, but I can only back that opinion up for Franck.