REEALY YOU SHOULD'VE BEEN THERE!
I've finally done it! My life's work is consummated! I've been working on an improviation on the easter introit, Resurrexi et adhuc tecum sum. It was mostly just in my mind, but I tried it today. It was so, umm, I don't think I should use the word that first came to my mind....uh..it was great.
WARNING: The following is full of obscure organist jargon. Read at your own risk.
I tell you how it went down: So I have for my registration:
Grande Orgue: 8' montre, 4' principal, 8' tromba, 8' spitzflote, mixture III, violoncello 16, flute harmonique 8' flute celeste 8', viol d'amour 8'. Positif is couple to grande orgue
Positif: 8' montre, 4' principal , 8' oboe, 8' bourdon, 2' piccolo, 16' waldhorn, 8' trompette, fourniture, flute 4' , viole celeste 8'
Antiphonale: Trompette en chamanade 8', Tuba mirabilis 8'
Pedal: soubasse 32' montre 8' montre 16', pousaune 16' flute 4'. Grande orgue and positif coupled to pedal.
I start out by simply playing the first seven notes of the introit on the antiphonale, then I play the first line (Resurrexi, et adhuc tecum sum, alleluia) on the grande orgue, underpined by pedal. I played the alleluia on the antiphonale, holding the last note for about five seconds with a short bit of pedaling, repeating the first seven notes and adding an arpeggio.
I play the whole introit through in this manner, alternating between dipasons and loud trumpets on different manuals as described. At the last chord, I hold it and do a short improv on the second subject of the introit (Posuisti super me manum tuam, alleluia) on the positif, using only flutes, but playing the alleluia on the grande orgue with the tromba.
Then back to my original registration for the last subject (mirabilis facta est scientia tua, alleluia, alleluia) This subject ends with a pedal solo. For the psalm verse ( Domine, tu probasti me et cognivisti me: tu cognovisti sessionem meam, et ressurectionem meam.) and gloria patri, I play simple V-VII chords on the positif (which has flutes and strings and is closed) while I add a second theme, based on the psalm tone. (played on the grande orgue with flutes and strings 8' and the ' principal, which together make a good-sounding solo registration.)
Then back to original resgistration (plus an added contre bombarde 32') to play the opening theme on the antiphonale's reeds, but this time in chords. Random playing, then some Dupre-esque chordal arpeggios* while the pedal plays the introit . To end, random improvisations and a short pedal solo on full organ to the end . It was all so cool that I tried to record it and upload it as my firt recorded song, only the camera did'nt work. I'll try again tomorrow.
*I say Dupre-eque because I stole them from Dupre's prelude and fugue in B major.