My apologies for the brevity of the this post. I am afraid I have run out of time, my own fault, but the Triduum is upon us. I have scheduled posts to appear on The Saint Lawrence Press blog. Most of what is written broadly applies here too.
The most significant differences between the Tridentine Rite and the 'modern' books concern the Office on the days of the Trdiduum.
A significant disruption occurred to the Lauds of Tenebrae in the 1911-13 reform.
On Mandy Thursday in the Tridentine rite the psalms sung were Pss. 50, 89, 62-66, Cantemus Domino & 148-149-150. In the 1911 reform these were replaced by Pss. 50, 89, 35, Cantemus Domino & 146.
On Good Friday in the Tridentine rite the psalms of Lauds were Pss. 50, 142, 62-66, Domine audivi auditionem & 148-149-150. These were replaced in 1911 by Pss. 50, 142, 84, Domine audivi auditionem & 147.
On Holy Saturday the traditional arrangement was Pss. 50, 42, 62-66, Ego dixi & 148-149-150. These were replaced by 50, 91, 63, Ego dixi & 150.
Of course on all the day psalm 50, Miserere me Deus, is said in a low voice at the end of Lauds and all the other Hours.
At Compline the invariable psalms 4, 30: vv 1 - 6, 90 & 133 are chanted. The 1911 reform excises the fragement of Ps. 30.
At Tenebrae all the psalms, whatever tone they are sung in, end with a cadence of a drop of a fourth, presumably an indication for the acolyte to extinguish a candle on the hearse. This vanished from the books published after 1911.
The Passion on Good Friday, and that sung on Palm Sunday, Tuesday and Wednesday, was sung to a lovely tone attributed to Palestrina and Guidetti. It is rather beautiful and more pleasing on the ear than the post 1911 tone where the Chronista part is merely the tone used for solemn Mattins lessons.
Again, my profound apologies for not posting more. I may be able to do something after Sunday retrospectively.
A very blessed Triduum and Pascha to all readers.