The conservatory opened after a grand ceremony in September 1878. Helped by a ground-breaking willingness to enroll women students, it proved to be an immediate success and Raff’s leadership rapidly established it as one of the foremost conservatories in Germany. The institution thrived - by the end of its first year the number of students had doubled to over 120
Surprisingly, all this activity doesn’t seem to have curbed Raff’s productivity as a composer and he still managed to complete eleven works during 1877 and 1878, four of which were major piece. The Violin Concerto No.2 Op.206 had been composed expressly for the great Spanish virtuoso Pablo de Sarasate but the two men quarreled, so it was premiered by Hugo Heermann. The other major composition of 1877 was Die Tageszeiten Op.209, described by Raff as a Concertante, a hybrid work for piano, choir and orchestra combining elements of piano concerto and choral symphony, setting a text by his young daughter Helene. The next year also saw two major works finished: the Symphony No.9 Im Sommer Op.208 and a lyric opera Bendetto Marcello WoO.46. The symphony was composed in the summer and autumn and premiered the next year but Raff had no expectation of the opera seeing the light of day, he seems to have composed it for his own pleasure and it wasn’t published or performed for over 120 years.
Raff’s enthusiasm and aptitude for teaching reasserted themselves, as did his principled streak; he taught the composition class himself but forbad performances of his own music, and unhesitatingly paid Stockhausen more than himself to secure the singer’s services. By all accounts he made an excellent director which is perhaps surprising when one remembers his inability to cope with his own household's finances. For his time he held a progressive attitude towards women; demonstrated firstly by employing Clara Schumann and eventually other women as teachers at the Hoch Conservatory and later by actively encouraging the admission of women students, with composition classes specifically for them - the first in Germany. In 1879 his achievement was recognised when Liszt made a spectacularly successful visit to the conservatory and was rapturously received by crowds in the street, applauding him as he stood with Raff on the balcony of the Raff’s apartment
His teaching style was remembered by a student: "His instruction was expressed in a stimulating and fertile way because of his great knowledge, not in music alone but in literature, old languages, mathematics and so on. He could lecture for three or four hours, getting carried away as one subject followed another; his deep musical memory continually giving him as examples material from the works of composers from all eras. Everything flowed in its own way; admittedly he explained more by means of his sharp mind than from his heart." Another wrote "As well as canons and fugues we had to compose old and new dances without mercy. Now we had to compose a four-part mens chorus, now a Sarabande or Tarantelle, now a mixed chorus. Within every period of eight days he asked for the composition of a set piece of music." Raff is portrayed as once composing a polka in C major at the blackboard "in a flash". His students at the conservatory seem to have been inspired by his leadership and example - he made himself as accessible as possible, saying "he who occupies an office must be like the pope in Rome, a servant of God's servant".
Foremost amongst the Frankfurt pupils in ability and in Raff's affection was undoubtedly Edward Macdowell, who was so highly thought of by Raff that he wanted him to join the faculty. The American's dedication to Raff's memory for the rest of his life is a testament to the regard in which the principal was held by his pupils. There were several other graduates from Raff's time in Frankfurt who made significant, if not quite so stellar, careers for themselves as academics and performers. The Florentine Lazzaro Uzielli (1861-1943) became a pianist and teacher of renown, eventually returning to the Hoch Conservatory to replace Clara Schumann. He went on to hold prestigious teaching posts in other German conservatories. Bridging the Wiesbaden and Frankfurt years was the composer and pianist Anton Urspruch (1850-1907), to whom Raff had first given private lessons in Wiesbaden before introducing him to Liszt. Urspruch returned to join the faculty of the Hoch Conservatory under Raff's directorship, as a teacher of piano. Violinist Fritz Bassermann (1850-1926) also returned to the institution's teaching staff after a distinguished career, numbering Paul Hindemith amongst his pupils. Adolf Göttmann (1861-1920)rose to the post of Royal Director of Music in Berlin. Other pupils well known in their day but now hardly meriting a footnote in musical lexicons include the Swiss vocal composer Gottfried Angerer (1851 - 1909), the English composer and teacher Algernon Ashton (1859-1937), the composer, arranger and pedagogue Theodor Müller-Reuter (1858-1919) and Heinrich Spangenberg (1861-1925), principal of his own conservatory in Wiesbaden. Despite Raff’s encouragement of women students, the only one who later made a name for herself as a composer was Mary Wurm (1860-1938), writer of piano works and songs.
During his remaining three and a half years heading Dr Hoch’s Conservatory Raff still found time to compose: a final eighteen works flowed from his pen. In 1879 he completed his last symphony, No.10 Zur Herbszteit Op.213, the final one of his quartet of symphonies celebrating the four seasons, but after its premiere late the following year he revised it significantly, replacing the slow movement (which was later published as the independent orchestral piece, Elegie WoO.48) and altering the finale. It was published shortly after Raff's death. The year’s other significant pieces were a set of four orchestral preludes to Shakespeare plays – The Tempest, Macbeth, Romeo & Juliet and Othello WoO.49-52 and a charming Suite for violin and piano Op.210. Only two works were completed in 1880, both again setting texts by his daughter Helene: a lyrical and finely wraught cantata Die Sterne WoO.53 and an extensive song cycle about the medieval troubadour Blondel de Nesle Op.211. 1881 was largely devoted to two projects: the writing of several piano works replacing those originally published at Mendelssohn’s urging by Breitkopf & Härtel in 1844/45, including a grand Piano Sonata Op.14, and completion of his final great work, the oratorio Welt-Ende – Gericht – Neue Welt Op.212, a setting of the biblical Book of Revelation, which was very well thought of and recognised as a work of importance. He only had time in 1882 to complete one sizeable work, the opera Die Eifersüchtigen WoO.54, which had to wait until his bicentenary in 2022 to reach the stage. Although most of these compositions were well received, Raff was aware that his days as a composer of the first rank were ending, and that his new pieces often gained only a succès d’estime. He still regarded himself as primarily a composer but all the praise which was showered upon him at his sixtieth birthday celebrations focused on his work as director of the conservatory, not as a creative artist.
For all the carping about his abilities as a composer Raff was universally acknowledged as a distinguished director and the position gave him great satisfaction but, although loved by his students and respected by the conservatory’s trustees, his final days there were clouded by two disputes. The singer Julius Stockhausen had a very "artistic" temperament. Raff recognised, though, that having Stockhausen on the faculty added greatly to the conservatory's prestige and its ability to attract students. Raff paid him substantially more than his own salary as director - 9000 Reichmarks as opposed to Raff's 7000 and Schumann's 5000. As Raff said: "Of course the Director also often receives less than the primadonna. Quite simply, my primadonna is Stockhausen". His primadonna repaid his generosity by involving him in a series of unseemly public disputes during 1880, which caused Raff much worry and a period of difficult relations with the board of trustees. Stockhausen left the Conservatory after only two years to found a competing school for vocalists. Secondly, the conservatory became a victim of its own success and outgrew its financial resources but Raff refused to countenance the measures which were needed to put it back on a sound footing. Difficult negotiations with the trustees were still underway when, worn down by heart disease and overwork, he suffered a heart attack early in 1882. Since his childhood his health had never been robust, and he had suffered minor heart ailments for many years. On the advice of his doctor he quickly returned to work, but he died suddenly on the night of 24 June 1882 from a second heart attack. He had celebrated his 60th birthday only a month before. A large procession of colleagues, students and friends, shocked by his sudden passing, accompanied his coffin through the streets of Frankfurt to the city’s main cemetery, where he was laid to rest. A grand monument was raised above his grave in 1903.
Naively believing that royalties from his music would provide a good income for his family after he died, Raff had refused the conservatory’s offer of a pension. Nonetheless, after his death the trustees generously granted Doris Raff a widow’s pension but, despite this, her finances were suddenly precarious and she and their daughter were soon forced to move to a smaller apartment in Frankfurt. Within only a few months they unwittingly become mired in a bitter dispute at the conservatory where the new director, Bernhard Scholz, implemented the changes which Raff had resisted. This led to several of Raff’s appointees leaving and founding a rival institution named (without his widow’s permission) in his honour and the furore resulted in Doris and Helene Raff leaving Frankfurt before the year was out for Munich, where they lived out their lives. Doris Raff survived her husband by 30 years and died in 1912.
.