The traumatic last weeks in Stuttgart left an indelible impression on Weber, who resolved thenceforth to hold himself to a higher level of fiscal and moral responsibility. To this end he started a diary on 26 February 1810 to mark the beginning of a new period in his life. He maintained this remarkable document (D-Bsb) until his death in 1826, and but for a few lacunae it records in detail Weber's daily activities and accomplishments, his expenses, personal and professional contacts, correspondence, performances, creative work, illnesses and impressions.
Arriving in Mannheim on 27 February 1810, Weber quickly established contacts with prominent professional and amateur musicians there and in nearby Heidelberg, including the lawyer Gottfried Weber, his brother-in-law the cellist Alexander von Dusch and the tenor Ludwig Berger. These contacts allowed him to participate in concerts in the vicinity shortly after his arrival and to give his own ‘academies’ in Mannheim on 9 and 28 March. Over the course of the next year he became a frequent participant in the concerts of the Carl-Stéphanie Museum, a society founded in Mannheim in 1808. Leaving his father in Mannheim, Weber then moved in April to Darmstadt, where he resumed studies with Abbé Vogler. As had earlier been the case, Weber reciprocated with work for Vogler, writing an analytical introduction to Vogler's revision of chorale settings by J.S. Bach and helping with a piano score for a new Vogler opera, Der Admiral. Vogler also entrusted Weber with the task of writing his biography. At this time Weber formed close friendships with two fellow students, Johann Gänsbacher (whom he had known in Vienna in 1803–4) and the young Meyerbeer.
With no position or steady income, Weber supported himself in a variety of ways that are mirrored in the compositions of the period. For his frequent appearances as a pianist and composer, he revised the First Symphony and composed the C major Piano Concerto, a set of variations for cello and orchestra (j94), the rondo for soprano and orchestra op.16 (j93) and a duet for two altos and orchestra (j107). Contracts with publishers allowed Weber to sell works composed at Stuttgart and new compositions, like the six songs of op.15 bought by Simrock. Simrock also published the six sonatas for piano and violin (j99–104) originally commissioned by André, who had rejected them, however, because he found them too difficult for the intended amateur market. Weber drew much-needed income from the sale of Silvana, which the theatre in Frankfurt purchased for 100 gulden and whose first performance it gave on 16 September 1810. Aristocratic patronage also remained important for Weber, who cultivated the support of Princess Stéphanie of Baden and Grand Duke Ludewig I of Hesse-Darmstadt. Weber's new one-act opera Abu Hassan (composed between 11 August 1810 and 12 January 1811) also figured in his hopes for patronage, as the Grand Duke rewarded him with a very generous gift of 440 gulden for the dedication of the work. Lastly, Weber negotiated to sell his incipient novel to the publisher J.F. Cotta.
Of particular importance during this period was the formation of a secret society called the Harmonischer Verein, a group that initially included Weber, Gottfried Weber, Dusch and Meyerbeer, and that later included Gänsbacher and a few others. According to the statutes that Weber drafted, the Verein, a society of musicians with literary skills, sought at one level idealistically to raise the standards of music criticism and taste through non-partisan reviews that would promote the good wherever it existed. At another level, however, the society had a practical function, as its members were obliged to promote the careers and works of their ‘brothers’ through reviews and notices. To spread their reputations as widely as possible, members were also urged to establish contacts with editors and publishers throughout the German-speaking world. The Verein also made preliminary, but unrealized, plans for its own musical journal. In order to maintain the secrecy necessary for the appearance of impartiality, the members employed pseudonyms. For example, Weber, the group's director, styled himself ‘Melos’, whereas Gottfried Weber, its secretary and archivist, was ‘Giusto’. Over the course of time, the society gradually ceased to function; however, Weber continued in later years as a conductor in Prague and Dresden to promote the works of his ‘brothers’ whenever the opportunity arose.
Weber left Darmstadt on 14 February 1811 to begin a long-planned tour with which he intended to establish his reputation, cultivate contacts for the Verein and educate himself as to the state of music. Travelling via Giessen, Aschaffenburg, Würzburg, Bamberg, Nuremberg and Augsburg (where he settled an outstanding debt with his former publisher Gombart by offering him the Momento capriccioso for piano and the five songs of op.13) he arrived in Munich on 14 March. With royal permission he gave a concert at the court theatre on 5 April, at which the court clarinettist Heinrich Baermann performed a newly composed Concertino, the first of a series of pieces written by Weber for him. The success of this work led immediately to royal commissions for two full-length clarinet concertos.
Because of the difficulties of arranging concerts during the summer months, Weber stayed in Munich throughout the summer of 1811 to supervise the première of Abu Hassan (4 June) and devote himself to composition and music criticism. On 9 August he set out for Switzerland to attend the music festival at Schaffhausen, enlist new allies for the Verein and present concerts of his own. He arrived on 19 August in Schaffhausen, where he was made an honorary member of the Société de Musique Helvétique. After giving a concert at Winterthur on 28 August, he went to Zürich to confer with the editor Hans Georg Nägeli and present a concert on 3 September. During his stay in Zürich he conceived a plan (ultimately unrealized) for a Noth- und Hülfs-Büchlein für reisende Tonkünstler, a kind of travel guide providing practical information for touring virtuosos about artistic conditions in cities and towns throughout Europe. Travel on foot from Zürich to Lucerne allowed Weber to experience sunrise on the Rigi; but, unable to arrange concerts in Lucerne, Solothurn or Berne, he spent ten days at Jegisdorf, near Berne, as the guest of a wealthy acquaintance, composing a concert aria (j121) and starting work on a quintet for clarinet and strings for Baermann. Weber ended his Swiss tour with a concert in Basle on 13 October and a stay at Schloss Wolfsberg, Ermatingen, on Lake Constance from 15 to 21 October.
Between 24 October and the end of November Weber was again in Munich. In preparation for his farewell concert on 11 November he revised the old Rübezahl overture as the overture Der Beherrscher der Geister and started work on a new piano concerto (j155, of which only the finale was ready by the time of the concert). Weber's last weeks in Munich were spent composing two works commissioned by the king, a concerto for the bassoonist Georg Friedrich Brand and an aria (j126) for the tenor Georg Weixelbaum, and completing three Italian duets and three canzonettas that he presented to the queen at a royal audience on 26 November.
Weber and Baermann left Munich on 1 December 1811 for a joint tour to Prague, Leipzig, Gotha, Weimar and Dresden. In Berlin they performed publicly on 15 and 25 March, following which Baermann continued the tour on his own while Weber remained in the Prussian capital for a production of Silvana. After taking charge of the rehearsals himself and recomposing the two principal arias, Weber conducted the première of the revised version on 10 July and the repetition on 14 July to general acclaim. In Berlin he learnt of the death of his father, but he also met a number of people with whom he formed lasting friendships, including F.F. Flemming, Friederike Koch, Hinrich Lichtenstein and F.W. Gubitz. This social circle, comprising mostly members of Zelter's Liedertafel, stimulated Weber to compose a number of choruses and solo songs during his sojourn. He also wrote the first of his four surviving piano sonatas (op.24), which he sold along with a collection of four songs (op.23) and the piano score of Silvana to the relatively new publishing firm of A.M. Schlesinger, who in the remaining years became Weber's principal publisher.
On 31 August 1812 Weber left Berlin for Gotha, where he had been invited by Duke Emil Leopold for an extended stay (6 September – 20 December). With few professional obligations or social distractions Weber was free to compose or complete a number of works, including the Second Piano Concerto, the variations for piano (j141) on a romance from Méhul's opera Joseph, a set of piano waltzes for the publisher Kühnel (j143–8), a concert aria (j142) for Duke Emil Leopold's son Prince Friedrich, a new duet for Abu Hassan and a setting of J.F. Rochlitz's hymn In seiner Ordnung schafft der Herr for chorus and orchestra.