Found, yet again, on youtube
An extract from Clive Brown's "Louis Spohr: A Critical Biography"
He (Spohr) also informed Hauptmann that he had begun rehearsals of Wagner’s Tannhäuser, which the Elector, having refused permission for its performance in 1846, had now permitted. Friedrich Wilhelm seems, however, to have regretted his decision, for in the middle of rehearsals he took steps to prevent any more of Wagner’s operas being performed in Kassel, by sending an order to the theatre stating: ‘Our general board of management of the Hoftheater must not buy any compositions in future from the composer Richard Wagner, formerly Kapellmeister and barricade fighter in Dresden
Spohr’s attitude towards Wagner’s opera (Tannhäuser) reveals much about his musical personality. During the rehearsal period he confessed: ‘There is much that is new and beautiful in the opera, but much that is most distressing to the ear.’ After the third performance he wrote again to Hauptmann setting out his thoughts about the opera in greater detail:
"The opera has gained many admirers through its seriousness and its subject matter, and when I compare it with other things produced in recent years, I am in agreement with them. Much that at first was very disagreeable to me I have become accustomed to with frequent hearings; only the lack of rhythm and the frequent absence of rounded periods is still very objectionable to me. The performance here is truly a very outstanding one, and few will be heard in Germany which arc so precise. In the enormously difficult ensembles for the singers in the second act not a note was left out last night. But for all that, there are several places where they make a truly horrifying music, particularly shortly before the place where Elisabeth throws herself on the singers who rush upon Tannhauser. - What faces would Haydn and Mozart make if they had to listen to such a hellish noise which is now given to us for music! The pilgrims’ chorus . . . was so perfectly in tune last night that for the first time I was able to reconcile myself to its unnatural modulations. It is remarkable what the human ear can become accustomed to by degrees."Reports of Spohr’s reaction reached Wagner’s ears, and in Mein Leben he remarked that that he had heard that,
‘...my Tannhauser, when it was performed at Kassel, had caused him so much pain and confusion that he declared he could no longer follow me, and feared that I must be on the wrong road’These reports were not entirely accurate, for Spohr was still anxious to produce Lohengrin and made strenuous efforts both to perform parts of it in the winter concerts and to persuade the Elector to allow it to be produced in the Hoftheater. He also attempted unsuccessfully to hear it elsewhere, and as late as 1858, the year before his death, he wrote on 23 August to his former pupil Hubert Ries in Hamburg that he hoped to get to see a production of a new Wagner opera which he believed was to be given there in the spring.
From: "Louis Spohr: A Critical Biography" By Clive Brown (pp 249-250) Click here for details