Does anyone know what the bass brass instruments are that play the 5/4 theme when we see Isengard for the first time after Saruman has begun to burn the surrounding forest to make his army of orcs and uruk-hai (i.e. when he's still holding Gandalf captive)? The instruments aren't edgy enough, and have too much roundness of tone, to be bass trombones. Are they Wagner tubas, by any chance?