Tritonus from Mannheim are sometimes compared to Emerson, Lake & Palmer, but they were definitely independent. At the keys - including the Mellotron - was Peter Seiler, who later had a good run with many of his own releases and gigs and is still active today, mainly in the field of electronics. Here is the digital edition of their first LP (from 1975), taken from the mother tape, as well as the two tracks from their first single (from 1973) as bonus. Although there is already a Japan CD of "Tritonus" available, it is sinfully expensive and difficult to obtain.
tritonus