Commercial and bootleg recordings of Callas from the late 1940s to 1953—the period during which she sang the heaviest dramatic soprano roles—show no decline in the fabric of the voice, no loss in volume and no unsteadiness or shrinkage in the upper register. Of her December 1952 Lady Macbeth—coming after five years of singing the most strenuous dramatic soprano repertoire—Peter Dragadze wrote for "Opera", "Callas's voice since last season has improved a great deal, the second passagio on the high B-natural and C has now completely cleared, giving her an equally colored scale from top to bottom." And of her performance of Medea a year later, John Ardoin writes, "The performance displays Callas in as secure and free a voice as she will be found at any point in her career. The many top B's have a brilliant ring, and she handles the treacherous tessitura like an eager thoroughbred."