The Dettmer square piano used in the recordings.
Here is a recording of a Dettmer square piano circa 1815. The recording was made in the workshop immediately after repair and restringing and therefore the instrument has yet to achieve the full sweetness of tone you would expect it to acquire after six months of bedding in. The piece was played by Kenneth Mobbs, formerly a Senior Lecturer in Music at the University of Bristol and currently Director of the Mobbs Early Keyboard collection.
Muzio Clementi - Scherzo (allegretto vivace) No 70 of “Gradus ad Parnassum” Pub.1826