German company EMT made a breakthrough in 1957 with the release of the EMT 140, which utilized a resonating metal plate to create ambience. Despite its roughly 600 pound weight, the EMT 140 plate provided a smaller solution to large echo rooms. Additionally, a remote controlled damping pad system allowed the engineer to adjust the reverb time, offering substantially more control than possible with a traditional chamber. The sheet metal plate is suspended from its frame by springs, a transducer mounted at the center of the plate drives movement, and returns consist of pickups mounted on the plate. While the 140 was originally available only in mono, EMT released a stereo model in 1961.
