The special case of the grand piano, called the rim, reveals the design legacy of Steinway & Sons behind the Essex. The rim contributes to the stability of the piano, offering support for the soundboard. The Essex grand piano outer rim is made of laminations of European Maple (Acer platanoides) while the inner rim is made of laminated European Beech (Fagus sylvatica).

The wide-tail design featured on all Essex grands is a special innovation by Steinway & Sons that creates 6% more surface area in the soundboard. This enriches the sound, giving the pianist the impression of playing on a larger instrument. The larger soundboard area also allows for better placement of the bass bridge — which yields more volume, greater tone, and a bass that sings.

Like all pianos designed by Steinway & Sons, the Essex contains a soundboard of solid, premium grade, straight-grained spruce chosen for its superb acoustic qualities. It also features a special tapered profile that is thicker in the treble and thinner in the bass, enabling freer vibration and better tonal volume.

Designed by Steinway & Sons, the plate is cast from gray iron and over engineered to provide strength to support 20 tons of string tension. Long-fiber cast iron creates a very dense plate, which does not absorb energy and yields a fuller tone.

Essex grand hammers are specified by Steinway and made by Imadegawa in Japan using German–made hammer felt and hornbeam moldings. Based on the exclusive designs of Steinway & Sons, the Essex action is made of wood (not plastic) and is characterized by a faster repetition, better stability, and heightened responsivenes — allowing the musician to play with maximum expression and control.