Abstract: An electronic keyboard instrument that emits sounds in both upward and downward directions from speakers solely for upward sound emission and from speakers solely for downward sound emission to realize acoustics similar to that of acoustic piano, and constitutes rear parts of resonance chambers in a speaker box by a common partition plate to prevent the speaker box from becoming complicated in construction. Woofers directed downward are disposed at a lower part of the speaker box, and squawker directed upward are disposed at an upper part of the speaker box. The internal space of the speaker box is partitioned by one horizontal partition plate into an upper space where resonance chambers for the squawkers are defined by vertical partition plates and a lower space where resonance chambers for the woofers are defined by vertical partition plates. Rear parts of the resonance chambers are constituted by the horizontal partition plate.

Abstract: An electronic keyboard instrument that emits sounds in both upward and downward directions from speakers solely for upward sound emission and from speakers solely for downward sound emission to realize acoustics similar to that of acoustic piano, and constitutes rear parts of resonance chambers in a speaker box by a common partition plate to prevent the speaker box from becoming complicated in construction. Woofers directed downward are disposed at a lower part of the speaker box, and squawker directed upward are disposed at an upper part of the speaker box. The internal space of the speaker box is partitioned by one horizontal partition plate into an upper space where resonance chambers for the squawkers are defined by vertical partition plates and a lower space where resonance chambers for the woofers are defined by vertical partition plates. Rear parts of the resonance chambers are constituted by the horizontal partition plate.