A connected speaker device for producing a linear array speaker, comprising: a first speaker; a first plate mounted on a bottom side of the first speaker; a second speaker; and a second plate which is mounted on a top side of the second speaker and connected to at least a part of the first plate, wherein the first plate comprises a first surrounding part arranged on a surface mounted onto the first speaker, wherein the surface is opposed to a first contacting surface and structures surrounded by the first surrounding part are received within the body of the first speaker, the second plate comprises a second surrounding part arranged on a surface mounted onto the second speaker, wherein the surface is opposed to a second contacting surface contacting the first contacting surface and structures surrounded by the second surrounding part are received within the body of the second speaker, the first plate is screwed to the first speaker through a first plurality of screw holes arranged outside the first surrounding part, and the second plate is screwed to the second speaker through a second plurality of screw holes arranged outside the second surrounding part, wherein a raised part having two conductive pads is arranged on the first contacting surface where the first plate contacts the second plate, and a recessed part having two conductive heads corresponding to the two conductive pads is arranged on the second contacting surface where the second plate contacts the first plate, wherein the conductive pads are electrically connected to a plurality of first contacting components arranged within an area surrounded by the first surrounding part, and the conductive heads are electrically connected to a plurality of second contacting components arranged within an area surrounded by the second surrounding part, and an elastic component is arranged between the conductive heads and the second contacting components to keep the conductive heads in close contact with the conductive pads and a distance D exists between a bottommost sound source in the first speaker and the first plate, and a distance d exists between a topmost sound source in the second speaker and the second plate, and a distance between the first speaker and the second speaker is equal to a sum of thicknesses 2H of the first plate and the second plate, wherein the distance between the bottommost sound source in the first speaker and the topmost sound source in the second speaker is substantially equal to D+d+2H and the connected speakers form a linear array speaker. a first speaker; a first plate mounted on a bottom side of the first speaker; a second speaker; and a second plate which is mounted on a top side of the second speaker and connected to at least a part of the first plate, wherein the first plate comprises a first surrounding part arranged on a surface mounted onto the first speaker, wherein the surface is opposed to a first contacting surface and structures surrounded by the first surrounding part are received within the body of the first speaker, the second plate comprises a second surrounding part arranged on a surface mounted onto the second speaker, wherein the surface is opposed to a second contacting surface contacting the first contacting surface and structures surrounded by the second surrounding part are received within the body of the second speaker, the first plate is screwed to the first speaker through a first plurality of screw holes arranged outside the first surrounding part, and the second plate is screwed to the second speaker through a second plurality of screw holes arranged outside the second surrounding part, wherein a raised part having two conductive pads is arranged on the first contacting surface where the first plate contacts the second plate, and a recessed part having two conductive heads corresponding to the two conductive pads is arranged on the second contacting surface where the second plate contacts the first plate, wherein the conductive pads are electrically connected to a plurality of first contacting components arranged within an area surrounded by the first surrounding part, and the conductive heads are electrically connected to a plurality of second contacting components arranged within an area surrounded by the second surrounding part, and an elastic component is arranged between the conductive heads and the second contacting components to keep the conductive heads in close contact with the conductive pads and a distance D exists between a bottommost sound source in the first speaker and the first plate, and a distance d exists between a topmost sound source in the second speaker and the second plate, and a distance between the first speaker and the second speaker is equal to a sum of thicknesses 2H of the first plate and the second plate, wherein the distance between the bottommost sound source in the first speaker and the topmost sound source in the second speaker is substantially equal to D+d+2H and the connected speakers form a linear array speaker.