Balanced-Armature Speaker Movement

Radio Record, Volume II, Issue 14, 19 October 1928, Page 27

Balanced-Armature Speaker Movement

pue principie of the balanced-arma-ture toud-speaker movement is in the accompanying diagram (a). The usual permanent-magnet is provided with a double-ended poll-piece on each extremity. thus giving an ad-

jacent north and south pole opposite each end of thea cature. The armature acts as the core of a small coil carfying the audio-frequency current. and is pivoted as indicated. The driving spindle to connect to the diaphragm is attached to one end of the "armature. The above principle has been simplified for commercial veproduction in some units ‘s shown in diagram B, which illustrates the balanced-arma-ture principle as embodied in the

"Blue Spot" balanced unit No. 66, and in the "Anchor" driving unit, both of which are stocked by the Roger Importing Co. Ltd., of 159 Manchester Street; Christchurch. On looking at diagram B it will be noticed that there are two extension pole-pieces on each pole of the permanent magnet, but arranged differently to the original seheme in order to eliminate the necessity for pivoting the armature, and by this means to secure parallel movement of it. The coil encircling the armatur is omitted for the sake of clearness. The Roger Co. stocks a large number of radio lines, including loud-speaker kits and complete speakers, receivers. valves, headphones, erystals, ete.