Recommended Connections
The 309 is a nominal 8-ohm impedance loudspeaker with a 10-watt input capability. However, it is also available with transformer, the 309-4T, and with transformer and grille, the 309-4TWB.
The 309-4T utilizes a 4-watt, 25/70.7/100-volt universal line matching transformer with power taps ranging from 0.5 to 4 watts as indicated in the table for the 309-4T. The transformer is mounted to the frame and the primary winding is accessible for the user to select any of the power taps indicated in the table for the 309-4T.
All wattages marked for the various taps refer to the load on the amplifier, with the insertion loss of the transformer being less than 2 dB.
Recommended Enclosures and Baffles
309-8A and 309-4T are designed to fit on standard 8-inch ceiling speaker baffles. Additionally, the 209 series loudspeakers will accommodate the use of any standard back enclosure with a diameter of 8.6 inches or greater and a depth of at least 3.5 inches.
Larger back volumes will increase the lowfrequency output. The frequency response of a 209 in a typical 0.25-cubic-foot and 1.8-cubic-foot back enclosure are shown in Figure 1.
Mounting
The 309 may be front- or rear-mounted against either surface of its mounting flange and requires a 18.4 cm (7.25 in.) diameter cutout and a 19.5 cm (7.68 in.) bolt circle. Normal fasteners up to 5 mm (0.20 in.) will fit through the eight holes in the frame. The 309 is designed for mounting on standard ceiling speaker baffles.
Figure 1, One-Third-Octave Polar Response Charts
Measurements were made in a 1.5 ft3 closed enclosure.
