| 摘要 |
<p>The appts. has two loudspeakers (5,6) which radiate vertically in opposite directions from a single acoustic enclosure (1) with airtight interior (12). They are driven in parallel via lines (8) from an amplifier (10). In the line to the downward-radiating speaker (5) a preferably coreless inductance (9) is inserted with a value chosen to suppress the medium and high frequencies. With speakers 10 cm in diameter the inductance may have a value of 7 mH. Advantageously both speakers may operate simultaneously in the band from 20 to 400 Hz, and the upper may be filtered between 400 Hz and 2 kHz according to the number of channels.</p> |
