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IV. TYPICAL APPLICATIONS
Subsonic Filter
Subsonic filters are commonly used in sound installations to filter out rumbles and other inaudible or unwanted low frequency signals and to
protect speaker drivers. Vented speaker enclosures in particular often exhibit a phenomenon in which the acoustical damping on the driver(s)
drops at extremely low frequencies below their own resonant frequency. In a situation like this, a
subsonic filter will help to prevent damage from over-excursion of the speaker cone.
Program settings:
1. Set the jumper on Jx01 to bypass the low-pass filter (across pins 1 and 2).
2. Set the jumper on Jx02 to enable the high-pass filter (across pins 2 and 3).
3. No jumper on Jx03.
4. Insert a resistor network in RNx04 that is appropriate to the desired roll-off frequency—typically 20, 30, 40, or 50 Hz.
Typ. 20–50 Hz
Subsonic roll-off
Use only these three digits to
determine resistance code.
Disregard the other
numerals and letters.
RESISTANCE
270
470
560
1.2K
1.5K
1.8K
2.0K
2.2K
2.7K
3.3K
4.7K
5.6K
6.8K
8.2K
12K
15K
18K
20K
22K
27K
33K
47K
56K
68K
82K
120K
CODE
271
471
561
122
152
182
202
222
272
332
472
562
682
822
123
153
183
203
223
273
333
473
563
683
823
124
Figure 5—UF-3 as a subsonic filter
Figure 4—SIP resistor network
identification