QSC Audio UF-3 owner manual IV. Typical Applications, Subsonic Filter

	RESISTANCE	CODE
	270	271
	470	471
	560	561
	1.2K	122
	1.5K	152
Use only these three digits to	1.8K	182
determine resistance code.	2.0K	202
Disregard the other	2.2K	222
numerals and letters.
	2.7K	272
	3.3K	332
	4.7K	472
	5.6K	562
	6.8K	682
	8.2K	822
	12K	123
	15K	153
	18K	183
	20K	203
	22K	223
	27K	273
	33K	333
	47K	473
	56K	563
	68K	683
Figure 4—SIP resistor network	82K	823
	120K	124
identification

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: Typ. 20–50 Hz

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).		Subsonic roll-off
3.	No jumper on Jx03.
		Figure 5—UF-3 as a subsonic filter

4.Insert a resistor network in RNx04 that is appropriate to the desired roll-off frequency—typically 20, 30, 40, or 50 Hz.

4