QSC Audio UF-3 owner manual Ultrasonic Filter, Bandpass Filter, CD Horn Equalization Filter

Ultrasonic Filter

An ultrasonic filter is useful for minimizing RF interference, oscillations, leakage or aliasing from digital devices, and other signals that are too high in pitch to hear but may wreak havoc in an amplifier system.

Program settings:
1.	Set the jumper on Jx01 to enable the low-pass filter (across pins 2 and 3).	Typ. 16–20 kHz
2.	Set the jumper on Jx02 to bypass the high-pass filter (across pins 1 and 2).
3.	Insert a resistor network in RNx02 that is appropriate to the desired roll-off frequency—	Ultrasonic roll-off

typically 16 or 20 kHz. Figure 6—UF-2 as an ultrasonic filter

Bandpass Filter

A bandpass filter may be useful if the speaker system driven by the amplifier has a limited bandwidth. Minimizing the out-of-the-passband energy may result in reduced distortion and better intelligibility.

Program settings:

1.Set the jumper on Jx01 to enable the low-pass filter (across pins 2 and 3).

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 corresponds to the lower limit of the desired frequency passband.

5.Insert a resistor network in RNx02 that corresponds to the upper limit of the desired frequency passband. This frequency must be higher than the one selected for the previous step.

CD Horn Equalization Filter

A constant-directivity horn requires a 6 dB per octave high-frequency boost from about 3.5 kHz to provide a flat frequency response. On the UF-3 you must use the CD horn equalization in conjunction with the high-pass filter.

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.Set the jumper on Jx03 to select the EQ curve you desire: across pins 1 and 2 for +6 dB at 20 kHz, or across pins 2 and 3 for +10 dB at 20 kHz.

4.Insert a resistor network in RNx04 that corresponds to the desired low-frequency roll-off.

Subsonic Filter with CD Horn EQ

Use settings 1, 2, and 4 from the Subsonic Filter, and setting 3 from the CD Horn Equalization Filter. This would be suitable only if the loudspeaker system uses passive crossovers.

CD Horn boost

Subsonic roll-off

Figure 7—UF-2 as a subsonic filter with CD horn EQ

Subsonic and Ultrasonic Filter

Use settings 2, 3, and 4 from the Subsonic Filter along with 2 and 3 from the Ultrasonic filter.

Typ. 16–

20 kHz

Typ.

20–50 Hz

Figure 8—UF-2 as a subsonic and ultrasonic filter

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