QSC Audio SUBWOOFER FILTER, SF-1 Configuration, Positions 1 through 4 and 9 and, Mono Sum

CONFIGURATION

SETTING THE SUBSONIC FILTER FREQUENCY

The subsonic (highpass) filter on Channel 1 cannot be bypassed, and Channel 2 should only be bypassed in the bridged mono mode. Plug-in SIP resistor network RN3 sets the high-pass frequency for both channels 1 and 2. Table 2 shows the resistor value to be used for the frequency you desire. Typical subsonic frequencies available with the provided SIP resistor networks are 20, 25, 32, 35, 40, 50, 63, and 80 Hz. Consult your subwoofer manufacturer if you are unsure of what frequency to use.

If you desire a 6-dB boost at the low end of the subwoofer frequency range, set the slide switch SW1 to “ON”; otherwise set it to “OFF.” Such a boost is popular with users of Electro-Voice B6 subwoofer enclosures.

		TABLE 2
Frequency	Resistor Network Value (RN3 or RN4)
20	82K	Factory set for RN3
25	68K
32	56K
35	47K
40	39K
50	33K
63	27K
80	20K
100	18K
135	12K
160	10K
200	8.2K
250	6.8K Factory set for RN4

SETTING THE SUBWOOFER UPPER FREQUENCY LIMIT

The low-pass filter sets the upper limit of the subwoofer frequency range. Plug-in SIP resistor network RN4 sets the low-pass frequency for both channels 1 and 2. Table 2 shows the resistor value to be used for the frequency you desire. Typical frequencies available with the provided SIP resistor networks are 100, 135, 160, 200, and 250 Hz. Consult your subwoofer manufacturer if you are unsure of what frequency to use. Whatever frequency you choose should be higher than that of the subsonic filter.

SETTING DIP SWITCH SW2

Determine the configuration you desire and set the DIP switches as described below.

Positions 1 through 4 and 9 and 10

First, decide whether you need “Mono Sum” or “Stereo” operation. This will determine the settings of positions 1 through 4 and 9 and 10 of DIP switch SW2.

•Mono Sum

Because it is difficult for listeners to sense directionality of low audio frequencies, many subwoofer systems are set up for monaural operation, with both channels summed together. For mono summed operation, set the amplifier mode switch to “STEREO” and SW2 as follows:

Position 1	OFF
Position 2	ON
Position 3	ON
Position 4	OFF
Position 9	OFF
Position 10	ON

Continue to “Positions 5 through 8” and set those switches to engage both channels’ low-pass filtering.

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