QSC Audio owner manual III. Programming the UF-3, Operation, Bypassing the Filtering

III. PROGRAMMING THE UF-3

The UF-3 circuit board has six 3-pin headers and four SIP resistor network sockets (see Figure 2). All are used for programming the module. The circuitry for the two channels is identical, so the headers and sockets are divided between them: those designated by a three-digit number starting in a “1” (headers J101, J102, and J103; and SIP resistor network sockets RN102 and RN104) are for Channel 1, while those with a three-digit number starting in a “2” are for Channel 2. The following instructions will use an “x” in place of the first digit, except where a specific channel

reference is necessary.	Channel 2
Channel 1

Notes on Stereo, Bridged, or Parallel

Operation	(low-pass bypass/enable) J101		1	J102 (high-pass bypass/enable)				1
			2		(low-pass bypass/enable) J202			2	J201 (high-pass bypass/enable)
Except for specialized bi-amp models such as the			3					3
			1	J103 (CD horn EQ)		(CD horn EQ) J203		1
			2					2
PowerLight 1.5X, 1.6HVX, or 3.8X, the amplifier in which the			3					3
UF-3 is installed has a switch for setting the operating		RN102			RN104	RN204				RN202
mode of the amplifier, i.e., stereo, parallel mono, or		(f of low-pass filter)			(f of high-pass filter)	(f of low-pass filter)				(f of high-pass filter)
bridged mono. In the signal flow, the UF-3 accessory is
located after the switch, so you must configure both
channels of the UF-3 accordingly, whatever the operating	Figure 2—UF-3 Circuit board jumper and resistor network locations
mode. Usually you would use identical settings on both
channels in stereo or parallel mode, depending on the application. If the amplifier is in bridged mode, bypass							1		Pins 1 & 2
							2
Channel 2 of the UF-3 and use the Channel 1 input and processing only.							3		shorted together
Bypassing the Filtering							1		Pins 2 & 3
							2
To completely bypass the filtering circuitry of a channel, set the jumpers on both Jx01 and Jx02 across pins 1 and							3		shorted together

2, which are the upper two pins on their headers (see Figure 3). Note: If you neglect to place jumpers on either

header, no signal will pass on that channel.	1
	2
	3
	Figure 3—Jumper positions

Frequency	SIP resistor
(Hz)	network value
80	120K
100	82K
120	68K
160	56K
200	47K
250	33K
500	18K
800	12K
1000	8.2K
1200	6.8K
1600	5.6K
2000	4.7K
2500	3.3K
5000	1.8K
8000	1.2K
16000	560
20000	470

Programming the Low-Pass Filter

To use the low-pass filter, set the jumper on Jx01 across pins 2 and 3, which are the lower two pins on their header. If, however, you do not wish to use the low-pass filter and want to bypass it instead, set the jumper across pins 1 and 2.

To set the corner frequency (at which the output is 6 dB down) of the low-pass filter, choose the appropriate value for RNx02; use the table at left.

If there is a resistor network already installed in the socket, carefully pull it straight out. Insert the pins of the new resistor network into the socket holes and carefully press the network into the socket. Be careful to avoid bending the pins of the resistor network. Orientation of the resistor network is unimportant, as long as all eight pins are well seated in the socket.

2