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Cinema Accessories for DCA Series amplifiers USER MANUAL ON 1 2 3 4 PU SH 5 6 7 8 9 10 w w w XC-3 LF-3 SF-3 OFF Two-way crossover with delay Low-frequency filter with delay Subwoofer filter *TD-000079-00* TD-000079-00 Rev. A 1 © Copyright 1998 QSC Audio Products, Inc. All rights reserved. "QSC" and the QSC logo are registered trademarks, and "DCA" and "DataPort" are trademarks, of QSC Audio Products, Inc. 2 CINEMA ACCESSORIES FOR DCA AMPLIFIERS I. Introduction This manual covers setup and operation of cinema crossover accessories for QSC DCA Digital Cinema Amplifiers. These accessories comprise three models: the XC-3 crossover, the LF-3 low frequency filter, and the SF-3 subwoofer filter. Together with DCA amplifiers, they allow you to assemble any type of cinema sound system, mono or multi-channel. Each accessory mounts directly to the back of the amplifier, from which Ch. 1 LF full-range audio audio plein registre Vollbereichaudio audio de gama llena it also draws its power. It has its own input and, if necessary, output XC-3 2-way crossover HF Ch. 2 DCA amplifier connectors. A male HD-15 connector conveys the audio signals into the amp through its DataPort. Frequency and delay parameters are user adjustable by inserting selected 8-pin SIP resistor networks (included with each unit) into sockets on the underside of the accessory. A DIP switch permits selection of functions such as delay and high-frequency boost. Using the XC-3 in a simple two-way system. In many speaker systems, a passive mid/high combination will handle the higher frequencies, creating essentially a three-way system. Ch. 1 MF XC-3 full-range audio audio plein registre Vollbereichaudio audio de gama llena 2-way crossover HF Ch. 2 DCA amplifier L Ch. 1 LF II. Description of Functions XC-3 This accessory is a two-way crossover, with the low frequency band fed to channel 1 of the amplifier and the high frequencies to channel 2. An all-pass filter on the low frequency band delays the audio signal, permitting time alignment of a cone driver with a high-frequency horn. A selectable high-frequency boost circuit provides several increments of compensation for screen Ch. 1 MF LF-3 low-frequency filter LF Ch. 2 DCA amplifier R full-range audio audio plein registre Vollbereichaudio audio de gama llena loss or constant-directivity horn equalization. A HF trim control XC-3 2-way crossover HF Ch. 2 DCA amplifier provides 0 to 20 dB of attenuation for matching levels between frequency bands. The XC-3 can be used by itself with one amplifier for a 2-way system (shown top left), or with the LF-3 and an additional amplifier for 3-way systems, as shown at left. The XC-3 has a pass-through output in parallel with the input for distributing the audio signal to the LF-3. The filter circuitry uses a 4th- Using the XC-3 and LF-3 in a stereo three-way system Ch. 1 SF-3 subwoofer filter DCA amplifier Ch. 2 order Linkwitz-Riley alignment with 24 dB/octave slopes. LF-3 Used in a system with the XC-3, the LF-3 performs the lowfrequency crossover functions in a 3-way system as shown at left. Unlike the XC-3, though, it is a device with two discrete channels; one LF-3 with an amplifier will support two other amplifiers with two XC-3 accessories, as shown. The 4th-order Linkwitz-Riley low-pass filters have 24 dB/octave slopes. Using the SF-3 with a discrete subwoofer channel 3 Each channel also has an all-pass filter providing delay for time alignment. Frequency and delay parameters for both channels are set individually, although in all but a few applications they would be set the same. Each channel also has a trim control providing 0 to 20 dB of attenuation to facilitate matching levels among the various frequency bands. SF-3 This subwoofer filter accessory has two summed inputs and a bandpass filter that defines the frequency range of the subwoofer program. The frequencies of the 2nd-order high-pass and 4th-order Linkwitz-Riley low-pass filters are both user-defined. The high-pass filter also has a switchable low-frequency boost feature: switched on, it provides a 6 dB bump at the selected high-pass frequency, useful for extending the low-end response of some speaker systems; off, the response is a flat Butterworth curve that is 3 dB down at the selected frequency. The output is parallel, feeding the same signal into both channels of the amplifier. The SF-3 has no delay function. A level trim control provides 0 to 20 dB of attenuation. The SF-3 can be used to derive subwoofer-range program from full-range audio, or it can be used with a discrete subwoofer channel in cinema sound systems. III. Configuring the accessories Configure each accessory before you mount it to the amplifier. If an accessory is already mounted to an amplifier, always turn the amp off before changing switch settings or input or output connections, or detaching the accessory. Use the tables on the following pages to determine the correct resistance for the desired frequency and delay settings. Use the diagram at the top of the opposite page to identify the values of the resistor networks. A flowchart for each model will assist you in setting the various parameters, and the chassis label on each accessory also details the correct DIP switch settings. An appendix in the back of this manual lists manufacturerrecommended crossover frequency and delay settings for various popular cinema speaker systems. The purpose of the delay functions in the XC-3 and LF-3 is to correct for time misalignments between different types of speaker driver in the overlap region between adjacent frequency bands. These time misalignments occur when the acoustical source points of the drivers for the adjacent frequency bands are physically at different distances from the listener(s). A delay compensation of 1 millisecond represents approximately 1.13 ft (13.5 in), or 34.4 cm. fXO LF delay 3-way 2-way +10 dB +7.5 dB +5 dB +2.5 dB fHP fXO XC-3 LF-3 NOTE: Even if you don't use a particular filter or delay feature on an accessory, put an unused SIP resistor network of any value into its socket to ensure circuit stability when it is powered up. The SIP resistor networks have no polarity and therefore do not need to be inserted in a certain direction. Make sure all eight pins are inserted properly into the sockets holes, and then gently but firmly press the network into the socket until it is fully seated. If a SIP resistor network is difficult to remove with your fingers, use a small screwdriver, prying gently first at one end of the SIP and then the other, until it is loose. LF flat Low pass filter on Low pass filter off LF boost Delay fHP fLP SF-3 Configurable functions of the three accessory models 4 Crossover freq. (fXO) 80 Hz 150 Hz 200 Hz 250 Hz 300 Hz 350 Hz 400 Hz 500 Hz 600 Hz 650 Hz 800 Hz 1 kHz 1.2 kHz 1.5 kHz SIP resistor value 68K 39K 27K 22K 20K 18K 15K 12K 10K 8.2K 6.8K 5.6K 4.7K 3.9K Delay (ms) 1.8 1.4 1.3 1.2 1 0.8 0.7 0.6 0.5 0.4 0.3 SIP resistor value 27K 22K 20K 18K 15K 12K 10K 8.2K 6.8K 5.6K 4.7K Use only these three digits to determine resistance code. Disregard the other numerals and letters. Use these tables with the XC-3 and LF3 to determine the correct resistor values for the crossover frequencies and delays you need. The shaded values are for the LF-3 and the highpass frequency (fHP) of the XC-3). RESISTANCE 2.7K 3.9K 4.7K 5.6K 6.8K 8.2K 10K 12K 15K 18K 20K 22K 27K 33K 39K 47K 56K 68K CODE 272 392 472 562 682 822 103 123 153 183 203 223 273 333 393 473 563 683 Identifying SIP resistor networks Setting up the XC-3 This procedure involves setting the DIP switches, as well as selecting and inserting SIP resistors into the appropriate sockets. Set switches 2, 9, and 10 to ON. The flowchart on the next page takes you through all the steps necessary before mounting the accessory to the amp. The illustration on the next page shows the locations of the sockets for the SIP resistor networks. The resistor networks have no polarity or directionality and therefore do not need to be inserted in any particular way, as long as each network pin goes into its own hole in the socket. XC-3 controls and switches 1 OFF ON 1 1 2 3 4 5 6 7 8 9 10 Use the tables at the top of this page to select the correct resistor networks for the settings you need. The SIPs supplied with the XC-3 provide a selectable frequency range for fXO of 80 Hz to 1.5 kHz, and delay settings from 0.3 to 1.8 milliseconds, plus bypass (no delay); contact QSC's Technical Services department if your application requires different settings. 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 HF boost = OFF HF boost = 2.5 dB HF boost = 5 dB HF boost = 7.5 dB HF boost = 10 dB 500 700 1k 2k 3k 4k 5k 6k 7k 8k 9k10k 15k 20k 30k 40k 50k Effects of high frequency boost on frequency response (crossover frequency = 500 Hz). A boost of +10 dB is most common for compensating for screen loss (attenuation of high frequencies as sound passes through screen perforations) and for constant-directivity horns. 5 J1 (fXO) 3-way Switches 7 & 8 = OFF 2- or 3-way? 2-way Switches 7 & 8 = ON Select fXO and fHP ; install appropriate SIPs in J1 (f XO ) and J7 (fHP ) Select fXO ; install appropriate SIP in J1 Install SIP (any value) in J7* No Switch 1 = OFF Need LF delay? Yes Switch 1 = ON J2 (LF delay) J7 (fHP) Install SIP (any value) in J2* Select delay; install appropriate SIP in J2 Locations of SIP sockets on the XC-3 When using the XC-3 in a three-way system in conjunction with the LF-3, the lower frequency (fHP) should match the crossover frequency of the LF-3 (fXO). The SIPs supplied with the XC-3 allow a selectable frequency range for fHP of 80 to 500 Hz. No Need HF boost? Yes 10 dB (CD horn) Switch 6 = ON; Switches 3­5 = OFF 7.5 dB Switches 3­6 = OFF Switch 3 = ON; Switches 4­6 = OFF 2.5 dB 5 dB FACTORY SIP SETTINGS fXO LF delay f HP 500 Hz (12K SIP resistor in J1) 1.8 ms (27K SIP resistor in J2) 80 Hz (68K SIP resistor in J7) Switch 4 = ON; Switches 3,5, 6 = OFF Switch 5 = ON; Switches 3,4, 6 = OFF *To ensure circuit stability Attach to amplifier Setup flowchart for the XC-3 FACTORY SWITCH SETTINGS Bi-amp mode (switches 7 & 8 = ON) LF delay active (switch 1 = ON) HF boost defeated (switches 3 through 6 = OFF) Switches 2, 9, & 10 = ON RECOMMENDED AMPLIFIER SETTINGS WITH THE XC-3 Clip limiters ON, both channels Stereo mode High-pass filter ON, both channels High-pass frequency 30 or 50 Hz, both channels 6 Setting up the LF-3 J8 (Ch. 1 fXO) J1 (Ch. 1 delay) This procedure involves setting the DIP switches, as well as selecting and inserting SIP resistors into the appropriate sockets. Set switches 2 and 4 through 9 to OFF, and switch 3 to ON. The flowchart below takes you through all the steps necessary before mounting the accessory to the amp. The LF-3 is typically used in a system in conjunction with the XC-3 crossover. For example, a stereo three-way system will require three DCA amplifiers, two XC-3 cinema crossover accessories, and one LF-3 lowfrequency cinema accessory, as shown on page 2. The typical input signal is full-range audio taken from the male XLR connector labeled "OUTPUT (TO LF-3)" on the XC-3. The illustration to the left shows the locations of the 1 2 3 4 5 6 7 8 9 10 OFF ON J6 (Ch. 2 fXO) J2 (Ch. 2 delay) Locations of SIP sockets on the LF-3 sockets for the SIP resistor networks. The resistor networks have no polarity or directionality and therefore do not need to be inserted in any particular way, as long as each network pin goes into its own hole in the socket. LF-3 controls and switches Select fXO for Ch.1 and Ch. 2; install appropriate SIPs in J8 (Ch. 1) and J6 (Ch. 2) Use the tables at the top of page 5 to select the correct resistor networks for the crossover frequency (fXO) and delay settings you need. The SIPs supplied with the LF-3 provide a range of frequency selections from 80 Hz to 500 Hz, and delay settings from 0.3 to 1.8 Yes No Switches 1 & 10 = OFF Install SIPs (any value) in J1 and J2* Need LF delay? milliseconds plus bypass (no delay); contact QSC's Technical Services department if your application requires different settings. When using the LF-3 in a three-way system in conjunction with the XC-3, the crossover frequency of the LF-3 (fXO) should match the lower high-pass frequency (fHP) of the XC-3. In most circumstances, the LF-3 would be used with an amplifier in stereo mode. But if two amp channels are needed for one low frequency signal, you can use the Channel 1 input Channel 1: Switch 10 = ON Channel 2: Switch 1 = ON Select delay for Ch.1 and Ch. 2; install appropriate SIPs in J1 (Ch. 1) and J2 (Ch. 2) Attach to amplifier *To ensure circuit stability Setup flowchart for the LF-3 of the LF-3 and parallel the inputs of the amplifier (using the amp's DIP switches). FACTORY SIP SETTINGS fXO Delay 350 Hz, both channels (18K SIP resistor in J6 & J8) 1.4 ms, both channels (22K SIP resistor in J1 & J2) FACTORY SWITCH SETTINGS Delay active, both channels (switches 1 & 10 = ON) Switches 2 and 4 through 9 = OFF; switch 3 = ON RECOMMENDED AMPLIFIER SETTINGS WITH THE LF-3 Clip limiters ON (both channels) Stereo mode; parallel mode in applications requiring dual LF amp channels with one source High-pass filter ON (both channels) High-pass frequency 30 or 50 Hz, depending on speaker (both channels)