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****** Page 2 ****** XEQ-2 ELECTRONIC CROSSOVER XEQ-2 ELECTRONIC CROSSOVER TABLE OF CONTENTS Section Sub-sect Description XEQ-2 Equalized Electronic Crossover 1.0 1.1 1.2 1.3 2.0 2.2 2.3 2.4 3.0 4.0 General Information Specifications General Servicing Information Repair Parts Disassembly Instructions Custom Frequency Calculation Module Construction Service Note Circuit Description Parts Lists Schematics PCB Assembly dwgs. Page 2 2 3 3 3 3 4 4 6 8 10 11 XEQ-2 EQUALIZED ELECTRONIC CROSSOVER 1.0 GENERAL INFORMATION The Electro-Voice XEQ-2 is a single channel equalized, electronic crossover. A plug-in 16 pin DIP module sets the crossover frequency. The module may be ordered from stock or custom made for non- standard crossover frequencies. By suitable strapping in the plug in module, the crossover slope.may be changed from 18 dB/octave to 12 or 6 dB/octave. The XEQ-2 can also provide required equalization for the Electro-Voice TL series low frequency 5/stems and HR series Constant Directivity horns. In addition, a third-order (18 dB/oct.) subsonic rolloff at 30 Hz is provided. TL series low frequency equalization is selected with a rotary snitch and HR eries equalization is selected via another 16 pin DIP module. A time delay control is provided which electron- icatly delays the low-frequency channel with respect to the high frequency channel. The amount of delay is continuously variable between 25 usec and 2 msec. Transformer balanced outputs are available as a user installable option. Instructions are packed with the transformer accessory (EV Model TRB-I ). one 1.1 SPECIFICATIONS Type: Equalized, electronic crossover Frequency Response: 30-20 kHz, ± 0.5 dB, -3 dB at 30 Hz sum of outputs, controls flat Noise Output: —90 dB V maximum re 1 V, 20 kHz noise bandwidth Total Harmonic Distortion: 0.02% typical, 0.1% max @ 20 kHz, t 20 dBm Overall Gain: 0 dB into high-Z load Minimum Load Z: 600 ohms Output Source Z: 47 ohms Input Configuration: Balanced or Unbalanced Input Z: 30 k balanced bridging, 15 k unbalanced Input CMR: 55 dB typical, 60—1 kHz Connectors: 1/4 inch tip-ring-sleeve phone jacks and X LR-3 RCA for low frequency summing Delay: Adjustable, 25 usec to 2 msec at 100 Hz low frequency output High Pass Filter: —3 dB at 30 Hz, 12 dB/octave Low Frequency EQ for Step-Down Operation of TL Bass Speakers: Second order, under-damped filter with switchable +6 dB boost frequency and flat position with 30 Hz rolloff Filter Type: Third-order Butterworth (18 dB/octave). See Table 1. Other orders and alignments by custom construction, high and low frequency crossover points independently chosen Plug-ln Horn/Driver Equalization: Flat module supplied, others listed in Table I HF Equalization: ± 4 dB at 10 kHz, Size: 1.73 inch x 19 inches x 4.875 inches Net Weight: 4.74 lbs Power Requirements: 90—120 V act 50-60 Hz, 8 W Accessories: Security Cover (supplied), TRB-I balanced output transformers, BMK blank module kit

****** Page 3 ****** XEQ-2 ELECTRONIC CROSSOVER 1.2 GENERAL SERVICING INFORMATION Most Electro-Voice circuitry is built around com- monly available IC operational amplifiers. A certain amount of familiarity with operational amplifier theory and operation will facilitate servicing this unit. Throughout this manual, the following con- vention will be used when discussing the various amplifier stages: Ul (1). This is to be interpreted as follows: Chip designation U 1, output pin = 1. The op-amp’s output pin is particularly significant because all of the unitis stages are referenced to ground. Thus, the normal quiescent voltage at any op-amp output is 0 volts dc, give or take a few millivolts. Any op-amp output that is not at 0 volts dc is suspect, especially if it is at or near one of the power supply rails. Beware: much of the circuitry is direct coupled. It is important to look backward towards the input to localize the exact cause of trouble. 1.3 REPAIR PARTS Service parts are available from the EV factory. Contact us by phone or mail. 2.0 DISASSEMBLY INSTRUCTIONS All circuitry is contained on one printed circuit assembly. Access the interior of the unit via the sheet metal screws securing the top cover. 2.1 B. c. D. E. 2.2 Main Board Removal Remove top cover screws and top cover. Remove all pot knobs and control nuts underneath. Disconnect the red power transformer connector. Remove screws from main PCB. Slide board toward rear of chassis until pots clear fron panel, lift up and out. Reverse this procedure to reassemble. CUSTOM CROSSOVER FREQUENCY CALCULATION Our address: Electro-Voice, Inc. 600 Cecil Street Buchanan, MI 49107—0186 (616) 695-6831 (8 am – 4 pm eastern time zone) If you are ordering parts and do not have the six digit part number, please include the model and serial number of the unit, the assembly part number and revision. The assembly part number/revision is a six digit, one letter code beginning with 800 that is rubber stamped on the parts side of the PCB assembly. In lieu of this information, the two digit/ one letter code etched into the foil side of the PCB is helpful. If you are ordering a control or switch, power, frequency, tell us the function name . . . input level, etc. In any event, be sure to include the following information: Your Name Shipping address (no post office boxes, please) City, State, Zip Daytime phone number Method of sh ipment (UPS ground if not specified) If you call us for assistance on/with a problem, please have the EXACT model number, serial and assembly part numbers handy. The XEQ-2 has maximally flat third-order Butter- worth filter characteristics when used with the supplied crossover frequency modules (800 Hz and 500 Hz). Other frequencies and characteristics are possible, with suitable choice of component values within the module. The component values for the “stock” modules are listed in Figure 2.3. The module supplies the tuning resistors (RHI, 2, 3, and RLI, 2, 3) for the high and low pass filters that make up the crossover portion of the XEQ-2. Since each is tuned separately, any combination of slope, overlap or underlap is possible. For sake of simplicity, information is given only for the case of the third-order Butterworth filters. This configuration gives a maximally flat response shape near the crossover frequency with 18 dB per octave slopes. This gives the best all around performance for the vast majority of applications. In the following formulas, f3 is the crossover fre- quency desired, sometimes referred to as the ‘kneet of the curve. Specifically, it is the frequency at which the response has been attenuated by 3 dB from the flat portion of the curve. When the f3’s of the low and high pass sections are made to coincide in frequency, as is usually the case, the total energy of the output channels, when added is independent of frequency/ thus providing ‘flat’ frequency response. Resistors R L 1, RL2 and RL3 determine the filter characteristic of the low pass filter section. Similarly, RHI, RH2, and RH3 determine the high- pass section filter characteristics. One-quarter watt film resistors having a resistance tolerance of 1% or two

****** Page 4 ****** XEQ-2 ELECTRONIC CROSSOVER 2% are recommended. In less critical applications, 5% resistors may suffice. MIL type RN55D resistors are easiest to use, however, conformally coated resistors may also be used. In the following formulas, R is given in ohms and f3 in Hertz. M stands for meg (as in megohm) LOW PASS SECTION RLI = 16.39 M/ (f3+6) RL2 = 116.97 M / (f3+6) RL3 = 21.03 M / (f3+6) HIGH PASS SECTION RHI = 24.32 M / f3 RH2 = 9.55 M / f3 RH3 = 167.3 M / (f3-7.6) After calculating the exact values, select the nearest standard value. For specialized applications (other slopes, and/or filter characteristics) consult the factory engineering department. 2.3 MODULE CONSTRUCTION Construct the module as shown in Figure 2.3. If you use other than molded case resistors (MIL type RN55D) make sure that the leads are free from coating material where they emerge from the body of the resistor. Use a low wattage iron, preferably with a small chisel tip. Flush cutting diagonal cutters will make installing the module cover easier. Temporarily installing the module in a spare dip socket helps keep the pins in alignment during soldering. Remember the jumper from pin 2 to pin 15. When finished, glue the cover on using ‘super glue’ or other suitable adhesive. SERVICE NOTE Early XEQ-2 units may experience intermittent outputs, for no apparent reason. Typically, this is caused by low line voltage, particularly when the ound system is stressed (asked to deliver large outputs). The culprit is the anti-thump relay, KI, intermittently dropping out, at the trough of the AC line voltage. To cure this problem, zener diode D 7 was changed from a 15 V, IN5245B to a 12 V, IN5242B. This lowers the drop-out threshold of the anti-thump relay. NOTES

****** Page 5 ****** 19] XEQ-2 ELECTRONIC CROSSOVER CROSSOVER MODULES POS. i 24K 19. 1K 26. EM-120 DESCR SC)QHZ 3C)üHZ SKHZ RL2 pos. 4 232K 147K 76. 16.5K poses RH2 POS.6 76. acnc.)76 so i c.)79 EQUALIZER MODULES POS. 1 BLANK BLANK BLANK BLANK &LANK POS. BLANK BLANK BLANE BLANE POS.2 JMFR JMPR JMPR JMPR JMFR JMPR pos. 2 BLANK BLANK J MFR BLANK BLANK BLANK 2.32K pos. 3 BLANE 100K Figure 2—3 0K • “-ilk: pcs. 5 4.7 SK DESCR HR—40 H R—60 FLAT HE—9040A 107S C) 72 801074 pos. 4 4B.7K ELANK 48.7K 2. 74K 1 . Z7K POS. BLANK ELANK BLANK BLANK BLANK BLANK POS. 7 340K 47. FOS. 7 JMPR 147K RHI pos.e 196K i 6. 2K 6.93K 3.48K pos.e 22. BLANK 4B. 7K 19. 4B.7K four

****** Page 6 ****** 8] XEQ-2 ELECTRONIC CROSSOVER CIRCUIT DESCRIPTION 3.0 INPUT DIFFERENTIAL AMPLIFIER 3.1 Input signals (balanced or unbalanced) are applied to unit gain differential amplifier Ul (2). Ul (2) buffers the input signal and presents a low source impedance to the active crossover filters. 3.2 ACTIVE CROSSOVER FILTERS Voltage follower IJI C3, C4, RHI, RH2, RH3 and R6 make up an active their order high pass filter. Resistors RHI, RH2 and RH3 control the corner frequency. Their values are computed as described in Section 2.2 of this manual. R6 ensures that CII (7) has a ground reference in the event that a crossover module is not plugged in to the front panel socket. Similarly, U2 RLI, RL2, RL3, C15, C16, C 17 make up an active third order low pass filter. RI-I, R12, and RL3 control the tuning. 3.3 HORN EQ When a constant directivity horn is used with a conventional compression driver, equalization is necessary to restore flat frequency response. This is because of the falling high frequency response of the compression driver and the constant direc- tivity horn’s lack of high frequency beaming. REI, RE2, C6 and C7 make up a bridged tee notch filter. RIO ensures that I-JS has a ground reference (through R8 and R9) if there is no equalization module plugged in. A similar network (RE4, RE-5, RE6, RE7, C8 and C9) is placed in the feedback loop of U5 (6)s. This results in a frequency response curve having a slight notch (caused by the C6/C7 network) followed by high frequency boost (C8/C9 network). Since all the resistors are plugged in via the equalization module, the overall curve may be optimized for many horn/driver combinations. 3.4 10 kHz EQ Both sections of 1.16 are used to provide a limited amount of high frequency EQ centered around 10 kHz. This allows modification of the high frequency curve provided by IJ5 and associated components for variations in individual drivers and personal taste. five L16 (1) is a simulated inductor. CIO series resonates with the simulated inductance at approximately 10 kHz. IJ6 (7) is the boost cut amplifier. When the wiper of the boost/cut pot R 15 moves toward R 14, the decreasing impedance of the series resonant circuit connected to R 14’s wiper causes a dip in the overall frequency response. When the wiper moves towards RI 7 i the feedback is shunted away at resonance, causing a peak in the frequency response. 3.5 HF OUTPUT AMPLIFIER U 7 (7) is the high frequency output amplifier. It uses a NE5534 as either a unity gain inverter or as a voltage follower. C 13 compensates IJ7 for unity gain. S 1, the phase snitch, determines which of the opamp’s differential inputs the input signal is applied to. 3.6 LOW FREQUENCY EQ IJ2 (1) is an active high pass filter. S2, the LF EQ switch, controls the cutoff frequency. In the FLAT position, IJ2 (1) becomes a second order (12 dB/ oct.) Butterworth high pass filter. At other positions, IJ2 (1) becomes an underdamped high pass filter. In an underdamped second order filter, a peak occurs in the frequency response just before the curve breaks away from flat response. Once past the peak frequency, the curve falls at 12 dB/octave. The peak frequency is noted in the switch markings on the front panel. The peak amplitude is approxi- mately 6 dB. 3.7 LOW FREQUENCY DELAY CIRCUIT IJ3 and IJ4 make up an allpass filter. This has the characteristic of frequency independent constant time delay up to a frequency defined as f = l/t where t = delay time in seconds and f = frequency in Hz. The frequency response is flat. IJ3 (7) is an inverting amplifier. Its input resistor is split in two to allow common bas mixing. By paralleling the junction of R35 and R36 with the identical point in another XEQ-2, the low frequency outputs are summed, for common (mono) bass appl ications. The output of IJ3 (7) is fed to IJ4 (6), which is also the low frequency output stage. IJ4 (6) is connected as an active phase shifter, with R39 controlling the phase shift. Overall positive feedback is applied via voltage follower IJ3 (1) and the associated RC networks.

****** Page 7 ****** XEQ-2 ELECTRONIC CROSSOVER 3.8 OUTPUT RELAY Both low and high frequency output amplifiers feed KI, a DPST reed relay. KI is delayed on at turn-on, but turns off instantly at turn-off. KI is powered from the raw dc power from. the bridge rectifier. Darlington transistor QI operates as a switch to energize KI’s coil. When power is applied, C41 charges through R56 until DTs zener voltage is reached. QI is turned on by the current through D7, closing the relay. On turn-off, C41 discharges quickly through D6 and the relay opens. BALANCED OUTPUT TRANSFORMERS 3.9 When the balanced output accessory is installed, transformers Tl and T 2 area connected to K I is outputs. They then feed the X LR output con- nectors. Both Tl and T2 are ratio, 600 ohm transformers. The installation instructions are packed with the transformers. 3.10 POWER SUPPLY The XEQ-2 requires ± 15 volts dc for operation. This is supplied by a regulated supply consisting of a full wave rectifier and two three-terminal regulator ICs. NOTES six

****** Page 8 ****** XEQ-2 ELECTRONIC CROSSOVER XEQ-2 MISCELLANEOUS PARTS Part Number 804209 804208 804037 800132 500704 500703 500702 500299 500200 5001 12 500107 500103 500102 500070 500050 460181 450238 450237 450236 450235 450234 450232 450231 450230 450229 450228 450227 450226 450225 450224 450208 450207 440138 440136 440134 440125 400065 400064 400051 303308 303121 303120 303107 303103 303030 301025 300103 300102 300084 Description XFMR assy, export X FMR assy, domestic Linecord PCB XEQ-2 Lckwshr, outside, CR, 7 mm Washer, appearance, 7 mm Nutr hex, 7MMX 0.75 mm SQSKTFH, 8X1/2 Screw, SM, blk PHP 8X1/2 Screw, PHP, biki 6X3/8 Screw, SM, Pl-IP, blk 6X1/2 Screw, blk, 6-32Xl/4 Screw, SCRU, blk, PHPt 6-32X3/8 SCRU, blk, PHPf 4-40X3/8 4-40X3/16 SCRU, Panel, Center, XEQ-2 crossover, 7 kHz Decal, Decal, crossover, 3.5 kHz Decal, crossover, 1.5 kHz crossover, 125 Hz Decal, crossover, blank Decal, horn EQW blank Decal, EO, flat EQ HR6040 Decal, EQ, HR40/HR60 Decal, EQ, SM120/HR120 Decal, EQ, HR90 Decal, EQ HR4020/HR9040 Decal, Decal, crossover, 800 Hz Decal, crossover, 500 Hz Cover, XEQ-2, screened Front panel, screened End panel, painted Chassis, XEO-2 painted Bracket, Power, XEQ-2 Plater adapter, ac pwr Knob, SM blk, w/line Cover, security, XEQ-2 Knob, pushbutton, grey Fuse, 32MA, slo blo Xprt Fuse, 1/16 A, slo blo Fuseholder, panel MT, dom Carrier, fuse, export Fuseholder, chass MT xprt Rubber feet Switch, RCKR, blk SPST Cover, dip plug, .40 high Dip plug, 16 pin Receptacle, ac pwr Part Number 007153 007103 007011 007010 007009 006021 005791 005790 005789 005788 005787 005786 005785 005784 005783 005782 005781 005780 005779 005778 005777 005776 005775 005774 005773 005772 005771 005770 005769 005768 005767 005766 005765 005764 005763 005762 005761 005760 005759 005758 005757 005756 005755 005754 005753 005752 005751 005750 005456 005432 005420 Description -15 v, 7915 ICt volt regt IC, volt +15 V, 7815 IC, single opamp, LF351 IC, dual opamp, LF353 single opamp, NE5534N Transistor, Darle 2N6427 RES, RES, R ESi RES, RES, MF, RN55D, RES, RES, MF, RN55D, RES, RES, RES, RES, MF, RN55D, RES, MF, RN55D, RES, RN55D, RN55D, MF, RN55D, 887 k R N 55D, RN55D, 162 k RN55D, MF, RN55D, 113k RES, MFt RN55D, 76.8 k ME-t RNS5D, MFt RN55D, 33.2 k MF, RN55D, 23.7 k RES, ME, RN55D, 16.9 k MF, RN5SD, MF, RN55D, 11.0 k MF, RN55D, 6.98 k MF, RN55D, RES, MF, RN55Dj 6.04 k RES, MF, RN55D, 3.48 k MF, RN55D, 3.01 k RES, MF, RN55D, 2.74 k MF, RN55D, 2.32 k MF, RN55D, 1.37 k RN55D, MF, RN55D, RES, MF, RN55D, k MF, RN55D, R N 55D, MFI RN55D, 68.1 k RES, MF, RN55D, 56.2 k RES, MF, RN55D, 39.2 k RES, MFI RN55D, 32.4 k RES, RN55D, 30.1 k RES, MFi RN55D, 26.1 k RES, MF, RN55D, 22.1 k MF, RN55D, 20.5 k RES, ME RN55D, 19.1 k RES, ME RN55D, 11.8 k RES, MFI RN55D, 3.92 k I .43M 196 k 124 k 47.5 k 16.2 k 14.0 k 6.34 k 4.64 k 340 k 232 k 147 k 100 k 48.7 k 41.2 k 4.75 k POT, PCB, Vert 5k LIN (B) POT, Dual, vert PCB 2xroo k POT, vert PCB 10 k LIN

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****** Page 13 ****** IE XEQ-2 ELECTRONIC CROSSOVER CF<OSSOVER MODULES DESCR i 2SHZ SOOHZ BOC'HZ . 5KHZ SEHZ 7. OEHZ 1 c.)77 BO C.) 79 ZOUALIZER MODULES DESCR HR.-SO FLAT FiOS. BLANK BLANK BLANK PQS. PLANK BLANK BLANK SLAt4k JMFF JHPR JMPR JMF•R J MPR POS. 2 BLANK BLANK JMF•R BLANK BLANK BLANK POS. 11.0b 2.32K pos. BLANK 1 CIOK RL2 POS. 4 een: 147K 76. en Z. 2K 16.9K RES POS. 4 4e.7K FLANK pos.s POS. S 4. 75k 4. 75K 92k: HR-4Cj20A HR-12t:j sy—120 HR-6040A C) 72 801 C)74 RH2 pos.b 76. 19. 11.8} 2.74K 1.37K 70S.6 BLANK BLANK BLANK SLANK BLANK BLANK RHJ POS. 7 21 47. SK 23. 7K FOS. 7 06. 100K 1K 147k Figure 2 -3 Rhi POS.g 196k 48.7K 6.98K POS. e 26. 1K 7K 19.1K 4 a. 7K four








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