User manual CROWN DC-300A

[. . . ] warrants to you, the ORIGINAL PURCHASER and ANY SUBSEQUENT OWNER of each NEW Crown1 product, for a period of three (3) years from the date of purchase by the original purchaser (the "warranty period") that the new Crown product is free of defects in materials and workmanship, and we further warrant the new Crown product regardless of the reason for failure, except as excluded in this Crown Warranty. NORTH AMERICA SUMMARY OF WARRANTY The Crown Audio Division of Crown International, Inc. , 1718 West Mishawaka Road, Elkhart, Indiana 46517-4095 U. S. A. warrants to you, the ORIGINAL PURCHASER and ANY SUBSEQUENT OWNER of each NEW Crown product, for a period of three (3) years from the date of purchase by the original purchaser (the "warranty period") that the new Crown product is free of defects in materials and workmanship. We further warrant the new Crown product regardless of the reason for failure, except as excluded in this Warranty. ITEMS EXCLUDED FROM THIS CROWN WARRANTY This Crown Warranty is in effect only for failure of a new Crown product which occurred within the Warranty Period. [. . . ] Input and output grounds are sometimes tied together for testing or metering. This can cause feedback oscillation from load current in the test loop. In some systems, even the AC power line may provide this feedback path. Proper grounding, input isolation and isolation of common AC devices in the system is good practice. HOW TO DETERMINE APPROPRIATE WIRE GAUGE It is important to use loudspeaker cables of sufficient gauge (thickness) for the length used. The resistance introduced by inadequate loudspeaker cables will reduce both the output power and the motion control of the loudspeakers. The latter problem occurs because the damping factor decreases as loudspeaker cable resistance increases. This is very important because the amplifier's excellent damping factor can easily be negated by using insufficient loudspeaker cables. Use the nomograph and the procedure that follow to find the recommended wire gauge (AWG or American Wire Gauge) for your system. 40 RL LOAD RESISTANCE (ohms) 30 RS DAMPING FACTOR 100 20 50 . 4 . 6 15 20 1 10 2 . 2 RL . 04 . 06 . 1 RS SOURCE RESISTANCE (ohms) 8000 5000 (ohms/1000 ft. ) 1000 2-COND. CABLE (feet) 5 10 20 50 100 200 500 10 9 2 8 7 1 6 10 6 5 20 5 1000 2000 4 5000 1 . 5 5 100 50 500 ANNEALED COPPER WIRE (AWG) #28 #26 #24 #22 #20 #18 #16 #14 #12 #10 #8 #6 #4 #2 #0 #00 #0000 10 Input Wiring Tips 1. Crown is not liable for injury or damage due to overdriven components. . 1 . 05 4 40 . 01 3 Example Shown: RL = 8 ohms; R = 0. 16 ohms or D. F. Note the load resistance of the loudspeakers connected to each channel of the amplifier. Always take the precaution of installing a high-pass filter on the amplifier inputs when a predominantly inductive load is used. A three pole (18 dB per octave) filter with a ­3 dB frequency of 50 Hz is recommended. (Depending on the system, it may be preferable to use a filter with a higher ­3 dB frequency. ) Such a filter can eliminate the subsonic frequency problems mentioned in Section 3. 3. 2. Another way to prevent the amplifier from activating its protection systems early and protect inductive loads from large low-frequency currents is to connect a 590 to 708 µF nonpolarized capacitor and a 4 ohm, 20 watt resistor at the output of the amplifier in series with the positive (+) lead of the transformer. This is depicted in Figure 3. 8. 4-ohm, 20-watt Resistor Use Good Connectors 1. To prevent possible short circuits, do not use loudspeaker cables with exposed male connectors. Do not use connectors that might accidentally tie two channels together when making or breaking connections, such as a standard three wire stereo phone plug. Do not use connectors with any tendency to short. + From Amplifier Output 590 to 708 µf Capacitor 120 VAC, N. P. + Inductive Load ­ ­ SOLVING OUTPUT PROBLEMS Sometimes high frequency oscillations occur which can cause your amplifier to prematurely activate its protection circuitry, resulting in inefficient operation. The effects of this problem are similar to the effects of the RF problem described in Section 3. 3. 2. Lace loudspeaker cables together to minimize the chance of them acting like an antenna to transmit or receive high frequencies that can cause oscillation. 3. 8 Inductive Load (Transformer) Network Note: The components shown in Figure 3. 8 are commonly available from most electronic supply stores. 3. 3. 4 Additional Load Protection Because your amplifier can generate enormous power, you may want to protect loudspeakers or other sensitive loads from excessive power that could result in damage. [. . . ] But some systems require their gain structures to be calculated based on a 0. 775 volt sensitivity, while others cannot deliver the voltage required to achieve full output. In these situations, your amplifier's 0. 775 volt input sensitivity setting offers a solution. A Crown Service Center W26 D7 R1 C5 D1 D2 R2 R4 Z1 D3 C7 D5 D100 R109 C108 R120 D103 Q106 L102 C4 W19 L202 D102 Q100 X26 R146 R22 R246 W29 W31 C6 H9 U200 Q201 C203 D101 R118 H4 R219 Q101 X16 C103 C8 D112 R113 H3 R147 W1 R102 U100 C106 W20 W24 R209 R3 C200 D107 C120 W28 D113 R157 D4 W32 W23 R158 C100 C109 D106 C105 R258 Q206 R110 R123 C114 W10 D104 D105 Z7 Q102 R202 R257 C219 R250 C220 R247 R222 R201 D213 X24 Q104 R106 R10 W5 W9 R218 D201 D203 R206 C208 C119 W2 R119 W30 R220 H5 R223 R105 D212 W11 Q105 R205 W17 W12 R128 Q202 W13 R210 C205 D202 R214 C111 Z4 R213 W6 D200 Q220 R153 R127 R122 C212 D204 D205 C209 Q200 R221 R152 R212 R24 Q121 Q119 Q103 D206 C206 L200 C213 R117 X27 X17 C210 Q207 R227 W16 R224 Q203 U1 R228 R229 R156 R126 L100 R252 C118 R254 D108 W22 D208 R226 Q204 X14 R151 C110 W15 C214 R26 R256 R215 R25 C218 Q219 Q221 W18 R253 R129 W21 R217 R216 W7 W3 R251 H1 C211 H2 Z6 Z99 Z5 Q205 W14 H11 R230 C221 R225 C121 R125 R130 Fig. 7. 1 Main Circuit Board (Component Side) and Input Sensitivity Jumper Locations Page 23 C113 D207 Z10 R154 W8 Q107 R121 W4 C112 R115 R116 R8 W27 R124 H6 Q120 R150 DC-300A Power Amplifier 8 Service This unit has very sophisticated circuitry which should only be serviced by a fully trained technician. 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