User manual CROWN DC-300A
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Manual abstract: user guide CROWN DC-300A
Detailed instructions for use are in the User's Guide.
[. . . ] 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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