w crolun INSTRUCTION MANUAL SERIAL NO ISSUED DC-300A DUAL CHANNEL LABORATORY AMPLIFIER CROWN INTERNATIONAL, INC.
0 w crown In-runaTlonac BATCH I D Proof of Performance Report SERIAL NO DCA-11 020163 DC-300A laboratory power amplifier Serial Number Line Voltage Requirement\ao,VAC Amcron Label 1. Quies. offset of less than 1OmV 2. 1 KHz 180 watts RMS minimum into 8 ohms, per channel, both channels operating, 0.1% total harmonic distortion 3. 4 ohm test CH.l CH.2 J J 4. Protection tests 5. Reliability test 6. 20KHz 1 5 5 w a t t s p e r c h a n n e l minimum RMS (both channels operating) into 8 ohm.
‘TOTAL PERFORM A N CE CROWN test and check-out procedures reflect our basic design IS WHAT COUNTS" 4. Protection Test - This is a test with a 2 ohm load which determines the threshold at which the protection circuitry will be activated. Sharp clipping should occur with no evidence of instability. The positive and negative limiters operated independently and therefore may not be activated simultaneously. 5.
TABLE OF CONTENTS Section 1 1 .1 1.2 1 .3 PAGE DESCRIPTION General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-l 2-2 2-3 2-4 2-5 2-6 2-7 2-8 2-9 2-10 3-l 3-2 3-3 3-4 3-5 Maximum Output vs. Load Impedance ............................................................................ output (Z) ............................................................................................................................ output IL I.. ........... . .............................................................................................................. Mounting Dimensions ............................................
Section 1 DESCRIPTION 1 .1 GENERAL DC-300A PICTORIAL The DC-300A is a dual-channel high-power amplifier for precision amplification of frequencies from DC to 20KHz. The unit features extremely low harmonic and intermodulation distortion, very low noise, highest “damping factor,” and quality parts and workmanship. Because of the large output power, It is possible to obtain a monaural 70-volt balanced line without using an output transformer.
1.2 SPECIFICATIONS 1.2.1 STEREO SPECIFICATIONS Output Power 155 watts per channel minimum RMS (both channels operating) into an 8 ohm load over a bandwidth of 1 Hz-20KHz at a rated RMS sum total harmonic distortion of 0.05% of the fundamental output voltage. Frequency Response ±0.1dB DC-20KHz at 1 watt into 8 ohms; ±ldB DC-100KHz. 1 KHz Power 180 watts RMS into 8 ohms, per channel, both channels operating, 0.1% total harmonic distortion. Harmonic Less than 0.001% from 20Hz-400Hz.
1 . 2 . 2 MONAURAL SPECIFICATIONS Output Power 310 watts minimum RMS into a 16 ohm load over a bandwidth of 1 Hz-20KHz at a rated RMS sum total harmonic distortion of 0.05% of the fundamental output voltage. Frequency Response ±0.15dB, DC-20KHz at 1 watt into 16 ohms; ±1 dB, DC-6OKHz at 1 watt into 16 ohms. 1 KHz Power 360 watts RMS into 16 ohms. Harmonic Distortion Less than 0.001% from 20Hz-400Hz and increasing linearly to 0.05% at 20KHz at 310 watts into 16 ohms. I.M. Distortion Less than 0.
4 1.2.3 GENERAL SPECIFICATIONS Hum and Noise (20Hz-20KHz) 110dB below rated output Phase Response +0, - 1 5 ° Zero to 20KHz at 1 watt Input Impedance 100K ohms at minimum gain, 10K ohms at maximum gain. Amplifier Output Protection Short, mismatch, and open circuit proof. Limiting is instantaneouswith noflyback pulses, thumps, cutout, etc. No premature limiting on transients. Overall Protection AC line fused. Thermal switch in AC line protects against overheating caused by insufficient ventilation.
10 TO DC 1K 100 10 10K 1OOK FREQUENCY (Hz) 60 10 100 1KHz FREQUENCY (Hz) 1OKHz 1OOKHz
Section 2 INSTALLATION 2.1 UNPACKING As soon as the amplifier shipment is received, please inspect for any damage incurred in transit. Since the unit was carefully inspected and tested at the factory, it left the factory unmarred. If damage is found, notify the transportation company immediately. Only the consignee may institute a claim with the carrier for damage during shipment. However, CROWN will cooperate fully in such an event.
CONTROL CENTER 3 to 2 WIRE ADAPTER / RIGHT SPEAKER SWITCHED OUTLET / POWER CABLE _ JJ lb--- CABLE TIE(S) SHIELDED AUDIO CABLES Or A o’hl TO ¼ " PHONE 7 MONO-STEREO SWITCH LEFT SPEAKER ) MDP PLUGS DUAL BANANA NOTE! / IN-LINE FUSES FIG. 2-2 NORMAL HI-N HOOK-UP 2.4 CONNECTING OUTPUT LINES Input and output connectors are located on the back of the chassis as shown in Fig. 2-3.
15 5000 RL LOAD 8000 7. .04 40 Rl 30 RESISTANCE R, s-.06 - R, SOURCE ~MOOO ft.1 -- ANNEALED - - .l DAMPING RESISTANCE (ohms) 2-COND. CABLE 1000 T COPPER 500.- WIRE -- IAWGI 20 50.---t24 15 10 9 8 7 6 5 4 FIG. 2-4 SOURCE RESISTANCE AND DAMPING FACTOR VS. LENGTH AND SIZE OF OUTPUT LEADS is provided for wire selection.
16 2. Connectors which might accidentally cause the two channels to be tied together during making and breaking of connection should not be used. A common example is the standard 3-circuit l/4 inch phone jack and plug when wired for stereo sound. 3. Connectors which can be plugged into AC power receptacles should never be used. 4. Connectors having low-current-carrying capacity 2. Connect output lines as per the following drawing, Figure 2-7.
the effect of the size of the blocking capacitor on the frequency response. Only a low-leakage type paper, mylar, or tantalum capacitor should be used for this purpose. power line may provide this feedback path. Proper grounding, and isolation of inputs of common AC line devices is good practice. Refer to Section 4.2, par. 5 for testing precautions. An extremely common form of this problem is encountered when using electrostatic loudspeakers or any other kind of load that is joined to the AC power mains.
In order to change the voltage, it is first necessary to carefully detach the bottom cover from the unit. On the back of the board-mount subchassis a terminal stripwith solder- on jumpers is used to make the line-to-transformer primaries connections (see Fig. 2-10). ALL VIEWS WITH BOTTOM PLATE REMOVED 1oov I I I I 120v See Note 2oov 220 v L I 2 4 0 V See Note I NOTE: The 120V and 240V connections require the changeover of the RED wire from TB-3 to TB-2.
Section 3 OPERATING INSTRUCTIONS 3.1 CONTROLS AND ADJUSTMENTS OPERA TING CONTROLS The DC-300A contains all the facilities essential for a 3.2 THE PROTECTION MECHANISMS high performance amplifier. The DC-300A is protected against all the common On the front panel are located independent level controls, hazards which plague highpower amplifiers, including a power switch, and pilot light.
A current limiter will not yield to the load butwill sustain the constant current demands of the inductive load without flyback. Early amplifier designs frequently employed fixed current limiters but had serious difficulty with obtaining reliable low frequency output while being capable of full-voltage 4 ohm output. Also, many earlier designs used fragile epibase or triple diffused outputs, which for reliable performance are poor mates for a current limiter protection scheme.
The fuse inherently protects the power supplies against overload. The AC line for 100, 120VAC is fused with a 1 OA 250V type A6 fuse (on 200, 220, 240VAC, 5A type MTH 250V). The use of any other size fuse will invalidate the warranty. Never change fuses with power applied! On each heat sink (see Fig. 2-2) is mounted a thermal switch which protects the amplifier against insufficient ventilation.
400 300 t 200 --7 A common problem which causes damage and irritation is the turn-on thump problem typical to many signal sources. Fig. 3-5 shows the schematic of a muter which, when inserted in the input signal line, mutes for several seconds before connecting the source to the amplifier, thereby eliminating turn-on transients. It also removes turn-off transients occurring after the relay drops open (=O.l sec.). Emmpl.: z:sn AllStir: a-9 l-- --10 N ” a W;; ..14 y E 43 ..16 g UJ e-20 ..
Section 4 CIRCUITRY bias current in the output transistors. The result is maximum efficiency with minimum crossover notch distortion and amplifier idling-heat. Thus there is no bias current adjustment, as the output circuit is not temperature-tolerance critical. Temperature drifts of bias are further controlled by bias servos which are mounted on the heat sinks. 4.
24 4.2 TEST PROCEDURES 8. Residual distortion and noise levels should be fully known for all the test equipment in order to accurately The sole function of this section is to list precautions evaluate the amplifier. essential to obtaining accurate measurements when dealing with high-power, high-purityamplifierssuch astheDC300A. 1. Use the proper line voltage, which is the one for which the amplifier is connected.
Section 5 APPLICATION NOTES APPLICATION NOTE NO. 1 V-l LIMITS OF A LOAD In applications where the input is sinusoidal and of small proportional frequency deviation, a relatively stable load may be resonantly tuned to present a real value of impedance to the amplifier. Evaluating the V-l (volt-ampere) needs of a load: Many loads exhibit large reactances (or energy storage), which limits a power amplifier’s ability to deliver a maximum power.
APPLICATION NOTE NO. 2 VFX-2 The CROWN VFX-2 is a dual-channel variable electronic filter-crossover. When used with a power amplifier it can greatly add to the total system capability. In combination with the DC-300A, the VFX-2 adds several convenient useful functions. The connections are made with the VFX-2 quickly and easily. If a balanced line is to be used with the unbalanced input of the DC-300A. the VFX-2 can serve asthe interface.
29 APPLICATION NOTE NO. 3 fairly share the responsibility, and since the protection cannot be exhaustively provided any other way, we feel WARNING that speaker manufacturers should provide protection tailored to their individual products.
PARTS LIST, DC-300A Page 1 Schematic Designation ClOO,
PARTS LIST, DC-300A Page 2 Schematic Designation Description Crown Part # RllO, R210 RlO 10K ohm V’Z watt 1% Film 2343 R112, R212 R5 8.2K ohm l/4 watt 10% 2877 R113, R213 5.6K ohm l/4 watt 10% 3220 R114, R214 68K ohm l/4 watt 10% 3620 R115, R215 R121, R221 820 ohm l/4 watt 10% 3301 R116, R216 82 ohm l/s watt 10% 3300 R117, R217 470 ohm VI watt 10% 2626 R118, R119, R124, R125, 120 ohm V’Z watt 5% Film 3837 R120, R220 R123, R223 15K ohm Y’z watt 10% 1064 R122, R222 R3 3.
PARTS LIST, DC-3OOA Page 3 Description Crown Part # QlOO, Q200 0101, Q201 MPSA93 3578 Q102,0202 Q105,0205 01 2N3859A (selected) 2961 Q104,0204 NSDI 28 4061 Q106.
PARTS LIST, DC-300A Page 4 Schematic Designation Description Crown Part # Other Information Captive stud, #lo x 1 l/4 3636 Used to mount coil assy. Nylon washer 3609 One used on each side of coil Nylon spacer 2762 Used in center of coil; over stud 3636 #lO internal star lockwasher 2279 To mount coil Hex nut, lo-32 2170 To mount coil Solder lug 806, #lO 3312 Mounted under nut; under coil HEATSINK BOARD ASSY. 41207 DC-300 heatsink 3561 Heatsink PC board 7954u Capacitors Cl 15.
PARTS LIST, DC-300A Page 5 Schematic Designation QllO,Q210 0111,0211 0112, Q212 Q113,0213 0115, 0215 Q116.0216 0117,0217 0118, Q218 Description Sel.
PARTS LIST, DC-300A Page 6 Description Crown Part # Other Information Brass tube 3637 To mount power switch 6-32 x 1 j/4 BHP screw 3634 To mount power switch G-6-G terminal strip 3503 Mounted on shield 6-32 x % BHP screw 2134CAD To mount terminal strip 6-32 hex nut 1889 To mount terminal strip G-6-G insulator 3600 Under terminal strip #6 internal star lockwasher 1823 To mount terminal strip l/4” expansion nut 2544 Mounted on shield in square holes #8 x 5/e SMT hex screw 2757 Us
PARTS LIST, DC-300A Page 7 Schematic Designation F2 Description Crown Part # #6 internal star lockwasher 1823 6-32 hex nut 1889 6-32 x % BHP screw 2176 1 O-24 x 3/ self-tap screw 4035 ABC 12A internal fuse (CSA) HTA fuseholder Fuse block Fl 1 OA 3 AB fuse Fl 5A ABC fuse Strain relief 112A 2-conductor hi-D jax 3/8” fiber shoulder washer Fiber flat washer Dual binding post #6 solder lug, 505 250 faston terminal 250 faston terminal housing C116, 216 5 MF, 7OV Cl 18, 218 .
