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_^.,_.. ._.. ,..-I_
THE
POWER AMPLI
FIER
for ASSEMBLY
and OPERATION
CAUTION: IF THE FUSES BLOW,
SOME DISTORTED SOUND CAN BE
HEARD. THEREFORE IF AMPLIFIER
MALFUNCTIONS, ALWAYS CHECK
LM153
Please refer to this serial
FOR BLOWN FUSES FIRST.
number in all communications
$3.00
regarding this equipment.
THE DAVID HAFLER COMPANY
5910 Crescent Boulevard, Pennsauken, New Jersey 08109
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Power Rating: Less than 0.025% total harmonic distortion at any power level up to 255 watts continuous average power per channel into 8 ohms at any frequency between 20 Hz and 20 kHz with both channels driven. IM Distortion (SMPTE): Less than 0.007% from 1 watt to 255 watts into 8 ohms Typical THD at 255 watts into 8 ohms: 1 kHz-0.002%; 10 kHz-0.007% Frequency Response into 8 ohms: -3 dB, 0.5 Hz to 120 kHz at 1 watt kO.5 dB, 5 Hz to 40 kHz at 255 watts Typical Channel Separation at 1 kHz: 60 dB
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INTRODUCTION The Hafler DH-500 is a two channel audio power limitation at the input, all other stages are free of any trans- amplifier designed to the very highest performance stan- ient overload. dards. It is available as a kit, or factory assembled. Its The fully complementary, symmetrical push-pull circuit power rating of 255 watts per channel is very conservative, is direct coupled throughout (except at the input). It uses and it can deliver appreciably higher powers into impe- all silicon d
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INSTALLATION The DH-500 may be installed out of sight in many appli- A power transformer of this size puts out a noticeable cations, where its power can be controlled by the AC hum field, even though the special design of this trans- switching of a preamplifier control unit. However, any former minimizes such radiation. If the amplifier is to be high power amplifier may draw enormous amounts of cur- installed close to a record player, you should first check for rent, so you should make sure your
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If the manufacturer of your speakers recommends a appropriate size for your speakers. specific fuse value for their protection, you should obtain 3AG type fuses of that value and substitute them for the Loudspeaker Power Ratings ones supplied. The speaker fuses are included in the There are no U.S. standards for rating the power han- amplifier design solely for speaker protection. They do not dling capabilities of loudspeakers. As a result the manufac- protect, or affect, the amplifier ’s operat
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number of specialty speaker cables preferred by perfec- It is important that the red terminals never be connected tionists. If you have 4 ohm speakers, larger wire is recom- together when operating in stereo. Thus it is important that mended than for the typical 8 ohm speakers, too. you carefully observe the proper connections when using a common ground device, to be sure there is no reversal. The black output terminals are connected to ground in- In the special case where the amplifier has been
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4. Allow the connection to cool undisturbed. strands secured, and also makes a good connection easier. Simply touch the wire with the iron for a couple seconds, Remember that the connection is made by the solder, and apply solder. Allow the excess to flow away onto the not by mechanically attaching the wire to the terminal. iron. When properly done, the wire is uniformly bright, Usually the wire is looped through the lug and crimped in and no larger than before. The hookup wire supplied with pla
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4 0 Select the two input sockets and 4 sets of hardware. MECHANICAL ASSEMBLY Install the sockets at LS and RS inside the chassis 1 0 For security in shipping, the power transformer so that the short lug is nearest the hole in the chas- and the amplifier module have been fastened to the sis between the two sockets. chassis. Remove the chassis cover, the inner front panel and the larger front plate, and set these aside. 5 0 Select the single ground lug (with lockwasher Be particularly careful in h
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Select the plastic encased relay, the longer 19 q Select the two 2 amp fuses and install them in the 90 L-shaped mounting bracket, and 2 sets of hard- round fuse holdders on the back of the chassis. This ware. Insert the screws through the bracket with will keep the caps from being loosened and lost. the bracket foot pointing away from the lugs at the opposite end of the relay. ‘lighten this hardware se- This completes the basic mechanical assembly of the curely, but do not risk breaking the pla
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There are two gauges of wire supplied with the kit. For While excessive heat or careless “scrubbing” with the iron connections which pass substantial current, the heavier can lift the circuit foil from the board, more people tend to wire is used. Other connections need only the lighter gauge use insufficient heat, making it difficult for the solder to wire. Connect the wires to the bottom of the module from flow smoothly around the connection. A smooth, bright the right side, connection is im
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40 0 Prepare two 9” white wires. Connect one to eyelet 52 q Select the spade lug and connect it to the free end of #8 of the left board. (S). Connect the other to the white wire from LT lug 6. Place this wire to the eyelet #6. (S). Bend these toward the bottom, and left, and twist it lightly together with the green wire twist them together. from L T lug 3. 41 0 Prepare a 3” white wire and connect it to eyelet #3. (S). When connecting wires to the PC-9 circuit board note that the eyelets on this
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62 0 Prepare a 3” white wire. Connect one end to RY lug 74 q Select the yellow and black twisted pair from the #4. (S). Connect the other end to red output termi- left side of the module. Connect the black wire to nal LR. (S). the short ground lug of input socket LS. (S-2). Connect the yellow wire to the long lug of LS. (S). 63 [7 Prepare another 3” white wire. Connect one end to RY lug #6. (S). Connect the other end to output terminal RR. (S). 75 0 Select the red and black pair from the right s
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80 0 Select the triad of black, red and yellow wires from The wiring of the amplifier is now to be completed with the under the module. These will be connected to the installation of the power transformer and two disc right end of the terminal strip, and to prevent the capacitors. The following instructions refer to the 120 volt heat from the large resistors from melting the insu- transformer supplied for the USA. If your kit is supplied lation on the wires, connect the wires from behind with th
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102 0 Select the remaining sheet metal screws and the 97 0 Select the .Ol mfd disc capacitor and trim each lead cover. Before closing up the unit, plug it in an d to 3/4". Strip two 1/2" lengths of insulation from a check to see that the fan turns. Because it normally piece of heavy wire, and install these on the capacitor leads. Connect one lead to DB lug #l. operates at low voltage for low speed, a new fan may need a bit of encouragement at first. Any stiff- (S-3). Connect the other lead to DB
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CIRCUIT DESCRIPTION potentiometer PI. Thus the signal sees the bases of transistors The DH-500 amplifier components have been selected to pro- Q12 and Q13 tied together. Pl adjusts the voltage to bias the tect against failure, and all parts are operated conservatively to amplifier for Class AB operation, and therefore determines the assure unaltered performance and proper operation for many quiescent (idle) current in the driver and output stages. Complete years. The semiconductors have been tho
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All resistors are ‘1’4 watt 5% carbon film unless otherwise noted. part N,,. All capacitors are 100 volt minimum unless otherwise noted Part No. Rl 470,000 ohms RC044 2 mfd, 5OV, Film CPl15 Cl R2 1,800 ohms RC023 c2 330 pF, Film CPl34 CC 124 R3 47,ooO ohms RC043 c3 .Ol mfd, Film R4 47,000 ohms RC043 c 4 .OOl mfd, Film CP136 R5 560 ohms RC045 c5 .OOl mfd, Film CP136 R6 560 ohms RC045 C6 1 mfd, Film CC125 R7 47,000 ohms RC043 c 7 .I mfd, Film CC1 25 R8 560 ohms 470 mfd, 6.3V, non-polar Electrolyt
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AC LINE CONNECTIONS FOR OVERSEAS USE multi-voltage transformer is installed. This, the 600 oh m The power transformer supplied in DH-500 amplifiers sold in the USA is intended for 120 volt, 60 Hz operation only. For use resistors, the mounting hardware, and the alternate line fuse are in other countries, a multi-voltage transformer is supplied in supplied in kits which include this transformer. Export versions, available at higher cost. It has dual tapped The diagrams below show pictorially and
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SMALL PARTS ENVELOPE KIT PARTS LIST Part No. Minor variations may sometimes be encountered in value or appear- 2 Bracket, L-shape, 2” MS153 ance. These will not affect performance. Some of the hardware listed 1 Bracket, L-shape, 3” MS154 here has been used to secure parts for shipping the kit. 1 Capacitor, 0.005 mfd Disc CZ113 1 Capacitor, 0.01 mfd Disc cz112 Part No. 1 Capacitor, 0.39 mfd Film CE117 Chassis MS127 1 Diode, IN4003 QDll5 Cover MS126 1 Inrush Limiter RZ016 Front plate (rack mount)
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DH-502 INSTALLATION INSTRUCTIONS 1. 3 Disconnect AC power from the DH-500 and remove all connect- 10. Remove the rear rop screw securing the right channel amplifier ing cables. circuit board to the hear sink just above where the twisted pair was disconnected. Do nor lose the fiber spacing washer which is Remove the 17 screws which secure the cover along the top front, 2. 3 between the circuit board and the heat sink. This washer is not sides and rear. Set cover aside. DO NOT GRAB THE AMPLI- use
