1 _^., . ,..-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 $ regarding this equipment. THE DAVID Hafler COMPANY. 5910 Crescent Boulevard, Pennsauken, New Jersey 08109. DH-500. POWER Rating: Less than 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.
2 IM Distortion (SMPTE): Less than from 1 watt to 255 watts into 8 ohms Typical THD at 255 watts into 8 ohms: 1 ; 10 Frequency Response into 8 ohms: -3 dB, Hz to 120 kHz at 1 watt dB, 5 Hz to 40 kHz at 255 watts Typical Channel Separation at 1 kHz: 60 dB. Signal to Noise Ratio: Exceeds 100 dB referred to 255 watts into 8 ohms, unweighted Exceeds 90 dB referred to 1 watt into 8 ohms, A weighting Input Impedance: 47,000 ohms Input Sensitivity: volts for 255 watts into 8 ohms; volts for 1 watt Damping Factor: 200 to 1 kHz into 8 ohms; 60 to 10 kHz into 8 ohms Rise Time: 10 kHz, 80 volts p/p square wave, 10% to 90%: us.
3 Slew Rate: 1 kHz, 120 volts p/p square wave: 45 V/us. Semiconductor Complement: 27 transistors, 12 POWER Mosfets, 33 diodes, 8 zener diodes, one integrated circuit, one diode bridge. POWER Consumption: 240 VA quiescent; 1200 VA @ rated POWER into 8 ohms, 2 channels Size: 7-l/4 high, 19 wide, 13 deep including handles Net Weight: 45 lbs. Shipping Weight: 49 lbs. CAUTION: For continued protection, replace the POWER fuse only with the same type and rating as indicated. WARNING: TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS EQUIPMENT.
4 TO RAIN OR MOISTURE. 0 Copyright 1987. All rights reserved. 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 POWER rating of 255 watts per channel is very conservative, The fully complementary, symmetrical push-pull circuit and it can deliver appreciably higher powers into impe- is direct coupled throughout (except at the input).
5 It uses dances below the rated 8 ohms. You must be very cautious all silicon discrete devices in a format which is directly re- in the application of this AMPLIFIER , as its output capability lated to the acclaimed Hafler preamplifier circuit. With its is more than most speakers can safely tolerate. We urge unconditional stability into virtually any load, and its you to read the Operation section of this manual so your enormous POWER capability, the result is complete freedom speakers will be reasonably protected.
6 The best protection from listening fatigue. The longer you listen to this re- is still common sense in choosing program levels which markable AMPLIFIER , the more certain you will be that you your speakers can tolerate. could not have made a better choice. While modest in cost, through the elimination of frills The DH-500 combines POWER MOSFET technology and gadgetry, the quality is evident not only in the sound, with a uniquely simple and effective circuit which reduces but in the conservatively rated components.
7 The over- all types of distortion at all POWER outputs, over the entire sized POWER transformer, the conservative operating levels audio spectrum, to levels where the finest test equipment of the MOSFETs, the computer-grade electrolytics total- has great difficulty in measuring it. The DH-500 sets a new ling 40,000 microfarads, the enclosed relay, the use of film high in reliability and resistance to abusive operating con- capacitors in signal circuits-all are evidence of the design ditions at such high powers.
8 This is one of the direct ben- efforts to achieve exceptional reliability simultaneo'usly efits of the POWER MOSFET's ability to current limit under with state of the art sonics and specifications. So rugged is abnormal conditions. the DH-500 that it can deliver over 20 amperes into a short circuit! Where the conventional bipolar transistor must be pro- tected by special circuits from entering thermal runa- For those with special POWER needs, the DH-500 can be way when it gets hot due to heavy signals, tending to get adapted to monophonic operation, delivering in excess of even hotter, the MOSFET self-corrects to reduce the cur- 800 watts into 8 ohms, by installing the DH-502 input rent, and thus the heat under the same conditions.
9 You bridging kit. thus gain the dual advantages of simpler circuitry and the elimination of one of the chief causes for distorted signals Those who have chosen to build this AMPLIFIER from the imposed on the music-the sound of the actuation of com- kit will find the assembly instructions assume no technical plex protective circuits. ability other than how to make a good solder connection. Even that has been described for those who are new to the The speed-measured as the slew rate-of the DH-500 fun of kit building.
10 Through pre-assembly and testing of delivers unmatched transient linearity, revealing the most the complete signal module, the performance of the kit has delicate nuances of the music. In refining the basic Hafler already been assured, for assembly involves little more MOSFET circuit the overall open loop gain was reduced than interconnection of the POWER supply and control ele- by using more local feedback in the input stage. This re- ments. You can look forward to just a few hours of con- quired less compensation to stabilize the circuit, with the struction fun, to hear the finest audio AMPLIFIER yet pro- result that it was faster overall.