THE PREAMPLIFIER DH-110 INSTRUCTIONS for ASSEMBLY and OPERATION LM132 $3.00 THE DAVID HAFLER COMPANY 5910 Crescent Boulevard, Pennsauken, New Jersey 08109 Please refer to this serial number in all communications regarding this equipment. DH-110 SPECIFICATIONS The numbers in parentheses refer to the paragraph in the IHF specifications manual which defines the test procedure. PHONO PREAMP SECTION Rated Output: 3 Wms, 8 Hz-105 kHz Maximum Output (3.5): 12 Vrms, 20 Hz-20 kHz at recording output Total Harmonic Distortion: Less than 0.0006% @ 1 kHz, 3 Vrms Frequency Response (3.13): +0, -0.25 dB, 20 Hz-20 kHz RIAA Equalization Accuracy: +0, -0.1 dB, 30 Hz-15 kHz Full Power Bandwidth: -6 dB, 4 Hz-210 kHz Sensitivity (3.7): 12.5 millivolts Maximum Input Signal @ 1 kHz (3.8): 300 millivolts; [3 V @ 20 kHz] Gain: 34 dB @ 1 kHz Input Impedance: 47,000 ohms in parallel with 30 pF; user adjustable. Plug-in capacitors are installed to increase this to 150 pF on Phono 1; 250 pF on Phono 2 Signal to Noise, weighted (3.12): 87 dB Slew Rate: 12 volts per microsecond LINE AMPLIFIER SECTION Rated Output: 3 Vrms, 4 Hz-210 kHz Maximum Output (3.5): 14 Vrms, 20 Hz-20 kHz Total Harmonic Distortion (3.4): Less than 0.001%, 20 Hz-20 kHz Frequency Response (3.13): +0, -0.1 dB, 20 Hz-20 kHz Full Power Bandwidth: -6 dB, 2 Hz-420 kHz Sensitivity (3.7): 50 millivolts Maximum Input Signal @ 1 kHz (3.8): 14 Vrms; volume control @ -20 dB Gain: 20 dB ± 1 d B Input Impedance: Greater than 25,000 ohms Signal to Noise, weighted (3.12): 90 dB Slew Rate: 12 volts per microsecond Rise Time: 2.5 microseconds maximum, Phono in / Line out, 10 Vp-p, 1 kHz square wave; load is 10,000 ohms in parallel with 10 nF Crosstalk (3.14): down 72 dB, any input to any output Separation (4.2): greater than 82 dB @ 1 kHz; greater than 52 dB @ 20 kHz Gain Tracking Error (4.4): less than 0.5 dB Maximum Output Noise: less than 350 microvolts, wideband less than 95 microvolts, `A' weighted [with 1 Kohm input termination, volume full CW] Bass Control: 217 dB @ 20 Hz, moving inflection, variable turnover Treble Control: ±17 dB @ 20 kHz, shelving @ 5 kHz, fixed turnover Filter Response: -3 dB @ 25 Hz; -6 dB @ 15 Hz; -12 dB @ 8.2 Hz; -25 dB @ 3 Hz Filter Cutoff (3.13.2.2.1; 3.13.2.2.2): 25 Hz; -12 dB/octave GENERAL SPECIFICATIONS Semiconductors: 30 transistors, 3 ICs, 12 diodes, 2 LEDs Inputs: 2 Phono, Tuner, Compact Disc or Video, 2 Tape recorders, EPL Outputs: 2 Tape (buffered), 2 Line, EPL, Headphone Jack Controls: Volume, Balance, Bass, Treble, Input Selector, Phono l/2 Selector, Monitor Selector, Mono-Stereo, Filter, External Processor Loop, Tone Control Engage, Power Intermodulation Distortion: Both SMPTE and CCIF IMD at operating levels from phono input to line output are below the residual of currently available instrumentation AC Supply Voltage: 100-130 and 200-260 VAC, 50/60 Hz Power Consumption: 3.5 watts AC Convenience Outlets: 3 switched, 5 amp continuous, 72 amp surge 1 unswitched, 5 amp continuous Size: 17" wide x 3" high x 8½" deep 19" rack mounting accessories included Shipping Weight: 12.5 lbs. Net Weight: 10 lbs. 2 © Copyright 1985. All rights reserved. INTRODUCTION Your preamplifier is the control center of your music system, acting as an interface between the sound sources-record players, tape recorders, FM and Video tuners-and the power amplifier which drives the loudspeakers. As the focal point of your system, it should be attractive and easy to use, versatile and yet functionally unobtrusive. It should contribute a minimum of noise or distortion while providing signal amplification, control of the signal level, and applicable modification of the frequency response. The DH-110 achieves all these objectives with great versatility, providing for two record players with magnetic cartridges, two tape recorders, a tuner, and an additional stereo input for a compact (digital audio) disc player or video audio. It also includes inputs and outputs for an external signal processor such as a graphic equalizer, time delay device, or noise reduction unit. The performance of the DH-110 is exemplary, and its assembly from an array of discrete components of exceptional quality should ensure reliability and longevity of its capabilities. Precise interchannel balance at all frequencies is maintained with close tolerance components, and RIAA phono equalization is engineered to very narrow limits, maintaining accurate phase relationships and correct spatial perspectives, as well as exceptional unit-to-unit consistency. The tone controls, which can provide contouring of response for individual needs when switched in, are normally isolated from the circuit for ruler-flat response. The components in the DH-110 have been selected for their superb audio performance as well as for their reliability. They have been incorporated in the unique Hafler fully complementary symmetry push-pull circuit in a carefully designed circuit board layout which reduces crosstalk and maintains separation for a synergistic audio result that defies comparison, regardless of cost. Those who have chosen to build the kit will find that its step by step instructions will ensure a properly working unit even for the novice builder. A substantial amount of preassembly has enabled us to check out each kit in nearly every aspect of performance, and makes the DH-110 a particularly fast, easy and enjoyable construction project, which you will likely complete in one evening. We suggest that you read the installation and operation sections of this manual carefully, even though much may be familiar to you. There are some subtle and significant points which may be new, and their proper appreciation will enable maximum satisfaction with your DH-110. We wish you to have the very best in sound. Exceedingly low noise and distortion is a hallmark of the DH-110. Noise is essentially inaudible in the absence of a signal, and distortion of all types, both steady state and transient, is at or below the threshold of the finest measurement capabilities. These excellent characteristics are maintained far outside the customary 20 Hz to 20 kHz band, and signals well beyond that are handled without the need to restrict bandwidth. CONTENTS Installation . . . . . . . . . . . . . . . . . . . . . . . . . . Page 4 .5 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Assembly Instructions. . . . . . . . . . . . . . . . . . . . .7 .9 Building the Kit . . . . . . . . . . . . . . . . . . . . . . . . . . PC-14 Diagrams . . . . . . . . . . . . . . . . . . . . . . . . .12 If a Problem Arises . . . . . . . . . . . . . . . . . . . . . . .15 Overseas AC Line Connections . . . . . . . . . . .15 Additional Information . . . . . . . . . . . . . . . . . . .16 Functional Block Diagram . . . . . . . . . . . . . . . .16 Component Values . . . . . . . . . . . . . . . . . . . . . .19 Schematic Diagram . . . . . . . . . . . . . . . . . . . . . .20 Kit Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 Service and Warranty . . . . . . . . . . . . . . . . . . . .23 Pictorial Diagram . . . . . . . . . . . . . . . . . . . . . Insert 3 The DH-110 is provided with accessory Rack Mount end caps in addition to the standard end caps installed on the unit. These accessory caps extend the width of the front panel to that of a standard 19" rack, with appropriate mounting holes. Installation instructions are detailed later in this manual under Additional Information. POWER CONNECTIONS The Additional Information section of this manual details the determination of the loading capacitor for a specified cartridge load. It also describes how the resistive load of the phono inputs may be changed, if needed, from the standard 47K ohms. Moving coil design cartridges often require an auxiliary step-up transformer or pre-preamplifier (head amplifier) because of their low output signal. The DH-110 has provision for internal addition of an accessory Hafler prepreamplifer which you or your dealer can install at any time. This enables the Phono 1 input to accommodate such cartridges directly. The Additional Information describes its installation. Adjacent to the Phono 1 input sockets are two Ground terminals on the back panel. These thumbscrews provide for connection of separate ground wires often provided on turntables, or as part of their audio cables. This `chassis ground' may sometimes reduce the hum level of a system when it is connected to an earth ground, such as a cold water pipe, or the ground wire of 3-wire house wiring. However, the need for such connection varies with individual situations. After the system is operative, using a phono source, experiment with and without an earth ground to determine which provides the lowest hum, and use that. IMPUTS-Tuner, CD/Video As assembled, units are normally wired for 120 VAC, 50-60 Hz, as in the USA, unless they are specially identified on the carton. In the Additional Information section you will find diagrams of alternate wiring of the power transformer to conform to other line voltages. The power regulation of the DH-110 will provide full performance with line voltages which may vary substantially from the standard. Units wired for 120 volts, for instance, will work properly with line voltages between 95 and 130 volts. Accessory AC outlets are provided on the back panel for other equipment. One unswitched outlet is provided for a turntable or tape recorder whose mechanical system may require disengagement through its own power switch. Most units, including power amplifiers, tuners, and many tape recorders and record players, may be connected to the switched outlets for convenient remote switching from the preamp's front panel. The DH-110 power switch has been tested to provide adequate capacity for any Hafler power amplifier and typical related equipment. You should heed the maximum power rating printed on the back panel of the unit. INPUTS-Magnetic Phono There are two pairs of phono inputs, identified as Phono 1 and Phono 2. These are independent, and thus they may have different capacitive termination for differing cartridge requirements. As assembled, Phono 1 is provided with a compensation capacitor of 120 picofarads, and Phono 2 is provided with 220 picofarads. One of these values will accommodate most `Moving magnet' cartridges. These have output levels intended for normal phono inputs (0.5 millivolts per centimeter or higher) and are the most popular. Some high output `moving coil' design cartridges are not sensitive to capacitive loading, so they may be used with either input. Though some phono cartridges are comparatively free of loading sensitivity, if the cartridge manufacturer specifies the proper load capacitance (which is the sum of the preamp's internal capacitance, and the cables you use, as well as the above described capacitor), the most accurate sound will be obtained by following that recommendation. If you have chosen the DH-110 for its sonic attributes, you will be more likely than most to be aware of these differences, and will want proper cartridge termination. These are high level (line-50 millivolts or more) signals from FM, AM or TV tuners, or compact digital audio disc, video disc, or VCR players. These inputs are grounded at the selector switch when they are not chosen for listening. The input impedance is approximately 33K ohms. INPUTS-Tape 1, Tape 2 These are at line level and impedance. They connect to Tape Play outputs on the tape deck. They are not grounded when unused, since they can be connected by either the main selector switch or the Tape Monitor switch. They are terminated with 1 megohm resistors to avoid a possible switching transient. RECORDING OUTPUTS These connect to the Line Inputs of tape decks. The two pairs of outputs are wired in parallel. Thus two tape recorders receive identical signals. These outputs are buffered with a series resistor, and have an output impedance of 1.5K ohms. To provide full specification performance, the total tape recorder load should not be lower than 10K ohms (i.e. two 20k ohm recorder inputs on each channel). Because it is possible that a preamplifier's overall performance may be adversely affected by rectification ef- 4 fects that can result from unpowered electronic circuits in the tape decks when they are connected to the Recording Outputs, it is recommended that tape recorders be switched on when the preamplifier is in use. This is a commonly overlooked cause of less-than-ideal preamplifier performance. Signals at these outputs are at line input level (phono signals are first amplified and equalized). These outputs are unaffected by external processing circuits, or by the DH-110's Mono, Filter, Tone or Volume controls. Only signals indicated by the Selector switch are available, including the other tape input, so tape copying is provided using either recorder as a source. LINE OUTPUTS which is otherwise a possibility. W ...