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DW 999 Pre-preamplifier Manual
Page 1 of 26
OWNER'S MANUAL
THE DAYTON WRIGHT Model 999 PRE-PREAMPLIFIER
Mark 1
DAYTON WRIGHT GROUP LTD.
97 Newkirk Road North, Richmond Hill,
Ontario L4C 3G4, CANADA
Revised: February 22, 1985
TABLE OF CONTENTS
mhtml:file://C:\Users\Sælger\Downloads\Dayton-Wright 999 Pre-preamplifier Manua...
12-12-2019
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Table of Contents
Summary of Contents for DW 999
- Page 1 DW 999 Pre-preamplifier Manual Page 1 of 26 OWNER'S MANUAL THE DAYTON WRIGHT Model 999 PRE-PREAMPLIFIER Mark 1 DAYTON WRIGHT GROUP LTD. 97 Newkirk Road North, Richmond Hill, Ontario L4C 3G4, CANADA Revised: February 22, 1985 TABLE OF CONTENTS mhtml:file://C:\Users\Sælger\Downloads\Dayton-Wright 999 Pre-preamplifier Manua...
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Page 2: Table Of Contents
DW 999 Pre-preamplifier Manual Page 2 of 26 Section Title (Page in printed manual) GENERAL INFORMATION Introduction........(4) Description........(4) Warranty........(4) Identification .........(5) Inquiries ........(5) INSTALLATION Introduction......... (6) Initial Inspection......(6) Claims........(7) Preparation for use ....(7) Repacking for shipment....(7) OPERATION Introduction ..........(9) Controls &... -
Page 3: General Information
This manual covers the installation, operation, and servicing of the Model Dw 999 Pre-preamplifier. Description: The DW-999 is a Infranoise (very low noise) Pre-preamplifier which is designed to amplify the low level low-impedance signals from a moving coil type of phono cartridge to the level where they are sufficient to drive the phono input of a conventional preamplifier. -
Page 4: Identification
DW 999 Pre-preamplifier Manual Page 4 of 26 up to two years from the date of customer Purchase, the latter in no case to exceed three years from the date of manufacture and in no case to be valid unless the customer has his original Bill of Sale clearly showing the Date of Purchase and the Name and address of the dealer from whom this unit was purchased. -
Page 5: Introduction
INSTALLATION Introduction: This section contains the information needed to perform an initial inspection of the DW 999 Pre- preamplifier as well as the installation steps normal to its use in an audio system. Also covered are the procedures to be followed if initial inspection reveals damage to the unit, as well as repacking of the unit for storage or reshipment. -
Page 6: Claims
(page 8) Section 3 OPERATION Introduction: This section covers the general operation of the DW 999 Pre-Preamplifier including its controls and its mhtml:file://C:\Users\Sælger\Downloads\Dayton-Wright 999 Pre-preamplifier Manua... 12-12-2019... -
Page 7: Controls & Connectors
Controls & Connectors: As noted, the DW 999 employs BNC Connectors for all Audio Signal Path Connections. As both these as well as phono connectors are used in video recording, BNC-to-Phono cables are usually available from dealers handling video accessories. We do not advise the employment of phono adaptors as these simply re- introduce the problems that we tried to avoid by using BNC units in the first place. -
Page 8: Adaptors
Control Location: 3.24 The DW 999 has two user adjustments. (NOTE: THE REGULATED VOLTAGE AND THE TRIMMER CAPACITOR ADJUSTMENTS (if the latter is used) HAVE BEEN PRESET AT THE FACTORY AND MUST NOT BE TOUCHED! These user adjustments are both accessible from the front panel. -
Page 9: Load Resistors
DW 999 Pre-preamplifier Manual Page 9 of 26 right of the case. The three binding posts in a line are, from left to right; the Left Channel Signal, Ground, the Case Ground (a green binding post) and the Right Channel Signal Ground. The Tone Arm Ground lead should be connected to whichever of the three ground terminals that results in the lowest noise figure being obtained. -
Page 10: Output Level Adjustment
RIAA curve, 2 volts at 20 kHz -20dB (or divided by 10) = .2 volts at 1kHz (200 millivolts). In practice the full 34 dB voltage gain of the DW 999 pre-preamplifier is rarely needed except with the very few ultra-low voltage moving coil units. Once the screwdriver-adjusted volume control is fully clockwise, the gain of the pre-preamplifier may be lowered 6 dB by rotating each of the two controls 10 turns counterclockwise. -
Page 11: Hum & Rf Problems
PRINCIPLES OF OPERATION Introduction: This section provides a brief overview of the theory of operation of the DW 999 Pre-preamplifier. General Theory: The use of a Pre-preamplifier or 'Head amp' rather than a transformer dates from the early 170's when Dayton Wright Associates and Mark Levinson both introduced units designed to operate from very low source impedance’s. -
Page 12: Block Diagram
In addition, the very low impedance require correspondingly low value feedback components, and this in turn requires an output stage that can handle the current demands of this low-impedance feedback. Block Diagram The DW 999 Pre-preamplifier block diagram: mhtml:file://C:\Users\Sælger\Downloads\Dayton-Wright 999 Pre-preamplifier Manua... 12-12-2019... -
Page 13: Specifics
DW 999 Pre-preamplifier Manual Page 13 of 26 (page16) Specifics: The following sections cover the operation of the stages in more detail. Input Cascode Stage: 4.41 The input stage consists of ten bootstrapped cascode stages operating in parallel. Each stage has a loo ohm resistor as a current equalizing resistor in its emitter bypassed with a .33 uF polypropylene capacitor and... -
Page 14: Current Sink
DW 999 Pre-preamplifier Manual Page 14 of 26 Current Sink: 4.42 This is a single NPN transistor using a 100 ohm emitter resistor and a base biasing network of 2 lN916 diodes to the negative rail (bypassed with a 22 uF tantalytic to lower noise), pulled up by a 5k6 resistor up to the ground rail. -
Page 15: Regulators
PERFORMANCE CHECK Introduction: This section covers a simplified procedure useful for establishing the proper performance of the DW 999 Pre-preamplifier. While the factory uses computer controlled test equipment, this is probably beyond the financial means of many who wish to verify the proper performance of the pre-preamplifier. -
Page 16: Equipment Required
Analyzer. (The output level on the pre-preamp should be fully up) Let the DW 999 warm up for 15 minutes, then set the output for 1.5volts RMS as indicated on the Distortion Analyzer. The analyzer is setup so that the Hum filter (400 Hz) is on, the noise Filter is set at 30 kHz and on, and a frequency of 1 kHz has been selected. -
Page 17: Replacement Parts
REPLACEMENT PARTS Introduction: There are few if any exotic parts used in the production of the DW 999 pre-preamplifier and there should be little need for replacement parts. It should be possible to obtain anything needed (save PC Boards and/or Sheet Metal Work at a local Electronics Parts supply house. - Page 18 DW 999 Pre-preamplifier Manual Page 18 of 26 C95,96 50-426-227A 220uF 10V AI.EL R Cap Philips 426UP10220 C10,14,18,22, C26,30,34,38,42,46,50,54,58,62, C66,70,74,80,82 50-470-C471 470uF 10V Al.El.Cap Philips 437EID470 C101,111 50-470-E222 2200uF 16V Al.El.Cap Philips 437ETE221 C92,98 50-470-C103 10,000 uF 10V Al.El. Cap...
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Page 19: Parts List
DW 999 Pre-preamplifier Manual Page 19 of 26 40-97-3921F 3k92 1% Mtl Film Res Philips MR3oF3K92 R79,92 2 40-97-4371F 4k32 1% Mtl Film Res Philips MR3OF4K37 R63,69 6 40-97-4751F 4k75 1% Mtl Film Res Philips MR3OF4K75 R64,70, R77,78,90,91 2 40-97-5621F 5k62 1% Mtl Film Res Philips MR3OF5K62 R71,84... -
Page 20: Ordering Information
Parts prices should be obtained by phoning: (416) 884-8586 - ask for the Parts Department NOTE: BE SURE TO INCLUDE THE MODEL AND THE SERIAL NUMBER OF 999 AS IT WILL BE ON OUR RECORDS. Please be advised that records are kept of quotations, and orders; from time to time we are aware of people trying to buy the special parts necessary to build a piece of equipment themselves. -
Page 21: Schematics
DW 999 Pre-preamplifier Manual Page 21 of 26 SCHEMATICS Introduction 7.1 This section covers some of the information needed to locate faults and to repair them. The schematics for the left and right channels are supplied along with a drawing of the circuit board layout. Please note that the board is approximately (but not exactly) symmetrical and there is complete electrical isolation between the two channels irrespective of whether the power supply is plugged in or not. - Page 22 DW 999 Pre-preamplifier Manual Page 22 of 26 A general malaise could be caused by a failure of one of the transistors in the paralleled-cascode input stage, that is either the input or upper transistor of the pair might fail. Remember that these PNP devices have a different pinout than the NPN'S.
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Page 24: Dc Voltages
DW 999 Pre-preamplifier Manual Page 24 of 26 (page31) DC Voltages: 7.4 These have been covered in the troubleshooting notes. Dissassembly and Reassembly: mhtml:file://C:\Users\Sælger\Downloads\Dayton-Wright 999 Pre-preamplifier Manua... 12-12-2019... -
Page 25: Switch Maintenence
Tweek on the switch contacts. A co tube of the former is packed with each DW 999 pre-preamplifier, and a drip of same should be used on the ground and central pin of all the BNCIS, the cable pins where the interconnect plugs into the phono arm, and on the cartridge corrections themselves. - Page 26 DW 999 Pre-preamplifier Manual Page 26 of 26 mhtml:file://C:\Users\Sælger\Downloads\Dayton-Wright 999 Pre-preamplifier Manua... 12-12-2019...
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