dm8 TM TABLE OF CONTENTS IMPORTANT SAFETY INSTRUCTIONS............................................................. 2 INTRODUCTION .................................................................................................... 3 ELECTRONIC DESIGN..................................................................................... 4 MICROPROCESSOR CONTROL ..................................................................... 5 INDUSTRIAL DESIGN...................................................................................... 6 MECHANICAL DESIGN ................................................................................... 7 INSTALLATION....................................................................................................... 8 UNPACKING ......................................................................................................... 8 POSITIONING ........................................................................................................ 8 FRONT PANEL CONTROLS ................................................................................. 9 REMOTE CONTROL ............................................................................................ 10 DISPLAY.................................................................................................................. 10 DISPLAY.................................................................................................................. 11 REAR PANEL ......................................................................................................... 12 CONNECTIONS..................................................................................................... 13 CONNECTING TO A POWER AMPLIFIER ............................................................... 13 REMOTE POWER AMPLIFIER CONTROL OUTPUT................................................ 14 BRIDGING........................................................................................................... 14 BREAK-IN PERIOD .............................................................................................. 14 PROGRAMMABLE INPUT SELECTIONS................................................................ 14 OPERATING INSTRUCTIONS........................................................................... 15 CONNECTING SIGNAL SOURCES ......................................................................... 15 HOME THEATRE PROCESSOR CONTROLLING VOLUME ...................................... 15 CONNECTING THE MAINS POWER SUPPLY CABLE ............................................ 15 REMOTE CONTROL BATTERIES.......................................................................... 15 SWITCHING THE UNIT ON ................................................................................... 16 ALLOCATING SIGNAL SOURCES AND THE REMOTE CONTROL ............................ 16 DE-ALLOCATING PROGRAM BUTTONS .............................................................. 16 DISPLAYED INFORMATION ................................................................................. 17 DISPLAY CONTRAST .......................................................................................... 17 BACK LIGHT....................................................................................................... 17 VOLUME............................................................................................................. 17 VOLUME ­ BALANCING FUNCTION.................................................................... 18 SWITCHING BETWEEN SOURCES......................................................................... 18 PHASE CONTROL................................................................................................ 19 ELECTRONIC PROTECTION AND RELIABILITY......................................... 19 SPECIFICATIONS & FEATURES ....................................................................... 20 CARE AND MAINTENANCE............................................................................... 22 TROUBLESHOOTING.......................................................................................... 23 SERVICE .................................................................................................................. 24 WARRANTY ........................................................................................................... 25 Page 1 of 26 dm8 TM Important Safety Instructions This product shall be connected to a MAINS socket outlet with a protective earthing connection. Only suitable approved MAINS cords, as per European individual country requirements in the CE Low Voltage Directive Scheme, shall be used with this unit. Do not use extension cords: To avoid safety hazards, use only the power cord supplied with your unit. We do not recommend that extension cords be used with this unit. Weighs 23 kg (50 lbs.) per unit. Shipping weight 36 kg (79 lbs) Designed for indoor use only. The dm8 preamplifier is not protected against liquids. The unit shall not be exposed to dripping or splashing. No objects filled with liquids, such as vases, shall be placed on the apparatus. No naked flame sources, such as lighted candles, should be placed on the apparatus. Designed to operate on any mains supply in the range of 90V to 240 V. 50 to 60 Hz, without any internal or external switches. There are no user serviceable components inside this unit. Do not attempt to open the preamplifier compartment: this may expose you to dangerous voltages and will void the warranty. Compartments are sealed at the factory. If the seals are broken, the warranty will be void and all service costs will be charged to the owner. Requires F 1A L 250v fuse for continued protection against the risk of fire. Never bypass or use any other type of fuse. The fuse is located on the rear panel in the main switch. 90 - 240 V 50 - 60 Hz 10A CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN Page 2 of 26 dm8 TM Introduction Congratulations on purchasing the HALCROTM dm8 preamplifier. It has taken two years and the generous contributions of leading reviewers, distributors and dealers from around the world to design, then create, the HALCROTM preamplifiers. We are confident that this combination of expertise, along with the know-how of the high-end audio industry's leading Research and Development team will ensure the success of the HALCROTM preamplifiers. The brief given to our R&D team, headed by Bruce Candy, was to produce two models of preamplifier to satisfy the needs of every audio connoisseur: Y Lowest distortion specifications of any preamplifier in the world. Y Physical dimensions to suit a standard domestic equipment rack, while retaining the stunning HALCROTM industrial design signature. Y Tractable controls. Y Superior reliability. Y Innovation in design. The HALCROTM dm8 & dm10 preamplifiers will add no colorations to the music. When used in conjunction with HALCROTM power amplifier(s), all you will hear is the original recording reproduced the way the artist intended it to sound. No transistor or valve-added sounds are present, just a level of musical purity that was thought impossible until now. Page 3 of 26 dm8 ELECTRONIC DESIGN By Bruce Candy In keeping with my philosophy of design, my basic aim was to produce a preamplifier with which I, personally, am quite satisfied. I sincerely hope that others will share my satisfaction with these products. As I saw it, the major issues were: Y Zero compromise on Transparency. Y Flexibility. Y Ease of use. Y Progressive design concepts. In order to meet this challenge, the resulting circuits have particular characteristics: Y First, all circuits in the preamp have distortion so low that it is immeasurable, whether THD, IM etc. Y Second, all circuits in the preamp exhibit exceptionally low noise (see specifications). Y Third, there is no compromise whatever with the choice of components (Vishay resistors, FKP1 capacitors etc). Y Fourth, the circuits are highly immune to electromagnetic interference. Some inputs and outputs include both first order filters and common mode chokes. Y Fifth, the power supply and microprocessor circuits are designed for minimal electromagnetic emissions (extensive 2nd to 6th order filters). Y Sixth, the power supply switching frequency was chosen to be much higher than the audio band (>200kHz). Y Seventh, the power supply rails are exceptionally well regulated, double regulation in fact (switch-mode and linear servo loops). Y Eighth, components and design are selected for high reliability. The volume control is implemented so as to include two identical stages in series. This minimizes output noise. The dm8 & dm10 preamplifiers feature balanced, unbalanced, current mode and bridged current mode outputs. The latter consists of a non-inverted and inverted current output. There is also an unbalanced output for tape and headphones. TM Page 4 of 26 dm8 Audible relay noise The dm8 & dm10 use mechanical relays in all switching including the volume control because they exhibit the following ideal characteristics ; · · · · zero ON resistance, infinite OFF impedance, very low OFF capacitance, zero distortion. TM In contrast, the now universally popular solid state relays/switches exhibit none of these ideal properties and detract from performance. Hence, sonically, HALCROTM feels that it is worth the side effect of mechanical clicking sounds when parameters are changed. MICROPROCESSOR CONTROL By Paul Rainbow The excellent audio electronics are complemented and controlled by a number of highly integrated micro-controllers located close to the electronics they serve. Being as near as possible to the controlled electronics allows short control paths and virtually eliminates internal connectors, thereby greatly increasing system reliability. Each amplifier channel has its own micro-controller; the front panel display and user interface has another. A fourth micro-controller, located on the rear connector panel, co-ordinates the activity of the others. The four microcontrollers are linked via only four interconnections each. A unique programming feature of the microprocessor has been developed which allows the user to dedicate a particular pair of input sockets to a specific input device. This feature provides the user with great flexibility for connecting input devices to the preamplifier. The rear panel has provision to accommodate five input devices into seven physical pairs of input sockets. There is one pair of current inputs, three pairs of balanced inputs and three pairs of unbalanced inputs. Phono inputs do not require programming as they are permanently allocated to the phono source (in the dm10). Page 5 of 26 dm8 INDUSTRIAL DESIGN By Max Dickison & Tony Kearney Product Form The aim when designing the dm8 and dm10 was to create a preamplifier that was unmistakably part of the HALCROTM product family, but at the same time a component that would compliment any high end audio system. The preamplifier had to sit comfortably within a contemporary domestic environment, retain the visual signature of the HALCROTM family of products which differentiates them from other high end audio products and have an appearance that reflected the high level of technical innovation. As with other HALCROTM products, softer forms and textures are used, all fasteners are concealed and the heatsinks are integrated into the external form to maintain simple, clean lines. Whilst the unique pillar forms of the power amplifiers have been carried through to the preamp, proportions have been reworked to allow this component to be either freestanding or housed within a standard 19" shelving system. Control Interface Knobs and buttons: The volume and input selector knobs use a unique magnetic incremental indexing mechanism developed to provide a very subtle and reliable indexing action. The knobs and buttons are finished in the same soft textural finish as the pillars. Display: A high-resolution display was chosen in order to provide clean simple graphics without the rough edges associated with displays of lesser quality. The graphic layout of the display has been optimized to give prominence to the functions that are viewed most often. These include volume levels, balance and input selection. Functions that are accessed less often are displayed in smaller type along the bottom of the screen. These include stereo/mono and in-phase/out-of-phase. The volume levels for each channel are displayed side-by-side so that when the levels are not equalized the user will easily notice it. TM Page 6 of 26 dm8 Remote control: When designing the HALCROTM Remote Control, we aimed to reflect the quality and forms of the HALCROTM preamplifiers. Machined from a solid aluminum extrusion, the remote rests comfortably in the hand with its minimalist array of buttons falling within the natural sweep of the thumb. Simple and logical to operate, every effort has been made to keep ...