dm10
TM
TABLE OF CONTENTS
IMPORTANT SAFETY INSTRUCTIONS................................................................2
INTRODUCTION..........................................................................................................3
ELECTRONIC DESIGN ........................................................................................................3
MICROPROCESSOR CONTROL............................................................................................6
INDUSTRIAL DESIGN .........................................................................................................7
MECHANICAL DESIGN.......................................................................................................8
INSTALLATION............................................................................................................9
UNPACKING......................................................................................................................9
POSITIONING ....................................................................................................................9
FRONT PANEL CONTROLS....................................................................................10
REMOTE CONTROL..................................................................................................11
DISPLAY........................................................................................................................12
REAR PANEL................................................................................................................13
CONNECTIONS..........................................................................................................15
CONNECTING TO A POWER AMPLIFIER ...........................................................................15
REMOTE POWER AMPLIFIER CONTROL OUTPUT ............................................................16
BRIDGING.......................................................................................................................16
BREAK-IN PERIOD ..........................................................................................................16
PROGRAMMABLE INPUT SELECTIONS ............................................................................16
OPERATING INSTRUCTIONS................................................................................17
CONNECTING SIGNAL SOURCES......................................................................................17
HOME THEATRE PROCESSOR CONTROLLING VOLUME ...................................................17
PHONO STAGE................................................................................................................17
CONNECTING THE MAINS POWER SUPPLY CABLE .........................................................18
REMOTE CONTROL BATTERIES ......................................................................................18
SWITCHING THE UNIT ON................................................................................................18
ALLOCATING SIGNAL SOURCES AND THE REMOTE CONTROL.........................................18
DE-ALLOCATING PROGRAM BUTTONS ...........................................................................19
SETTING THE LOAD RESISTANCE/CAPACITANCE FOR MOVING MAGNETIC
CARTRIDGE PHONO PLAYERS..........................................................................................19
DISPLAYED INFORMATION .............................................................................................19
DISPLAY CONTRAST.......................................................................................................19
BACK LIGHT...................................................................................................................19
VOLUME.........................................................................................................................20
STORED VOLUMES .........................................................................................................20
VOLUME – BALANCING FUNCTION................................................................................21
MONO/STEREO FUNCTION..............................................................................................21
PHASE CONTROL............................................................................................................21
SWITCHING BETWEEN SOURCES.....................................................................................22
ELECTRONIC PROTECTION AND RELIABILITY.............................................22
SPECIFICATIONS & FEATURES OF THE HALCRO DM10.............................23
CARE AND MAINTENANCE...................................................................................25
TROUBLESHOOTING...............................................................................................26
SERVICE........................................................................................................................27
WARRANTY.................................................................................................................28
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dm10
Important Safety Instructions
This unit 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 dm10 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 unit.
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.
Do not attempt to open the unit as this will void the warranty and
will expose you to dangerous voltages.
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
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
50 - 60 Hz
TM
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dm10
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Introduction
Congratulations on purchasing the HALCRO™ dm10 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
HALCRO™ 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 Halcro
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:
Ÿ Lowest distortion specifications of any preamplifier in the world.
Ÿ Physical dimensions to suit a standard domestic equipment rack, while
retaining the stunning Halcro industrial design signature.
Ÿ Tractable controls.
Ÿ Superior reliability.
Ÿ Innovation in design.
The HALCRO™ dm8 & dm10 preamplifiers will add no colorations to the
music. When used in conjunction with HALCRO™ power amplifiers, 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.
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:
Ÿ Zero compromise on Transparency.
Ÿ Flexibility.
Ÿ Ease of use.
Ÿ Progressive design concepts.
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In order to meet this challenge, the resulting circuits have particular
characteristics:
Ÿ First, all circuits in the preamp have distortion so low that it is
immeasurable, whether THD, IM etc.
Ÿ Second, all circuits in the preamp exhibit exceptionally low noise (see
specifications).
Ÿ Third, there is no compromise whatever with the choice of components
(Vishay resistors, FKP1 capacitors etc).
Ÿ Fourth, the circuits are highly immune to electromagnetic interference.
Some inputs and outputs include both first order filters and common
mode chokes.
Ÿ Fifth, the power supply and microprocessor circuits are designed for
minimal electromagnetic emissions (extensive 2nd to 6th order filters).
Ÿ Sixth, the power supply switching frequency was chosen to be much
higher than the audio band (>200kHz).
Ÿ Seventh, the power supply rails are exceptionally well regulated,
double regulation in fact (switch-mode and linear servo loops).
Ÿ Eighth, components and design are selected for high reliability.
The figure below shows a functional block diagram of the preamplifier
(Diagram 1). As can be seen, the phono stage has 4 stages. Firstly, there is an
ultra low noise input stage with a gain of x 20 for moving coil cartridges. This
can be switched out of the circuit train.
Diagram 1
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dm10
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The first stage is followed by a high input impedance (FET input) low noise
amplifier with a gain selectable to x 4 or x 8. The output of this stage is fed to
an inverting amplifier with a gain selected to be x -2 if the high input
impedance amplifier stage gain is selected to be x 4, or x -1 if the high input
impedance amplifier stage is selected to be x 8. (The “minus” indicates
inverting.) The output of the inverting amplifier is connected back to the high
input impedance amplifier stage input via a continuously variable
potentiometer. A continuously variable capacitor is also connected to this
input and to ground. The variable resistor and capacitor set the load
impedance of the high input impedance amplifier stage and act to load
moving magnet cartridges.
This configuration forms an active load. The variable capacitance sets the load
capacitance and the load resistance is 1/8th of the value of the potentiometer
resistance. This configuration lowers the noise floor at high frequency, and its
attributes are described below.
The output of the high input impedance amplifier stage is, as well, fed to a
15Hz 3rd order high-pass Bessel filter. This acts as a “rumble-filter.”
Following this is the RIAA equalization stage. The RIAA equalization adheres
to the RIAA specification within 0.25dB at all frequencies.
The output of this RIAA stage is fed to a low noise input selector stage which
has a gain of 2. In truth, if a phono input is selected, this gain can be set to
either 1 or 2, depending upon the gain of the selected phono input. Some
inputs are balanced inputs and one input is a current input with a load
impedance of 51 ohms, for optimal inter-connect load matching. The
equivalent input noise of the voltage inputs is approximately 3.5nV/sqrt(Hz),
and that of the current input is 13pA/sqrt(Hz).
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.
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Audible relay noise
The dm8 & dm10 use mechanical relays in all switching including the volume
control because they exhibit the following ideal characteristics:
Ÿ zero ON resistance,
Ÿ infinite OFF impedance,
Ÿ very low OFF capacitance,
Ÿ zero distortion.
In contrast, the now universally popular solid state relays/switches exhibit
none of these ideal properties and detract from performance. Hence,
sonically, HALCRO™ 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 six input devices into nine physical pairs of input sockets. There
are two pairs of dedicated phono inputs, 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.
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INDUSTRIAL DESIGN
By Max Dickison & Tony Kearney
Product Form
The aim when designing the dm8 & dm10 was to create a preamplifier that
was unmistakably part of the HALCRO™ 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 HALCRO™ 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 HALCRO™ 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 or 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.
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Remote control:
When designing the HALCRO™ Remote Control, we aimed to reflect the
quality and forms of the HALCRO™ preamplifiers. Machined from a solid
aluminum extrusion, the remote rests comfortably in the right 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 this product
free of unnecessary complexity.
MECHANICAL DESIGN
By Lance Hewitt
The HALCRO™ dm8 & dm10 can boast their spectacularly low noise and
distortion specifications while their cases contain inherently noisy digital
circuitry, including a switch-mode power supply, partly due to the
mechanical design of their circuit boards and the boxes that contain them.
Supports of folded aluminum serve not only as bases to which the electronics
are anchored, but also to shield different sections of the circuitry from one
another.
Each of the audio, panel and display, and power supply sections is contained
within its own internal aluminum enclosure. Cables connecting the separate
sections are few and short, minimizing both radiation and reception of
unwanted signals.
Please enjoy the HALCRO™ audio experience.
HALCRO™ has enjoyed creating perfect audio reproduction for the world's
music connoisseurs.
If you wish to contact HALCRO™ to supply feedback on your purchase or for
general enquiries, please feel free to contact us:
Email: admin@halcro.com
Telephone: +61 8 8238 0807.
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dm10
Installation
Ensure you have read the Important Safety Instructions section on page 2 prior to
installing your HALCRO™ preamplifier. If you require assistance in the unpacking and
installation of your HALCRO™ preamplifier, please contact your dealer.
Unpacking
Undo the 4 fasteners at the base of each box. Then remove the upper part of the container
by lifting directly upwards, being careful not to rub it against the preamplifier. (To have
gained access to this manual you must have completed the above steps.)
Remove the material wrapping and foam pieces, then lift the preamplifier from the base
of the container. (It is recommended that the user take off all jewelry that may scratch the
unit and put on the white cotton gloves provided with the unit).
Remove the center piece of foam in base of transit case, to locate the remote control and
power cable.
Remove the covering from the unit. Please save it for later use.
Move the unit to its final location (see Positioning).
Important
Do not connect any cables as yet.
Safely store the packaging for future relocation of the unit and shipping if service is
required.
TM
Positioning
The HALCRO™ dm10 preamplifier can be placed anywhere indoors. There is no need to
leave room around the unit to allow it to breathe. The dm10 does not generate significant
amounts of heat.
To ensure ultimate performance and to avoid potential safety hazards, place the unit on a
firm and level surface. When placing the unit on a shelf, be certain that the shelf and
mounting hardware can support the weight of the product.
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