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
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
TM
Page 2 of 26
dm8
TM
Introduction
Congratulations on purchasing the HALCRO™ 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
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 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
TM
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.
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 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.
Page 4 of 26
dm8
TM
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.
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 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
TM
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 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-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.
Page 6 of 26
dm8
TM
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 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 and 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
Facsimile: + 61 8 8238 0852
Page 7 of 26
dm8
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™ dm8 preamplifier can be placed anywhere indoors. There is no need to
leave room around the unit to allow it to breathe. The dm8 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.
Page 8 of 26
Figure 1
dm8
Front Panel Controls
1. LCD Information
Display
2. Balance Control Left
3. Standby/On button
1. LCD Information Display: This
display delivers messages and system
status to assist you in operating the unit.
See page 11 for a complete breakdown on
the display.
2. Balance Control Left: Using this
button in conjunction with Balance
Control Right (Fig 1, 5), the user can
change the relative volume for the left
and right channels. Pressing the Left
button will increase the volume on the
left hand channel and decrease the
volume on the right.
3. Standby/On button: The HALCRO™
dm8 is designed to remain in standby
mode when not in use. This button will
toggle the unit between Standby and On.
To turn the unit off completely, use the
rear panel Master Power Switch (Fig 6, 6).
4. Mute button
5. Balance Control Right
6. Input Select Control
7. Volume Control
TM
8. Phase button
9. Remote Sensor
Window
4. Mute button: Depressing this button
will Mute the output to the speakers.
5. Balance Control Right: Using this
button in conjunction with Balance
Control Left (Fig 1, 2), the user can
change the relative volume for the left
and right channels. Pressing the Right
button will increase the volume on the
right hand channel and decrease the
volume on the left.
6. Input Select control: By turning this
knob, the preamplifier will scroll through
all the programmed input devices (CD
player, Tuner, DVD, etc.) attached to the
unit.
Page 9 of 26
Figure 2
dm8
TM
7. Volume control: Turn this knob
clockwise to increase the volume and
counter-clockwise to decrease the
volume. To mute the system, when the
speakers are balanced, continue to turn
the knob counter-clockwise until the
word MUTE appears on the display, or
press the Mute button (Fig 1, 4)
Remote Control
1. Volume buttons
2. Mute button
3. Standby/On button
1. Volume buttons: For
volume control and also
used in conjunction with
the function button for
various function selections.
2. Mute button: Press to
Mute the sound, press
again to reactivate the
sound.
3. Standby/On button:
Press to toggle the system
between Standby and On.
8 Phase Button: Depressing this button
will toggle the unit between in-phase and
out-of-phase mode.
9 Remote sensor window: Behind this
window is a sensor that receives infrared
signals from the remote control. Aim the
remote at this area and do not block or
cover this sensor window.
4. Signal Source buttons
5. Function button
4. Signal source buttons:
Press to select any one of 5
signal sources on the dm8.
5. Function button: Press
to choose the following
functions: speaker balance,
in and out of phase and to
toggle the system between
stereo and mono. See
relevant operating
instructions for full details.
Note: Remote control takes 3 x AAA batteries (supplied)
Page 10 of 26
Figure 3
Figure 5
Figure 4
dm8
Display
TM
1. Main Information Display
2. Signal Source Indicators
1. Main Information Display: The
information provided on this display
changes depending on what function is
currently being processed.
In normal use it will display the volume
of both the left and right of the system
(Fig 4).
When a different input signal source is
selected it will appear on the main
display (Fig 5) for a few seconds.
3. Signal Source Location Indicator
4. Phase Indicator
2. Signal Source Indicator: Displays the
signal source which is currently selected.
3. Signal Source Location Indicator:
Displays which input the signal source
has been connected to.
4. Phase Indicator: Displays whether the
unit is in- or out-of-phase.
Page 11 of 26
Figure 6
dm8
Rear Panel
TM
1. Programmable inputs
2. Program buttons
3. Tape Monitor outputs
5. Remote sensor window
6. Mains power switch,
socket and fuse holder
4. Output sockets
1. Programmable inputs: Provides
connection to your signal sources. It does
not matter which input each source is
connected to, as these inputs are allocated
using the remote control.
2. Program buttons: Allows the inputs to be
programmed to the remote control. They
will remain illuminated once they have been
allocated – see Connecting signal sources and
allocating signal sources and the remote control
(page 15/16)
3. Tape Monitor outputs: For recording
direct to tape.
4. Output sockets: Provide connect from the
Pre Amplifier to Power Amplifier(s).
5 Remote sensor window: Behind this
window is a sensor that receives infrared
signals from the remote control. Aim the
remote at this area.
7. Remote Power
Amplifier output
8. Output selector switch
6. Mains power switch, socket and fuse
holder: Once the dm8 has been
programmed, the main power switch can be
left on and the dm8 left in standby when not
in use. If the main power switch is turned
off, all programming is stored in memory.
7. Remote Power Amplifier Control
output: Connect a cable from this output to
the power amplifier(s) and the dm10 will
switch the power amplifier(s) between
Standby and On.
8. Output selector switch: Allows the user
to select the type of output required,
Balanced, Unbalanced and Current. see
Comments on the different dm8 Outputs (page
14).
Page 12 of 26
TM
dm8
Connections
Connecting to a power amplifier
Each dm8 has:
2 pairs of unbalanced current outputs. 1 pair is used in un-bridged mode and both are used
for driving bridged amplifiers, 2 pairs of unbalanced voltage outputs and 2 pairs of balanced
voltage outputs. Select the method you wish to operate your power amplifiers in, and connect
the 2 units using high quality cables.
Outputs are color coded:
Positive +, Right channel (Red Bezel).
Negative -, Left channel (White Bezel).
The dm8 will control power amplifiers from balanced and unbalanced voltage sources, as well
as an unbalanced current source. The dm8 will also control power amplifiers in bridged pair
configuration. Custom made cables are required to run bridged power amplifiers from the
balanced Voltage Output. (Fig 7).
Figure 7
Comments on the different dm8 Outputs
The balanced voltage outputs or current-mode outputs are most desirable for minimising earth
loop generated mains hum and ripple, or high frequency interference if they are a problem.
Earth loop generated mains hum and ripple, or high frequency interference should not be a
problem unless the source equipment is poorly designed.
Power Amplifiers with current-mode inputs are rare and are most likely to have an RCA input
socket. The advantages of this are:
Ÿ Earth loop generated mains hum and ripple are minimized.
Ÿ Cable, plug and socket-generated interference is minimized (from poor connections
which may be affected by sound vibration for example).
The unbalanced output is quite satisfactory so long as earth loop generated mains hum and
ripple are not a problem.
Page 13 of 26
TM
dm8
Remote Power Amplifier control Output
The dm10 has a remote power amplifier control output (fig 6,15) which will remotely switch
the HALCRO™ amplifiers from Standby to On. Cables can be purchased through HALCRO™
for details please email us at: service@halcro.com .
Bridging
The dm8 will control bridged power amplifiers. For details please email us at:
service@halcro.com A bridging kit can be purchased through HALCRO™.
Break-in period
The dm8 does not require a break-in period. The electronic break-in period is completed at the
factory.
Programmable Input Selections
The dm8 has seven available pairs of programmable input connectors, three unbalanced, three
balanced voltage inputs and one unbalanced current input. All inputs that have a signal
source connected must be programmed by the remote control. Any input can be programmed
to connect any source. Each button on the remote control can have only one signal source
programmed to it at any time.
Input
Modes
Unbalanced current
input
Balanced voltage input XLR: Low source
Unbalanced voltage
input
Required output
source impedance
RCA: Infinite source
impedance
impedance
RCA: Low source
impedance
Input impedance
50ohm input impedance
10kohm + 10kohm input
impedance
10kohm input impedance
Page 14 of 26
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dm8
Operating Instructions
Connecting signal sources
As a safety precaution please ensure that the unit is not connected to the mains power while
connecting signal sources.
When you originally receive your preamplifier all the inputs are de-allocated.
If you are changing your signal source units, de-allocate the input source first – follow De-
allocating Program Buttons instructions (Page 16)
Connect all signal source units (e.g. CD player) to the terminals (Fig 6, 1) at the rear of the
preamplifier, make note of which input each signal source unit is connected to.
Home Theatre Processor controlling volume
As a safety precaution please ensure that the unit is not connected to the mains power while
connecting a Home Theatre Processor.
Connect your Home Theatre Processor to any of the programmable inputs at the rear of the
preamplifier.
Program the preamplifier to the unit using Allocating signal sources and the remote control on
page 19. We recommend you use the DVD function.
To set the preamplifier to operate with zero gain, adjust both volume channels to 0.0db. The
preamplifier will then have no effect on the volume. You will now be able to control the
volume of your system by using your Home Theatre Processor volume control.
Connecting the Mains Power Supply Cable
Plug the main power cable into the dm8’s mains power socket on the rear of the unit. (Fig 6, 6).
Remote Control Batteries
Remove the battery cover from the rear of the unit, insert the three supplied AAA batteries into
the unit (ensure that the polarity is correct). Refit the battery cover.
If the remote control will not be used for a period longer than 1 month remove the batteries.
Page 15 of 26
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dm8
Switching the unit on
Switch the main power switch to On.
When the unit is switched on at the main power switch (Fig 6, 6) the pre- amplifier will go into
Standby mode.
Switch the unit on by pressing the Standby/On button on the unit or the remote control. To
return the unit to Standby mode press the Standby/On button again.
Note: To continue the set up process, the unit must be On, not in Standby.
Allocating signal sources and the remote control
All inputs must be allocated using the remote control (Fig 7). Note: The Phono selection is
permanently allocated to the Phono inputs.
Once the signal source units (e.g. CD player) have been connected to the input connector
terminals (Fig 6, 7) at the rear of the preamplifier, ensure that the preamplifier is On, not in
Standby mode.
Depress the applicable program button (situated above the connectors) and simultaneously
point the remote control to a remote sensor window and press the button on the remote control
which best describes the signal source unit you have connected.
The program button will flash twice and will remain illuminated, indicating that this pair of
input connectors are now allocated to the selected signal source unit. Repeat this process for
all signal source units (maximum 5 plus Phono).
If the device label that is being depressed on the remote control has been previously allocated
to another connector pair, this pair will now be de-allocated.
De-allocating Program Buttons
Note: Ensure the location being de-allocated is not the currently selected input, the currently
selected input can not be de-allocated.
Press and hold the applicable program button and simultaneously point the remote control to
a remote sensor window and press the Mute button. The Program Button will flash twice and
then remain off. This input has now been de-allocated and can be used for another signal
source unit.
Page 16 of 26
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dm8
Displayed information
In normal use the center of the display will display the volume of both the left and right of the
system. When a different signal source is selected, it will appear in the center of the display for
a few seconds (fig3, fig4).
Display Contrast
To adjust the display contrast, press and hold any of the Program Buttons on the rear panel
(fig 6, 8) and turn the Volume control on the front panel until the desired contrast is achieved.
Back Light
The backlight can be turned on and off by using the remote control. Press the function button
once (fig 7, 5) then the Mute button (fig 7, 2) to toggle the back light on and off.
Volume
After power up and switching from Standby to ON the preamplifier will enter the mode it was
last in when the power was turned off.
Front Panel:
To change the overall volume of the unit, use the Volume Control Knob (Fig 1, 7). Turn knob
clockwise to increase the volume (the maximum volume is +20db) and counter-clockwise to
decrease the volume (the minimum volume is -60db).
To mute the system, press the Mute button (Fig 1, 4), the output to the power amps is then
disabled The display will show the word MUTE. If the Mute button or volume button is
pressed the output to the power amplifiers is reactivated.
Remote Control:
To change the overall volume of the unit, use the volume buttons on the remote control (Fig
2,1)
To Mute the loudspeakers, press the Mute button (Fig 2,2). To un-mute the loudspeakers press
the Mute button again or press either volume button.
Page 17 of 26
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dm8
Volume – balancing function
The volume can be evenly distributed though the speakers or one channel can be louder than
the other. To equalise the outputs of the speakers to the same volume, depress both the L & R
balance buttons (Fig1, 4&7) on the front of the unit at the same time.
Front Panel:
Using either the Balance Control Right (Fig 1, 5) or the Balance Control Left (Fig 1, 2), the user
can change the relative volume for the left and right channels. Depressing the Right button
will increase the volume on the right hand channel and decrease the volume on the left.
To change the overall volume of the unit, use the Volume Control Knob (Fig 1, 7). Turn knob
clockwise to increase the volume and counter-clockwise to decrease the volume. To mute the
system, when the speakers are balanced, continue to turn the knob counter-clockwise until the
word MUTE appears on the display, or press the Mute switch (Fig 1, 4).
Remote Control
Using the Function key on the remote control the user can change the relative volume for the
left and right channels.
Depress the function key once (Fig 2, 5). The display on the preamplifier (Fig 3) will display
BALANCE, then use the Volume buttons on the remote control. Depressing the - VOL button
will increase the volume on the left and decrease the volume on the right. Depressing the +
VOL button will increase the volume on the right and decrease the volume on the left.
The volume can be evenly distributed through the speakers or one channel can be louder than
the other. To balance the outputs of the speakers to the same volume, depress both the L & R
(Fig1, 2&5) balance buttons on the front of the unit at the same time.
Switching between sources
To select a device, press the appropriate button on the remote control or turn the selector knob
on the front panel until the device you require appears in the center of the display. After a few
seconds, the center of the display will reverts to displaying the volume level, though the
selected program source will remain on the lower left hand corner of the display. Only
allocated devices are available. Note: The Phono Input is always allocated.
If a source is selected (either through the front panel or remote control) and the correct source
is not selected, ensure that the program button adjacent to the input connectors for the selected
source is illuminated. If it is not, these input connectors will need to be re-allocated, refer to
Connecting signal sources and Allocating signal sources and the remote control, page 19
Page 18 of 26
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dm8
Phase Control
To toggle the unit between in-phase and out-of-phase mode depress the phase switch on the
front panel (Fig 1,10) or depress the function key (Fig 7, 5) on the remote control twice, the
display (Fig 3) will display In or Out, now press either of the volume buttons on the remote
control to toggle the unit between in-phase and out-of-phase mode.
Electronic Protection and Reliability
Components
Our components are selected not only for performance, but reliability as well.
For Example:
All HALCRO™ electrolytic capacitors are rated at a minimum of 105 degrees C instead of the
usual 85 degrees C rating. The operational life of electrolytic capacitors is severely shortened at
temperatures near their maximum temperature rating. This is shown in the table below.
All HALCRO™ integrated circuits are at least “industrial grade” rather than the usual
“commercial grade.” Industrial grade components are rated at least from –40 degrees C to +85
degrees C whereas commercial grade components are only rated between 0 to 70 degrees C. In
addition, the electronic specifications of industrial grade components are superior to
commercial grade.
Electrolytic
capacitor
temperature
rating
85 C (most
commonly
used)
105 C (used in
HALCRO™
preamplifiers)
Mains transient overload protection
The mains input is protected against all but the most severe mains input transients. Two
independent circuits achieve this.
Mean lifetime
at 40 degrees
Centigrade
50,000 Hours 2,000 Hours (0)
180,000 Hours 8,000 Hours 2,000 Hours
Typical data
Mean lifetime
at 85 degrees
Centigrade
Mean lifetime
at 105 degrees
Centigrade
Page 19 of 26
dm8
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SPECIFICATIONS & FEATURES
HALCRO dm8
Remote Control Preamplifier
Inputs
§ 3 RCA Unbalanced Voltage Mode
§ 3 XLR Balanced Voltage Mode
§ 1 RCA Unbalanced Current Mode
§ Any 5 of the above I/Ps are user
programmable to respond to the device
names: CD, DVD, Tuner, Tape, Aux.
Outputs
§ 2 Pair RCA Unbalanced Voltage Mode,
Bridgeable
§ 2 Pair XLR Balanced Voltage Mode,
Bridgeable
§ 2 Pair RCA Unbalanced Current Mode,
1 pair for un-bridged connection, the
other pair used in bridged mode
§ 1 Pair RCA Tape output
§ 6-pin XLR power ON/OFF, pulsed and
level output control
Power supply
Switch-mode, >200kHz CW, 4th order
mains filter, 4th order supply rail filter.
EMC fully complies with EMC and CE
standards. Circuit contains extensive mains
transient protection and fault sensing
protection.
85-240VAC, 50-60Hz
Power consumption.
100W max via IEC input
Mains voltage.
All voltages from 85VAC through to
240VAC at 50Hz through to 60Hz or 120V
through to 340V D.C. (Power supply
will operate up to 270VAC but IEC sockets
rated up to 240V by regulatory authorities.)
Remote Control: 3 x AAA batteries
Dimensions
Ÿ Width: 448mm, 17.64 inches
Ÿ Depth: 400mm, 15.74 inches
Ÿ Height: 240mm, 9.44 inches
Ÿ Weight: 22.5kg, 49.6lbs
Shipping Dimensions
- In Timber case
Ÿ Width: 585mm, 23 inches
Ÿ Depth: 535mm, 21 inches
Ÿ Height: 515mm, 20 inches
Ÿ Weight: 36 kg, 79.4 lbs
Remote Control dimensions
Ÿ Length: 183mm, 7.2 inches
Ÿ Width: 50mm, 1.96 inches
Ÿ Thickness: 24mm, .94 inches
Ÿ Weight: 280gm, .6 lbs
Gain
Un-balanced and balanced -60dB to +20dB
set by volume control
Input impedance
10kohm + 10kohm balanced
10kohm unbalanced
50ohms for current mode
Output impedance
170 + 170ohms balanced and 170ohms
unbalanced.
>30kohms current mode
340ohms tape
Distortion
Unmeasurable- below noise floor.
At full specified output, < 250 parts per
billion (-132dB) for balanced and unbalanced and current modes
PCB
4-layer PCBs for ultra high accuracy
reference potentials
Volume control
-60dB to +20dB in 0.5dB steps.
Page 20 of 26
dm8
SPECIFICATIONS & FEATURES
HALCRO dm8
Remote Control Preamplifier
Display:
Backlit LCD (Back light can be turned off –
see page 16) Displays L&R volume setting,
selected input and phase.
Controls
On/Standby:
Ÿ Front Panel: 1 x Push Button
Ÿ Remote Control: 1 x Push Button
Volume:
Ÿ Front Panel: Optical Rotary Encoder
with Halcro Flux Detent
Ÿ Remote Control: 2 x Push Buttons
Input Select.
Ÿ Front Panel: Optical Rotary Encoder
with Halcro Flux Detent
Ÿ Remote Control: 5 x Push Buttons
Balance:
Ÿ Front Panel: 2 x Push Buttons
Ÿ Remote Control: Function Key, 2 x
Push Buttons
Mute:
Ÿ Front Panel: 1 x Push Button
Ÿ Remote Control: 1 x Push Button
Phase:
Ÿ Front Panel: 1 x Push Button
Ÿ Remote Control: Function Key, 1 x
Push Button
Program Button:
Ÿ Rear Panel: 7 x Push Buttons
TM
Components
Vishay 0.5% resistors and FKP1 1250V or
MKP10 capacitors in critical audio signal
paths.
Input programming
Up to 5 signal source units can be
connected to the 7 physical inputs. The
assigned source is defined on the display
and on the remote control. This is
memorised and may be either re-allocated
or de-allocated. Allocation is performed
using the remote control and a remote
input receiver. A remote input receiver
resides behind the front and rear panel for
flexibility. The program status of each input
is displayed on a LED adjacent with each
input.
Memory
All volume (gain) settings for each
programmed input (source) are memorised
when the unit is switched off or another
source is selected. Upon re-selection of the
input, or upon power up, the previously
memorised volume is reinstated.
This accommodates differing source
outputs. For example, a modern CD player
may have an output up to a few volts,
whereas an older type of analogue tape
recorder may only output a few
hundred millivolts.
Page 21 of 26
TM
dm8
Care and Maintenance
The HALCRO™ dm8 preamplifier has been designed for indoor use only. Under no
circumstances should the preamplifier be allowed to get wet. The only maintenance required is
to keep the unit clean.
Important.
HALCRO™ takes no responsibility for any damage caused through careless or improper
cleaning techniques. Never use flammable or corrosive products when cleaning the dm8.
Please read the following procedures very carefully.
The outer surface of the unit is anodized aluminum which, while being very durable, will be
marked if rubbed with an abrasive cloth.
Prior to cleaning, turn the power to the unit off at the mains.
Use only extremely soft cloths.
Use a soft dry cloth to remove any dust.
Add 15 milliliters (.5 Oz) of very mild household dishwashing detergent to a 4-litre (1 gal.)
bucket of lukewarm water. Immerse the soft cloth in the bucket of water, then wring the cloth
out thoroughly until the cloth is nearly dry.
The slightly damp cloth should only ever be used to clean the anodized aluminum surfaces.
Never clean any electrical fittings, terminals or the front and rear Labels with the damp cloth.
The labels can be cleaned using an extremely soft polishing cloth, which must be dry. No
moisture should ever be allowed to enter the units’ compartments through the joins in the
panels.
After using the slightly damp cloth, wipe over the surfaces with a soft dry cloth, then allow the
dm8 to air for at least one hour prior to turning the power back on.
If you are unsure about cleaning the preamplifier and require more information, please ask
your dealer or contact HALCRO™ at service@halcro.com .
Page 22 of 26
TM
dm8
Troubleshooting
The dm8 contains no user serviceable parts inside the compartments. Do not attempt to open
the unit as this will void the warranty and will expose you to dangerous voltages. For all
service requirements please contact your dealer or email HALCRO™ at service@halcro.com
If the dm8 does not operate as expected first switch the dm8 back to Stand-by and then switch
the main power switch off. Once the display has turned off switch the main power switch
back on and then switch the unit from Stand-by to On. This will reset the microprocessors in
the dm8.
Symptom Suggestion
No display characters
or illumination
No audio output Ensure the input to which your source is connected and
Will not select source Ensure the source is connected to a programmed input
Can not de-allocate
input
Remote control does
not work
If none of the above rectifies the problem please contact your dealer or contact HALCRO™ at
service@halcro.com for service.
Check mains power input is connected and turned on.
Check fuse.
allocated to is selected.
Ensure the output select switch is set to the correct
position output mods.
Ensure the dm8 is not muted, or the volume is too low.
and the Program Button adjacent to the input is
illuminated.
Ensure you are not trying to de-allocate an input that is
currently selected on the display screen. The software
does not allow this.
Change batteries.
Remote transmitter may overload the receiver if too close
i.e. less than 100mm (4”).
Page 23 of 26
TM
dm8
Service
The dm8 has been designed for maximum reliability. If a problem does occur with your unit,
please contact your dealer or contact HALCRO™ at service@halcro.com
Your dealer can help with trouble shooting prior to organising service for your dm8. Your
dealer or the HALCRO™ service department will always try to help you correct any basic
problems at your home via email or telephone. Simple trouble-shooting may remedy the
problem and not interrupt your listening pleasure due to the dm8 not having to leave your
home.
If service is required, all problems must be described in as much detail as possible. This will
help streamline the service process.
Return authorization from HALCRO™ prior to shipment must be obtained for any service
requirements. To obtain this authorization, please ask your dealer or email us at
service@halcro.com .
The original packaging is required for shipping purposes. HALCRO™ will not be responsible
for any damage caused to your preamplifier during shipping due to improper packaging. If
the packaging needs to be replaced on its arrival at the factory, you will be charged the
replacement cost.
Page 24 of 26
TM
dm8
Warranty
IMPORTANT - Please read the following details very carefully
HALCRO™ products are warranted to be free of defects if used under normal conditions for a
period of ninety (90) days from the date of purchase. To extend the warranty period to four (4)
years for the dm8, please complete and return the warranty registration form.
As mentioned previously, do not attempt to open any of the preamplifier compartments. The
compartments are sealed at the factory. If any of the seals are broken, the warranty will be void
and all service, repair and freight costs will be charged to the owner. Willful damage,
tampering and damage caused by moisture are not covered by the warranty.
The warranty will only be recognized by HALCRO™ if a copy of the original receipt from your
dealer showing all details, including the date of purchase, accompanies the completed
warranty registration form. The warranty period will commence at the date of purchase, not at
the date the warranty registration form is received by HALCRO™.
Return authorization from HALCRO™ prior to shipment must be obtained for any warranty
requirements. To obtain this authorization, please ask your dealer or email HALCRO™ at
service@halcro.com .
The original packaging must be used for shipping for warranty or service requirements. If you
have misplaced or damaged the original packaging, you can purchase new packaging through
your dealer or
The warranty registration form is included in this owner's manual on the following page.
Please cut it out carefully along the line up the left-hand side of the page and return it to
HALCRO™. You will find the address and facsimile details on the warranty registration form.
PLEASE COMPLETE ALL SECTIONS OF THE FORM, THEN FAX OR POST THE
COMPLETED WARRANTY REGISTRATION FORM TO HALCRO™ IMMEDIATELY. WE
WILL THEN NOTIFY YOU OF ITS ARRIVAL AND ACCEPTANCE.
Page 25 of 26
dm8
Warranty Registration Form
One form must be completed for every preamplifier.
Title……………
First name………………………….. Surname……………………….
Address………………………………………………….…………………………………
…………………………………………………………………….…………………………..
Zip or post code………………………Country……………………………………….
Date of Birth: Day………..Month………….Year…………..
Phone numbers: Home (……)…………………….. Work (……)…….……………..
Facsimile numbers: Home (……)………………… Work (……)…….……………….
Email address………………………………………………
PRODUCT DETAIL
Model number dm8
Serial number ……….…….. (located on a badge at the bottom of rear panel)
Date of purchase: Day..……….Month………..Year…………..
Purchased from (Dealer name)….…………………………………….………………...
You must attach a copy of the original receipt for the warranty to be accepted.
Please describe the main function for the preamplifier.
Domestic use Commercial demonstration use
Please refer to the previous page for details of the warranty period for your model.
Post to, HALCRO™,
118 Hayward Avenue
Torrensville, South Australia, 5031.
Fax to, +61 8 8238 0852
TM
Page 26 of 26
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