Audio Research Reference 6 User manual

Reference 6
H I G H D E F I N I T I O N ®

Thank You.
Thank you for choosing the
Reference 6 to be a part of
your high performance music
listening system. Since 1970,
Audio Research has been creating
some of the world’s nest
audio equipment. Each piece is
handcrafted in Minnesota, and has
been designed to provide many
years of listening enjoyment.
We understand you are eager
to begin listening; however,
please take a few minutes to
read through this guide for
useful information concerning
the operation of your new
preamplier. Once installed,
please allow an appropriate
break-in period to fully appreciate
the benets this preamplier
will provide to your system.
After reading the user guide, if
you have any further questions
regarding your preamplier,
contact your dealer or Audio
Research customer service - they
will be happy to help you make the
most of your new component.
Happy Listening!

4
Contents
Warnings
Installation
Before Operating the Reference 6
In Your System
A Note about Vacuum Tubes
Connections
Back Panel Connections
Input Connectors
Output Connectors
Record Output
A.C. Power Connection
RS-232, IR Input and 12 V trigger
5
6
7
7
8
9
9
9
9
9
Operation
Front Panel Controls and Display
Start-Up
Shut-Down
Break-in
Front Panel Controls
Remote Only Functions
Settings Menu
System Settings - Menu Tree
Settings Menu
Auto Shutdown
Processor Mode
Tube Hours
Display Brightness
Volume Reset
Input Naming
10
11
11
11
12
13
14
15
15
16
16
17
17
17
Maintenance
Vacuum Tubes
Service
Cleaning
Disposal and Recycling Guidelines
Fuse Values and Locations
Warranty
Specications
18
18
18
18
19
20
21

5
Warnings
To prevent re, or shock hazard, do not
expose your Reference 6
to rain or moisture.
Do not place objects containing
water on top of this unit.
This unit contains voltages which can cause
serious injury or death. Do not operate
with covers removed. Refer servicing
to your authorized Audio Research
dealer or other qualied personnel.
The detachable power cord on your
Reference 6 is equipped with a heavy
gauge, 3-conductor cable and a standard
three-prong grounding plug. For absolute
protection, do not defeat the ground power
plug. This provides power line grounding
of the Reference 6 chassis to provide
absolute protection from electrical shock.
The appliance coupler (a.c. power connector)
at the rear of this unit must be accessible
for emergency power disconnect.
The power button on the front of this
unit, when o, does not disconnect
all power from this unit. This unit
is in sleep mode when not on.
For continued protection against re hazard,
replace the fuse only with the same type
and rating as specied at the fuse holder
(see page 19 for fuse information).
This unit is RoHS compliant.
The Reference 6 has automatic muting to
help protect system components in the
event of low line voltage. When sensing
low line voltage, the preamp displays ‘Low
Line’ and automatically goes into ‘Mute’.
This condition will persist until the line
voltage returns to a safe operating level;
please note the unit will remain in ‘Mute’
even after ‘Low Line’ no longer appears.
Note that automatic muting is only
designed to protect against power line
interruptions or severe voltage drop. It
will not mute in the event of subsonic
transmissions from a faulty input source,
amplier failure or speaker malfunction.
A note about packaging...
Save all packaging in a dry place away from
re hazard. Your Reference 6 preamplier
is a precision electronic instrument
and should be properly cartoned any
time shipment is made. You may not
have occasion to return your unit to the
factory for service, but if that should
prove necessary, or other occasion
requiring shipment occurs, the original
packaging will protect your Reference
6 from unnecessary damage or delay.

6
Before operating the Reference 6
Your Reference 6 preamplier is shipped
with the vacuum tubes packed in a
separate foam-lined carton. These must
be unpacked and installed before you
attempt to operate the preamplier.
Included are six 6H30 tubes for the
analog stage, and a 6H30 and 6550WE
used in the power supply. Proceed
according to the following instructions.
Installation
Remove all screws fastening the top cover.
Carefully remove each vacuum tube
from its protective foam and match its
location ‘V’ number (written on the base
of the tube) to the ‘V’ number printed
next to each socket. Firmly seat each
tube in its matching socket, taking care
to ‘key’ the tube pins to the socket holes.
Retain the tube carton with other packing
materials for possible future use.
Refasten top cover on the preamplier.
V6 V4 V2
V5 V3 V1
V7
V8

7
Installation
In your system
To ensure normal component life and safe
operation this unit must be operated
only in an upright position. Adequate
airow and proper cooling can occur
only if there is no restriction above and
behind the unit and on either side.
The special non-marring elastomer feet
provide adequate spacing and stability
only on a smooth, hard surface, and also
assist to isolate the preamplier from
spurious vibrations. For upright stability
and best performance, never operate
the unit while it is sitting on a soft
surface such as a thick rug or carpet.
Due to its weight, this preamplier must
be supported on a surface specically
rated for such a load. Check with the
manufacturer of your support system to
be sure it is rated to handle this weight.
If the unit is to be operated in an enclosure
such as an equipment rack, make certain
that adequate airow above and to
each side of the unit is provided. Audio
Research recommends a minimum of
6-8 inches (15-20 cm) of clearance above
the Reference 6 to maintain proper
ambient operating temperature.
The ‘ambient’ operating temperature should
never exceed 120° F or 49° C. Improper
installation will cause premature tube
failure and will aect your warranty,
as well as the service life of the unit.
It is normal for a vacuum tube preamplier
to run quite warm, and if used for
prolonged periods, hot to the touch.
All components within are, however,
operated at safe, conservative levels
and will not be improperly aected
thereby, providing the requirements
outlined above are adhered to.
A Note about Vacuum Tubes
The vacuum tubes in your Reference 6 have
been burned in, tested and electrically
matched to provide the best performance
and reliability of your preamplier. That
said, vacuum tubes must be replaced
from time to time. The 6H30 tubes in
the Reference 6 should have an expected
life of approximately 4,000 hours,
while the 6550WE tube in the power
supply should have a life expectancy of
approximately 2,000 hours. These life
expectancies are only approximate.

8
Connections
A.C. Mains connector
Fuse Holder
RS-232 connector
Control
connections
Balanced Inputs Single-ended Inputs
Main Outputs
Back Panel Connections
Record Outputs

9
Connections
Input Connectors
The Reference 6 provides eight pairs of
input connectors; four balanced and four
single-ended, labeled BAL 1-4 and SE 1-4.
Output Connectors
Two pairs of BAL/SE main outputs are
provided. The outputs are connected
in parallel. If using both outputs
simultaneously, the combined input
impedance of the amplier(s) being
driven by the Reference 6 must be
greater than or equal to 20k Ohms.
Record Output
The record output should be connected to
your recorder’s ‘Record’ or ‘Line’ inputs.
These outputs provide a xed-level two-
channel signal (left and right) to your
recorder from whichever input is selected.
The non-variable output level will be the
same as the output of the selected source.
It is possible to dub or copy from one
recorder to another by connecting the
output of the source recorder to an unused
set of stereo inputs. The signal will then
be routed to the Record Out connectors
when that input source is selected.
Warning
Do not connect the record output directly to
an amplier. This will send full output (with
no volume attenuation) to the amplier(s),
and could cause serious serious damage
tot the amplier(s) or loudspeakers.
A.C. Power Connection
It is important that the Reference 6 be
connected via its supplied 20 amp IEC
14-gauge power cord to a secure, dedicated
A.C. power receptacle. Never connect to
convenience power receptacles on other
equipment. Only use the power switch
on the front of the Reference 6 for On/
O control of the preamplier, or the
IR input, RS232 or remote control.
RS-232 Input
The RS-232 input allows connection of
a control or automation system.
IR Input
The IR input allows a remote IR sensor or
repeater system to be connected to the
Reference 6 for control purposes, utilizing
a standard mono 1/8” connector.
12V Trigger Out
The +12V DC trigger out jack provides
the ability to remotely turn on and
o the preamplier and other linked
components such as power ampliers
having similar capabilities.
Important
Use the best available speaker wires
and interconnects. Audio Research
cannot emphasize this enough. As
better components and systems are
developed, it becomes increasingly
important to avoid the limitations of
inferior system interconnections.
It is important sonically that your entire
system be connected so that the audio
signal arriving at the speakers has correct,
or ‘absolute’ polarity (i.e., non-inverted).

10
Operation
Front Panel Controls and Display
Input Select
Vacuum Flourescent
Display Volume
Power On/O
Menu
Enter
(used with Menu)
Mono/Stereo
Invert Phase
Mute

11
Operation
Start-Up
• Secure all rear-panel connections between
Reference 6, power amplier(s) and input
sources.
• Plug three-prong power cord from
rear of chassis into grounded A.C. wall
outlet. The Power switch defaults to ’o’
when the unit is plugged into a power
receptacle.
• Press power switch (either on the remote
or front panel). The preamplier will
begin the warm-up sequence, which lasts
approximately 45 seconds, during which
‘MUTE’ will ash on the display. After the
warm-up sequence is complete, the unit
will be muted. Depress the front panel
‘MUTE’ button or the Mute button on the
remote to initiate normal operation. You
may depress the Mute button prior to the
unit completing the warm-up cycle;
‘MUTE OFF’ will ash on the display until
the warm-up cycle is complete.
• Select input source and adjust the volume
as necessary.
Shut-Down
• Activate ‘MUTE’ function.
• Turn o power amplier(s).
• Press Power switch to ‘o’.
• Turn o input sources.
Note
The Reference 6 should be turned on
before the amplier in your system. If the
Reference 6 is turned on after the amplier,
it will amplify any extraneous turn-on
noises the preamplier or other source
components might generate, which could
potentially damage the loudspeakers.
Good operating practice dictates that
the amplier should be turned on last,
and turned o rst in an audio system.
Break-in
All quality stereo equipment benets from
a break-in period; during this time, the
various components, wiring and solder
connections change as electrical signals
pass through them. While your Reference
6 will sound fantastic out of the box, it
will only improve with continued use.

12
Front Panel Controls
The Reference 6 has two microprocessor-
driven rotary controls and six buttons
(Power, Menu, Enter, Mono, Invert, and
Mute).
Left Rotary control (Input Select)
Select input by rotating the control to the
left or right. The screen displays the current
input on the left side of the display.
Right Rotary control (Volume)
Adjust volume (output level) up or down
for both L and R channels. Volume control
is also selectable via VOL UP and VOL DN
buttons on the remote control. Volume
adjustment is indicated in the display
window by numeric digits on 0–103 scale.
Do not turn volume up beyond normal
listening levels when ‘mute’ is engaged to
avoid unexpected or possibly damaging
sound levels. Reduce volume level
whenever changing input sources, even
when muted.
The right rotary control also functions to
change settings when in the menu.
Power On/O
Supplies power from A.C. wall outlet
to preamp; indicated by active display
window. The Reference 6 requires
approximately 45 seconds to warm up; this
time is required to stabilize the vacuum
tubes. See ‘Start-Up Procedure’ on page 11
for details.
Menu
The menu button enters the setup menu
of the Reference 6 to allow customizing
certain settings of the preamplier. See
page 15 for further details about using the
setup menu.
Enter
The enter button is used in conjunction with
the Menu button to make changes to the
systems settings of the Reference 6.
Mono
Toggle between Stereo and Mono output.
Invert
The invert button allows the absolute phase
of the recording to be switched between
‘normal’ (in-phase) and ‘invert’ (180°
inversion).
Mute
When activated, Mute electrically disables
all outputs of the preamplier; indicated
by ‘MUTE’ in display window, beneath the
volume number. This control should be
activated before switching inputs, changing
connections or shutting down your audio
system to help protect your amplier and
speakers from unexpected signal pulses.
When deactivated, ‘MUTE’ is cleared
from the display window allowing normal
operation.
Operation

13
Operation
Remote Only Functions
In addition to the controls found on the
front panel, the remote control oers
access to the following additional
features of the Reference 6.
Hours
Pressing the ‘HOURS’ button will display
the total accumulated hours of operation
for the Reference 6. This is useful to
determine the approximate number of
hours the vacuum tubes have been in
use. After ve seconds, the display will
revert to the normal operation screen.
After replacing vacuum tubes, the hours
counter should be reset (see instructions
under ‘Settings Menu’ on page 16).
Note
The installed 6H30 vacuum tubes have
an average life span of approximately
4,000 hours, and the 6550WE has an
average life span of approximately 2,000
hours. After this time, we recommend
replacing them to maintain the best
performance of your preamplier.
Input Select Buttons
The input buttons labeled BAL 1-4 and SE
1-4 allow direct selection of each of the
eight inputs available on the Reference 6.
Display Brightness Adjustment
The front panel display has six brightness
settings, as well as the ability to dim
the display completely. To change the
brightness, use the ‘DSP UP’ or ‘DSP DN’
buttons on the remote. Note that when
the display is completely dimmed, a
small square appears in the middle of the
display to indicate the unit is powered on.
Balance
The Balance control adjusts the output from
center position to the left or right channels,
which in turn will shift the center point of
the sonic image. This is useful in the event
the main listening position is not centered
between the speakers, or can help with
certain room anomalies.
To adjust the balance, press the ‘BAL L’ or
‘BAL R’ button on the remote. The balance
scale will appear in the middle of the
display, and the indicator block will move in
the selected direction:
After ve seconds of inactivity, the
balance scale will disappear from the
screen. If the balance has been shifted
to the right or left, ‘R+’ or ‘L+’ will
appear at the bottom left corner.

14
Operation
System Settings - Menu Tree

15
Operation
Settings Menu
The Reference 6 has been designed
with a simple, intuitive menu to allow
adjustment of the various features of
the preamplier. To adjust the settings,
press the ‘MENU’ button on the remote
or front panel. If no further action is taken
with the preamplier or remote for ve
seconds, the Reference 6 reverts back to
its normal operation screen. Continuing
to press the ‘Menu’ button will toggle you
through the dierent setting options:
While a menu item is displayed, press
‘ENTER’, followed by rotating the
volume knob on the front panel, or
using the volume up/down buttons on
the remote to adjust the settings of
that particular selecton. After making
the appropriate change, pressing the
‘ENTER’ button will conrm the new
setting, and the display will show ‘OKAY’
for ve seconds before reverting back
to the normal operation screen.
Note
For the following menu settings, please refer
to the menu tree on page 14 for examples
of the front panel display.
Both the ‘MENU’ and ‘ENTER’ buttons (found
on the front panel and remote), as well as
the volume knob (or the up/down volume
buttons on the remote) are used to make
changes to the menu settings. Note that
the ‘MENU’ button can also be used to
back out of a menu selection, returning to
the main settings options.
Auto Shutdown
The Reference 6 is equipped with an auto
shut o feature, designed to turn the
preamplier o after a period of time
during which it is not used. The auto shut
o feature senses any interaction with
the preamplier, such as button presses,
changing the volume, remote usage, etc.
To change/disengage the auto shutdown
feature, press the ‘MENU’ button
until the ‘AUTO SHUTDOWN’ screen
is displayed. Using the volume knob
on the front panel, or the volume up/
down buttons on the remote, you have
the option for ‘o’ (no auto shutdown)
or 1-8 hours. Once you have made a
selection, press ‘ENTER’ to conrm. The
display will show ‘OKAY’ before reverting
back to the normal operation screen.
Note
The auto shutdown feature is not in the
signal path of the preamplier and has no
deleterious sonic eect to music playback.

16
Processor Mode
The Reference 6 has the ability to assign
unity gain (also called ‘pass through’) to
one of the eight inputs available in the
event it will be integrated into a system
with a secondary control device, such as a
surround sound processor. When an input
is assigned as the processor input, the
volume control on the Reference 6
is disabled so that the processor’s
volume is the only control used.
To set up a processor input, connect the
left and right output channels from
your surround sound processor to the
left and right inputs of your choice
on the Reference 6. Press the ‘MENU’
button until ‘PROCESSOR MODE’
is displayed, and press ‘ENTER’.
With ‘PROCESSOR’ displayed, turn the
volume knob, or use the up/down
volume buttons on the remote, to select
the desired input for processor mode.
Press the ‘ENTER’ button to select
the input, and ‘ENTER’ once again to
conrm the selection. The Reference
6 will display ‘OKAY’ and show the
selected input on the bottom line.
When using the input selected for processor
mode, note that in place of the volume
number on the operation screen, a
‘pass through’ symbol will be shown.
Warning
When processor mode is assigned to an
input, do NOT connect a source (such as
a CD player or phono stage) to that input.
This will send full output from the source
to your amplier(s), and could cause
serious damage to your loudspeakers or
amplier(s) - not to mention your ears!
Operation
Tube Hours
The tube hours display shows the
accumulated time the Reference 6 has been
powered on. This is useful for determining
the number of usage hours of the installed
vacuum tubes. See A Note about Vacuum
Tubes on page 7 for specic information
regarding the tubes in the Reference 6.
To reset the tube hours counter, press
the ‘MENU’ button until ‘TUBE HOURS’
is shown. Press the ‘ENTER’ button to
display ‘ENTER TO RESET’. Press ‘ENTER’
again and the display will read ‘ENTER TO
CONFIRM’. A nal press of the ‘ENTER’
button will reset the tube hour counter
to 0 and the display will show ‘OKAY’.
Note
Once the hour counter has been
reset, the total accumulated
hours cannot be recalled.

17
Display Brightness
The display brightness feature oers six
dierent settings (including o) for the
vacuum ourescent display on the front
panel. When the lowest setting (o) is
selected, the display will remain on for
ve seconds after any button is pushed,
after which it will revert to a black screen
with a small, illuminated square in the
center to indicate the unit is powered on.
To change the display brightness, press
the ‘MENU’ button until ‘DISPLAY
BRIGHTNESS’ appears. Press the enter
button. Using the volume knob on the front
panel, or the up/down volume buttons on
the remote, change the display brightness
to your preference. Once you have selected
the appropriate brightness, there is no need
to press ‘ENTER’ or any further buttons.
Note
The remote control oers direct control
of the display brightness via two buttons
labeled ‘DISP UP’ and ‘DISP DN’. You
can choose to use these buttons as an
alternate to the settings menu.
Operation
Volume Reset
The volume reset feature tells the Reference
6 to either remember the volume settings
for each individual input, or to reset them
to zero after a power o cycle. When
volume reset is set to ‘OFF’, the Reference
6 will also remember settings after a power
cycle.
To change the status of the volume reset,
press the ‘MENU’ button until the display
reads ‘VOLUME RESET’. Press ‘ENTER’,
and use the volume knob on the front
panel, or the up/down volume buttons on
the remote, to select ‘ON’ or ‘OFF’. Press
‘ENTER’ to choose the appropriate setting,
and ‘ENTER’ once again to conrm. The
display will read ‘OKAY’ and show the
current setting for volume reset.
Input Naming
The Reference 6 is pre-loaded with a
selection of names which can be assigned
to the eight inputs of the preamplier,
allowing for easier identication of the
various inputs. When selected, the chosen
input name will display above the default
name (BAL 1, SE 3, etc.) on the normal
operation screen.
To select an input name for any of the
inputs, press the ‘MENU’ button until
‘INPUT NAMING’ is displayed. Press the
‘ENTER’ button, and use the volume knob
on the front panel, or the up/down volume
buttons on the remote, to select the
desired input for naming. Press ‘ENTER’ to
engage the naming utility, and using the
volume knob or up/down volume buttons,
select the appropriate name for the input.
Press ‘ENTER’ a nal time to conrm the
input name. The display will show ‘OKAY’.

18
Vacuum Tubes
It is recommended that you replace the
6H30 vacuum tubes of your Reference 6 in
sets. All of the tubes in your preamplier
have been matched to have similar
operating characteristics, to provide
the best sound quality and reliability.
Servicing
Because of its careful design and exacting
standards of manufacture, your Reference
6 preamplier should normally require
only minimal maintenance to maintain
its high level of performance.
Should you need service, please contact your
authorized Audio Research dealer or other
qualied technician. Additional questions
regarding the operation, maintenance
or servicing of your preamplier, please
contact the Customer Support Department
of Audio Research Corporation at
[email protected] or call
763-577-9700. You may also initiate a
service request by visiting the Audio
Research website
(www.audioresearch.com) and
selecting ‘Service Repair’ at the
top right of the home page.
Caution
Your Reference 6 preamplier contains
sucient levels of voltage and current to
be lethal. Do not tamper with a component
or part inside the unit. Even with the
power turned o, a charge remains in the
energy storage capacitors for some time.
Cleaning
To maintain the new appearance of this
preamplier, occasionally wipe the
front panel and top cover with a soft,
damp (not wet) cloth to remove dust.
A mild, non-alkaline soap solution
may be used to remove ngerprints or
similar smudges. Cleaners containing
abrasives should not be used as they
will damage the anodized nish of the
front panel. A small, soft paintbrush is
eective in removing dust from bevels,
and other features of the front panel.
Disposal and Recycling Guidelines
To dispose of this electronic product, do
not place in landll. In accordance with
the European Union Waste Electrical
and Electronic Equipment (WEEE)
directive eective August 2005, this
product may contain regulated materials
which upon disposal require special
reuse and recycling processing.
Please contact your dealer or importing
distributor for instructions on proper
disposal of this product in your country.
Or, contact Audio Research Corporation
(763.577.9700) for the name of your
importing distributor and how to contact
them. Packing and shipping materials
may be disposed of in a normal manner.
Maintenance

19
Maintenance
The Reference 6 has three replaceable fuses
to help protect the unit in the event of a
spurious electrical surge or other situation.
When replacing fuses, please use only
the specied ratings. Using ‘slugs’ or
other devices intended to bypass the
function of the fuse will not only void
the warranty in the event of damage,
but could also cause serious system
failure, re, or personal injury.
A.C. Mains Fuse
120 V units: 5A slow blow
220-240 V units: T4
CE Fuse
220-240 V units only: T1A
Note: 120 V units will have a wire
jumper in place of the fuse.
Microprocessor Fuse
120 V units: 250mA
220-240 V units: T125 mA
Fuse Values and Locations
A.C. Mains Fuse
CE Fuse
(220-240 V units only)
Microprocessor
Fuse

20
Warranty
Audio Research Corporation products are
covered by a 3-Year Limited Warranty
or a 90-Day Limited Warranty (vacuum
tubes). This Limited Warranty initiates
from the date of purchase, and is
limited to the original purchaser,
or in the case of demonstration
equipment, limited to the balance
of warranty remaining after original
shipment to the retailer or importer.
In the United States, the specic terms,
conditions and remedies for fulllment
of this Limited Warranty are listed on
the warranty card accompanying the
product in its shipping carton. The
warranty terms are also available on the
internet at www.audioresearch.com/
en-us/company/warranty-statement.
Outside the United States, the authorized
importing retailer or distributor has
accepted the responsibility for warranty of
Audio Research products sold by them.
The specic terms and remedies for
fulllment of the Limited Warranty may
vary from country to country. Warranty
service should normally be obtained from
the importing retailer or distributor from
whom the product was purchased.
In the unlikely event that technical service
beyond the ability of the importer is
required, Audio Research will fulll the
terms and conditions of the Limited
Warranty. Such product must be
returned at the purchaser’s expense to
the Audio Research factory, along with a
photocopy of the dated purchase receipt
for the product, a written description
of the problem(s) encountered, and
any information necessary for return
shipment. The cost of return shipment
is the responsibility of the purchaser.