Audio Research High Definition Reference 80S User manual

H I G H D E F I N I T I O N®
Reference 80S

There is only One Reference®

Thank You.
Thank you for choosing the
Reference 80S to be a part of your
high performance music listening
system. Since 1970, Audio Research
has been creating some of the
world’s finest 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 amplifier. Once installed, please
allow an appropriate break-in period
to fully appreciate the benefits this
amplifier will provide to your system.
After reading the user guide, if you
have any further questions regarding
your amplifier, contact your dealer or
Audio Research customer service -
they will be happy to help you make
the most of your new component.
Happy Listening!

Contents
5-6
7
8
8
9
10
11
11
11
12
12
13
13
13
14
14
15
16
17
17
18
19
19
20
20
20
21
22
23
Safety Instructions
Warnings
Installation
Connections
Operation
Maintenance
Warranty
Specifications
Vacuum Tube Placement
Before Operating the Reference 80S
Tube Cage Removal
Tube Cage Installation
Ventilation Requirements
In Your System
Vacuum Tube Life Expectancy
Back Panel Connections
Input Connectors
Output Connectors
Impedance Matching
Remote Turn On
RS-232
A.C. Power Connection
Back Panel Controls
Front Panel Controls
Start Up
Shut Down
Front Panel Button Controls
Hour Counter
Break In
Vacuum Tubes
Service
Cleaning
Disposal and Recycling Guidelines

5
Safety Instructions
The lightning flash with arrowhead symbol with an equilateral triangle, is
intended to alert the user to the presence of uninsulated ‘dangerous voltage’
within the product’s enclosure that may be of sucient magnitude to constitute
a risk of electric shock to persons.
The exclamation point within an equilateral triangle is intended to alert the
user to the presence of important operating and maintenance (service)
instructions in the literature accompanying the product.
The 3 wavy lines symbol within an equilateral triangle is intended to alert the
user to the presence of a hot surface on the exterior case of the product.
• Read these instructions.
• Keep these instructions.
• Heed all warnings.
• Follow all instructions.
• Do not use this apparatus near water
• Clean only with dry cloth.
• Do not block any ventilation openings. Install in accordance with the manufacturer’s
instructions.
• Do not install near any heat sources such as radiators, heat registers, stoves, or other
apparatus (including amplifiers) that produce heat.
• Do not defeat the purpose of the polarized or grounding-type plug. A polarized plug has
two blades with one wider than the other. A grounding-type plug has two blades and a
third grounding prong. The wide blade or the third prong are provided for your safety. If
the provided plug does not fit into your outlet, consult an electrician for replacement of
the obsolete outlet.

6
Safety Instructions
• Warning: The apparatus shall be connected to a mains socket outlet with a protective
earthing connection.
• Protect the power cord from being walk on or pinched particularly at plugs,
convenience receptacles, and the point where they exit from the apparatus.
• Only use attachments/accessories specified by the manufacturer.
• Unplug this apparatus during lightning storms or when unused for long periods of time.
• Refer all servicing to qualified service personnel. Servicing is required when the
apparatus has been damaged in any way, such as power supply cord or plug is
damaged, liquid has been spilled or objects have fallen into the apparatus, the
apparatus has been exposed to rain or moisture, does not operate normally, or has
been dropped.
• WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE
THIS APPARATUS TO RAIN OR MOISTURE.
• DO NOT EXPOSE THIS APARATUS TO DRIPPING OR SPLASHING AND THAT NO
OBJECTS FILLED WITH LIQUIDS, SUCH AS VASES, SHOULD NOT BE PLACED ON THE
APPARATUS.
• TO COMPLETELY DISCONNECT THIS APPARATUS FROM THE AC MAINS,
DISCONNECT THE POWER SUPPLY CORD FROM THE AC RECEPTABLE.
• THE MAINS PLUG OF THE POPWER SUPPLY CORD SHALL REMAIN READILY
ACCESSIBLE.
• The user-replaceable rear panel fuse of the Reference 80S shall only be replaced with
a fuse of the correct breaking capacity and voltage rating as specified below and on the
rear panel of the amplifier.
100-127V T5AL250V MDQ (ARC part 34500505)
220-240V T2.5AL250V (ARC part 34600303)
• Speaker terminal banana jacks are plugged/capped for units sold in countries where
this is required due to power cord plub pin shapre.

7
To prevent fire, or shock hazard, do not
expose your Reference 80S 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 qualified
personnel.
The detachable power cord on your
Reference 80S 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 80S 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 fire haz-
ard, replace the fuse only with the same
type and rating as specified at the fuse
holder
This unit is RoHS compliant.
Handling and moving the Reference
80S
The Reference 80S weighs 62 lbs. (28
kg). When lifting, note the rear of the am-
plifier with the power and output trans-
formers is the heavy end.
A note about packaging...
Save all packaging in a dry place away
from fire hazard. Your Reference 80S
preamplifier 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
80S from unnecessary damage or delay.
Important
The AC power supply cord
must be disconnected from the
amplifier before replacement or
installation of vacuum tubes.
Warnings

8
Installation
Before operating the Reference 80S
Your Reference 80S amplifier 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 amplifier. Included
are four matched KT150s and two
matched 6H30 tubes.
Follow the procedure on the next pages
to remove the top cage prior to vacuum
tube installation.
Vacuum Tube Installation
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 screened next
to each socket on the top plate of the
Reference 80S. Firmly seat each tube in
its matching socket, taking care to align
the key at the base of each KT150 to its
socket hole.
The 6H30 tubes in V5 and V6 are not
keyed, and care must be taken to align
the pins to the sockets. A small flashlight
can assist.
HIGH DEFINITION
V1 V2 V3 V4
V5 V6
Vacuum Tube Placement

9
Tube cage removal and installation
CAUTION: THIS STEP FOLLOWED BY USER IS ALLOWED ONLY ONCE FOR THE INITIAL
INSTALLATION BEFORE POWERING UP THE PRODUCT FIRST.
Warning: Tube replacement shall be done by skilled or service personnel, or qualified
technician.
Important
The AC power supply cord must be disconnected from the amplifier before
replacement or installation of vacuum tubes.
To remove the cage:
Use the supplied 7/64” hex driver to remove the (3) cap screws and nylon washers at the
rear of the top cage, per illustration 1:
Gently slide the cage to the rear. Then lift it up and o the chassis, per illustrations
2 and 3.
Illustration 1
Illustration 2

10
Installation
Illustration 3
To install the cage:
Gently place the cage on top of the chassis. Ensure the sides of the cage are fully seated
on the top plate.
Slowly slide the cage forward until the two locating screws engage with the cap screws
behind the front panel.
See illustration 4. When the cage rear flange is flush with the rear edge of the chassis the
cage is fully installed. Note that you may have to slightly squeeze in the sides to allow
slots in the cage flange to align with the top plate cap screws.
Illustration 4

11
Ventilation Requirements
The Reference 80S employs forced air
cooling using an ultra-quiet internal fan,
located on the bottom cover near the
front of the chassis. This fan draws cool
air from under the unit, circulates the
air internally to cool components, and
exhausts the heated air from grilles on the
chassis top plate and transformer cover.
It is very important that cooling airflow to
this fan not be impeded in any way by
placing the unit on carpet or a soft surface
that might allow the Reference 80S to
settle into the surface and impede the
airflow.
A minimum of 8 inches (21cm) clearance
is required above the top of the amplifier.
If the unit is operated in an enclosure or
equipment rack, keep in mind the above
ventilation requirements to make certain
that adequate airflow above, to each side
and to the rear is provided.
The ambient operating temperature
should never exceed 86⁰F (30⁰C).
Improper installation will cause premature
component and /or tube failure and will
aect your warranty as well as the service
life of the unit. If you have any questions
about correct installation, please consult
with your authorized Audio Research
dealer or contact the factory at service@
audioresearch.com.
In Your System
To ensure normal component life and
safe operation, this unit should only be
operated in an upright position. The
special non-marring elastomer feet
provide adequate spacing and stability
only on a smooth, hard surface, and must
be on a dedicated shelf or amp stand
capable of supporting 62 lbs. Check with
the manufacturer of your support system
to be sure it is rated to handle this weight.
The Reference 80S power transformer
generates a magnetic field that could, in
some installations, induce hum in sensitive
electronics such as turntables, phono
cartridges and phono stage preamplifiers.
For this reason, we recommend that any
such products and their interconnecting
cables be kept a minimum of 12” away
from the Reference 80S.
Vacuum Tube Life Expectancy
The vacuum tubes in your Reference
80S have been burned in, tested and
electrically matched to provide the
best performance and reliability of your
amplifier. That said, vacuum tubes wear
out with use and must be periodically
replaced. The KT150 output tubes in the
Reference 80S should have an estimated
life of approximately 3000 hours, while
the smaller 6H30 tubes should have a
life expectancy of approximately 4000
hours. These life expectancies are only
approximate. Please consult with your
dealer or Audio Research customer
support for more information. Warning:
Tube replacement shall be done by
skilled or service personnel, or qualified
technician.

12
Connections
MINNEAPOLIS, MINNESOTA
REFERENCE 80S
STEREO AMPLIFIER
BALANCED
SINGLE
ENDED
LOW
FAN SPEED
HIGHDEFEAT
AUTO
SHUT OFF
BALANCED
SINGLE
ENDED
4 Ω0 Ω8 Ω16 Ω
WARNING
RISK OF HAZARDOUS ENERGY! MAKE PROPER SPEAKER CONNECTION
SEE OWNER MANUAL
HOURS
WARNING
TO PREVENT FIRE AND SHOCK HAZARD
DO NOT EXPOSE THIS DEVICE TO RAIN
OR MOISTURE.
UNIT MUST BE OPERATED IN HORIZONTAL POSITION.
-DO NOT OPERATE WITH COVERS REMOVED-
UNIT CONTAINS VOLTAGES WHICH MAY BE HAZARDOUS
LEFT INPUTS
BALANCED
SINGLE
ENDED
4 Ω0 Ω8 Ω16 Ω
WARNING
RISK OF HAZARDOUS ENERGY! MAKE PROPER SPEAKER CONNECTION
SEE OWNER MANUAL
RS-232
IN OUT
+12V
REMOTE TURN ON
CAUTION
FOR PROTECTION AGAINST FIRE HAZARD
REPLACE ONLY WITH SAME RATING FUSES
500 WATTS MAX 50/60Hz~
CLASS 2 WIRINGCLASS 2 WIRING
T3.15AL250V
(220-250V)
T5.0AL250V
(100-120V) L
R
RIGHT INPUTS
Do not connect the balanced XLR input
connectors and single-ended RCA input
connectors at the same time – connect
one pair or the other the same way for
both channels.
Input Connectors
The Reference 80S uses a fully balanced
circuit topology and has a pair of balanced
XLR input connectors and a pair of single-
ended RCA input connectors on the rear
panel. The rear panel switch must be in
the appropriate labeled position for either
balanced or single-ended use. Connect
your preamplifier’s output to the Reference
80S input connectorsbefore turning on the
amplifier.
Back Panel Connections
Output Connectors
Input Connectors
Auto Shut O
Fan Speed
Bal/Single-Ended
AC Power Coupler
RS-232
Remote Turn On

13
Output Connectors
Heavy-duty output terminals are provided
on the rear panel for 4, 8, or 16-ohm
speaker impedance loads. Using high-
quality speaker cables, securely fasten
the (-) speaker lead to the appropriate
(black) terminal, then the (+) lead to the
matching (red) terminal. 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).
Do not over tighten the output terminal
connectors on the amp (use a hex driver
and tighten snugly - do not over tighten).
Follow your speaker manufacturer’s
impedance specification. The Reference
80S puts out the same amount of power
whether the 4, 8, or 16-ohm terminals are
used.
Impedance Matching
It is important to use as close as possible
an impedance match between the
amplifier and speaker for optimum transfer
of power to the speaker with minimum
distortion. In the case of speaker systems
with significant variations in impedance
throughout the frequency spectrum,
such as most electrostatic types,
determine the best impedance match
empirically for best overall sonic results by
trying dierent output taps. Connect the
Reference 80S input to the preamplifier
or electronic crossover using only the
highest grade of audio interconnect
cables. To avoid sonic degradation use
the shortest practical length of cables.
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.
Remote Turn-on
The Reference 80S has a built-in 12V DC
remote turn-on/o circuit for operation by
a master control system in a home theater
or large audio system. Use a 3.5mm (.140”)
diameter mini plug to connect to the +12V
IN jack on the rear of the Reference 80S.
The tip of the mini plug is +12V and the
sleeve is ground.
The +12V IN jack should be connected to
the +12V DC output of the master control
system, using a continuous +12V DC
signal at 12mA for the duration of amplifier
on-time. Do not use a momentary or data
pulse control signal.
The +12V DC remote jacks have polarity
protection, so they will not operate if
a-12V DC signal is accidentally connected,
or if the control wires are reversed.

14
RS-232 Control
The Reference 80S has an RS-232
connector on the back panel, in the
event the amplifier is incorporated
into an automated or two-way remote
communication system. Please see your
dealer or contact service@audioresearch
to acquire specific codes relative to the
RS-232 control.
A.C. Power Connection
It is important that the Reference 80S
be connected via its supplied 20 amp
IEC 12-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 80S for On/O control of the
amplifier, or the 12V start-up trigger or RS-
232 for remote installations.
The AC power source for the Reference
80S amplifier should be capable of
supplying 15 amperes for 100 or 120 volt
units, or 10 amperes for 220 or 240 volt
units.
For the very best performance, the
Reference 80S should be connected to its
own AC power circuit branch, protected
by a dedicated circuit breaker. The
preamplifier and other audio equipment
should be connected to a dierent power
circuit and breaker, if possible.
The Reference 80S uses a grounding
system that does not require a ground
lifter adapter plug on the A.C. power cord
to minimize hum. The power cord supplied
with the Reference 80S has a standard
grounding plug to provide maximum safe-
ty when properly connected to a ground-
ed wall receptacle. If there is any question
regarding proper grounding procedures
in your installation, seek help from a qual-
ified technician. Caution should be taken
before using custom after-market power
cords: they must be at least 12-gauge and
have a standard grounding plug properly
installed. These power cords are to be
used with caution, at the sole risk of the
owner. If electronic crossovers or other
AC powered equipment is used with the
Reference 80S it may be necessary to use
‘ground lifter’ adapters on the power plugs
of that equipment to minimize system hum.
Generally, the lowest hum is achieved
when the only direct connection between
audio common ‘ground’ and true earth
ground occurs in the preamplifier, through
its grounded power cord. Other equip-
ment in the system should have some
form of isolation to prevent ground loops
and associated hum.

15
Back Panel Controls
High/Low Fan Speed
Allows adjusting fan speed to either low or
high-speed setting.
Balanced/Single Ended
Select balanced switch position for
balanced input connection operation or
single-ended switch position for single-
ended input connection operation.
Do not connect BAL and SE cables
simultaneously. (See Input Connectors
paragraph under Connections section for
further information.)
Auto Shut O/ Defeat
Allows selecting auto shut-o feature or
turning o this feature (see separate Auto
Shut O paragraph under this Operation
section for a more detailed description of
this function).
About Auto Shut O
The Reference 80S auto shut-o feature is
designed to turn the amplifier o after two
hours of no signal being present at the
output of the amplifier.
In the event that quiet music is listened
to at very low volumes, there may not
be adequate signal for the auto shut o
circuit, resulting in the amplifier turning
itself o. If this is the case, please
disengage the auto shut o feature.
The auto shut o feature control switch
is located on the back panel of the
Reference 80S.
Note
The auto shut o feature is not in the
signal path of the amplifier and has
no deleterious sonic eect on music
playback.

16
Operation
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WAT T S
REFERENCE 80S VACUUM TUBE POWER AMPLIFIER
HIGH DEFINITION ®
POWER
METER
LIGHT
TUBE
MONITOR
ULTRALINEAR
TRIODE
Front Panel Controls
Power
Meter
Light
Tube
Monitor
Ultralinear
Triode
GhostMeter™

17
Start-Up
• Secure interconnects between the
amplifier and your preamplifiero the
appropriate output terminals.
• Attach supplied power cord to rear IEC
inlet of amplifier, and plug other end into
grounded A.C. power receptacle.
• Turn on preamp and all other
components; mute preamp output.
• Press Reference 80S front panel power
switch. Green power LED will flash on/o
for approximately 2 minutes during the
auto mute cycle to allow the amplifier
to stabilize voltage before becoming
active. The LED will stay on brightly,
once the amplifier has stabilized.
• Unmute preamplifier output, initiate
source component signal, and adjust
gain as appropriate.
Note
The Reference 80S should be turned
on after the other components of your
system. If the Reference 80S is turned on
before other components, the amplifier
will amplify any extraneous turn-on noises
those components might generate, which
could potentially damage loudspeakers.
Good practice dictates that the amplifier
should be turned on last and turned o
first in an audio system.
Shut-Down
• Mute preamplifier output.
• Turn o Reference 80S via front panel
power switch (or 12V trigger or RS-232).
Note
To prevent stress to the power supply
and vacuum tubes, the control circuitry is
programmed with a “hot restart” lockout
to prevent turning the unit on within 2
minutes of shutting the unit o. If the
Reference 80S power switch is pressed
during this lockout period, the power
LED will illuminate red to indicate lockout
operation. After 2 minutes, normal turn on
can be initiated.

18
Power
Turns power of Reference 80S on or o.
GhostMeter™ Light
Adjusts meter light LED display brightness
to one of four levels of brightness
including “o”.
Tube Monitor
Allows checking the operation of each of
the four KT 150 output tubes (V1-V4). The
LED associated with each output tube will
illuminate when operating properly. See
Auto Bias section under Operation for
further explanation of its operation.
Pentode/Triode
Allows selecting pentode (approximately
70 watts per channel) operation –
indicated by green color of LED
above this function button, or triode
(approximately 35 watts per channel)
operation – indicated by blue white color
of the power-on LED.
Auto Bias
The Reference 80S incorporates a highly
sophisticated auto-bias circuit. There
are no user-adjustable bias controls.
There should never be a need to check
or adjust the auto-bias circuit: once it is
factory set, no additional adjustment is
required. The auto-bias circuit will ‘lock in’
the idle current of each bank of two KT150
output tubes approximately two minutes
after the Reference 80S is turned on, and
continually compensates to maintain the
proper bias as the tubes age. Auto-bias
sets the idle current at 65mA per tube.
It is always recommended owners
purchase replacement tubes from Audio
Research Corp. While the auto bias
adjusts the idle current of each of the four
KT150 output tubes, matched tube sets
will provide optimum performance and
longest tube life.
The auto bias circuit will not
accommodate output tubes with
extremely high or low plate current
readings. Aftermarket tubes may not be
tested to the same rigorous standards
as Audio Research tests, so care must
be exercised when installing aftermarket
tubes. If uncertain about aftermarket tube
requirements, please contact service@
audioresearch.com for recommendations.
Audio Research supplies the KT150 output
tube in the Reference 80S, providing the
highest power and best sound possible in
this amplifier design.
Audio Research has tested the Reference
80S with KT120, KT88 and 6550WE
output tubes. The Reference 80S will
produce less power with any of these
tubes and the sound will be degraded.
Under no circumstances should any tube
not electrically equivelant to the KT150,
KT88 or 6550WE be installed. Tubes
such as the EL34, KT77, 6L6 should never
be installed. Installing tubes such as
these will void the factory warranty and
Audio Research will not be liable for any
damage. Contact service@audioresearch.
com if you have questions regarding tube
compatability.
Operation

19
Hour Counter
An LCD hour counter of elapsed tube
operating time can be viewed on the back
panel. This displays accumulated hours of
vacuum tube service life. If the amplifier
is unplugged from A.C. supply, the total
accumulated hours are retained. Next
to the hour counter is a recessed hour
counter reset button; after replacing vac-
uum tubes, press this button to reset the
hour counter back to zero. Note that once
the hour counter has been reset, it is no
longer possible to recall the previous hour
count.
Break-in
All quality stereo equipment benefits 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
80S will sound very good out of the box, it
will only improve with continued use.

20
Maintenance
Vacuum Tubes
It is recommended that you replace the
vacuum tubes of your Reference 80S
in sets. All of the tubes in your amplifier
have been matched to have similar oper-
ating characteristics, to provide the best
sound quality and reliability. In the event
you need to replace a single output tube,
please refer to the numbers written on the
silver base at the bottom of the vacuum
tube when placing an order. KT150 tubes
should be replaced at approximately
3000 hours. 6H30 tubes should be re-
placed before 4000 hours.
Servicing
Because of its careful design and exacting
standards of manufacture, your Reference
80S amplifier 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 qualified technician. Additional
questions regarding the operation,
maintenance or servicing of your
amplifier, please contact the Customer
Support Department of Audio Research
Corporation at service@audioresearch.
com 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’ found under ‘Support’ at the top
right of the home page.
Caution
Your Reference 80S preamplifier
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
The Reference 80S uses one bottom-
cover-mounted ultra-quiet fan for forced
air cooling of internal components. Over
time, depending upon the environment
in which the Reference 80s is installed,
dust will build up inside the chassis that
may impede proper cooling, which could
reduce component life. Audio Research
therefore strongly recommends the
owner have the Reference 80S cleaned
of internal dust buildup either every two
years of operation, or when the vacuum
tube sets are replaced –whichever occurs
first. Please contact your authorized
Audio Research dealer, service center,
or [email protected] for
instructions and assistance with this
cleaning operation.