Boulder 1161 User manual

1161 Stereo Power Amplier
Boulder Ampliers, Inc.
255 S. Taylor Ave.
Louisville, CO 80027
[phone]
www.boulderamp.com
www.facebook.com/BoulderAmpliersInc
06/01/2019
Rev. 1.0
P/N: 91058

About
About Boulder Ampliers, Inc.
Boulder was founded in 1984 and is the last high-performance audio
manufacturer operating in North America to still perform all of its own
design, engineering and manufacturing in-house. While this form of
production may be more costly than outsourcing, the resulting quality
control and reliability of the nished products are never compromised.
In 2016, Boulder moved into a new, purpose-built production facility to
increase manufacturing efciency and offer space for expansion to meet
the needs of future growth.

Thank You
Congratulations and thank you for selecting the Boulder 1161 Stereo
Power Amplier for your high-performance sound system. We are certain it
will provide you with many years of listening pleasure.
The 1161 represents the concerted efforts of numerous Boulder designers,
engineers, and technicians working to bring you the best audio playback
components in the world. This amplier is among the best that Boulder has
to offer.
Please take a few minutes to read through this instruction manual prior
to using your 1161. This will help you understand the many functions
and capabilities of the amplier. It will also allow you to maximize the
exceptional performance for which it was designed.
Your Boulder 1161 Stereo Power Amplier has undergone extensive
laboratory tests for safety, functionality, and technical excellence. In
addition, it has been individually subjected to rigorous listening trials in
our sound room utilizing a wide range of musical material. No product
ever leaves our factory until we are totally satised that it achieves its full
potential.

Table of Contents
Getting Started
Placement of the 1161 Stereo Power Amplier•••••••••••••••••••••••1-1
Connecting to the AC Mains Outlet •••••••••••••••••••••••••••••••1-1
Connecting to a Network ••••••••••••••••••••••••••••••••••••••1-3
Connecting to a Balanced Source ••••••••••••••••••••••••••••••••1-3
Connecting to an Unbalanced Source••••••••••••••••••••••••••••••1-3
Polarity ••••••••••••••••••••••••••••••••••••••••••••••••••1-5
Connecting Your Loudspeakers••••••••••••••••••••••••••••••••••1-5
Operation
Powering Up ••••••••••••••••••••••••••••••••••••••••••••••2-1
Input DC Offset Voltage Detection •••••••••••••••••••••••••••••••2-3
Clip Detection •••••••••••••••••••••••••••••••••••••••••••••2-3
Thermal Protection ••••••••••••••••••••••••••••••••••••••••••2-3
Maintenance ••••••••••••••••••••••••••••••••••••••••••••••2-4
Remote Control
Remote Operation ••••••••••••••••••••••••••••••••••••••••••3-1
External IP Control Systems ••••••••••••••••••••••••••••••••••••3-1
Boulder Net •••••••••••••••••••••••••••••••••••••••••••••••3-1
Fault Conditions
Errors Requiring Boulder Dealer Service •••••••••••••••••••••••••••4-1
Operational Errors ••••••••••••••••••••••••••••••••••••••••••4-1
Appendix
Technical Specications •••••••••••••••••••••••••••••••••••••••5-1
Dimensions & Weights •••••••••••••••••••••••••••••••••••••••5-3
1161 Amplier Dimensions ••••••••••••••••••••••••••••••••••••5-4
Troubleshooting ••••••••••••••••••••••••••••••••••••••••••••5-5
Notes •••••••••••••••••••••••••••••••••••••••••••••••••••5-6

Getting Started
1-1
Getting Started
Getting Started
1-1
Placement of the 1161 Stereo Power Amplier
Your Boulder 1161 Stereo Power Amplier is designed to reduce
interference from external magnetic and radio elds (RF). While place-
ment is not critical, known magnetic elds should be avoided.
The 1161 Stereo Power Amplier will generate some heat. Therefore,
it should be located in an area with ample air circulation. Specically,
be certain that the heat sinks are unobstructed by objects that could
potentially block airow. Do not place the amplier on deep carpet
and be sure that the amplier has a minimum of 3 inches (8 cm) of free
airspace on all sides.
You may want to have access to the rear panel for cable changes.
Although input cables can be as long as necessary, it is suggested that
speaker cables be as short as possible.
Connecting to the AC Mains Outlet
Your 1161 Stereo Power Amplier is supplied with a mains power
cable suitable for the location where it was purchased. It is construct-
ed of large enough wire gauge and a plug appropriate for your AC line
voltage. Do not substitute another power cable.
Exact voltage and frequency compatibility is stated in the specications
section. See page 5-1.
Once the 1161 Stereo Power Amplier is connected to a live mains
outlet and the rear panel switch is moved to the “On” position, the LED
on the front panel will illuminate red for a short time. During this time
the 1161 is booting up.

Getting Started
1-2
Getting Started
Getting Started
1-2
The LED will then pulse white on and off, indicating that the supervis-
ing microprocessor is powered up and the amp is ready to be turned
on using the front panel Standby button.
AC Mains

Getting Started
1-3
Getting Started
Getting Started
1-3
Connecting to a Network
In order for the 1161 to download software updates as necessary, it
will need to be connected to a network with an active Internet connec-
tion.
Connect a network cable between the 1161 and a network router or
switch. Use either Ethernet connector on the rear panel of the 1161; it
does not matter which one you use.
Connecting to a Balanced Source
To fully realize the sonic potential of your 1161 Stereo Power Ampli-
er, always use balanced connections. Balanced cables minimize inter-
ference from magnetic and RF sources.
Connect the cables from your source or preamplier outputs to the
input connections provided on the rear panel of the 1161.
Connecting to an Unbalanced Source
Although the inputs are of the 3-pin XLR-type, an unbalanced source is
easily accommodated by using a special cable. This cable has an RCA-
type connector on the source end and a 3-pin XLR connector on the
1161 Stereo Power Amplier end.
The negative input (pin 3) should be wired to ground only at the RCA
connector. This brings the negative input reference of the 1161 to the
unbalanced source ground, thus reducing loops.
Another option for accommodating unbalanced sources is the Boulder
ABL2 Input Adapter. It converts a balanced input into an unbalanced
RCA input at the rear panel of the 1161. Like the above cable, the neg-
ative input of the 1161 is connected to the ground of the RCA connec-

Getting Started
1-4
Getting Started
Getting Started
1-4
tor. However, the negative side will then share the shield wire with the
chassis ground and will not have very good hum rejection.
Please contact your authorized Boulder dealer for further information
about the ABL2 Input Adaptor.
Input Input Ethernet

Getting Started
1-5
Getting Started
Getting Started
1-5
Polarity
Please note that the 1161 Stereo Power Amplier conforms to the
AES standard of pin 2 as the “high,” “positive,” or “hot” pin for the bal-
anced input.
The polarity of the 1161 Stereo Power Amplier is such that a posi-
tivegoing transition at pin 2 will produce a positive-going transition at
the “+” output terminal.
Connecting Your Loudspeakers
Do not use a wrench or any other type of tool on the output terminal
binding posts. Tighten these connectors by hand only.
WARNING: This is a high-powered amplier! There is high voltage
potential at the terminals when driven. Connections should only be made
with the AC mains disconnected!
Select speaker cable spade terminals that will accept .250-inch (6 mm)
diameter binding posts.
There is no provision for the use of banana plugs. Banana plugs are
proven to lose spring tension and come loose over time, increasing
contact resistance and distortion. We also do not recommend the use
of banana plugs at the speaker end for these reasons.

Getting Started
1-6
Getting Started
Getting Started
1-6
Polarity
Please note that the 1161 Stereo Power Amplier conforms to the
AES standard of pin 2 as the “high,” “positive,” or “hot” pin for the bal-
anced input.
The polarity of the 1161 Stereo Power Amplier is such that a posi-
tivegoing transition at pin 2 will produce a positive-going transition at
the “+” output terminal.
Connecting Your Loudspeakers
Do not use a wrench or any other type of tool on the output terminal
binding posts. Tighten these connectors by hand only.
WARNING: This is a high-powered amplier! There is high voltage
potential at the terminals when driven. Connections should only be made
with the AC mains disconnected!
Select speaker cable spade terminals that will accept .250-inch (6 mm)
diameter binding posts.
There is no provision for the use of banana plugs. Banana plugs are
proven to lose spring tension and come loose over time, increasing
contact resistance and distortion. We also do not recommend the use
of banana plugs at the speaker end for these reasons.

2-1
Operation
Operation
Powering Up
With all connections made, you are ready to listen to your Boulder
1161 Stereo Power Amplier.
To turn the amplier on, turn the rear panel Master AC Switch to the
ON position. The amplier will go through a turn-on sequence, during
which time the power LED will illuminate red.
After about 20 seconds the LED will then slowly pulse white on and
off, indicating that the supervising microprocessor is powered up. At
this time, press the front panel button to bring the unit out of Standby
mode.
Because of the large inrush currents associated with the large toroidal
transformer, power relays are used to turn on the amplier. These are
under control of the supervising ARM processor. During the power
up sequence, you will hear two sets of two relay clicks, separated by
intervals of two seconds.
Once powered up, the front panel LED will steadily glow white to indi-
cate normal operation.
To turn the amplier off, press the Standby button again. The indicator
will then slowly and continuously change from white, to dark, and
back to white. This indicates that the amplier is in Standby mode.
NOTE: Because the 1161 greatly reduces power consumption when in
Standby mode, it is only necessary to place the amplier in Standby when
not in use. You do not need to turn the 1161 off via the Master AC Switch
on the rear panel. The 1161 was designed for years of operation in this
manner and no damage to the unit will occur.

2-2
Operation
Operation
Powering Up
With all connections made, you are ready to listen to your Boulder
1161 Stereo Power Amplier.
To turn the amplier on, turn the rear panel Master AC Switch to the
ON position. The amplier will go through a turn-on sequence, during
which time the power LED will illuminate red.
After about 20 seconds the LED will then slowly pulse white on and
off, indicating that the supervising microprocessor is powered up. At
this time, press the front panel button to bring the unit out of Standby
mode.
Because of the large inrush currents associated with the large toroidal
transformer, power relays are used to turn on the amplier. These are
under control of the supervising ARM processor. During the power
up sequence, you will hear two sets of two relay clicks, separated by
intervals of two seconds.
Once powered up, the front panel LED will steadily glow white to indi-
cate normal operation.
To turn the amplier off, press the Standby button again. The indicator
will then slowly and continuously change from white, to dark, and
back to white. This indicates that the amplier is in Standby mode.
NOTE: Because the 1161 greatly reduces power consumption when in
Standby mode, it is only necessary to place the amplier in Standby when
not in use. You do not need to turn the 1161 off via the Master AC Switch
on the rear panel. The 1161 was designed for years of operation in this
manner and no damage to the unit will occur.

2-3
Operation
Operation
Input DC Offset Voltage Detection
The Boulder 1161 is a direct-coupled power amplier with a servo for
zeroing out DC voltage offset coming from the preamplier or other
sources connected to the amplier’s input.
If the DC at the inputs is sufcient to cause potentially damaging
voltage at the output terminals, a protection circuit will mute the am-
plier’s output by electronically disconnecting the loudspeakers. The
front panel LED will also turn red. This condition will continue until the
source of DC is corrected or removed.
If the indicator remains red, it is recommended that the user correct
the DC offset of the source device before continuing.
Clip Detection
Clipping of the waveform results when any amplier is driven beyond
it’s rated power. A clip detection circuit is included for protection in
the 1161 Stereo Power Amplier.
The front panel LED will indicate clipping by momentarily turning from
white to red. Both voltage and current modes of clipping are detected,
although it is generally only voltage clipping that occurs.
Thermal Protection
A thermal protection circuit prevents high operating temperatures
that are unpleasant to the touch and potentially harmful to the am-
plier. A thermal cutout circuit will mute the amplier when the tran-
sistor cases reach 70°C, and the front panel LED will turn red. If this
happens, the output level of the system should be reduced and more
ventilation should be provided for the amplier. Once the amplier
temperature cools to 60°C operation may resume.

2-4
Operation
Operation
Maintenance
No routine maintenance is required for the 1161 Stereo Power Ampli-
er. However, to keep operating temperatures at a minimum, be sure
that the heat sinks are not obstructed and remove any dust buildup
that may occur.
Input DC Offset Voltage Detection
The Boulder 1161 is a direct-coupled power amplier with a servo for
zeroing out DC voltage offset coming from the preamplier or other
sources connected to the amplier’s input.
If the DC at the inputs is sufcient to cause potentially damaging
voltage at the output terminals, a protection circuit will mute the am-
plier’s output by electronically disconnecting the loudspeakers. The
front panel LED will also turn red. This condition will continue until the
source of DC is corrected or removed.
If the indicator remains red, it is recommended that the user correct
the DC offset of the source device before continuing.
Clip Detection
Clipping of the waveform results when any amplier is driven beyond
it’s rated power. A clip detection circuit is included for protection in
the 1161 Stereo Power Amplier.
The front panel LED will indicate clipping by momentarily turning from
white to red. Both voltage and current modes of clipping are detected,
although it is generally only voltage clipping that occurs.
Thermal Protection
A thermal protection circuit prevents high operating temperatures
that are unpleasant to the touch and potentially harmful to the am-
plier. A thermal cutout circuit will mute the amplier when the tran-
sistor cases reach 70°C, and the front panel LED will turn red. If this
happens, the output level of the system should be reduced and more
ventilation should be provided for the amplier. Once the amplier
temperature cools to 60°C operation may resume.

3-1
Remote Control
Remote Control
Remote Operation
Remote control and operation of the Boulder 1161 Stereo Power
Amplier is possible by the use of a 12V trigger, an external IP control
system, or Boulder Net.
12V Trigger
The 1161 has a 1/8” minijack that will allow it to be turned On or Off.
To complete the 12V trigger system, a cable must be connected be-
tween the 1161 and a source component or preamplier with a 12V
trigger output. The 1161 supports both continuous and toggle 12V
trigger commands.
External IP Control Systems
Modern home integration and automation systems are generally
controlled through a home LAN (Local Area Network) via the use of IP
(Internet Protocol) commands. When connected to a LAN, the 1161 is
able to receive and respond to these commands through its Ethernet
connection on the rear panel.
For further information about IP control and automation systems, please
contact your authorized Boulder dealer.
Boulder Net
Boulder has developed an IP control system that is Open Home com-
pliant and unique to Boulder products. When multiple Boulder prod-
ucts are all connected to a LAN, the Boulder Net system will allow
you to turn various products on or off and control the functions of all
connected components via an application that is downloadable to a
mobile tablet or phone. Status messages can also be passed to Boulder
products with a display.

3-2
Remote Control
Remote Control
For further information about Boulder Net, please see the Boulder Net
Manual or visit www.boulderamp.com.

Fault Conditions
4-1
Fault Conditions
Errors Requiring Boulder Dealer Service
If the 1161 Stereo Power Amplier will not turn on and the front panel
LED blinks red, an error requiring dealer service has occurred. The
indicator may ash red in a specic sequence to dene its error code
for an authorized Boulder technician.
If you are experiencing this problem with your 1161, contact your
Boulder dealer immediately.
Operational Errors
At times the 1161’s front panel LED may ash red but continue oper-
ating normally. This is an Operational Error and indicates that there
is a fault somewhere else in the system or in the use of the amplier.
Conditions that will be indicated as Operational Errors may include:
• DC offset at the input of the amplier (from a source or preampli-
er)
• Thermal limit or safe operating temperature of the amplier ex-
ceeded
• Clipping of the output signal

Fault Conditions
4-2
Fault Conditions
Errors Requiring Boulder Dealer Service
If the 1161 Stereo Power Amplier will not turn on and the front panel
LED blinks red, an error requiring dealer service has occurred. The
indicator may ash red in a specic sequence to dene its error code
for an authorized Boulder technician.
If you are experiencing this problem with your 1161, contact your
Boulder dealer immediately.
Operational Errors
At times the 1161’s front panel LED may ash red but continue oper-
ating normally. This is an Operational Error and indicates that there
is a fault somewhere else in the system or in the use of the amplier.
Conditions that will be indicated as Operational Errors may include:
• DC offset at the input of the amplier (from a source or preampli-
er)
• Thermal limit or safe operating temperature of the amplier ex-
ceeded
• Clipping of the output signal

5-1
Appendix
Appendix
Technical Specications
Continuous Power, Each Channel
Watts Ω THD THD @ 20kHz
150 8 0.003% 0.01%
150 4 0.004% 0.015%
150 20.005% 0.025%
Peak Power, Each Channel
Watts Ω
200 8
350 4
450 2
Equivalent Input Noise (EIN), 20kHz BW 1.5 µV
Magnitude Response, 20 to 20kHz +0.00, -0.04 dB
Magnitude Response, -3dB at 0.015Hz, 150kHz
Voltage Gain 26 dB
Input Impedance Balanced: 200kΩ,
Unbalanced 100kΩ
Common Mode Rejection (Balanced only) 60 Hz: 90dB,
10kHz: 70dB
Inputs 3-pin Balanced
Output Connectors 6 mm / .250-inch
wingscrews
Power Requirements 100, 110-120, & 220-
240 VAC