Boulder 861 Stereo Power Amplifier Instruction Manual
- May 15, 2024
- Boulder
Table of Contents
Boulder 861 Stereo Power Amplifier
Specifications
- Model: 861 Stereo Power Amplifier
- Manufacturer: Boulder Amplifiers, Inc.
- Address: 255 South Taylor Avenue, Louisville, CO 80027, U.S.A.
- Telephone: 303-495-2267
- Email: sales@boulderamp.com
- Website: www.boulderamp.com
Placement of the 861 Stereo Power Amplifier
Ensure proper ventilation and place the amplifier on a stable surface away
from heat sources.
Connecting to a Network
To enable software updates, connect the amplifier to a network using an
Ethernet cable to the rear panel Ethernet connector.
Connecting to a Balanced Source
For optimal sound quality, use balanced connections by connecting cables from
your source to the input connections on the rear panel.
Connecting to an Unbalanced Analog Source
If using an unbalanced analog source, connect it to the designated input
connections on the rear panel.
Connecting to$ the AC Mains Outlet
Connect the power cord to a suitable AC mains outlet following safety
guidelines.
255 South Taylor Avenue Louisville, Co 80027 U.S.A Tel: 303-495-2267
- E-mail: sales@boulderamp.com
- Web: www.boulderamp.com
861 Stereo Power Amplifier
Boulder Amplifiers, Inc. 255 S. Taylor Avenue Louisville, CO 80027 (303) 495-2267 www.boulderamp.com
- BoulderAmplifiersInc
- @boulderamplifiers
- @BoulderAmps
About
About Boulder Amplifiers, 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 finished products are never compromised.
In 2016, Boulder moved into a new, purpose-built production facility to
increase manufacturing efficiency and offer space for expansion to meet the
needs of future growth.
Thank You
Congratulations and thank you for selecting the Boulder 861 Stereo Power Amplifier for your high-performance sound system. We are certain it will provide you with many years of listening pleasure.
The 861 represents the concerted efforts of numerous Boulder designers, engineers, and technicians working to bring you the best audio playback components in the world. Please take a few minutes to read through this instruction manual prior to using your 861. This will help you understand the many functions and capabilities of the device. It will also allow you to maximize the convenience and performance for which it was engineered.
Your Boulder 861 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 satisfied that it achieves its full potential.
Introduction
Placement of the 861 Stereo Power Amplifier
Your Boulder 861 Stereo Power Amplifier is designed to reduce interference
from external magnetic and radio fields (RF). While placement is not critical,
known magnetic fields should be avoided.
The 861 Stereo Power Amplifier will generate some heat. Therefore, it should
be located in an area with ample air circulation. Specifically, be certain
that the heat sinks are unobstructed by objects that could potentially block
airflow. Do not place the amplifier on deep carpet and be sure that the
amplifier 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.
Connections
Connecting to a Network
In order for the 861 to download software updates as necessary, it will need
to be connected to a network with an active Internet connection. Connect a
network cable between the 861 and a network router or switch. Use the Ethernet
connector on the rear panel of the 861.
Connecting to a Balanced Source
To fully realize the sonic potential of your 861 Stereo Power Amplifier,
always use balanced connections. Balanced cables minimize interference from
magnetic and RF sources.
Connect the cables from your source or preamplifier outputs to the input
connections provided on the rear panel of the 861.
Connecting to an Unbalanced Analog Source
Although the inputs and outputs are all of the 3-pin XLR type, an unbalanced
source can easily be accommodated by using an unbalanced to balanced cable.
This cable has an RCA phono-type connector on the source end and a 3-pin XLR
connector for the input/output on the 861 end.
The negative input (pin 3) should be wired to ground only at the RCA phono
connector. This brings the inverted input reference of the 861 to the
unbalanced source ground, thus reducing ground loops.
Another option for connecting unbalanced sources is the Boulder ABL2 input
adapter. It converts a balanced input into an RCA phono input at the rear of
the 861. Like the above cable, the negative input of the 861 is connected to
the ground of the RCA phono. However, this negative side will then share the
shield wire with the chassis ground and will not have the best hum rejection.
Connecting to the AC Mains Outlet
Your 861 Stereo Power Amplifier is supplied with a mains power cable suitable
for the location where it was purchased. It is constructed 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 specifications
section. See page 51.
Once the 861 Stereo Power Amplifier 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 861 is
booting up. The LED will then pulse white on and off, indicating that the
supervising microprocessor is powered up and the amp is ready to be turned on
using the front panel Standby button.
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 amplifier! 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.
Note: 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.
Operation
Powering Up
With all connections made, you are ready to listen to your Boulder 861 Stereo
Power Amplifier.
To turn the amplifier on, turn the rear panel Master AC Switch to the ON
position. The amplifier 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 amplifier. 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 indicate
normal operation.
To turn the amplifier 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 amplifier is in Standby mode.
NOTE: Because the 861 greatly reduces power consumption when in Standby mode,
it is only necessary to place the amplifier in Standby when not in use. You do
not need to turn the 861 off via the Master AC Switch on the rear panel. The
861 was designed for years of operation in this manner and no damage to the
unit will occur.
Input DC Offset Voltage Detection
The Boulder 861 is a direct-coupled power amplifier with a servo for zeroing
out DC voltage offset coming from the preamplifier or other sources connected
to the amplifier’s input.
If the DC at the inputs is sufficient to cause potentially damaging voltage at
the output terminals, a protection circuit will mute the amplifier’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 amplifier is driven beyond it’s
rated power. A clip detection circuit is included for protection in the 861
Stereo Power Amplifier.
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 amplifier. A thermal
cutout circuit will mute the amplifier when the transistor 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
amplifier. Once the amplifier temperature cools to 60°C operation may resume.
Maintenance
No routine maintenance is required for the 861 Stereo Power Amplifier.
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.
Errors Requiring Boulder Dealer Service
If the 861 Stereo Power Amplifier will not turn on and the front panel LED
blinks red, an error requiring dealer service has occurred. The indicator may
flash red in a specific sequence to define its error code for an authorized
Boulder technician. If you are experiencing this problem with your 861,
contact your Boulder dealer immediately.
Operational Errors
At times the 861’s front panel LED may flash red but continue operating
normally. This is an Operational Error and indicates that there is a fault
somewhere else in the system or in the use of the amplifier.
Conditions that will be indicated as Operational Errors may include:
- DC offset at the input of the amplifier (from a source or preamplifier)
- Thermal limit or safe operating temperature of the amplifier exceeded
- Clipping of the output signal
Programming
HTML Programming
- Though it is not necessary to use any of the HTML programming functions, you may find them helpful in setting up and personalizing your 861.
- All HTML programming is accomplished by accessing the 861 HTML page while the unit is powered up and connected to a live computer network. Once the page is accessed, the various programming functions can be viewed, changed, and saved.
- To access the 861’s HTML page, you will need a computer that is connected to the same network as the 861 to enter the 861’s network address into a web browser.
- To find the 861’s network address, go into settings on the Boulder Controller App, then press the System Settings button in the Settings menu, followed by the Network Settings button. You will see a list of information about the 861, including:
MAC Address:
Network Address:
SSID: BoulderAmplifiers-(serial number)
Network Address: If the 861 is attached to an active network, the network
address or IP address of the unit will be indicated here. This number should
be entered in the address bar of a web browser to access the 861’s HTML
programming page. The HTML page will then load onto your browser.
Appendix
- Technical Specifications
- Continuous Power, 8 Ohms 50W
- Peak Power, 8 Ohms 75W
- Continuous Power, 4 Ohms 90W
- Peak Power, 4 Ohms 110W
- Peak Power, 2 Ohms 200W
- Balanced Analog Inputs 1 Pair of Balanced 3 pin XLR
- Outputs .25″ (6 mm) Binding Posts
- Distortion, THD 0.01%
- Equivalent Input Noise (EIN), 20 kHz 2.6 μV
- Input Impedance 100k Ω Balanced
- Frequency Response, 20 Hz to 20 kHz +0.00, -0.04 dB
- Frequency Response, -3 dB 0.015 Hz & 150 kHz
- Maximum Analog Gain 26.0 dB
- Power Requirements (Country Specific configured) 100V, 120V, 240V 50-60Hz
- Power Consumption 550W Max
Note: All measurements taken at 120V
-
Weights and Dimensions
861 Stereo Power Amplifier Chassis: 12” W x 12” D x 3.25” H
(21.5 lbs) -
30.5 cm W x 30.5 cm D x 8.3 cm H
(9.75 kg) -
Shipping: 24” W x 23” D x 14” H
(25 lbs) -
61 cm W x 59 cm H x 36 cm H
(11.34 kg)
Appendix
861 Stereo Power Amplifier Dimensions
Troubleshooting
| Symptom | Cause | Remedy |
|---|---|---|
| No Power Indication | Master AC Power Switch on rear panel is not ON |
Turn on Master AC Power Switch
861 is not plugged in| Connect power cord to AC mains outlet
861 boot-up is locked| Turn off unit from Master AC switch and back on
Home circuit breaker is tripped| Reset home circuit breaker
Low line voltage| Have line voltage checked
Defective power cable| Have power cable tested or replaced
Power Indication but No Sound| No signal from one channel| Check
cables, connections, swap cables and see if the problem follows
No signal out of 861| Check interconnect and speaker cables, make sure it is
out of standby and power LED is Solid White
References
Read User Manual Online (PDF format)
Read User Manual Online (PDF format) >>