Boulder 2108 User manual

2108 Phono Preamplier
Boulder Ampliers, Inc.
255 S. Taylor Ave.
Louisville, CO 80027
[phone]
www.boulderamp.com
www.facebook.com/BoulderAmpliersInc
Rev. 1.0
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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 2108 Phono
Preamplier for your high-performance sound system. We are certain it will
provide you with many years of listening pleasure.
The 2108 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 moments to read through this
instruction manual prior to using your 2108. This will help you understand
the many functions and capabilities of the phono preamplier. It will also
allow you to maximize the convenience and performance for which it was
engineered.
Your Boulder 2108 Phono Preampli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
Introduction ••••••••••••••••••••••••••••••••••••••••••••••1-1
Audio Features ••••••••••••••••••••••••••••••••••••••••••••1-1
Operational Features••••••••••••••••••••••••••••••••••••••••1-1
Unpacking and Care ••••••••••••••••••••••••••••••••••••••••1-2
Before You Start •••••••••••••••••••••••••••••••••••••••••••1-3
How to Clean the Casework •••••••••••••••••••••••••••••••••••1-4
Installation •••••••••••••••••••••••••••••••••••••••••••••••1-5
Placement and Installation ••••••••••••••••••••••••••••••••••••1-5
Connections ••••••••••••••••••••••••••••••••••••••••••••••1-6
Making Connections to the 2108 Phono Preamplier••••••••••••••••••1-6
Making Connections to the 2100 Power Supply••••••••••••••••••••••1-7
Connecting the 2108 to the 2100 Power Supply •••••••••••••••••••••1-8
Connecting the Analog Outputs ••••••••••••••••••••••••••••••••1-9
Connection to AC Mains ••••••••••••••••••••••••••••••••••••1-10
Turntable Connection Types ••••••••••••••••••••••••••••••••••1-11
Connecting a Turntable •••••••••••••••••••••••••••••••••••••1-12
GROUND ••••••••••••••••••••••••••••••••••••••••••••••1-13
Connecting a Cartridge Demagnetizer•••••••••••••••••••••••••••1-14
Connecting the Outputs to a Balanced Preamplier••••••••••••••••••1-15
Connecting the Outputs to an Unbalanced Preamplier •••••••••••••••1-16
Setup and Loading •••••••••••••••••••••••••••••••••••••••••1-17
Personality Cards •••••••••••••••••••••••••••••••••••••••••1-17
Moving Coil or Moving Magnet Selection •••••••••••••••••••••••••1-18
Cartridge Loading Adjustment - Resistive•••••••••••••••••••••••••1-19
Cartridge Loading Adjustment - Capacitive •••••••••••••••••••••••1-22
Gain Selection Adjustment•••••••••••••••••••••••••••••••••••1-23
Demagnetizer Pass-Through Selection•••••••••••••••••••••••••••1-24
Operation
Power •••••••••••••••••••••••••••••••••••••••••••••••••••2-1
Standby ••••••••••••••••••••••••••••••••••••••••••••••••••2-2
Mute ••••••••••••••••••••••••••••••••••••••••••••••••••••2-3
Input Selection •••••••••••••••••••••••••••••••••••••••••••••2-4
Demag•••••••••••••••••••••••••••••••••••••••••••••••••••2-5
Mono •••••••••••••••••••••••••••••••••••••••••••••••••••2-6
Equalization •••••••••••••••••••••••••••••••••••••••••••••••2-7
Low Cut Filter•••••••••••••••••••••••••••••••••••••••••••••2-10
Connections••••••••••••••••••••••••••••••••••••••••••••••2-11

Table of Contents
Appendix
Technical Specications •••••••••••••••••••••••••••••••••••••••3-1
Dimensions & Weights••••••••••••••••••••••••••••••••••••••••3-2
2108 Preamplier Section Dimensions•••••••••••••••••••••••••••••3-3
2100 Power Supply Section Dimensions •••••••••••••••••••••••••••3-4
Troubleshooting ••••••••••••••••••••••••••••••••••••••••••••3-5
Notes •••••••••••••••••••••••••••••••••••••••••••••••••••3-7

Getting Started
1-1
Getting Started
The 2108 Phono Preamplier embodies years of development and is
the evolution of the legendary 2008 Phono Preamplier, one of the
greatest phono preampliers ever made. Here are some of the fea-
tures that set the 2108 apart from the competition:
Audio features:
• Fully-balanced inputs and outputs.
• Surface-mount design (SMD) circuitry wherever possible.
• Three pairs of balanced inputs and two pairs of balanced outputs
on XLR connectors.
• Boulder’s own discrete 99S and 995S gain stages.
• Fully-adjustable resistive and capacitive load settings to match a
wide range of phono cartridges.
• Standard RIAA equalization as well as EMI, Columbia, and FFRR
(London/Decca) for records produced before 1955.
Operational features:
• Fully-machined, non-resonant chassis design.
• Switchable gain for MC (moving coil) or MM (moving magnet) car-
tridges.
• Logic control to reduce operational noise.
• Mono mode to optimize monaural playback with stereo cartridges
• Four power supplies (Standby, analog left, analog right, and con-
trol) in a separate power supply enclosure.

Getting Started
1-2
Getting Started
Unpacking and Care
The 2108 Phono Preamplier comes in two boxes and both are very
heavy. They feature nely nished casework. Please use care when
unpacking, lifting, and installing the two sections to avoid damage to
the metalwork and furniture. The 2108 Phono Preamplier weighs 37
lbs. (16.8kg) and the Power Supply weighs 48 lbs. (21.8 kg).
The Power Supply section is front-end heavy. Please be aware of this
when lifting it to avoid any accidental damage.
Be sure to save all packing materials! The 2108 is shipped in a foam
wrap to protect the ne nish of both sections. Try not to damage this
wrap in the event that the unit must be transported in the future.

Getting Started
1-3
Getting Started
Before You Start
The 2108 system comes in two assemblies that must be put in place
and connected: the 2108 Audio section and the 2100 Power Supply
section.
You should have received two large, heavy boxes. The pieces included
inside them are:
1. 2108 Audio section
2. 2100 Power Supply section
• 1 x AC power cord
• Accessory box #1 containing:
• 3 x DC cables
3. Accessory box #2 containing:
• Owner’s Manual
• PHRCA RCA-to-XLR Adaptors
• Two spare Personality Cards with labels
• Ground wire
If any of these pieces are missing or damaged, please contact your
dealer immediately and before continuing the installation.

Getting Started
1-4
Getting Started
How to Clean the Casework
If the 2108 must be cleaned, use only a soft, lint-free cloth moistened
with plain water.
Never use any type of chemical cleaner unless recommended by your
dealer or the Boulder factory.
Do not use bleach! Bleach will remove the anodized surface of the
casework.
Never use any type of abrasive to clean the casework.
If you have any questions, please contact your authorized Boulder
dealer.

Getting Started
1-5
Getting Started
Installation
Placement and Installation
Your Boulder 2108 Phono Preamplier is designed to reduce the ef-
fects that external magnetic elds and radio frequencies (RF) have on
its circuitry. While placement is not critical, because of the high gain of
the 2108, known magnetic elds should be avoided whenever possi-
ble. Power transformers in other pieces of nearby equipment should
be placed a minimum of 12 inches (30 cm) away.
Because it is very heavy, the 2108 must be placed on a sturdy, stable
surface.
Do not place in an enclosed rack without ventilation. Both sections
of the 2108 must have at least 2 inches (5 cm) of airspace around the
chassis for proper cooling and airow.
Be sure to leave access to the AC mains and DC power cables when
installing. Depending on how easy it is to access the back panels of the
2108 and 2100, it may be wise to preinstall the power and intercon-
nect cables before placement.

Getting Started
1-6
Getting Started
Connections
Making Connections to the 2108 Phono Preamplier
Input Connections
1. Input 1
2. Input 2
3. Input 3
4. Ground (or Earth) Binding Posts
5. Cartridge Demagnetizer Pass-through
Output Connections.
6. Right Outputs
7. Left Outputs
Power Supply Connections.
8. Power R Audio
9. Power L Audio
10. Power Digital (Control)
1
6 7
2 23 3
8 910
5 1
4
5
98 10

Getting Started
1-7
Getting Started
Making Connections to the 2100 Power Supply
1. AC Mains Connection
2. Master AC Power Switch
3. Right Audio DC Power
4. Left Audio DC Power
5. Digital (Control) DC Power
1
3 45
2

Getting Started
1-8
Getting Started
Connecting the 2108 to the 2100 Power Supply
Connect the DC cables from the 2100 power supply to the 2108 Pho-
no Preamplier. Because the cable connectors are keyed, they cannot
be installed incorrectly.
Please note that the Digital (Control) DC cable has a different number
of pins and cannot be connected to the Audio power connectors.
WARNING: Do not turn on the 2100 until all DC power connections have
been made!
It is important never to disconnect any of the DC power cables when the
unit is powered ON via the AC master power switch or damage may occur,
even when the 2108 is in Standby mode!
Always turn the unit OFF from the rear panel of the 2100 power supply
before disconnecting any of the DC power cables.

Getting Started
1-9
Getting Started
Connecting the Analog Outputs
Connect the left and right interconnect cables from one of the 2108’s
LEFT OUTPUTS and RIGHT OUTPUTS to your preamplier or inte-
grated amplier’s left and right input connections. To maintain best
sound quality, Boulder recommends that balanced audio connections
always be used. Because the 2108’s output connections are in paral-
lel, it does not matter which connection you use, as there is no sonic
difference.
The 2108 has balanced audio connections via XLR jacks. If you are
connecting the 2108 to a preamplier or amplier that does not have
balanced input connections, you will either need a pair of Boulder
XLR-to-RCA adaptors (ABL2) or need to have your cables properly
terminated. A diagram for the proper cable conguration is shown
below.
2108

Getting Started
1-10
Getting Started
Connection to AC Mains
Connect the AC power cord to the 2100’s AC Mains Connection and
plug it into your AC mains wall outlet.
WARNING: It is important never to disconnect any of the DC power cables
when the unit is powered ON via the AC master power switch or damage
may occur, even when the 2108 is in Standby mode!
Always turn the unit OFF from the rear panel of the 2100 power supply or
disconnect the AC mains power cord before disconnecting any of the DC
power cables.

Getting Started
1-11
Getting Started
Turntable Connection Types
To get started listening, you only need to connect a turntable to the
2108 as you would any other phono preamplier. Please take note of
the following:
The 2108 can be connected to many different types of turntables. To
fully realize the sonic potential of your 2108 Phono Preamplier, use
balanced cable connections with XLR terminations whenever possible.
Balanced XLR cables minimize interference from magnetic, hum, and
RF sources.

Getting Started
1-12
Getting Started
Connecting a Turntable
Because a phono cartridge is actually a balanced source, balanced
inputs are provided on the 2108. Connect the output cables from your
turntable to the LEFT and RIGHT CHANNEL INPUT 1 connections of
the 2108.
For turntables or systems that have more than one tonearm connec-
tion, connect the additional phono sources to the left and right con-
nections for INPUT 2 and INPUT 3.
Please note the following instructions to avoid picking up hum in the
system:
Do not short pin 1 (chassis/ground) to either pin 2 or 3 of the XLR con-
nector at any point in the cable, turntable chassis, or tonearm. This will
cause hum in the system. Pins 2 and 3 must only be connected directly
to the cartridge pins. Proper wiring diagrams are shown on the next
page.
Use only a connection from Pin 1 of the turntable’s XLR connector to
the turntable chassis or the provided ground wire from the 2108’s
rear panel Ground Binding Post to the turntable chassis. Using both
may form a ground loop, which will cause hum.
If your turntable does not have XLR connections, one pair of Boulder
PHRCA Phono Adaptors is provided. These will convert the 2108’s
inputs to RCA and give acceptable performance. A separate ground
wire is also provided.
CAUTION: If your turntable does not have XLR connectors, do not use the
Boulder ABL2 input adaptor or any other “standard” RCA to XLR adaptors.
These are not intended for phono use, as they short pin 1 to pin 3 and will
cause hum in your system. Only use the Boulder PHRCA Phono Adaptors.
UNBALANCED RCA CABLE, PIN 2+ INPUT, PIN 3- INPUT, PIN 1

Getting Started
1-13
Getting Started
GROUND

Getting Started
1-14
Getting Started
Connections
Connecting a Cartridge Demagnetizer
The 2108 is able to connect an external cartridge demagnetizer to
your phono cartridge via a pair of RCA connectors on the rear panel.
Connect each channel of the demagnetizer to the RCA inputs labeled
DEMAG on the rear panel of the 2108.
WARNING: Do not demagnetize a moving magnet (MM) cartridge or dam-
age to the cartridge will occur!
For Further information about the demagnetizer circuit, please see
pages 1-24 and 2-5.

Getting Started
1-15
Getting Started
Connecting the Outputs to a Balanced Preamplier
The 2108 has balanced output connections on XLR jacks. With the
low output impedance of the 2108 Phono Preamplier, distances of
more than 100 meters between the 2108 and preamplier or integrat-
ed amplier are practical.
Connect the LEFT and RIGHT OUTPUT interconnects from the 2108
to your preamplier or integrated amplier’s left and right inputs. To
maintain the best sound quality, Boulder recommends that balanced
interconnections always be used. Because the 2108’s dual output con-
nections are in parallel, it does not matter which connection you use,
as there is no sonic difference between the two.