Boulder 1108 User manual

1108 Phono Preampli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: 91059

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 1108 Phono
Preamplier for your high-performance sound system. We are certain it will
provide you with many years of listening pleasure.
The 1108 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 1108. 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 1108 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 1108 Phono Preamplier ••••••••••••••••••1-6
Connecting the Analog Outputs ••••••••••••••••••••••••••••••••1-7
Connection to AC Mains •••••••••••••••••••••••••••••••••••••1-8
Turntable Connection Types •••••••••••••••••••••••••••••••••••1-9
Connecting the Outputs to a Balanced Preamplier ••••••••••••••••••1-10
Unbalanced RCA Cable •••••••••••••••••••••••••••••••••••1-11
Connecting the Outputs to a Balanced Preamplier ••••••••••••••••••1-12
Connecting the Outputs to an Unbalanced Preamplier •••••••••••••••1-13
Setup and Loading •••••••••••••••••••••••••••••••••••••••••1-14
Personality Cards •••••••••••••••••••••••••••••••••••••••••1-14
Moving Coil or Moving Magnet Selection •••••••••••••••••••••••••1-15
Cartridge Loading Adjustment - Resistive •••••••••••••••••••••••••1-16
Cartridge Loading Adjustment - Capacitive •••••••••••••••••••••••1-19
Operation
Power •••••••••••••••••••••••••••••••••••••••••••••••••••2-1
Standby ••••••••••••••••••••••••••••••••••••••••••••••••••2-2
Mute ••••••••••••••••••••••••••••••••••••••••••••••••••••2-3
Input Selection •••••••••••••••••••••••••••••••••••••••••••••2-4
Mono •••••••••••••••••••••••••••••••••••••••••••••••••••2-5
Equalization •••••••••••••••••••••••••••••••••••••••••••••••2-6
Low Cut Filter ••••••••••••••••••••••••••••••••••••••••••••••2-9
Recording ••••••••••••••••••••••••••••••••••••••••••••••••2-10
Connections ••••••••••••••••••••••••••••••••••••••••••••••2-10

Table of Contents
Appendix
Technical Specications •••••••••••••••••••••••••••••••••••••••3-1
Dimensions & Weights •••••••••••••••••••••••••••••••••••••••3-2
1108 Preamplier Section Dimensions •••••••••••••••••••••••••••••3-3
Troubleshooting ••••••••••••••••••••••••••••••••••••••••••••3-4
Notes •••••••••••••••••••••••••••••••••••••••••••••••••••3-6

Getting Started
1-1
Getting Started
The 1108 Phono Preamplier embodies years of development and is
the second generation of 1000-level phono preamplier from Boulder.
Here are some of the features that set the 1108 apart from the com-
petition:
Audio features:
• Fully-balanced inputs and output circuitry
• Surface-mount design (SMD) circuitry wherever possible.
• Two pairs of balanced inputs and two pairs of balanced outputs on
XLR connectors.
• Boulder’s own 983 and 985 gain stages.
• Fully-adjustable resistive load settings to match the needs of your
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 and loading for MC (moving coil) or MM (moving
magnet) cartridges.
• Full logic control to reduce operational noise.
• Mono mode to optimize monaural playback with stereo cartridges.
• Ultra-efcient and noise optimized power supply to reduce inter-
ference with the delicate analog phono signal.

Getting Started
1-2
Getting Started
Unpacking and Care
The 1108 Phono Preamplier comes packed in a single box and is
heavy. It features nely nished casework. Please use care when
unpacking, lifting and installing the unit to avoid damage to the metal-
work or furniture. The 1108 Phono Preamplier weighs 37 Lbs (16.8
kg).
Be sure to save all packaging materials! The 1108 is shipped in a foam
wrap to protect the metal work’s ne nish. 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 1108 is a single-chassis unit that must be put in place and con-
nected.
You should have received a large, heavy box. The pieces included in-
side are:
1. 1108 Phono Preamplier
2. 1 x AC power cord
3. Instruction Manual
4. PHRCA RCA-to-XLR Adaptors
5. Spare Personality Cards with labels
6. Ground wire
If any of these pieces are missing or damaged, please contact your
Boulder dealer immediately before continuing the installation.

Getting Started
1-4
Getting Started
How to Clean the Casework
If the 1108 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 1108 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 1108, 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 heavy, the 1108 must be placed on a sturdy, stable sur-
face.
Do not place in an enclosed rack without ventilation. The 1108 should
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 the AC mains cable when installing the
1108. Depending on how easy it is to access the back panel of the
1108 it may be wise to preinstall the power and interconnect cables
before placement.

Getting Started
1-6
Getting Started
Connections
Making Connections to the 1108 Phono Preamplier
Input Connections
1. Input 1
2. Input 2
3. Ground (or Earth) Binding Posts
Output Connections
4. Right Outputs
5. Left Outputs
Power Supply Connections
6. AC Mains
7. Master AC Power Switch
7
124 5 2
3
61

Getting Started
1-7
Getting Started
Connecting the Analog Outputs
Connect the left and right interconnect cables from one of the 1108’s
LEFT OUTPUTS and RIGHT OUTPUTS to you preamplier or inte-
grated amplier’s left and right input connections. To maintain the
best sound quality, Boulder recommends that balanced audio connec-
tions always be used. Because the 1108’s output connections are in
parallel, it does not matter which connections you use, as there is no
sonic difference.
The 1108 has balanced audio connections via XLR jacks. If you are
connecting the 1108 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.
1108

Getting Started
1-8
Getting Started
Connection to AC Mains
Connect the AC power cord to the 1108’s AC Mains Connection and
plug into your AC mains wall outlet.
Always turn the unit OFF from the rear panel before disconnecting the AC
Mains power cable.

Getting Started
1-9
Getting Started
Turntable Connection Types
To get started listening, you only need to connect a turntable to the
1108 as you would any other phono preamplier. Please take note of
the following:
The 1108 can be connected to many different types of turntables. To
fully realize the sonic potential of your 1108 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
1-10
Getting Started
Connecting the Outputs to a Balanced Preamplier
Because a phono cartridge is actually a balanced source, balanced
inputs are provided on the 1108. Connect the output cables from your
turntable to the LEFT and RIGHT CHANNEL INPUT 1 connections of
the 1108.
For turntables or systems that have more than one tonearm connec-
tion, connect the additional phono sources to the left and right con-
nections of INPUT 2.
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 1108’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 1108’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.

Getting Started
1-11
Getting Started
UNBALANCED RCA CABLE: PIN 2 + INPUT, PIN 3 - INPUT, PIN 1
GROUND

Getting Started
1-12
Getting Started
Connecting the Outputs to a Balanced Preamplier
The 1108 has balanced output connections on XLR jacks. With the low
output impedance of the 1108 Phono Preamplier, distances of more
than 100 meters between the 1108 and preamplier or integrated
amplier are practical.
Connect the LEFT and RIGHT OUTPUT interconnects from the 1108
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 1108’s dual output
connects are in parallel, it does not matter which connection you use,
as there is no sonic difference between the two.

Getting Started
1-13
Getting Started
Connecting the Outputs to an Unbalanced Preamplier
If you are connecting the 1108 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.
This cable connects pin 1 of the XLR to the shield of the cable and pin
2 to the center pin of the RCA. It leaves the negative output (pin 3)
unconnected.
Connecting the unused output pin (usually pin 3) to ground will cause
excessive ground currents and degrade performance. Use an ohm me-
ter or continuity checker to determine how your cable is wired.
NOTE: The 1108 Phono Preamplier conforms to the standard of pin 2 as
high or “hot” for all balanced analog inputs and outputs.
1108

Getting Started
1-14
Getting Started
Setup and Loading
Personality Cards
Each input connector of the 1108 has a slot below it for a Personality
Card, one for the left and right channel of each input. These cards have
three functions:
1. Selection of the type of cartridge to be used with the input (MC or
MM)
2. Adjustment for loading the cartridge to be used with the input
On each Personality Card there is a DIP switch selector for choosing
the cartridge type.
WARNING: Always press the Standby button on the front panel to place
the 1108 in Standby mode before removing or installing any Personality
Card! Failure to place the unit in Standby mode may result in very loud pops
through the system!
To remove a Personality Card, pull the tab on the card until it slides out
of the rear panel. You may have to pull hard to remove the card. To in-
stall a Personality Card, push it into the rear panel until it is completely
seated and the face of the card is ush with the with the rear panel.

Getting Started
1-15
Getting Started
Moving Coil or Moving Magnet Selection
Set the Cartridge Type DIP Switch to either MC (Moving Coil) or MM
(Moving Magnet), depending on the type of cartridge mounted to your
turntable.
From the factory, the Personality Cards for INPUT 1 and INPUT 2 are
set to the MC position. When the Cartridge Type DIP Switch is set to
the MC position, an additional low-noise 24 dB gain stage is inserted
at the input for a total of 70 dB of gain.