CONGRATULATIONS!
Thank you for purchasing the Niles SI-2125, one of the most flexible and
convenient amplifiers ever offered. Like all Niles products, the SI-2125 is built to
the highest standards of quality control and reliability. With proper installation and
operation, you'll enjoy years of trouble-free use.
Niles manufactures the industry's most complete line of custom installation
components and accessories for audio/video systems. For a free full line catalog write:
Niles, Catalog Request, P.O. Box 160818, Miami, Florida 33116-0818
TABLE OF CONTENTS
INTRODUCTION
2
3
FEATURES AND BENEFITS
INSTALLATION CONSIDERATIONS
FRONT AND REAR PANEL DETAILS
INSTALLATION
5
9
11
15
16
18
OPERATION
TROUBLESHOOTING GUIDE
SPECIFICATIONS
The lightning flash with arrowhead symbol, within 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 sufficient magnitude
to constitute a risk of electric shock to persons.
CAUTION
CAUTION: TO REDUCE
THE RISK OF ELECTRICAL
SHOCK, DO NOT REMOVE
COVER. NO USER-SERVICE-
ABLE PARTS INSIDE. REFER
SERVICING TO QUALIFIED
SERVICE PERSONNEL.
The exclamation point within an equivalent triangle is
intended to alert the user to the presence of important
operating and maintnance (servicing) instructions in the
literature accompaying the appliance.
CAUTION: TO PREVENT ELECTRICAL SHOCK, MATCH WIDE BLADE OF PLUG TO WIDE SLOT, FULLY INSERT
ATTENTION: POUR EVITER LES CHOCS ELECTRIQUES, INTRODUIRE LAME LA PLUS LARGE DE LA FICHE
DANS LA BOURNE CORRESONDANTE DE LA PRISE ET POUSSER JUSQU’AU FOND
WARNING: TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR
MOISTURE
1
FEATURES AND BENEFITS
Real World Power
The SI-2125 delivers 125 watts per channel at 8 Ohms, 200 watts per channel at
4 Ohms and 300 watts bridged at 8 ohms. You’ll get tremendous bass and dynamics
from every pair of speakers powered by an SI-2125.
Transparent Sound
The audio circuitry of the SI-2125 is constructed using the finest parts available;
including 1% metal film resistors, high quality capacitors, and oversized heat sinks.
All this attention to technical detail creates a sound that is clear and uncolored with
phenomenal imaging.
Freedom From Crosstalk
Each channel of the SI-2125 is powered via its own independent power supply. This
increases the isolation between the two channels, and eliminates cross talk
guaranteeing you absolute silence as the backdrop to your music.
Current For Reactive Loads
The high current design of the SI-2125 assures that even unusual and reactive loads
are handled with aplomb. A massive toroidal transformer with two separate windings
for each of the power supplies supplies more than ample current to your system.
Freedom from Fan Noise
The oversized heat sinks inside the SI-2125 allow the amplifier to stay cool even when
operating into low impedance loads—without the noise of fan-cooled amplifiers.
Independent Level Controls
Each channel has its own independent level control enabling you to precisely
match the SI-2125 to the rest of your system. The level controls also enable you
to limit the volume, preventing abuse of the system.
Lifetime Connections
The SI-2125 features gold plated stereo inputs, the cascade stereo outputs as well as
the five way binding posts are gold plated to ensure perfect connections without
corrosion for years to come.
3
Turn-On Modes
The SI-2125 features three turn-on modes: 1. Music Sense 2. External Voltage Trigger
3. Manual Turn-On via the front panel switch. You can configure the
SI-2125 to interface with any kind of system and have the unit automatically turn on.
Automatic Protection
The SI-2125 is equipped with sophisticated protection circuits. In the unlikely event
that a problem occurs, the amplifier shuts itself off. When conditions return to
normal, regular operation resumes.
Status Display for Troubleshooting
LED's on the front panel indicate Power, Active Status, and a Protection Warning. With
a glance at the front panel, a troubleshooter is quickly provided with key information!
Control Output
A 12 volt DC output is provided whenever the amplifier is on, allowing you to
operate voltage-triggered devices like motorized screens and curtains.
Bridged Mode
The SI-2125’s can be operated in a bridged mono configuration. In this
configuration, it can deliver upwards of 300 watts. Bridged mode is perfect for
subwoofer, rock speakers or any applications requiring high power output.
Designed and Engineered in the USA
Limited two year parts and labor Warranty.
4
INSTALLATION CONSIDERATIONS
Placement
Place the SI-2125 on a flat level surface like a table or shelf. It should be placed
upright so that its weight rests on the four attached feet. Placing the weight of the
amplifier on the rear or front panel for even an instant will result in damage to the
amplifier's connectors and controls.
The SI-2125, like any hi-fi component, will last much longer if it is given adequate
ventilation for proper cooling. When installing the SI-2125 in a cabinet, be sure that
the rear of the cabinet is open to fresh air to provide proper cooling (see Figure 1). If
the cabinet’s design will not accommodate an open rear, install two small “boxer
fans” to provide continuous air flow into and out of the cabinet (see Figure 2). Place
the SI-2125 so that there is at least 7" of free air space above the chassis. If the
amplifier is located on a carpeted surface, place a board under the amplifier's feet.
Do not block the ventilation holes on the top and bottom of the SI-2125.
CAUTION! When using low impedance speaker loads (less than 8 ohms Normal
Mode) refer to figure 2 for proper placement.
The SI-2125 is equipped with an internal transformer, which generates a powerful
magnetic field which could induce hum in a turntable (particularly a turntable
equipped with a moving coil cartridge). Do not place a turntable directly above
or directly adjacent to the SI-2125.
Figure 1
Figure 2
Boxer Fan (55 CFM)
directly centered 7"
on top of the SI-2125.
Boxer Fan (55 CFM)
directly centered 2"
behind the SI-2125.
Make sure that there is a minimum of 7" of free air
space above the amplifier for proper ventilation.
If the cabinet rear is not open to fresh air or if you’re using
low impedance loads, install two “boxer fans” to provide
continuous air flow into and out of the cabinet.
Allow a minimum of 2" of depth behind unit
to accommodate cables and connectors.
5
Turn-On Modes
The SI-2125 draws more current than a preamplifier’s switched AC outlet can
safely supply. Also, your preamplifier may “thump” at dangerous volumes if the
amplifier is already on when the preamp turns on. It is usually best to turn the
amplifier on only when it is needed. The Turn-On Mode selector switch gives you
three options for turning the SI-2125 on and off.
Constant - The auto turn-on circuitry is off. The front panel master power switch
operates the amplifier. In is “On”, out is “Off”.
Audio Sense - The master switch on the front panel must be in the “On” position.
The amplifier is off when there is no audio signal present at either the left or the
right input, but the sensing circuitry is on. The turn-on sensing circuitry looks for
a tiny amount of audio signal present at any of the audio inputs. If it detects a
signal, the amplifier is turned on. Once the audio signal stops, the sensing circuit
waits two minutes, then turns the amplifier off.
3-30 Volt AC/DC Opto-Isolated Voltage Trigger - The master switch on the front
panel must be in the “On” position. The amplifier is off when there is no 3-30V AC
or DC voltage detected at the trigger input. Once the sensing circuitry detects a
voltage, the amplifier is turned on. Once the voltage stops, the sensing circuit
instantly turns the amplifier off. Voltage triggers can be supplied by Niles automated
switchers, some video projectors, some surround sound processors, or something
as simple as a 16 volt AC wall adapter (Niles XF00008) plugged into the switched
outlet of your stereo receiver. DO NOT USE A DC WALL ADAPTER. The long
discharge time of the DC adapter’s filter capacitor will delay the turn-off of the
amplifier.
If you are using a wall adapter or external power supply to provide the trigger, it
doesn't have to be very large (a minimum current capability of 2.5 milliamps for a 3
volt trigger increasing up to a minimum of 38 milliamps for a 30 volt trigger).
6
Bridged Mode
The SI-2125’s bridged mode switch allows you to create a more powerful
amplifier by combining both channels into one (8 ohm minumum). In the bridged
mode, connect the speakers to the left red positive terminal and the right red
positive terminal. In the bridged mode the right channel’s red terminal becomes
positive and the left channel's red terminal becomes negative.
DO NOT USE THE BLACK NEGATIVE (-) TERMINALS. THE SIGNAL IS AT THE
RED POSITIVE (+) TERMINALS ONLY.
Multiple Speaker Loads
The SI-2125 is stable into very low impedance loads. This means you can safely
operate three pairs of 8 ohm speakers (a 2.67 ohm load) directly connected to the
SI-2125. Note that the SI-2125 does not have on/off speaker switching built in.
When the amplifier is on, so are all of the speakers. (for more information on
proper amplifier placement, see Installation Considerations on page 5, Figure 2).
Niles makes a number of different speaker selection and impedance matching systems.
Speaker selection systems allow each pair of speakers to be turned on and off from your
equipment location (or even via remote control). That way, you know that the speakers
in the bedroom are off so you can avoid waking a sleeping spouse! These speaker
selectors provide an easy way to terminate all of the wires for more than three pairs.
Testing and troubleshooting a new system is much easier with the individual room
labels and on/off switches of a Niles speaker selection system. Additionally, Niles
speaker selection systems offer impedance matching features which will allow you to
connect up to ten pairs of speakers to your SI-2125 amplifier.
TECH TIP
Wire size is expressed by its AWG (American
Wire Gauge) number. The lower the number, the
larger the wire, i.e. twelve AWG is physically
larger than fourteen AWG.
7
Niles SI-2125
Niles HDL-6 Speaker Selection System
AMPLIFIER
L- R-
SPEAKER
6
SPEAKER
5
SPEAKER
4
SPEAKER
3
SPEAKER
2
SPEAKER
1
L+
R+
L+
L
-
R
-
R+
L+
L
-
R
-
R+
L+
L
-
R
-
R+
L+
L
-
R
-
R+
L+
L
-
R
-
R+
L+
L
-
R
-
R+
ON OFF
NILES
CONSTANT
PROTECTION
Niles Audio
Corporation, Inc.
Miami, Florida USA
Speaker selection systems allow each pair of speakers to be turned on and off from your
equipment location (or even via remote control).
Cable and Wire
It will be easier to reconfigure or troubleshoot your system in the future if you
label the cables and wires for their destination or source, rather than which
terminal of the SI-2125 they are connected to.
The SI-2125 connects to your sources via shielded line level audio cables with
RCA phono plugs. Use high quality cables with your Niles amplifier for the lowest
possible noise and best overall performance. Your Niles dealer can recommend
the proper cable.
The SI-2125 connects to your speakers using 2 conductor speaker wire. For most
applications, we recommend you use 16 or 18 gauge wire. For wiring runs longer
than 80 feet, we recommend 14 gauge wire. The binding posts of the
SI-2125 will accommodate up to 12 gauge wire. Larger sizes can be accommodated
by attaching banana plugs to the wire. Note that the binding posts accept dual
banana or single banana connectors.
8
Red “Power” LED confirms the amplifier is
connected to a live AC power outlet. (and
that the master power switch is on).
Green“Active” LED lights when the
amplifier circuitry has been turned on by
the Turn-On circuits.
Front panel “Master Power” switch turns
off the entire amplifier, including the
Turn-On circuitry.
The red “Protect” LED indicates the amp has shut
down because there is a fault in the speaker, the
wiring, or with the SI-2125 itself.
Main Inputs enable you to route a stereo
line level source to the SI-2125.
Cascade Outputs of the main input enable
you to daisy chain multiple amplifiers.
“Turn-On Mode” switch
3.5 Mini Plug socket
for voltage input.
3.5mm Mini Plug socket for
12v DC Control output.
9
Level Adjustment screws enable you to preset
the maximum system volume (or match levels
with another amplifier).
Bridge mode switch
IEC receptacle for AC
power cord.
Binding posts for speaker connections.
10
INSTALLATION
Pg. 11 Setting The Turn-On Mode Switch
11 Control Output
Pg. 13 Line Level Audio Inputs
13 Cascade Audio Outputs
14 AC Power plug
12 Speaker Wire Connections
Setting the Turn-On Mode Switch
The SI-2125 has three turn-on modes. Select which mode you desire by sliding
the mode switch. See Installation Considerations on page 6 for more information
about each of the turn-on modes.
Slide the switch with your fingernail or a
1/8" slotted screwdriver blade.
Control Output
This terminal provides a 12v DC signal
suitable for triggering Niles automated
switchers, some motorized screens, some
electric curtain controls, etc. The trigger
voltage is present only when the amplifier is
active or “on”. When the amplifier turns “off”,
the 12 volt signal is off.
Using the
3.5 mm jack.
STEP
DESCRIPTION
1. Check the requirements of the
device you want to control.
The control output has a maximum
current capability of 12vDC 150 mA.
2. Connect the 3.5mm Jack to the
control output maintaining proper
polarity (tip = +)
Niles makes an accessory cable
plug FG00724.
11
Speaker Wire Connections
CAUTION! All speaker wire connections must be made with the amplifier Off.
Bare Wire
Banana Plugs
Unscrew the red or
black plastic knob,
insert the bare wire
end into the opening,
and then tighten the
knob until the wire is
securely clamped.
There are many types of
banana plugs, some
crimp, some solder. The
Niles gold banana plug
has
a
quick-connect
binding post for the
bare wire on the body
of the plug. A banana
plug is simply inserted
into the jack at the
end of the amplifier’s
binding post. Dual
banana plugs will fit the
SI-2125 binding posts.
STEP
DESCRIPTION
1. Label all wires.
If you label the wires for their destination,
rather than which terminal of the SI-2125
they are connected to, it will be easier to
reconfigure your system in the future.
2. Connect one stripped wire end or
banana plug to the black terminal
and one to the red terminal.
A. Split the speaker wire insulation so that
at least two inches of each conductor are
separated.
B. Strip one half inch of insulation from the
end of each conductor of the speaker wire
C. Attach banana plugs or twist the strands of
wire together and insert them into the
appropriate binding post.
CAUTION- Avoid even a single strand
of wire touching the chassis or another
connector.
12
Line Level Audio Input
CAUTION! THE AMPLIFIER MUST BE OFF WHENEVER YOU MAKE CHANGES
TO THE INPUT CONNECTIONS.
STEP
DESCRIPTION
1. Label all of the interconnecting
cables for the sources they connect to.
Use audio patch cables with RCA phono
plugs attached to the ends.
2. Connect the sources by inserting the
RCA plugs into the amplifier’s jacks.
Connect outputs from your sources to
inputs on the amplifier. Never connect a
source or preamplifier’s input (e.g., record
inputs) to the inputs of your SI-2125.
Cascade Audio Outputs
The “Cascade Audio Outputs” enable you to connect another amplifier to your
preamplifier output. The connectors are gold-plated RCA phono jacks. Connect
them to another amplifier’s inputs with a standard audio patch cable. The outputs
are not buffered; if you wish to daisy-chain more than 5 Niles amplifiers you
will need a Niles AVDA-3 buffered distribution amplifier. A single AVDA-3 will
allow you to daisy-chain 5 amplifiers from each of its 3 outputs, allowing 15
SI-2125 power amplifiers to be fed from the same master preamplifier. If your
preamp has a vacuum tube output stage, you must use a Niles AVDA-3 to drive
more than a single SI-2125.
13
AC Power Plug
STEP
Plug the female IEC socket of the
supplied AC cord into the IEC
receptacle on the rear of the amplifier.
Just like a computer or printer, the SI-2125
has an AC cord which unplugs either at the
amp or at the wall for your convenience.
If you use a grounded power strip, surge
suppressor or extension cord, verify that
proper ground is maintained.
Plug the 2 prong plug into
120V 60 Hz wall outlet.
The SI-2125 draws
approximately 700 watts from an AC wall
outlet. Use the auto turn on circuit instead.
a
maximum of
CAUTION! Typically the
preamp/receiver’s switched outlet
is not rated for a power amplifier.
14
OPERATION
Power Switch
The front panel switch is a master or “vacation” power switch. No matter which
turn-on mode you have selected, the master power switch will turn off all
circuitry—including the sensing circuitry. If you will not be using the amplifier for
an extended period of time, turn the master power switch “Off” (push button
switch out). When you would like to return to normal operation, turn the switch
”On” (push button switch in).
Power LED
The power LED indicates that the AC cord is plugged into a working AC power
receptacle and that the power switch is in the ”On” position.
Active LED
The rear panel turn-on mode switch determines when and how the amplifier will
turn on. The ”Active” LED indicates that the amplifier is operating.
Protection LED
The front panel protection LED indicates that the amplifier has been shut down
because of either a fault in the wiring or the speaker, or with the SI-2125 itself.
Level Adjustment Screws
The front panel level adjustment screws allow you to adjust the level of the
SI-2125 relative to other amplifiers in your system. Use a 1/8" slotted screwdriver
to adjust the screws. If the SI-2125 is the only amplifier in your system, leave the
screws at their factory default position (turned fully clockwise).
Cleaning and Maintenance
The internal parts of the SI-2125 are electronic and require no maintenance.
Once a year it is appropriate to twist the RCA connectors on each input to remove
corrosion and improve conductivity. You can clean the amplifier with soft cloth or
paper towel dampened with water or a mild detergent. Do not use any spray-type,
abrasive cleaners on the amplifier.
15
TROUBLESHOOTING GUIDE
When there is a problem consult this guide first. If the problem persists, or you
have additional questions, call your local Niles dealer or Niles Technical Support
at 1-800-289-4434. The most common problems relate to hook up. Call from
your telephone extension nearest the system.
POSSIBLE CAUSES AND TEST PROCEDURE
SYMPTOM
Short circuit or loose wire at the speaker or
No sound on one channel
amplifier terminals. Check that the connections are
secure and that there are no loose strands of wire
crossing from the positive to the negative terminals
at the back of the amplifier and /or the speaker.
Short circuit or a break in the speaker wire. Dis-
connect the speaker wire at both ends, separate the
2 conductors at both ends and test with a meter for
a short circuit. If there is no short, connect the two
conductors at one end and test with a meter for
continuity.
Speaker is not working. Connect the speaker to a
channel that plays another speaker.
Audio cable to input is bad. Connect another cable
that is known to be good.
Audio cable to the main inputs is bad. Connect
another cable that is known to be good.
No sound on both channels
Hum from the speakers
Hum may be caused by a ground loop between
two of the other components in the system. To test
for another ground loop, try reversing the AC plugs
of each of the components in the system.
16
TROUBLESHOOTING GUIDE (continued)
POSSIBLE CAUSES AND TEST PROCEDURE
SYMPTOM
Check for faulty cables, faulty source material, an
ungrounded phono system or a defective component.
Hum from the speakers
AC power cord must be plugged into a working outlet.
Master power switch must be on.
Amp will not turn on
Bass sound is weak and
the stereo image is
“phasey” or “blurry”
sounding in one room
The loudspeakers are wired out of phase.
Reverse the connections at the back of one speaker.
Make sure that the Bridge Mode Switch is in the
stereo position if the amplifier is being used in a
stereo configuration.
17
SPECIFICATIONS
Design Principle
Linear voltage/current amplification.
Continuous Average Power Output
125 watts per channel RMS at 8 ohms.
200 watts per channel RMS at 4 ohms.
300 watts bridged channel RMS at 8 ohms.
Input Impedance
18K ohms
Input Sensitivity
.878V for 8Ω rated output
Overall Voltage Gain
33 dB
Frequency Response
Bandwidth Limited from 10 Hz to 100 kHz
Total Harmonic Distortion
8 Ohms
.02% THD from 20 Hz to 20 kHz @ full rated power
4 Ohms
.02% THD from 20 Hz to 20 kHz @ full rated power
Overall Dimensions
17" wide 5 1/2" high (including feet) 13-1/8" deep
Weight
26 lbs
18
Niles Audio
Corporation
12331 S.W. 130 Street
Miami, Florida 33186
Tel: (305) 238-4373
Fax: (305) 238-0185
©2003 Niles Audio Corporation. Because Niles strives to continuously improve its
products, Niles reserves the right to change product specifications without notice.
Niles, the Niles logo and Blending High Fidelity and Architecture are registered
trademarks of Niles Audio Corporation. Systems Integration Amplifier and
BusMatrix are trademarks of Niles Audio Corporation Printed in the Malaysia 9/03
DS00354AMY
I N S T A L L A T I O N
&
O P E R A T I O N G U I D E
SI-2125
®
Systems Integration Amplifier
®
B L E N D I N G H I G H F I D E L I T Y A N D A R C H I T E C T U R E ®
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