INSTALLATION CONSIDERATIONS

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.

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.

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Niles Audio SI-2125 manual Tech TIP
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SI-2125 specifications

The Niles Audio SI-2125 is a versatile and powerful amplifier designed to meet the demands of modern audio systems, whether for home theater setups or multi-room audio solutions. Offering robust performance and user-friendly features, it stands out in the crowded field of amplifiers.

At the heart of the SI-2125 is its high-power output capability, delivering 125 watts per channel at 8 ohms. This ensures that it can drive a wide range of speakers, providing clean and dynamic sound that enhances the listening experience. The amplifier operates efficiently, allowing it to run cool, reducing the risk of overheating during extended use.

One of the standout features of the SI-2125 is its versatile connectivity options. It comes equipped with multiple input options, including both balanced XLR and unbalanced RCA connections. This flexibility enables easy integration into various audio setups, whether it’s a dedicated home theater system or a more extensive multi-zone audio installation. The amplifier also includes a trigger input for automatic power on/off, which simplifies operation and enhances convenience.

The SI-2125 incorporates high-quality components that contribute to its impressive sound quality. It features a toroidal transformer, which is known for its efficiency and low electromagnetic interference, resulting in a cleaner sound. The amplifier also utilizes a distinctive Class AB design, which balances the advantages of both Class A and Class B amplification, providing ample power while maintaining excellent audio fidelity.

Another noteworthy characteristic of the SI-2125 is its robust build quality. The amplifier comes housed in a durable chassis, designed to minimize vibrations and protect the internal components. This not only enhances longevity but also helps maintain the integrity of the sound. The front panel features a sleek design with clearly labeled controls that provide easy access to essential functions, including volume control and input selection.

In addition to performance, the SI-2125 also supports a range of advanced features aimed at enhancing usability. This includes a unique feature set that accommodates various speaker configurations, allowing users to optimize their audio experience to suit their specific preferences and room acoustics.

Overall, the Niles Audio SI-2125 is an exceptional choice for anyone seeking a high-performance amplifier that combines power, versatility, and ease of use. Its impressive specifications and thoughtful design make it an ideal addition to any serious audio setup, ensuring that listeners can enjoy their favorite music and movies with remarkable clarity and fidelity.
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