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3.Connect the two pairs of speakers in parallel. If you connected 8 ohm speak-

ers the total impedance of both pairs is 8 ohms (16 ⎟ 2 = 8).

Note: If each of the four speakers is 8 ohms, the total speaker impedance of the combined series/parallel connection described above is also 8 ohms. Like- wise, the total speaker impedance is 4 or 16 ohms if the speakers are 4 or 16 ohms, respectively.

4.Connect the speakers’ negative (–) ter- minals to the COM terminal on the back of the amplifier.

5.Connect the speaker’s positive (+) ter- minals to the speaker terminal (4Ω, 8Ω, or 16Ω) on the back of the amplifier that matches the total speaker impedance as calculated in Step 3.

Connecting Speakers with Trans- formers

For the best results when you connect two or more speakers to your system, use a line transformer (not supplied) for each speaker.

Transformers offer these advantages:

•You can connect speakers with different impedances without causing differ- ences in output between the speakers.

•You can add or remove a speaker from the system without having to recalculate the entire system’s impedance.

•You can reduce signal loss when you use speaker wire over 50 feet long.

Line transformers have several connectors called taps.

Taps

The primary taps (on one side of the trans- former) are the inputs and are rated in watts. The secondary taps (on the opposite side of the transformer) are the outputs and are rat- ed in ohms.

Primary

Secondary

Taps

Taps

Cautions:

•Before you connect the speakers, be sure the total wattage of the primary tap you intend to use does not exceed the amplifier’s maximum 100-watt output power rating.

•Avoid multiple connections to the 70V RMS and COM terminals on the back of the amplifier.

Connections

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Radio Shack MPA-125 owner manual Connecting Speakers with Trans- formers, Transformers offer these advantages
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MPA-125 specifications

The Radio Shack MPA-125 is a versatile and powerful amplifier that was designed to meet the demands of audio enthusiasts and professionals alike. Renowned for its robust performance and reliability, the MPA-125 has garnered a reputation as a dependable choice for a variety of sound applications, from home audio systems to live sound reinforcement.

One of the standout features of the MPA-125 is its impressive power output. With a rating of 125 watts per channel at 8 ohms, this amplifier ensures that audio signals are delivered with clarity and precision, making it suitable for driving a wide range of speakers. The 2-channel design allows for stereo applications, providing a rich and immersive listening experience. Additionally, the MPA-125 can operate at a low impedance, ensuring compatibility with various speaker configurations.

The MPA-125 is equipped with several advanced technologies that enhance its performance. The built-in thermal protection circuit safeguards the amplifier from overheating, allowing it to operate efficiently even during extended use. The amplifier also features a soft clipping circuit, which prevents distortion during peak output levels, ensuring that audio quality remains consistent and clear at high volumes.

User-friendly design is another hallmark of the MPA-125. The front panel includes easy-to-use volume controls, indicator lights, and speaker output terminals. The amplifier is designed for straightforward integration into existing audio setups, making it accessible for users of all experience levels. The balanced XLR inputs provide a secure and noise-free connection, ideal for professional audio applications.

Constructed with high-quality components, the MPA-125 is built to last, ensuring longevity and sustained performance over time. Its compact form factor makes it easy to incorporate into various environments, from home theaters to portable sound systems.

Overall, the Radio Shack MPA-125 is a reliable and powerful amplifier that brings out the best in audio equipment. Its combination of solid performance, user-friendly features, and advanced technologies makes it an excellent choice for anyone looking to elevate their audio experience, whether for casual listening or professional use.
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