Chapter 3: Operation

CHAPTER 3

OPERATION

FRONT PANEL CONTROLS

The following diagram shows the various front panel controls, as described next.

RA150

RA300

ON-OFF SWITCH

Press the switch to turn the amplifier on, and again to turn the amplifier off.

Upon turning on the amplifier, the power indicator LED will light. Note that in direct sunlight, this light may not be easily visible.

When powering a system on or off, it is usually advisable to turn on the power amplifiers last and to turn them off first, so that any turn on or turn off transient signals generated by other equipment in the system are not amplified and sent to the loudspeakers.

RA500

VOLUME CONTROLS

Detented level controls are on the front panel, where they can be easily adjusted if necessary. These regulate the input signal going into the RA150/300/500. Always turn the volume controls all the way down (counterclockwise) when making input or output connections to the RA150/300/500. Power should be off as well. It’s also good practice to turn the volume controls all the way down when turning on power just in case a signal source feeding the RA150/300/500 is “live.”

However, the RA150/300/500’s output protection relays have a 4.5 second turn-on delay which keeps the loudspeakers disconnected while the system is powering up. These relays also disconnect the load very quickly when power is removed from the amplifiers, thus minimizing the chance that turn-off transients originating elsewhere in the system will be sent to the speakers. So, if the RA150/300/500 power switch is left on and the entire system is powered up on a single master AC switch, transient "thumps" should not be a problem.

MUTE SWITCH

Because turning the RA150/300/500 on and off generates no spikes within the amplifier, the power switch doubles as a mute switch or “panic button.” For example, if there is a serious feedback problem, you can simply turn off the RA150/300/500, then chase down the source of the problem.

RA150/300/500 Reference Manual

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Alesis RA500, RA150, RA300 manual Operation, Front Panel Controls, ON-OFF Switch, Volume Controls, Mute Switch

RA150, RA500, RA300 specifications

The Alesis RA series of amplifiers—comprising the RA300, RA500, and RA150—have earned a respected spot in the audio equipment landscape, catering to both musicians and audio professionals. With a blend of innovative technology, robust performance, and user-friendly features, these amplifiers offer solutions for various sound requirements.

Starting with the RA300, this amplifier delivers a solid output of 150 watts per channel at 4 ohms, making it ideal for smaller studio setups or personal listening environments. It is built with a lightweight yet durable design, employing a modern Class AB architecture that ensures low distortion and high audio fidelity. The RA300 features comprehensive input options, including balanced XLR and quarter-inch TRS inputs, allowing seamless integration into diverse setups. Additionally, the built-in protection circuitry prevents overheating and damage during prolonged use, ensuring longevity and reliability.

The RA500 steps up the power and performance, presenting a robust 250 watts per channel at 4 ohms, making it suitable for larger venues and demanding applications. It utilizes advanced thermal management technology, which aids in efficient heat dissipation, ensuring the amplifier operates smoothly even under heavy load. The RA500 also boasts significant dynamic range and headroom, making it a preferred choice for professional environments where audio clarity and volume are paramount. The addition of a frequency response that spans from 20Hz to 20kHz means it can faithfully reproduce a wide range of audio frequencies.

Meanwhile, the RA150 serves as a versatile option for various applications, delivering 75 watts per channel at 4 ohms. Despite its compact size, the RA150 does not compromise on sound quality or functionality. Its Class AB amplifier technology results in enhanced audio accuracy, making it popular among beginner studios and educational settings. The straightforward controls and indicators ensure that users can quickly adjust settings for optimal performance.

All three amplifiers in the Alesis RA series share a common goal: to provide high-quality sound amplification without unnecessary complexity. Their combination of solid construction, advanced technologies, and thoughtful features make them suitable for a multitude of audio environments—from home studios to professional gigs. Whether you opt for the RA300, RA500, or RA150, you are investing in a reliable tool designed to deliver exceptional audio performance, catering to the needs of discerning audiophiles and professionals alike.