Alesis RA300, RA150, RA500 manual To feed the same source to several different amplifiers

Page 19

Chapter 2: Connections

Isolation transformer or direct box

If your mixer or other sound source doesn't have a balanced output, you may turn it into a balanced signal with an external device, either active (electronic, powered) or passive (a transformer). These commonly available audio accessories have a balanced line output, usually in the form of an XLR connector, and an unbalanced line input, usually in the form of a 1/4" phone jack.

A line transformer can also convert balanced signals to unbalanced signals. Advantage of a transformer: High signal carrying capacity, no power required, generates no hiss. Disadvantages: Inexpensive transformers may color the sound due to frequency response irregularities and can pick up hum due to inductive nature of transformers. Very high-fidelity models are expensive.

Active direct boxes use an active electronic circuit to drive a balanced line, but does not work in the other direction. Advantages: Good frequency response specs, no inherent hum pickup, less expensive than transformers. Disadvantages: Requires power, generates some noise.

To feed the same source to several different amplifiers:

The input impedance of the Alesis amplifiers is 20 kΩ in balanced and 10 kΩ in unbalanced configuration. Thus, the inputs of several amplifiers may be connected in parallel if desired. The maximum number of amplifier channels will depend on the minimum output load impedance of the device feeding the amplifiers. For example, if the minimum output load impedance of the source device is 600 Ω, up to 30 amplifier channels may be connected to it in parallel without overloading the source device’s output.

However, use of a distribution amplifier is recommended in large systems.

To use the amplifier in Bridged Mono mode:

Connect the input signal to Channel A/Left only. Move the recessed slide switch under the right input connectors to the Bridged Mono position. Do not connect any signal to the Channel B/Right input jack. Leave the input level control for Channel B down. See page 20 for output wiring in Bridged Mono configuration.

RA150/300/500 Reference Manual

17

Page 18 Page 20
Image 19
Page 18 Page 20
Contents Reference Series Power AmplifiersAlesis Contact Information Contents Introduction HOW to USE this ManualSafety Symbols Used in this Product Important Safety InstructionsInstructions DE Sécurité Importantes French Symboles Utilisés Dans CE ProduitLesen Sie die Hinweise EMC CE Declaration of ConformityPrincipal Features About this Manual Reference Series FeaturesConnections Power ConsiderationsAC Cord and Grounding VOLT/230 Volt Operation Electrical Service toFuse Operating Environment Temperature Considerations in Rack MountingOther Rack Mounting Tips Avoiding Electromagnetic Interference Mounting on a Shelf or in a NON-RACK EnclosureInputs Input Jack CharacteristicsTo use an unbalanced source with an Alesis amplifier Balanced wiring of an XLR input ConnectorCables Cable Wiring TipsTo connect a balanced line output to feed the RA150/300/500 Balanced or UNBALANCED?To connect an unbalanced source to the amplifier input To feed the same source to several different amplifiers To use the amplifier in Bridged Mono modeSpeaker Cables ConnectorsOutputs Whats the Load IMPEDANCE?To connect speaker cable to the connectors Connecting Speaker Cables to Binding PostsShould you use bridged mode? To connect a speaker in bridged mono modeImportance of Speaker Polarity Output Connections for Bridged OperationOperation ON-OFF SwitchVolume Controls Mute SwitchBack Panel Controls Meters RA300 and RA500Checking for Proper Polarity Choosing the Correct Speakers Using the RA150 AS a Headphone AmplifierAbout Ground Loops Device a Shielded cable Path Device B To AC power serviceSetting the Gain Properly System Setup and TestingOutput RELAYS/THERMAL Cycling Amplifier input clippingTroubleshooting Index TroubleshootingCleaning Care and MaintenanceRefer ALL Servicing to Alesis Customers Outside the USA and Canada Obtaining Repair ServiceReference SpecificationsDimensioned drawings RA300 RA500 Architects and Engineers Specifications Index Please Register Your Product Online Alesis Limited WarrantyWarranty

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.
Top Page Image Contents