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REFERENCE SERIES
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POWER AMPLIFIERS
REFERENCE MANUAL
©2000 Alesis Corporation
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Alesis RA150-500 Reference Manual © Copyright 2000, Alesis Studio Electronics, Inc. All rights reserved. Reproduction in whole or in part is prohibited. “RA150/300/500” and “Reference Series” are trademarks of Alesis Studio Electronics, Inc. ALESIS CONTACT INFORMATION Alesis Studio Electronics, Inc. 1633 26th Street Santa Monica, CA 90404 USA Do not use this address for repair service. Telephone: 800-5-ALESIS (800-525-3747) E-Mail: support@alesis.com Website: http://www.alesis.com
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CONTENTS Introduction......................................................2 Connectors..............................................18 How to Use This Manual...........................2 Speaker Cables........................................18 Connecting Speaker Cables to Binding IMPORTANT SAFETY INSTRUCTIONS.... 3 Posts.......................................................19 The Importance of Speaker Polarity..........20 Instructions de Sécurité Importantes (French)......4 Output Connections f
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Introduction/Safety Instructions HOW TO USE THIS MANUAL INTRODUCTION This manual is divided into the following Thank you for purchasing this Alesis RA150, RA300, sections describing the various functions and or RA500™ Reference Series power amplifier. To applications for the RA series amplifier. Though take full advantage of this amplifier’s functions, and we recommend you take time to read through to enjoy long and trouble-free use, please read this the entire manual once carefully, those havi
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Introduction/Safety Instructions IMPORTANT SAFETY INSTRUCTIONS 11. Unplug this apparatus during lightning storms SAFETY SYMBOLS USED IN THIS PRODUCT or when unused for long periods of time. This symbol alerts the user that there are important operating and maintenance 12. Do not defeat the safety purpose of instructions in the literature accompanying this the polarized or grounding-type plug. A unit. polarized plug has two blades with one wider than the other. A grounding-type plug has two
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Introduction/Safety Instructions INSTRUCTIONS DE SÉCURITÉ IMPORTANTES (FRENCH) 8. Ne pas installer à proximilé de sources de chaleur SYMBOLES UTILISÉS DANS CE PRODUIT comme radiateurs, cuisinière ou autre appareils (don’t les amplificateurs) produisant de la chaleur. Ce symbole alèrte l’utilisateur qu’il 9. Ne pas enlever la prise de terre du cordon secteur. Une prise murale avec terre deux existe des instructions de fonctionnement et de broches et une troisièrme reliée à la terre. Cette maint
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Introduction/Safety Instructions BEIM BENUTZEN DIESES PRODUKTES BEACHTEN SIE BITTE DIE SICHERHEITSHINWEISE: (GERMAN) FOLGENDEN 1. Lesen Sie die Hinweise. 2. Halten Sie sich an die Anleitung. und deshalb nicht mehr normal arbeitet oder heruntergefallen ist. 3. Beachten Sie alle Warnungen. 14.Dieses Gerät produziert auch im 4. Beachten Sie alle Hinweise. normalen Betrieb Wärme. Achten Sie 5. Bringen Sie das Gerät nie mit Wasser in deshalb auf ausreichende Lüftung mit Berührung. mindestens 15 cm A
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Introduction/Safety Instructions CE DECLARATION OF CONFORMITY Manufacturer’s Name: Alesis Corporation Manufacturer’s Address: 1633 26th Street Santa Monica, CA 90404 USA declares, that the product: Product Name: RA150/300/500 Model Type: Audio amplifier conforms to the following Standards: Safety: EN60065 EMC: EN55103:1997 Class B (all tests were performed with fully- shielded cabling.) European Contact: Sound Technology 17 Letchworth Point, Letchworth, Hertfordshire, SG6 1ND, England. Phone: +4
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Chapter 1: Introduction CHAPTER 1 ABOUT THE RA150/300/500 plugs. A recessed rear panel switch allows easy PRINCIPAL FEATURES selection of stereo or bridged monaural operating modes. AC power entry is via a detachable, grounded IEC connector cable. Please remember that a power amplifier is a high-current, high-power device and AMPLIFIER TOPOLOGY should be treated with respect and care. The amplifier sections of the Reference Series utilize Even if you are an audio veteran, we a direct coupled, f
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Introduction: Chapter 1 Reference Series Features- ABOUT THIS MANUAL • DC coupled, fully complementary discrete In most respects, the three different amplifiers amplifier topology covered by this manual are similar except for their power ratings. Operational differences will be • Actively biased, dual differential input noted individually. stages • Wide bandwidth, low distortion design • Fully protected from all fault conditions • LED output level metering (RA 300, RA 500) • Front panel level
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Chapter 2: Connections CHAPTER 2 CONNECTIONS UNPACKING AND INSPECTION POWER CONSIDERATIONS Your Alesis RA150/300/500 was carefully packed THE AC CORD AND GROUNDING at the factory, and the shipping carton was designed The RA150/300/500’s IEC-spec AC cord (do not to protect the unit during shipping. Do not discard substitute any other type of AC cord) is designed to the packing materials; they may be helpful in the connect to an outlet that includes three pins, with unlikely event that you need
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Connections: Chapter 2 120 VOLT/230 VOLT OPERATION ELECTRICAL SERVICE TO THE RA150/300/500 The Alesis Reference Series amplifiers feature dual- voltage operation. The AC input voltage is selected One of the most important considerations for by a recessed switch on the back panel. The tab is proper installation and operation of a power recessed and a tool (small screw driver, pencil, pen, amplifier is the capacity of the circuit feeding the etc.) is required to shift from 120-volt to 230-volt
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Chapter 2: Connections refrigerators, coffee pots, toasters, air conditioning, • You may wish to leave an empty rack space or stage lighting, plug the RA150/300/500 into a above or below the amp to promote good air different circuit with a lesser load. flow. If multiple amplifiers are mounted in the same rack, there should be at least one rack space left between them; solid blank panels may OPERATING ENVIRONMENT be used to fill the spaces, but perforated grilles used as fillers will help exhau
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Connections: Chapter 2 MOUNTING ON A SHELF OR IN A AVOIDING ELECTROMAGNETIC NON-RACK ENCLOSURE INTERFERENCE To mount the amplifier on a shelf or other flat Because the RA150/300/500 contains a large power surface, Alesis recommends using the enclosed transformer, we recommend that you do not: stick-on feet to avoid scratching the shelf’s surface with the amplifier bottom. To properly mount the • Place the RA150/300/500 next to an unshielded stick-on feet: video monitor, as the magnetic fields m
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Chapter 2: Connections INPUTS INPUT JACK CHARACTERISTICS The RA150/300/500 include two balanced, 1/4" These are compatible with the low-impedance, TRS (tip-ring-sleeve, 3-conductor) phone jack unbalanced or balanced, line-level outputs typically inputs, and unbalanced RCA/phono inputs. The emanating from equipment such as mixers, RA300 and RA500 feature combination XLR input synthesizers, samplers, direct boxes, crossovers, etc. jacks as well. The inputs are wired according to IEC Electric gui
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Connections: Chapter 2 To use an unbalanced source with an Warning: Be sure that the AC power is off prior Alesis amplifier: to connecting or disconnecting any signal wiring. Connect the High (+) signal wire as shown in Table 1 and connect the shield wire to both the Low (–) The input circuits of the Alesis amplifiers are and Audio Ground input connections. See Figures electronically balanced. They may be fed from 4 and 6. If a two-wire (tip and sleeve only) phone either symmetrical (“balanc
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Chapter 2: Connections CABLES CABLE WIRING TIPS Use only high quality cables when interfacing If you decide to wire your own cables, Alesis equipment with the RA150/300/500. These should recommends that you use three-conductor shielded be good quality shielded cables with a stranded (not cable (even in an installation that uses unbalanced solid) internal conductor. Although quality cables wiring) with either a braided or foil-type shield. cost more, they do make a difference. Route cables Conn
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Connections: Chapter 2 BALANCED OR UNBALANCED? If you have the RA150, which doesn't have an XLR input, you may use an XLR-F to TRS-M cable With long cable runs (e.g., over 6 meters/20 feet) in or adapter. The 1/4" input jack of the RA150 is noisy electrical environments, the cable itself can act balanced. (See Figure 5 on page 17.) as an “antenna” and pick up RF fields, AC hum, or other types of interference. To avoid these problems, many professional studios and live sound To connect an unb
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Chapter 2: Connections Isolation transformer or direct box To feed the same source to several If your mixer or other sound source doesn't have a different amplifiers: balanced output, you may turn it into a balanced signal with an external device, either active The input impedance of the Alesis amplifiers is 20 (electronic, powered) or passive (a transformer). kΩ in balanced and 10 kΩ in unbalanced These commonly available audio accessories have a configuration. Thus, the inputs of several amp
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Connections: Chapter 2 SPEAKER CABLES OUTPUTS The cables you use between the RA150/300/500 Warning: Be sure that the AC power is off prior and its speakers are very important. Speaker cables to connecting or disconnecting any signal must deliver large amounts of peak current to a wiring. speaker. To complicate matters further, a speaker represents an inductive load, and is more difficult to drive than a purely resistive load. Speakers are also WHAT'S THE LOAD IMPEDANCE? very low impedance dev
