Alesis RA500, RA300, RA150 User Manual

4 (1)

REFERENCE SERIES

POWER AMPLIFIERS

REFERENCE MANUAL

©2000 Alesis Corporation

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

CONTENTS

Introduction ......................................................

2

How to Use This Manual...........................

2

IMPORTANT SAFETY INSTRUCTIONS....

3

Instructions de Sécurité Importantes (French)......

4

Beim Benutzen dieses Produktes beachten Sie

 

bitte die folgenden Sicherheitshinweise:

 

(German) ..........................................................

5

CE Declaration of Conformity.............................

6

ABOUT THE RA150/300/500.............

7

Principal Features ..............................................

7

The Chassis ..............................................

7

Inputs and Outputs...................................

7

Amplifier topology ...................................

7

Protection Circuitry ..................................

7

About this manual .............................................

8

CONNECTIONS ...................................

9

Unpacking and Inspection..................................

9

Power Considerations........................................

9

The AC Cord and Grounding ....................

9

120 Volt/230 Volt Operation....................

10

Fuse.......................................................

10

Electrical Service to the RA150/300/500...

10

Operating Environment ...................................

11

Temperature Considerations in Rack

 

Mounting...............................................

11

Other Rack Mounting Tips ......................

11

Mounting on a Shelf or in a Non-Rack

 

Enclosure ...............................................

12

Avoiding Electromagnetic Interference ....

12

Inputs .............................................................

13

Input Jack Characteristics ........................

13

Cables....................................................

15

Cable Wiring Tips...................................

15

Balanced or Unbalanced? ........................

16

Outputs ..........................................................

18

What's the Load Impedance? ...................

18

Connectors..............................................

18

Speaker Cables........................................

18

Connecting Speaker Cables to Binding

 

Posts.......................................................

19

The Importance of Speaker Polarity ..........

20

Output Connections for Bridged

 

Operation ...............................................

20

OPERATION......................................

21

Front Panel Controls.........................................

21

Volume Controls .....................................

21

On-Off Switch .........................................

21

Mute Switch............................................

21

Protect/Clip Indicators............................

22

Meters (RA300 and RA500 only)...............

22

Back Panel Controls..........................................

22

AC Voltage Switch ..................................

22

Stereo/Bridged Mono Switch...................

22

Checking For Proper Polarity ............................

22

Using the RA150 as a Headphone Amplifier.......

23

Choosing the Correct Speakers..........................

23

About Ground Loops........................................

24

System Setup and Testing .................................

25

Setting the Gain Properly.........................

25

Output Relays/Thermal Cycling ..............

26

TROUBLESHOOTING..........................

27

Troubleshooting Index......................................

27

Care and Maintenance ......................................

28

Cleaning .................................................

28

Refer All Servicing to Alesis .....................

28

Obtaining Repair Service .........................

29

Customers outside the USA and

 

Canada: ..................................................

29

SPECIFICATIONS...............................

30

INDEX.............................................

34

ALESIS LIMITED WARRANTY ............

35

RA150/300/500 Reference Manual

1

Introduction/Safety Instructions

INTRODUCTION

Thank you for purchasing this Alesis RA150, RA300, or RA500™ Reference Series power amplifier. To take full advantage of this amplifier’s functions, and to enjoy long and trouble-free use, please read this user’s manual carefully.

HOW TO USE THIS MANUAL

This manual is divided into the following sections describing the various functions and applications for the RA series amplifier. Though we recommend you take time to read through the entire manual once carefully, those having general knowledge about amplifiers should use the table of contents to look up specific functions.

Chapter 1: Introduction. If you want to start using the RA150/300/500 right away, here’s a one-page guide to hooking it up and trying it out.

Chapter 2: Connections. This chapter gives detailed instructions for connecting the RA150/300/500 to a variety of typical sound systems.

Chapter 3: Operation. This section explains how to run the Reference Series Amplifier properly.

Chapter 4: Troubleshooting. This chapter contains troubleshooting tips and service information should problems occur.

When something important appears in the manual, an icon (like the one on the left) will appear in the left margin. This symbol indicates that this information is vital when operating the RA150/300/500.

2

 

 

RA150/300/500 Reference Manual

Introduction/Safety Instructions

IMPORTANT SAFETY INSTRUCTIONS

SAFETY SYMBOLS USED IN THIS PRODUCT

This symbol alerts the user that there are important operating and maintenance instructions in the literature accompanying this unit.

This symbol warns the user of uninsulated voltage within the unit that can cause dangerous electric shocks.

This symbol warns the user that output connectors contain voltages that can cause dangerous electrical shock.

PLEASE FOLLOW THESE PRECAUTIONS

WHEN USING THIS PRODUCT:

1. Read these instructions.

2.Keep these instructions.

3.Heed all warnings.

4.Follow all instructions.

5.Do not use this apparatus near water.

6.Clean only with a damp cloth. Do not spray any liquid cleaner onto the faceplate, as this may damage the front panel controls or cause a dangerous condition.

7.Do not block any of the ventilation openings. Install in accordance with the manufacturer's instructions.

8.Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat.

9.Protect the power cord from being walked on or pinched, particularly at plugs, convenience receptacles, and the point where they exit from the apparatus.

10.Use only attachments or accessories specified by the manufacturer.

11.Unplug this apparatus during lightning storms or when unused for long periods of time.

12. Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has two blades with one wider than the other. A grounding-type plug has two blades and a third grounding prong. The wide blade or the third prong are provided for your safety. When the provided plug does not fit into your outlet, consult an electrician for replacement of the obsolete outlet.

13.Use only with a cart, stand, bracket, or table designed for use with professional audio or music equipment. In any installation, make sure that injury or damage will not result from cables pulling on the apparatus and its mounting. If a cart is used, use caution when moving the cart/apparatus

combination to avoid injury from tip-over.

14. Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in any way, such as when the power-supply cord or plug is damaged, liquid has been spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped.

15.This unit produces heat when operated normally. Operate in a well-ventilated area with at least six inches of clearance from peripheral equipment.

16.This product, in combination with an amplifier and headphones or speakers, may be capable of producing sound levels that could cause permanent hearing loss. Do not operate for a long period of time at a high volume level or at a level that is uncomfortable. If you experience any hearing loss or ringing in the ears, you should consult an audiologist.

RA150/300/500 Reference Manual

3

Introduction/Safety Instructions

INSTRUCTIONS DE SÉCURITÉ IMPORTANTES (FRENCH)

SYMBOLES UTILISÉS DANS CE PRODUIT

Ce symbole alèrte l’utilisateur qu’il existe des instructions de fonctionnement et de maintenance dans la documentation jointe avec ce produit.

Ce symbole avertit l’utilisateur de la présence d’une tension non isolée à l’intérieur de l’appareil pouvant engendrer des chocs électriques.

Ce symbole prévient l'utilisateur de la présence de tensions sur les raccordements de sorties, représentant un risque d'électrocution.

VEUILLEZ SUIVRE CES PRÉCAUTIONS LORS

DE LUTILISATION DE LAPPAREIL:

1. Lisez ces instructions.

2.Gardez ces instructions.

3.Tenez compte de tous les avertissements.

4.Suivez toutes les instructions.

5.N’utilisez pas cet allareil à proximité de l’eau.

6.Ne nettoyez qu’avec un chiffon humide. Il est potentiellement dangereux d'utiliser des pulvérisateurs ou nettoyants liquides sur cet appareil.

7.Installez selon les recommandations du constructeur.

8.Ne pas installer à proximilé de sources de chaleur comme radiateurs, cuisinière ou autre appareils (don’t les amplificateurs) produisant de la chaleur.

9.Ne pas enlever la prise de terre du cordon secteur. Une prise murale avec terre deux broches et une troisièrme reliée à la terre. Cette dernière est présente pour votre sécurité. Si le cordon secteur ne rentre pas dans la prise de courant, demandez à un électricien qualifié de remplacer la prise.

10.Evitez de marcher sur le cordon secteur ou de le pincer, en particulier au niveau de la prise, et aux endroits où il sor de l’appareil.

11.N’utilisez que des accessoires spécifiés par le constructeur.

12.N’utilisez qu’avec un stand, ou table conçus pour l’utilisation d’audio professionnel ou instruments de musique. Dans toute installation, veillez de ne rien endommager à cause de câbles qui tirent sur des appareils et leur support.

13.Débranchez l’appareil lors d’un orage ou lorsqu’il n’est pas utilisé pendant longtemps.

14.Faites réparer par un personnel qualifié. Une réparation est nécessaire lorsque l’appareil a été endommagé de quelque sorte que ce soit, par exemple losrque le cordon secteur ou la prise sont endommagés, si du liquide a coulé ou des objets se sont introduits dans l’appareil, si celui-ci a été exposé à la pluie ou à l’humidité, ne fonctionne pas normalement ou est tombé.

15.Puisque son fonctionement normale génère de la chaleur, placez cet appareil au moins 15cm. des équipments péripheriques et assurez que l’emplacement permet la circulation de l’air.

16.Ce produit, utilisé avec un amplificateur et un casque ou des enceintes, est capable de produite des niveaux sonores pouvant engendrer une perte permanente de l’ouïe. Ne l’utilisez pas pendant longtemps à un niveau sonore élevé ou à un niveau non confortable. Si vous remarquez une perte de l’ouïe ou un bourdonnement dans les oreilles, consultez un spécialiste.

4

RA150/300/500 Reference Manual

Introduction/Safety Instructions

BEIM BENUTZEN DIESES PRODUKTES BEACHTEN SIE BITTE DIE

FOLGENDEN SICHERHEITSHINWEISE: (GERMAN)

1. Lesen Sie die Hinweise.

2.Halten Sie sich an die Anleitung.

3.Beachten Sie alle Warnungen.

4.Beachten Sie alle Hinweise.

5.Bringen Sie das Gerät nie mit Wasser in Berührung.

6.Verwenden Sie zur Reinigung nur ein weiches Tuch. Verwenden Sie keine flüssigen Reinigungsmittel. Dies kann gefährliche Folgen haben.

7.Halten Sie sich beim Aufbau des Gerätes an die Angaben des Herstellers.

8.Stellen Sie das Gerät nich in der Nähe von Heizkörpern, Heizungsklappen oder anderen Wärmequellen (einschließlich Verstärkern) auf.

9.Verlegen Sie das Netzkabel des Gerätes niemals so, daß man darüber stolpern kann oder daß es gequetscht wird.

10.Benutzen Sie nur das vom Hersteller empfohlene Zubehör.

11.Verwenden Sie ausschließlich Wagen,

Ständer, oder Tische,

die speziell für

p r o f e s s i o n e l l e

A u d i o -

u n d

Musikinstrumente geeignet sind.

Achten

Sie immer darauf, daß die jeweiligen Geräte sicher installiert sind, um Schäden und Verletzungen zu vermeiden. Wenn Sie einen Rollwagen benutzen, achten Sie darauf, das dieser nicht umkippt, um Verletzungen auszuschließen.

12.Ziehen Sie während eines Gewitters oder wenn Sie das Gerät über einen längeren Zeitraum nicht benutzen den Netzstecher aus der Steckdose.

13.Die Wartung sollte nur durch qualifiziertes Fachpersonal erfolgen. Die Wartung wird notwendig, wenn das Gerät beschädigt wurde oder aber das Stromkabel oder der Stecker, Gegenstände oder Flüssigkeit in das Gerät gelangt sind, das Gerät dem Regen oder Feuchtigkeit ausgesetzt war

und deshalb nicht mehr normal arbeitet oder heruntergefallen ist.

14.Dieses Gerät produziert auch im normalen Betrieb Wärme. Achten Sie deshalb auf ausreichende Lüftung mit mindestens 15 cm Abstand von anderen Geräten.

15.Dieses Produkt kann in Verbindung mit einem Verstärker und Kopfhörern oder Lautsprechern Lautstärkepegel erzeugen, die anhaltende Gehörschäden verursachen. Betreiben Sie es nicht über längere Zeit mit hoher Lautstärke oder einem Pegel, der Ihnen unangenehm is. Wenn Sie ein Nachlassen des Gehörs oder ein Klingeln in den Ohren feststellen, sollten Sie einen Ohrenarzt aufsuchen.

RA150/300/500 Reference Manual

5

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 fullyshielded cabling.)

European Contact:

Sound Technology

 

17 Letchworth Point, Letchworth,

 

Hertfordshire, SG6 1ND, England.

 

Phone: +44.1462.480000

 

Fax: +44.1462.480800

October 2000

 

6

RA150/300/500 Reference Manual

Chapter 1: Introduction

CHAPTER 1

ABOUT THE RA150/300/500

PRINCIPAL FEATURES

Please remember that a power amplifier is a high-current, high-power device and should be treated with respect and care. Even if you are an audio veteran, we urge you to read the entire manual to make the best use of the RA150/300/500.

Thank you for purchasing an Alesis Reference Series power amplifier, one of the most advanced and highest value amplifiers available.

The Alesis models RA150, RA300, and RA500 provide extremely accurate sonic quality as well as measured specifications, but their conservative design and careful attention to electronic protection means they will continue to operate at top condition without special attention, year after year.

THE CHASSIS

The Alesis Reference Series amplifiers are constructed on rugged, heavy gauge steel chassis. All units feature rack mount faceplates. For maximum reliability and low-noise operation the amplifiers use convection cooling with massive extruded aluminum heat-sinks for reliable operation under all ambient and load conditions. The design of the external chassis protects rear panel connectors (except RA 150). All models feature detented front panel input level controls, and overload/protect indicators. The RA300 and RA500 amplifiers incorporate bar graph LED power metering.

INPUTS AND OUTPUTS

The input sections of the amplifiers utilize precision electronically-balanced input circuitry for low noise balanced input operation. All units have 1/4” balanced TRS input connectors. The RA300 and RA500 also have XLR connectors. Unbalanced RCA (phono) style input connectors are also used. The output connectors are industry-standard, heavyduty dual binding posts, which can accept large diameter wire or 3/4" (19 mm) spaced dual banana

RA150/300/500 Reference Manual

plugs. A recessed rear panel switch allows easy selection of stereo or bridged monaural operating modes. AC power entry is via a detachable, grounded IEC connector cable.

AMPLIFIER TOPOLOGY

The amplifier sections of the Reference Series utilize a direct coupled, fully complementary circuit topology. The input stages are a dual differential type with active current sources. Output from the differential amplifiers are coupled to balanced level shifters operating on isolated boost rails for improved efficiency and higher performance. These stages then drive discrete, high current, triple darlington output stages, fully rated for continuous 4 ohm operation with 2 ohm dynamic stability (stereo mode only). The output stages are biased for class AB operation. Emphasis is placed on maintaining wide bandwidth, linearity and stability under all operating conditions. An active DC servo circuit is employed to automatically null DC output voltage offsets. All models feature bridged mono operation.

PROTECTION CIRCUITRY

Protection for the amplifier consists of active circuitry that continuously monitors the output stage for excessive DC offset, short circuits and thermal overload. In the event of an output fault, the protection circuitry will activate the output relay and disconnect the loudspeaker load. This circuitry will also mute the amplifier during power on/off transitions.

The power supplies of the amplifiers utilize heavyduty stacked steel EI laminated transformers for maximum performance and reliability. High current bridge rectifiers, massive secondary capacitors and current in-rush limiters are used in all models. All models are designed for 120/230-volt operation with an external voltage selection switch.

All components are of high quality and mechanical construction and are optimized for high reliability under adverse physical and electrical conditions.

7

Introduction: Chapter 1

Reference Series Features-

DC coupled, fully complementary discrete amplifier topology

Actively biased, dual differential input stages

Wide bandwidth, low distortion design

Fully protected from all fault conditions

LED output level metering (RA 300, RA 500)

Front panel level controls

Overload/Fault indicators

Bridged mono operation

Balanced 1/4” & RCA single-ended input connectors

XLR input connectors (RA 300, RA 500)

Heavy-duty, dual binding post output connectors

Relay-controlled turn on/off

Silent, convection-cooled design

Heavy-duty steel chassis

ABOUT THIS MANUAL

In most respects, the three different amplifiers covered by this manual are similar except for their power ratings. Operational differences will be noted individually.

8

RA150/300/500 Reference Manual

Alesis RA500, RA300, RA150 User Manual
It is important to register your purchase; if you have not already filled out your warranty card and mailed it back to Alesis, please take the time to do so now.
Carefully unpack the amplifier and inspect it for physical damage originating in shipping. If damage is discovered and the amplifier was shipped to you, immediately contact the transportation carrier and make certain that the packing materials are preserved for inspection. You as the consignee must make any shipping claims; neither your dealer nor Alesis can do this for you. If the amplifier was not shipped to you, i.e. you picked it up from your dealer, contact the dealer as soon as possible for assistance.
RA150/300/500 Reference Manual
Alesis Warranty card
Power cable
This instruction manual
Your Alesis RA150/300/500 was carefully packed at the factory, and the shipping carton was designed to protect the unit during shipping. Do not discard the packing materials; they may be helpful in the unlikely event that you need to return your RA150/300/500 for servicing, or for transporting the amplifier when it is not mounted in a rack or other enclosure.
The shipping carton should contain the following items:
• RA150/300/500 amplifier
UNPACKING AND
INSPECTION

Chapter 2: Connections

CHAPTER 2

CONNECTIONS

POWER CONSIDERATIONS

THE AC CORD AND GROUNDING

The RA150/300/500’s IEC-spec AC cord (do not substitute any other type of AC cord) is designed to connect to an outlet that includes three pins, with the third, round pin connected to ground ("earth"). The ground connection is an important safety feature designed to keep the chassis of electronic devices such as the RA150/300/500 at ground potential. Unfortunately, the presence of a ground contact in an AC socket does not always indicate that an outlet is properly grounded. Use an AC line tester to determine this. If the outlet is not grounded, consult with a licensed electrician.

The audio ground (pin 1 of the XLR, the sleeve of the 1/4" jack) is not isolated from the chassis.

Tip: You don't have to use the provided 6-foot long AC cord. Many electronic stores carry the standard "NEMA-to-CEE" cable in lengths from 6 inches to 20 feet. This is better than wrapping the cord in a coil if it is too long, or using extension cords if it is too short.

DO NOT OPERATE ANY ELECTRICAL EQUIPMENT WITH UNGROUNDED OUTLETS. PLUGGING THE RA150/300/500 INTO AN UNGROUNDED OUTLET, OR “LIFTING” THE UNIT OFF GROUND WITH A THREE-TO-TWO WIRE ADAPTER, CREATES A HAZARDOUS CONDITION. ALESIS CANNOT BE RESPONSIBLE FOR PROBLEMS CAUSED BY USING THE RA150/300/500 OR ANY ASSOCIATED EQUIPMENT WITH IMPROPER AC WIRING.

9

Connections: Chapter 2

120 VOLT/230 VOLT OPERATION

The Alesis Reference Series amplifiers feature dualvoltage operation. The AC input voltage is selected by a recessed switch on the back panel. The tab is recessed and a tool (small screw driver, pencil, pen, etc.) is required to shift from 120-volt to 230-volt operation. Units sold in areas with 120V power (as in the United States) should come with the switch already set to that position.

Before connecting the amplifier to AC power for the first time, make sure that this switch is set correctly for the country you're using the amp in.

If you change the voltage when travelling, you must also replace the power fuse with the proper amperage (see page 10) and obtain the proper detachable IEC power cable for the country.

FUSE

If the fuse blows, replace with a fuse of the correct type only; use of any higher amperage value will void the warranty. FUSES ARE FOR YOUR

PROTECTION—NEVER SUBSTITUTE A FUSE OF A HIGHER RATING, OR BYPASS IT.

All fuses are the "Slo-Blo" type, sized at 5mm diameter x 20mm:

Model

100-120 volt

220-240 volt

RA150

T3.15AL250V

T1.6AL250V

RA300

T6.3AL250V

T3.15AL250V

RA500

T10AL250V

T5AL250V

The fuse will not blow unless the unit is overstressed. Before replacing the fuse, correct the condition that caused it to blow in the first place.

ELECTRICAL SERVICE TO THE

RA150/300/500

One of the most important considerations for proper installation and operation of a power amplifier is the capacity of the circuit feeding the AC mains voltage to the amplifier. If the line does not have sufficient current and voltage capacity, the amplifier may not be able to deliver its full rated output, both steady state and peak, with the result that the sound character can dramatically suffer. In short, any amplifier will only sound good when connected to adequate AC power.

The maximum audio output rating of each amp (200 watts bridged for the RA150 to 1000 watts bridged for the RA500) does not represent the total AC power consumption by the unit. The following table shows the power consumption at rated output:

Model

Rated AC

Maximum

 

consumption

(peak)

RA150

270 watts

390 watts

RA300

500 watts

650 watts

RA500

840 watts

1080 watts

Note that in typical studio applications the average power consumption will be much less.

When not being driven, current consumption is 30 watts or less. Under most circumstances, normal household or commercial power outlets will be adequate. (A standard 15-amp circuit is capable of supplying 1800 watts.) However, peak power consumption may momentarily be 100 to 200 watts higher on transient peaks; if you're connecting a lot of other equipment to the same circuit you should plan for an extra 20% headroom to avoid blowing a circuit breaker. Note that when multiple devices are plugged into a single AC outlet, the possibility of overheated connections can exist. Long AC extension cables may also degrade the supply power.

Electrical standards have taken enormous strides toward increased safety over the past few decades thanks to circuit breakers, ground fault interrupters, and improved wiring and insulation materials. Unfortunately, some clubs are situated in older buildings whose wiring may not meet current safety standards, or have wiring that has deteriorated over the years. Make sure the circuit supplying power to the RA150/300/500 can supply enough current to run it properly. If the circuit has to supply other high-powered consumption units such as

10

RA150/300/500 Reference Manual

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