User manual ALESIS RA100

[. . . ] ALESIS RA-100 Reference Manual CHAPTER 1 ­ GETTING TO KNOW THE RA-100 1. 1 INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Principal Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Unpacking and Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 About This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 CHAPTER 2 ­ INSTALLATION 2. 1 REAR PANEL CONNECTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. 2 POWER CONSIDERATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Fuse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 The AC Cord. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Electrical Service to the RA-100. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. 3 OPERATING ENVIRONMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Thermal Considerations in Rack Mounting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Mounting on a Shelf or in a Non-Rack Enclosure. . . . . . . . . . . . . . . . . . . . . . . 7 Avoiding Electromagnetic Interference. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2. 4 INPUTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Input Jack Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Cables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Cable Wiring Tips. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Adapting the RA-100 to Balanced Lines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2. 5 OUTPUTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Connector Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Output Cables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Connecting Cables to Push Connectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 The Importance of Speaker Polarity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 CHAPTER 3 ­ USING THE RA-100 3. 1 FRONT PANEL CONTROLS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Volume Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 On-Off Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Mute Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Clip Indicators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3. 2 CHECKING FOR PROPER POLARITY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3. 3 CHOOSING THE CORRECT SPEAKERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3. 4 ABOUT GROUND LOOPS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 CHAPTER 4 ­ TYPICAL APPLICATIONS 4. 1 STUDIO MONITOR AMP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4. 2 SOUND REINFORCEMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4. 3 KEYBOARD AMPLIFICATION SYSTEM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4. 4 GUITAR AMPLIFICATION SYSTEM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4. 5 BIAMP SOUND REINFORCEMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 CHAPTER 5 ­ MAINTAINANCE/SERVICE 5. 1 GENERAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Cleaning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Refer All Servicing to Alesis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 CHAPTER 6 ­ TROUBLESHOOTING Hum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 No Volume. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Distorted or Low Level Sound. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Thin Sound/Sound that Changes Unpredictably in a Room. . . . 23 CHAPTER 7 ­ SPECIFICATIONS DO NOT REMOVE THE RA-100 TOP COVER. REFER SERVICING TO A QUALIFIED REPAIR TECHNICIAN. CHAPTER 1: MEET THE RA-100 1. 1 INTRODUCTION Principal Features Congratulations on your purchase of the Alesis RA-100 Reference Amplifier. With all the wondrous advances in both analog and digital electronics in the past few years, it's easy to forget that an audio chain is only as good as its weakest link. With low-cost digital devices now offering sound quality unheard of only a few years ago, Alesis has applied its expertise toward creating a sonically accurate, stable, and affordable stereo power amplifier that's suitable for the digital age. [. . . ] Advantages: Available "free" if you have a 1622, flat frequency response, no inherent hum pickup. Disadvantages: Generates some hiss, optimized primarily for low level signals. It is possible to feed just one of the balanced lines, 10 along with ground, into the RA-100. The following diagram shows an adapter that assumes pin 2 of the XLR connector is "hot. " Female XLR Connector 2 shield 1 3 (no connection) If pin 3 is hot, then do not connect pin 2 to anything, and connect the wire from the 1/4" phone jack tip to pin 3 of the XLR female connector. If your system uses stereo phone jacks to carry balanced line signals (the tip and ring should carry the in-phase and out-of-phase signals, respectively, although this may be reversed in some systems), then an adapter is not necessary. Simply plug a stereo cord from the balanced phone jack into the RA-100's input; it will ignore the ring connection and amplify only the tip connection. Disadvantages: No inherent hum and noise rejection; defeats advantages of balanced line operation 1/4 inch phone jack 2. 5 OUTPUTS Connector Options The RA-100 is intended to drive loads of 4 or greater. There are two speaker connection output options for each channel: 1/4" mono phone jack, and push clip terminals (red = "hot" output, black = ground). There is greater surface area contact than with phone connectors, thus promoting a better electrical connection between the speaker wire and amplifier. Phone jack connections are used for sound reinforcement or any situation when quick setup and breakdown are important. You are also less likely to accidentally reverse the wires if they are permanently connected to phone plugs. Output Cables Speaker cables must deliver large amounts of peak current to a speaker. To complicate matters further, a speaker represents an inductive load, and is more difficult to drive than a purely resistive load. Any resistance between the amp output and speakers will degrade the damping factor, efficiency and ultimately, the sound quality. Therefore, the cables you use between the RA-100 and its speakers are very 11 important. Alesis recommends stranded, rather than solid, cables for flexibility and ease of installation. Because they lack sufficient currentcarrying capacity, the amp and speakers will not perform properly and the sound may be degraded. If you make your own cables use electrical zip cord, which is designed to handle several amps of current, or heavy-gauge speaker cables if possible/affordable. In any event, the thicker the cable, the lower the resistance and the better the current-carrying capability. Standard hookup wire is not acceptable; the minimum acceptable wire type is the common "zip cord" used to connect AC to appliances. The following table relates the wire gauge to the how many feet of cable is required at different impedances to produce a 1 dB power loss. For cables run up to about 25 feet, 16 to 18 gauge wire is satisfactory. Cable length that produces 1 dB of power loss wire gauge 6 8 10 12 14 16 18 20 22 at 4 feet 1200 800 475 300 190 120 75 50 30 at 4 meters 366 244 145 91 58 37 23 15 9 at 8 feet 2425 1600 950 600 375 240 150 100 60 at 8 meters 740 488 290 183 114 73 46 30 18 In recent years, expensive audiophile cables of high current capacity have appeared. [. . . ] The low frequencies go to one RA-100 which drives the low frequency speaker system; the other RA-100 handles the higher frequencies and drives a set of high frequency speakers. 21 CHAPTER 5: MAINTENANCE/SERVICE 5. 1 GENERAL INFORMATION Cleaning Disconnect the AC cord, then use a damp cloth to clean the amplifier's metal and plastic surfaces. For heavy dirt, use a non-abrasive household cleaner such as Formula 409 or Fantastik. DO NOT SPRAY THE CLEANER DIRECTLY ONTO THE FRONT OF THE UNIT AS IT MAY DESTROY THE LUBRICANTS USED IN THE SWITCHES AND CONTROLS!Spray onto a cloth, then use the cloth to clean the unit. Maintenance Here are some tips for preventive maintenance. [. . . ]