™ REFERENCE MANUAL ©2001 A LESIS CORPORATION
Alesis M1 Active Mk2 Reference Manual © Copyright 2001, Alesis Studio Electronics, Inc. All rights reserved. Reproduction in whole or in part is prohibited. “M1 Active Mk2” and “Superport” 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.
Contents/Safety Warnings CONTENTS Introduction 2 IMPORTANT SAFETY INSTRUCTIONS ......................................................3 Safety symbols used in this product 3 Instructions de Sécurité Importantes (French) 5 Information to the User for Class A Digital Device (FCC Part 15, Class A) 7 CE Declaration of Conformity 8 ABOUT THE M1 ACTIVE MK2 ...............................................................
Contents/Safety Warnings INTRODUCTION Thank you for purchasing the Alesis M1 Active Mk2 Biamplified Reference Monitors. To take full advantage of the M1 Active Mk2’s operation, and to enjoy long and trouble-free use, please read this user’s manual carefully. We value any comments you may have about this monitor system, this manual, your Alesis dealer or our factory service. Please take a minute now to fill out your warranty card and tell us what you think.
Contents/Safety Warnings 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. 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.
Contents/Safety Warnings 10. Protect the power cord from being walked on or pinched, particularly at plugs, convenience receptacles, and the point where they exit from the apparatus. 11. Use only attachments or accessories specified by the manufacturer. 12. Use only with a cart, stand, bracket, rack, 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.
Contents/Safety Warnings 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. VEUILLEZ SUIVRE CES PRÉCAUTIONS LORS DE L’UTILISATION DE L’APPAREIL: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Contents/Safety Warnings BEIM BENUTZEN DIESES PRODUKTES BEACHTEN SIE BITTE DIE FOLGENDEN SICHERHEITSHINWEISE: (GERMAN) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 6 Lesen Sie die Hinweise. Halten Sie sich an die Anleitung. Beachten Sie alle Warnungen. Beachten Sie alle Hinweise. Bringen Sie das Gerät nie mit Wasser in Berührung. Verwenden Sie zur Reinigung nur ein weiches Tuch.
Contents/Safety Warnings INFORMATION TO THE USER FOR CLASS A DIGITAL DEVICE (FCC PART 15, CLASS A) This equipment has been tested and found to comply with the limits for a class A digital device pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment.
Contents/Safety Warnings CE DECLARATION OF CONFORMITY This product conforms to current applicable CE standards for safety. For a detailed description of the standards used, please see the web site Alesis.com.
About the M1 Active Mk2 CHAPTER 1 ABOUT THE M1 ACTIVE MK2 UNPACKING AND INSPECTION Your M1 Active Mk2 Biamplified Reference Monitors were packed carefully at the factory, and the shipping carton was designed to protect the speakers during shipping. Please retain this container in the highly unlikely event that you need to return the speakers for servicing.
About the M1 Active Mk2 INSIDE YOUR NEW SPEAKERS ✪ If you’re in a hurry to get started, skip ahead to Chapter 2, “Speaker Installation”, for connection and placement tips. ABOUT POWERED MONITORS The M1 Active Mk2s combine a speaker and amplifiers in the same compact cabinet. Powered monitors are growing in popularity over the traditional separate amplifier and speakers for a number of reasons, convenience and ease of hookup being only one of them.
About the M1 Active Mk2 TONE Tonally, every effort has been made to create a powered monitor that is as linear as possible, representing a flat frequency response from 50Hz to 20KHz ±2dB. (see p. 21) Additionally, the use of electronic crossovers within the critical upper midrange frequencies has reduced phase and time delay anomalies often associated with passive crossovers.
About the M1 Active Mk2 THE M1 ACTIVE MK2 BI-AMPLIFIERS & ELECTRONIC CROSSOVERS The M1 Active Mk2 uses a 75W woofer amp and a 25W tweeter amp along with 4th order high and low pass electronic crossover filters centered at 2000Hz. Electronic crossovers, which separate the frequencies before being sent to the amplifiers, have fewer phase problems and less power loss than the traditional passive crossover used after the amplifier.
About the M1 Active Mk2 THE M1 ACTIVE MK2 POWER SUPPLY The M1 Active Mk2 employs a regulated switching power supply. This type of supply has previously only been available in amplifiers sold at the very high end of the Pro Audio market. Most power amp customers are familiar with the large transformer and output capacitors in high quality amplifiers. These large components are used to keep the amplifier’s supply rails as close to DC as possible. For traditional supplies, bigger is better.
About the M1 Active Mk2 W HY THE TWEETERS ARE OFFSET The M1 Active Mk2 speakers have been developed as a mirror-imaged pair with dual front mounted ports and an offset tweeter. In some applications, an extremely wide dispersion tweeter, such as used in the M1 Active Mk2, will exhibit response dips if mounted exactly on center. Wave-guide style tweeters, used in other products, purposely limit dispersion and thus can be center mounted.
About the M1 Active Mk2 ABOUT NEARFIELD MONITORING In the early days of recording, most recording studios used big monitor speakers almost exclusively. Unfortunately, they also required high powered amplifiers and expensive acoustic treatment (often poorly done) of the entire control room. Still, a well-constructed big monitoring system really was impressive to listen to, a fact not overlooked by the studio owners who wanted to impress the record company executives who paid for the big studio's time.
About the M1 Active Mk2 16 M1 Active Reference Manual
Speaker Installation CHAPTER 2 SPEAKER INSTALLATION Like any speaker system, your M1 Active Mk2 speakers will work best when properly positioned in a suitable acoustic environment. Achieving proper speaker placement is usually straightforward, but even with nearfield monitors, speaker placement and the acoustics of the listening room itself are too often overlooked and can become significant contributors to an inaccurate and uninspiring monitoring environment.
Speaker Installation Direct Path Re flec tion Monitors placed on the console’s meter bridge can directly radiate back onto the console control panel causing a strong delayed reflection at the listening position This kind of speaker placement also couples acoustic energy from the speaker's cabinet more readily into the console's chassis. Both conditions should be reduced by placing the speakers on their own stands acoustically detached from, and slightly behind, the console as shown below.
Speaker Installation Careful consideration should also be given to the physical spacing between the speakers. Alesis recommends that the distance between the speakers for stereo applications equal the distance between the listener and either speaker. In other words, the listener and the two speakers are at the three corners of a triangle having equal- length sides. The illustration below shows this concept.
Speaker Installation STEREO NEARFIELD PLACEMENT OF THE M1 ACTIVE MK2 NOTE: We recommend that the M1 Active Mk2 speakers be placed with the tweeters to the inside, not the outside, of the listening triangle. The “classic” studio monitor layout used to be that the tweeters be placed to the outside of a horizontally-oriented speaker. In the past, this configuration was actually beneficial in time aligning the tweeter with the woofer if the cabinets were not toed-in toward the listener.
Speaker Installation HORIZONTAL PLACEMENT RECOMMENDATION Traditionally, proper horizontal placement of speaker systems slightly behind (not on) a meter bridge accomplished two purposes: it allowed both woofer and tweeter to be at ear level, and many times, it permitted the recording engineer to see over the speakers and into the studio. Horizontal placement is a recommended arrangement with the M1 Active Mk2 because the left and right mirror-imaged pair permits a symmetrical alignment of drivers and ports.
Speaker Installation VERTICAL PLACEMENT RECOMMENDATION Vertical placement of the M1 Active Mk2 as shown in Figure 3 is highly recommended. This position will simulate the soundfield that will be heard in most consumers’ homes and (to a great extent) their cars. For this reason, even if the M1 Active Mk2s are positioned horizontally for all of the mixing, the vertical position should always be used in the final "playback check" mode.
Speaker Installation PLAYBACK CHECK MODE (VERTICAL MID-FIELD) After you’ve got your mix just right it’s always good practice to perform a “playback check” by standing the M1 Active Mk2s vertically and making the listening triangle larger. The purpose of the playback check is to simulate what your masterpiece will sound like in a “typical” home listening environment. It is in this configuration that the imaging specificity of your mix can best be evaluated.
Speaker Installation PLUGGING THE PORTS TO ADJUST FOR ROOM ACOUSTICS The low frequency response of the M1 Active Mk2s can be custom tailored by plugging the ports. If the speakers must be placed less than one foot from a front wall, or if they are too close to a corner, then the bass may become exaggerated and inaccurate.
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Speaker Installation CONNECTIONS The M1 Active Mk2 has been designed to be as simple as possible to set up and use. However, please follow the instructions to ensure that you get the best possible performance from your monitors. Before connecting the speakers, make sure the power switches of the M1 Active Mk2s and any equipment they will be connected to are turned OFF. AC POWER CABLE READ ALL SAFETY WARNINGS IN THE PREVIOUS SECTION OF THIS MANUAL TO ENSURE SAFE OPERATION OF THESE UNITS.
Speaker Installation POWER SWITCH The POWER switch is located on the back panel. A blue power indicator lamp is on the front panel. INPUT CONNECTIONS Almost any conventional line-level source may be plugged into the M1 Active Mk2’s LINE INPUT jack. The Line Input jack accepts both XLR and 1/4” input plugs wired either balanced or single-ended (unbalanced).
Speaker Installation But do NOT plug the speaker output of an amplifier, receiver, or similar device into the LINE INPUT jack. Use only line-level sources. Plugging too loud of a signal into the LINE INPUT jack may damage the electronics. Balanced +4 dBu line level sources: Professional recording and processing equipment typically provides a balanced, 3-conductor signal output that is a higher voltage (1.24 volts nominal level) than most synthesizers and stereo equipment.
Speaker Installation TO SET THE LEVEL WITH A MIXER: 1. Turn on all system components (the M1 Active Mk2s last) and turn the M1 Active Mk2’s INPUT LEVEL control all the way down. 2. Play program through the mixer and raise the mixer’s fader levels until its meter averages around “0 VU”. 3. Raise the Control Room Output to its nominal position (usually “2 o’clock” or 3/4 of the way up). 4.
Speaker Installation AVOIDING DAMAGE The best protection against speaker failure is to mix at a reasonable listening level. With a +4 dBu input and the input level control set to “6”, the M1 Active Mk2 speakers produce a sound pressure level (SPL) of 85 decibels at 1 meter, which is a good working level for mixing. At maximum output before clipping, they can generate peak levels ≥ 118 dB SPL at one meter – a level which may cause hearing loss after prolonged exposure.
Surround Sound CHAPTER 3 SURROUND SOUND ABOUT SURROUND SOUND Surround sound is the term used for several different systems which use multiple channels of playback in the listening room to recreate a truly threedimensional sound experience. The practice of recording music-only in surround sound is a fairly recent innovation. Surround sound for video, however, has been around for over ten years.
Surround Sound CENTER SPEAKERS IN MUSIC MIXES In video applications, with left, center and right channels all set to deliver equal output, the ear tends to hear dialog as coming only from the center channel. (It’s a psychoacoustic effect because all right and all left channel signals are fed to the center.) In Dolby Pro Logic, the center channel information is derived from sum and difference information encoded in the left and right channels.
Surround Sound PLACEMENT OF THE CENTER M1 ACTIVE MK2 SPEAKER IN THE STUDIO The left, center and right speakers should all be placed in an arc so that the distance of all drivers to the listener is identical (see page 29). The equilateral listening triangle as described earlier for stereo (two-channel) playback should be retained, with the center speaker placed vertically in the center, exactly between the left and right (vertical) M1 Active Mk2s.
Surround Sound PLACEMENT OF REAR SURROUNDS The following suggestions for optimal M1 Active Mk2 placement are derived from several sources: 1) Standard industry practice for home installations as recommended by the manufacturers of surround encoder/decoder units; 2) recommendations developed by Tom Holman for setting up THX surround theater sound systems, and 3) Alesis engineers’ experience fine-tuning the performance of the SMS Monitoring System in order to find the mounting configuration which results in
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Surround Sound W ALL MOUNTING Once your have located the general area for the horizontal and vertical position, you need to find a wall stud. Attach shelving brackets or other commercial speaker-mounting device into the wall stud, then attach the M1 Active Mk2s to the mount, allowing room for the rear-panel input and AC connections. The M1 Active Mk2s weigh 19.5 lbs.
Surround Sound MIXING FOR DISCRETE SIX CHANNEL REPRODUCTION: MATCHED VS. SPECIALIZED SPEAKERS While most speaker systems for monitoring music in surround use the same speaker cabinet in all positions, both front and rear, keep in mind that most consumer video surround installations use a different speaker in the rear channels. These rear speakers typically do not have the same directionality or wide frequency response of the M1 Active Mk2s.
Surround Sound mid bass (about 80Hz) on up. In the rear go the subwoofers and sometimes, small full range drivers which provide “fill”. So, in essence, today’s best car audio systems are designed to produce an enveloping environment very similar to that of a home theater.
Troubleshooting CHAPTER 4 TROUBLESHOOTING TROUBLESHOOTING INDEX If you experience problems while using the M1 Active/Surround systems, please use the following table to locate possible causes and solutions before contacting Alesis Technical Support for assistance. Symptom Hum or buzz Cause Ground loop between source and speaker Solution Use balanced cables. Put M1 Actives on the same AC power circuit as the mixer.
Troubleshooting MAINTENANCE CLEANING The cabinet surfaces of the M1 Active Mk2 are covered with a vinyl laminate. Clean these surfaces when necessary with a lint-free cloth dampened in warm soapy water. USE ONLY A DRY CLOTH ON THE BACK PANEL OF THE POWER AMPLIFIER. Do not attempt to clean the cabinet with a brush (which may damage the surface) or a sponge (which may leave small crumbs in the texture). Do not attempt to clean either of the drivers.
Troubleshooting the drivers will not be pressed on by the packing in shipment. Shipping damage caused by inadequate packing is not covered by the Alesis warranty. Tape a note to the top of the unit describing the problem, include your name and a phone number where Alesis can contact you if necessary, as well as instructions on where you want the product returned. Alesis will pay for standard one-way shipping back to you on any repair covered under the terms of this warranty.
Specifications SPECIFICATIONS ENCLOSURE MATERIALS AND CONSTRUCTION Front baffle painted in metallic charcoal-gray, one inch (1”) thick MDF with radiused edges to minimize diffraction. Sides and rear baffle covered in metallic charcoal-gray vinyl laminate, over five-eighths inch (0.625”) thick MDF. Dual ports with 45° inlet and flared front baffle outlet allow precise, phase accurate woofer-to-port frequency transition. Ports also aid in cooling internally mounted primary amplifier heat sink.
Specifications CROSSOVER SECTION Crossover type: Input Impedance: Low Frequency Filter: 4th-order, 24dB/octave Linkwitz-Riley @ 2000Hz 20kΩ balanced 10kΩ unbalanced 4th order optimal Q high pass filter at 48Hz with +3 dB equalization AMPLIFIER SECTION LOW FREQUENCY AMPLIFIER Rated power output: Distortion: Slew rate: Signal-to-Noise ratio: 75 watts, 6Ω load <0.
INDEX 1/4” input plugs, 27 AC cables, 26 AC power, 13, 26, 43 amplifiers, 10, 12, 43 balanced, 27 biamplified, 10 center channel, 32 crossover, 11, 43 frequency response, 43 with ports plugged, 24 front baffle, 42 fuse, 13 Ground loop, 39 grounding, 26 INPUT LEVEL, 28 detent, 29 interference, 7 LINE IN, 27 Magnetic shielding, 11, 42 mounting, 19 nearfield, 15 noise, 26 phase, 39 44 placement, 17 horizontal, 21 surround, 34 vertical, 22 Playback check mode, 23 Polarity, 27 ports, 14 plugging, 24 power supp
ALESIS LIMITED WARRANTY ALESIS CORPORATION ("ALESIS") warrants this product to be free of defects in material and workmanship for a period of one (1) year for parts and for a period of one (1) year for labor from the date of original retail purchase. This warranty is enforceable only by the original retail purchaser and cannot be transferred or assigned. The purchaser should complete and return the enclosed warranty card within 14 days of purchase.
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