Alesis M1 Active Mk2 Reference Manual
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Alesis M1 Active Mk2 Reference Manual

Biamplified reference monitors
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REFERENCE MANUAL
©2001 A
C
LESIS
ORPORATION

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Summary of Contents for Alesis M1 Active Mk2

  • Page 1 ™ REFERENCE MANUAL ©2001 A LESIS ORPORATION...
  • Page 2 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.

  • Page 3: Table Of Contents

    ... 31 URROUND OUND About surround sound Center speakers in music mixes Placement of the center M1 Active Mk2 speaker in the studio Placement of rear surrounds Mixing for discrete six channel reproduction: matched vs. specialized speakers ...39 ROUBLESHOOTING Troubleshooting Index Maintenance ...42...

  • Page 4: Introduction

    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.

  • Page 5: Important Safety Instructions

    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. M1 Active Mk2 Reference Manual Contents/Safety Warnings MPORTANT NSTRUCTIONS...
  • Page 6 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.

  • Page 7: Instructions De Sécurité Importantes (French)

    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. M1 Active Mk2 Reference Manual ÉCURITÉ MPORTANTES ’...
  • Page 8 Contents/Safety Warnings ENUTZEN DIESES BITTE DIE FOLGENDEN 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. Sprühen Sie keine flüssiger Reiniger auf die Oberfläche, dies könnte zur Beschädigung der Vorderseite führen und auch weitere Schäden verursachen.
  • Page 9 FCC Rules. NDUSTRY ANADA NTERFERENCE AUSING ICES-003 I SSUE This Class A digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations. M1 Active Mk2 Reference Manual SER FOR LASS 15, C LASS IGITAL PPARATUS QUIPMENT Contents/Safety Warnings...

  • Page 10: Ce Declaration Of Conformity

    Contents/Safety Warnings CE D ECLARATION OF 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. ONFORMITY M1 Active Reference Manual...

  • Page 11: About The M1 Active Mk2

    ✪ 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. The M1 Active Mk2s are designed as mirror-imaged pairs. If you have received a pair where the tweeters are both on the same side, contact your dealer immediately.

  • Page 12: Inside Your New Speakers

    About the M1 Active Mk2 NSIDE YOUR NEW SPEAKERS ✪ If you’re in a hurry to get started, skip ahead to Chapter 2, “Speaker Installation”, for connection and placement tips. BOUT POWERED MONITORS The M1 Active Mk2s combine a speaker and amplifiers in the same compact cabinet.
  • Page 13 Active Mk2 will always remain constant. BOUT THE DRIVERS The M1 Active Mk2’s 6.5” woofer cone is made of proprietary non-woven carbon fiber. This material is 25% lighter than polypropylene with twice the stiffness for quicker transient response in the low-to-midbass region and vastly improved midrange intelligibility (over polypropylene at 2000 Hz).
  • Page 14 M1 A CTIVE CROSSOVERS The M1 Active Mk2 uses a 75W woofer amp and a 25W tweeter amp along with 4 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.
  • Page 15 M1 A CTIVE 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.
  • Page 16 This (flat power response) more closely characterizes the way humans hear. On a horizontal polar response curve of the M1 Active Mk2, with the cabinet placed vertically, the tweeter response at one meter stays essentially symmetrical on either side of the cabinet’s centerline. This is because the angle subtended between the cabinet-centerline-to-tweeter-centerline (.5”),...

  • Page 17: About Nearfield Monitoring

    Now, even the big studios use smaller speakers to augment their big monitoring systems, and nearfield monitors have become proven tools in the recording business. M1 Active Mk2 Reference Manual About the M1 Active Mk2...
  • Page 18 About the M1 Active Mk2 M1 Active Reference Manual...

  • Page 19: 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.
  • Page 20 Speaker Installation Monitors placed on the console’s meter bridge can directly radiate back onto the console control panel causing a strong delayed 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.
  • Page 21 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.

  • Page 22: Stereo Nearfield Placement Of The M1 Active Mk2

    M1 A CTIVE 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.
  • Page 23 In this orientation there will be much less chance of first reflections from either sidewalls or the console coloring your mix. M1 Active Mk2 Reference Manual...
  • Page 24 ERTICAL LACEMENT 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"...
  • Page 25 (A 12” three-way with woofer on bottom, midrange in the center and tweeter at the top is a line source, as are most forms of tower speakers.) When the M1 Active Mk2 is set vertically in its “column” configuration, the horizontal dispersion (left and right) of the speaker is widest, and the vertical dispersion (up and down) is narrowest.
  • Page 26 The “plug” can be wad of cloth to completely block the port(s) or a more porous material like fiberfill which will give less bass attenuation. The bass output of the M1 Active Mk2 is thus easily variable depending on in-room positioning and/or personal preference.
  • Page 27 Speaker Installation M1 Active Mk2 Reference Manual...

  • Page 28: Connections

    Speaker Installation ONNECTIONS 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.
  • Page 29 Their average signal level is about 1/3 of a volt. They have a 2-conductor output jack that is either a 1/4" phone or "RCA phono" type. These may be plugged directly into the M1 Active Mk2’s LINE IN jacks. M1 Active Mk2 Reference Manual...

  • Page 30: Setting The Input Level Control

    “Nominal” means its normal average level, expecting peaks from 8 to 15 dB above that on occasion. For the best signal-to-noise ratio, everything before the M1 Active Mk2 should be as loud as possible. The M1 Active Mk2s’ INPUT LEVEL control, being last in the signal chain, is the worst place to make up gain lost earlier in the system.
  • Page 31 (all settings, especially near the extremes of the range, are subject to a plus or minus 2 dB error): Mark 0 (MIN) 10 (MAX) * denotes recommended setting for control room use M1 Active Mk2 Reference Manual Speaker Installation -10 dBV +4 dBu nominal nominal...
  • Page 32 While the biamplified design of the M1 Active Mk2 avoids the common “blown tweeter” problem of conventional designs (when a broadband amplifier clips on a bass note, it sends unusually high energy to the tweeter, which tries to reproduce the square wave), it is not invulnerable.

  • Page 33: Surround Sound

    Powered monitors like the Alesis M1 Active Mk2 Biamplified Reference Monitor have proven to be a simple, cost-effective way to add five-channel surround to control rooms.

  • Page 34: Center Speakers In Music Mixes

    Surround Sound ENTER 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.

  • Page 35: Placement Of The Center M1 Active Mk2 Speaker In The Studio

    (vertical) M1 Active Mk2s. It does not matter what type of M1 Active Mk2 is used for the center speaker (tweeter in or tweeter out). Since M1 Active Mk2s are sold as pairs, a 5-channel system requires the purchase of a single speaker, breaking up a pair.

  • Page 36: Placement Of Rear Surrounds

    Surround Sound LACEMENT 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’...
  • Page 37 Surround Sound M1 Active Mk2 Reference Manual...
  • Page 38 Surround Sound 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.

  • Page 39: Mixing For Discrete Six Channel Reproduction Matched Vs Specialized Speakers

    They do this by placing high quality drivers in the front of the vehicle which produce frequencies from the M1 Active Mk2 Reference Manual Surround Sound...
  • Page 40 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. The use of M1 Active Mk2s (or any monopolar speaker) as full-range surrounds would be useful in the following cases: •...

  • Page 41: Troubleshooting

    ROUBLESHOOTING 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 No sound Unfocused sound, bass frequencies muddy or missing...

  • Page 42: Maintenance

    AINTENANCE LEANING 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.
  • Page 43 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.

  • Page 44: Specifications

    Specifications NCLOSURE ATERIALS AND 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.

  • Page 45: Crossover Section

    ENERAL Power Consumption: AC Dropout Voltage: Weight: Dimensions (H x W x D): M1 Active Mk2 Reference Manual -order, 24dB/octave Linkwitz-Riley @ 2000Hz 20k balanced 10k unbalanced order optimal Q high pass filter at 48Hz with +3 dB equalization MPLIFIER 75 watts, 6 load <0.02% THD @ 30 watts/8...

  • Page 46: 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...

  • Page 47: Alesis Limited Warranty

    Proof of purchase must be presented in the form of a bill of sale, canceled check or some other positive proof that the product is within the warranty period. ALESIS reserves the right to update any unit returned for repair. ALESIS reserves the right to change or improve design of the product at any time without prior notice.
  • Page 48 M1 Active Reference Manual...

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