Alesis M1 Active Mk2 User Manual

REFERENCE MANUAL

™

©2001 ALESIS 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: [e-mail]
Website: http://www.alesis.com

Contents/Safety Warnings

CONTENTS

Introduction 2

I

MPORTANT 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

A

BOUT THE M1 ACTIVE MK2 ...............................................................9

Unpacking and Inspection 9
Inside your new speakers 10
About Nearfield monitoring 15

S

PEAKER INSTALLATION.................................................................... 17

Avoiding reflections in the studio 17
Stereo nearfield placement of the M1 Active Mk2 20
Connections 26
Setting the Input Level control 28

S

URROUND SOUND ............................................................................ 31

About surround sound 31
Center speakers in music mixes 32
Placement of the center M1 Active Mk2 speaker in the studio 33
Placement of rear surrounds 34
Mixing for discrete six channel reproduction: matched vs. specialized speakers

T

ROUBLESHOOTING ...........................................................................39

Troubleshooting Index 39
Maintenance 40

S

PECIFICATIONS ................................................................................42

Enclosure 42
Transducers 42
Crossover section 43
Amplifier Section 43
Acoustic Section 43
General 43

I

NDEX.............................................................................................. 44

A

LESIS LIMITED WARRANTY ..............................................................45

37

M1 Active Mk2 Reference Manual 1

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.

HOW TO USE THIS MANUAL

This manual is divided into the following sections describing the various
features of the M1 Active Mk2. Though we recommend you take time to read
through the entire manual once carefully, those having general knowledge
about monitors should use the table of contents to reference specific
functions.

Chapter 1: About the M1 Active Mk2. Engineering specifications and
reasons why nearfield monitors have become so popular.

Chapter 2: Speaker Installation.

M1 Active Mk2s to a mixer or other line-level source and discusses proper
speaker placement for stereo operation.

Chapter 3: Surround Sound. If you are using the M1 Active Mk2 speakers in
a multichannel surround sound setup, you’ll find helpful setup and operation
information here.

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

This chapter explains how to connect the

✪ 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 M1 Active Mk2s.

2 M1 Active Reference Manual

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. Do not spray any liquid cleaner onto the
speakers or rear panel, as this may damage the speakers, controls or cause
a dangerous condition.

7. 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. 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.

M1 Active Mk2 Reference Manual 3

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. If a cart is used, use caution when moving the
cart/apparatus combination to avoid injury from tip-over.

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

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 product 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.

4 M1 Active Reference Manual

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. 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. Ne pas vaporiser de liquide nettoyant sur l’appareil,

cela pourrait abîmer les contrôles de la face avant ou engendrer des conditions dangeureuses.

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, rack 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. Cet appareil produit de la chaleur en fonctionnement normal. Si cet appareil est utilisé dans

un rack, veillez à sa bonne ventilation lors de son utilisation. Ne pas faire fonctionner dans
un rack fermé. S’il y a d’autres appareils dans le rack générant beaucoup de chaleur, éloignez
les. Ne pas intercaler cet appareil entre deux appareils produisant beaucoup de chaleur.

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.

M1 Active Mk2 Reference Manual 5

Contents/Safety Warnings

BEIM BENUTZEN DIESES PRODUKTES BEACHTEN SIE

BITTE DIE FOLGENDEN

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. Sprühen Sie keine flüssiger Reiniger auf
die Oberfläche, dies könnte zur Beschädigung der Vorderseite führen und auch weitere
Schäden verursachen.

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, Racks oder Tische, die speziell für
professionelle Audio- und 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. Bei normalem Betrieb des Gerätes kommt es zu Wärmeentwicklungen. Wenn Sie das Gerät
in einem Rack eingebaut haben, sollte während des Betriebes die Zufuhr von Kühlluft stets
gewährleitstet sein. Arbeiten Sie nie bei geschlossenem Rack. Bei mehreren Rackgeräten
sollten diese mit einem geringen abstand voneinander eingebaut werden. Stapeln Sie dieses
Gerät nicht zwischen Geräten mit hoher Wärmeentwicklung.

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.

SICHERHEITSHINWEISE: (GERMAN)

6 M1 Active Reference Manual

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. This equipment
generates, uses and can radiate radio frequency energy and, if not installed
and used in accordance with the instructions, may cause interference to radio
communications. Operation of this equipment in a residential area is likely to
cause interference in which case the user will be required to correct the
interference at his own expense.

The user is cautioned that changes and modifications made to the equipment
without the approval of manufacturer could void the user’s authority to
operate this equipment.

Use only shielded and grounded cables with this equipment to ensure
compliance with FCC Rules.

INDUSTRY CANADA (DIGITAL APPARATUS)
I

NTERFERENCE-CAUSING EQUIPMENT STANDARD

ICES-003 ISSUE 2

This Class A digital apparatus meets all requirements of the Canadian

Interference-Causing Equipment Regulations.

M1 Active Mk2 Reference Manual 7

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.

8 M1 Active Reference Manual

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.

The shipping carton should contain the following items:

• This instruction manual

• M1 Actives with the same serial numbers as shown on the shipping
cartons

• Two AC power cords (NEMA to CEE type)

• Alesis warranty card

• Two pieces of adhesive-backed non-skid foam

✪ 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.

M1 Active Mk2 Reference Manual 9

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. You can connect a powered speaker
directly to any line-level source (normally, the control room output of a
mixer) simply by connecting a patch cord.

Another benefit is improved sound quality. With careful design, the speaker,
amplifier and electronic crossover can be optimised for each other. The M1
Active Mk2s are biamplified, meaning that low frequencies and high
frequencies are handled not only by separate speakers (the tweeter and the
woofer), but by separate amplifiers. A pair of M1 Active Mk2s contain a total
of four power amplifiers. Because of the increased efficiency of
biamplification, these are much louder than a single-channel power amplifier
of the same wattage feeding a passive crossover, as in other designs. New
technology makes it possible to make these high-wattage amplifiers small
enough to fit inside the speaker cabinet, with very little weight or size gain.

Since the M1 Active Mk2s are self-powered, DO NOT connect them to
the speaker output of another amplifier (such as a powered mixer or hi­fi receiver). Connect them only to the line-level outputs of such devices
(+4 dBu nominal, +24 dBu maximum).

10 M1 Active Reference Manual

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. By including discrete
woofer and tweeter amplifiers and application-specific electronic high and
low pass crossover filters in the same enclosure the tonal accuracy of the M1
Active Mk2 will always remain constant.

ABOUT 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).
The non-woven carbon fiber cone, along with the closed cell synthetic rubber
surround, are both nearly impervious to ozone, direct sunlight, heat and
humidity. Therefore, after an initial break-in period, the sound should remain
virtually unchanged for the life of the product.

Alesis’ proprietary-design tweeter features a special wave guide baffle to
improve polar response, a silk dome, and low viscosity ferrofluid formulated
specifically to retain the best balance of transient response to power handling.
The shielded tweeter utilizes a vented pole piece with a separate rear
chamber to lower the free air resonance. The low 2000Hz crossover point of
this tweeter produces a very widely dispersed, low-distortion signal within
the critical midrange frequencies. It is these frequencies which are often the
most problematic to get “right” during a mix. The tweeter is designed for an
optimal response for non-fatiguing, long term, high level, nearfield
mixdowns. This design results in a flat, linear mix when played back on home
or car systems from appropriate distances.

MAGNETIC SHIELDING

Your M1 Active Mk2s are at home in recording environments wherein video
is a major component. They are magnetically shielded for use in fairly close
proximity (3” minimum) to a computer monitor or video screen. (Non­shielded components can make the colors of a screen “smear” or appear out
of focus if the speaker is too close.) Magnetic shielding was designed into
both the woofer and the tweeter from the beginning so that the system
exhibits about low magnetic leakage. Shielding of both the woofer and the
tweeter is accomplished by the use of a second opposing-field-oriented
“bucking” magnet.

M1 Active Mk2 Reference Manual 11

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 4

th

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. Fourth-order filters
are steep (24 dB per octave), which minimizes the interaction between woofer
and tweeter near the crossover point. Additionally, the high pass (tweeter)
section of this system employs an electronic time alignment circuit. Thus the
“launch” of frequencies from both the woofer and the tweeter will originate
at exactly the same time.

There are several advantages to using built-in amplifiers and active
(electronic) crossovers versus a passive network system, most of which have
been previously enumerated in Vance Dickason’s “Loudspeaker Design
Cookbook”:

• Lower intermodulation distortion due to amplifier operation over a more

narrow bandwidth. Also, clipping caused by low frequency overload is
reduced, being limited to only one driver within a two driver system.

• Increased dynamic range. The M1 Active Mk2’s 75W and 25W amplifiers

in their bi-amp setup will clip at about the same levels as one 200W
amplifier operating into a passive crossover.

• Improved transient response.

• Better amplifier/speaker coupling for woofers.

• Better crossover performance working into a constant impedance load.

• Better subjective sound quality than high level (passive) networks.

• Easier control over driver sensitivity differences.

• Easier manipulation of phase, time delay, resonance, and various kinds of

shaping, contouring and equalization.

• Specifically in the case of the M1 Active Mk2, the wide, mid-frequency

polar response of the tweeter can be utilized down to a low 2000 Hz
thereby mating more cohesively with the 6.5" non-woven carbon fiber
(NWCF) woofer. This low crossover point is only possible through the use
of a steep, electronic fourth-order (24 dB per octave rolloff) high pass filter.

12 M1 Active Reference Manual

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.

But by using Pulse Width Modulation (PWM) and output voltage feedback in
the M1 Active Mk2, we have the equivalent of near-infinite transformer and
output capacitors, but at a fraction of the cost. PWM provides protection
from line voltage surges that would otherwise destroy the amplifier. No
user-replaceable fuse is required because nuisance tripping is eliminated.
And finally, PWM practically eliminates hum because the line frequency (60
Hz) transformer is replaced with a very high frequency (130,000 Hz)
transformer.

The regulated supply rails increase the amplifier dynamic range and reduce
clipping distortion under heavy loading. The compact size of the supply does
not significantly reduce the internal air volume of the speaker cabinet. And
lastly, full power can be maintained even with low or “flat-topped” line
voltages.

Note, however, that this switching supply is NOT a universal voltage
type that may be used with any input voltage in any country simply by
changing the cord. If you wish to use the M1 Active Mk2s in a country
whose line voltage is other than 120 volts AC, they must be internally
modified or used with a step-down transformer.

THE CABINET AND PORT DESIGN

The M1 Active Mk2 cabinet construction employs vinyl composite material
laminated to a .625” MDF (medium density fiberboard) core for the four sides
and the rear. The front panel is 1” thick MDF, to withstand the greater
demands of the drivers mounted on it. The entire cabinet is braced
extensively in random fashion to dissipate intramodal vibration.

M1 Active Mk2 Reference Manual 13