Alesis MATICA User Manual

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ALESIS

Matica 500/900

Reference Manual

Contents

 

CONTENTS

 

1: Introduction .............................................................................

3

About Alesis Maticaª Amplifiers.........................................................................

3

Why Another Power Amplifier? ............................................................................

4

2: Installation ...............................................................................

5

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

5

Physical

Installation.............................................................................................

5

Electrical

Installation............................................................................................

6

Audio Installation: Input Wiring............................................................................

7

Audio Installation: Output Wiring .........................................................................

8

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

10

3: Amplifier Operation................................................................

13

4: In Case Of Trouble..................................................................

15

5: Reference.................................................................................

17

Preliminary Amplifier Specifications ....................................................................

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Matica 500/900 Reference Manual

Introduction

CHAPTER1

INTRODUCTION

CHANNEL A

 

POWER

 

CHANNEL B

 

CLIP

 

 

 

CLIP

 

5

 

 

 

5

 

4

6

 

4

6

 

3

7

3

 

7

 

2

8

2

 

 

8

 

 

 

 

 

AC

1

9

1

 

9

BRKR

0

100

 

0

100

 

Figure 1: Amplifier front panel controls.

About Alesis Maticaª Amplifiers

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

Your Alesis High Speed, Wide Bandwidth amplifier provides extremely accurate sonic quality as well as measured specifications, but its conservative design and careful attention to electronic protection means that it will continue to operate at top condition without special attention, year after year.

Matica amplifiers use the newest generation of linear semiconductor devices for improved performance. Their high slew rate of 80 V/μs insures that they will not generate significant TIM (transient intermodulation) distortion. The outstanding signal to noise ratio (typically better than 103 dB, A weighted, below rated output) and very low harmonic distortion (typically below .009% midband) make them ideally suited for the most critical studio monitoring applications.

These amplifiers, however, are in rugged, roadworthy packages which are of minimum size consistent with conservative electronic design principles. Their power transformers have unusually high current capability for their size, thus insuring both stable power output and minimum interference with adjacent equipment.

The CoolSyncª (patent pending) transistor cooling dynamically adjusts the rate of front to back airflow depending on the power density of the program material, thus anticipating the need for cooling rather than merely reacting to temperature. The airflow cools all components, not merely the output transistors.

Detented level controls are on the front panel, where they can be easily adjusted if necessary. Both the power switch and the circuit breaker are on the front panel so that in case of problems, the breaker can be reset without requiring access to the rear of the amplifier. Clip lights for each channel indicate the onset of actual

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Introduction

clipping, not just a designated output voltage which may not correspond to the clipping point if power line voltage is low.

The rear panel inputs can be via gold plated 1/4" (6.3 mm) phone jacks, gold plated 3 pin XLR-typeconnectors or barrier screw terminals, all of which are standard equipment. Outputs are onfive-waybinding posts which can accept large diameter wire or 3/4" (19 mm) spaced dual banana plugs. A recessed rear panel switch allows easy selection of stereo or bridged monaural operating modes. Separate signal and chassis ground points are available to handle any grounding scheme.

Matica amplifiers have high current output protection relays which disconnect the output in the event of overtemperature, DC offset, audio signals below 5 Hz on the output terminals or excessively low line voltage. When AC power is applied to the amplifier, the relay does not engage immediately; a 4Ð5 second delay allows the amplifier circuitry to stabilize and prevents turn-ontransients from other equipment powering up during that time from being reproduced by the loudspeakers.

The cooling fan is also momentarily exercised at high speed at turn-on.When AC power is turned off, the speaker protection relays immediately disconnect, thus keeping turn-off transients from reaching the speakers. Additional protection circuitry keeps RFI out of the audio circuits, assuring clean, stable operation in difficult environmental conditions.

An aLinkª 25-pinconnector is provided for future expansion by the user. Among the planned accessories for attachment to this connector are outboard signal processors, electronic crossovers and remote controllers. Also planned are an internal module to allow softturn-onand remoteturn-on/turn-off;the internal module is for installation by qualified personnel. See your Alesis dealer for information on these options.

Why Another Power Amplifier?

Professional power amplifiers of today tend to fall into several groups. Those aimed at the performing musicianÕs sound reinforcement needs are often designed for the highest possible power output at the lowest possible price. Those intended for portable sound reinforcement are frequently designed for minimum weight and size, while fixed reinforcement amplifiers are often made to fit a laundry list of requirements.

In all too many of these situations, the sonic character of the amplifier is low on the list of design priorities. A professional amplifier must be reliable under all circumstances, of course, because peopleÕs livelihoods and even their safety can depend on its proper operation. And yet, the primary purpose of any audio amplifier is reproducing sound with as high quality as possible.

The new Alesis amplifiers meet the stringent requirements of both fixed and touring sound reinforcement, but they do not sacrifice sonic excellence to achieve their professional credentials. Highly sophisticated engineering which takes advantage

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Introduction

of recent developments in electronic componentry, and innovative design concepts make the Alesis power amplifiers ideal for any professional application.

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Installations

CHAPTER2

INSTALLATIONS

Unpacking and Inspection

Carefully unpack the amplifier and inspect it for physical damage originating in shipping. Do not discard the packing materials; they may be helpful in shipping the amplifier when it is not mounted in a rack or other enclosure.

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.

Physical Installation

Alesis Matica 500 and Matica 900 amplifiers take up only two rack spaces each (3.5Ó panel height). If multiple amplifiers are mounted in the same rack, there should be at least one rack space left between them; solid blank panels may be used to fill the spaces, but perforated grilles used as fillers will help exhaust the hot air from within the rack.

An exhaust fan is required in a rack with a closed back to assure sufficient air exhaust capacity. If the rack has a door limiting access to the front panels, the door should have ventilation grilles in it or other provisions should be made to assure a free flow of air through the front panels of the amplifiers.

Note: Unusually high ambient or operating temperatures may cause the thermal protection circuitry to open the internal output protection relay. Once the amplifier has cooled, the relay will automatically close and the amplifier will resume operation without user intervention.

While the amplifier's 14 gauge front panels are strong enough to support their entire weight in fixed installations, Alesis strongly recommends using the Matica's rear rack supports in all installations. Support at the rear is a must for portable and road use.

Matica amplifiers are well shielded; however, mounting low level electronics some distance away from power amplifiers is common practice to reduce the possibility of electromagnetic interference into the low level units, which may sometimes be unusually susceptible to picking up such radiation.

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Installations

Electrical Installation

One of the most important considerations for proper installation and operation of a power amplifier is the capacity of the line feeding the mains voltage to the amplifier. If the line does not have sufficient current 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.

For best performance, assure that the power line feeding each amplifier can supply adequate line voltage and current. Under most circumstances, normal household or commercial power outlets will be adequate. However, when low impedance loads are used with high maximum output power, additional current capacity may be required.

The Audio Ground is DC isolated from the chassis, although there is an RF bypass capacitor between Audio Ground and the chassis ground as part of the MaticaÕs RFI protection circuitry. If a hard-wiredconnection between Audio Ground and the chassis is desired, a jumper wire may be connected between the Audio Ground screw on the input barrier strip and the adjacent ground screw on the chassis. The amplifier is shipped with no connection between these screws, which is the preferred method of use.

The AC cord is designed to be fed by an outlet that includes a solid earth ground. This ground connection is an important safety feature designed to keep the chassis of electronic devices such as the Matica amplifiers 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.

Do not operate any electrical equipment with ungrounded outlets. Plugging a Matica amplifier into an ungrounded outlet or ÒliftingÓ the unit off ground with a three-to-two wire adapter can create a hazardous condition. Alesis cannot be responsible for problems caused by using Matica amplifiers or any associated equipment with improper AC wiring.

Note: Alesis amplifiers arepre-wiredat the factory for the line voltage in the country where the amplifier is intended for sale and are supplied with appropriate line cords. They are not readily convertible to other voltages. Before connecting them to the power line, check to be certain that they are properly wired for use in your country.

When wiring a rack, it is good installation practice to route all AC wiring along one side of the rack and all audio wiring along the other side to avoid coupling ACborne interference into the audio.

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Installations

Audio Installation: Input Wiring

MATICA

INPUT

OUTPUT

MODEL

POWER

POWER

500

600 VA

250 W@4Ω

900

1200 VA

450 W@4Ω

 

 

USE CLASS 2

 

 

WIRING

120 V60 Hz

ALESIS CORPORATION, LOS ANGELES

SOUND REINFORCEMENT DIVISION

MATICAPOWER AMPLIFIER

Patent Pending

MOUNT IN RACK ONLY. INSTALLER SUR SUPPORT DE MONTAGE SEULEMENT.

WARNING/AVIS:

SHOCK HAZARD – DO NOT OPEN

RISQUE DE CHOC ELECTRIQUE´ – NE PAS OUVRIR

TO PREVENT ELECTRICAL SHOCK DO NOT REMOVE COVERS.

NO USER SERVICEABLE PARTS INSIDE.

REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.

TO REDUCE THE RISK OF FIRE OR ELECTRICAL SHOCK

DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE.

 

 

B

BRIDGED

A

 

 

OUTPUT

MONO

OUTPUT

 

 

 

 

DUAL

 

 

 

 

CHANNEL

AUDIO INPUT WIRING

 

 

=

TIP

= PIN 2

 

FOR BRIDGED MONO

=

RING

= PIN 3

 

=

SLEEVE = PIN 1

 

USE A INPUT

Figure 2: Amplifier rear panel controls and connections.

Warning: Be sure that the AC power is off prior to connecting or disconnecting any signal wiring.

The input circuits of the Alesis amplifiers are electronically balanced. They may be fed from either symmetrical (ÒbalancedÓ) or unbalanced sources. There are two combination XLR/1/4Ó (6.3 mm) jacks provided, one for each channel, and a barrier screw terminal strip for connecting bare wire or crimp terminals. See Figure 2.

The inputs are wired according to IEC standards:

Connection

XLR

Phone Jack

Audio Ground

Pin 1

Sleeve

High (+)

Pin 2

Tip

Low (Ð)

Pin 3

Ring

Table 1: Input Wiring

 

 

Figure 3. Balanced wiring of an XLR input connector.

Figure 4. Unbalanced wiring of an XLR input connector.

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Installations

Figure 5. Balanced wiring of a 1/4Ó (6.3 mm) three-wirephone plug.

Figure 6. Unbalanced wiring of a 1/4Ó (6.3 mm) three-wirephone plug

All input wiring should be done with shielded cable. To use an unbalanced source with an Alesis amplifier, connect the High (+) signal wire as shown in Table 1 and connect the shield wire to both the Low (Ð) and Audio Ground input connections. See Figure 4 and 6. If a two-wire(tip and sleeve only) phone plug is used for an unbalanced input, the sleeve of the plug will automatically connect the Low and Audio Ground connections together inside the amplifier.

Long input cable runs, particularly in areas with high electrical interference, should be done with symmetrical (ÒbalancedÓ) configuration, if possible, to lessen the possibility of interference being picked up by the cables.

Since the input jack and barrier screws for each channel are connected in parallel, only one of these should be used unless the same signal is to be connected in parallel to another amplifier channel.

The input impedance of the Alesis amplifiers is 20 kΩ in balanced or unbalanced configuration. Thus, the inputs of several amplifiers may be connected in parallel if desired. The maximum number of amplifier channels will depend on the minimum output load impedance of the device feeding the amplifiers. For example, if the minimum output load impedance of the source device is 600ÊΩ, up to 30 amplifier channels may be connected to it in parallel without overloading the source deviceÕs output.

To use the amplifier in Bridged Mono mode, connect the input signal to Channel A only and move the recessed slide switch to the Bridged Mono position. The Channel B input will be inactive. See below for output wiring in Bridged Mono configuration.

Audio Installation: Output Wiring

Warning: Be sure that the AC power is off prior to connecting or disconnecting any signal wiring.

Alesis amplifiers can reliably drive 2 Ω loads in Stereo mode and 4Ω loads in Bridged Mono mode. However, the impedance of a loudspeaker varies with frequency, and its nominal rated impedance is not necessarily its minimum impedance. Some loudspeakers carry both nominal and minimum impedance specifications, and some are supplied with impedance curves. When connecting

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