Alcons ALC4 User manual

Table of contents ________________________________________________

1. Introduction ____________________________________________________________________________________________ 3

2. Important safety instructions ______________________________________________________________________________ 6

3. Precautions_____________________________________________________________________________________________ 7

4. Installation _____________________________________________________________________________________________ 8

5. Overview ______________________________________________________________________________________________ 11

6. Connections ___________________________________________________________________________________________ 14

7. Operation _____________________________________________________________________________________________ 21

8. Safety ________________________________________________________________________________________________ 23

9. Service and support_____________________________________________________________________________________ 25

10. Specifications_________________________________________________________________________________________ 27

11. Block diagram ________________________________________________________________________________________ 28

ALC4 User’s Manual. Rev. 0 3

1. Introduction___________________________________________________

Dear customer,

Congratulations on your purchase of an Alcons Audio ALC4 professional power amplifier, and thank you for your confidence in Alcons products. We are very

honoured to welcome you to the growing family of Alcons ambassadors!

For your safety, please read the Important safety instructions and the Precautions section before installing and operating the amplifier.

The ALC4 Amplifier Loudspeaker Controller is a combination of a loudspeaker controller and a high efficiency power amplifier. The ALC4 is designed to

guarantee the best loudspeaker drive, with maximum sound- and operating reliability. The amplifier stage consists of a 2x 2 kW amplifier in Class-G design,

supplied from a conventional power supply with a torodial transformer and a massive 400 Joule capacitor bank with a large dynamic reserve for sustained high

power output even in two ohm loads.

In order to maintain strict quality standards, all Alcons products are burned-in and thoroughly tested before shipping. The proven combination of advanced

design, quality construction and active protection circuits is your guarantee of fail-safe reliability and many years of trouble-free operation, while enjoying the

excellent specifications. You can depend on consistent, stable performance, even in the most demanding fixed or mobile sound reinforcement applications.

Speakon® and PowerCon® are trademarks of Neutrik®AG.

ALC4 features

Dual Power Supply

The ALC4 is equipped with separate power supplies for both channels.

Balanced input stages

Balanced XLR inputs make the amplifier less susceptible to noise and AC hum pickup, especially when using long cable runs.

Signal link outputs

The XLR link output connectors are internally hardwired to the input connectors and can be used to daisy chain the input signals to another amplifier.

Dual output connectors

Each channel of the ALC4 is equipped with two four pole Speakon® outputs for easy installation.

ALC4 User’s Manual. Rev. 0 4

1. Introduction___________________________________________________

Inputs in parallel mode

Inputs in parallel mode can be used if you want to drive both channels with one signal, without the need for link- or Y-cables.

Bridged mono mode

Bridged mono mode combines the output power of the two amplifier channels into one loudspeaker load, resulting in twice the voltage swing and four times the

power in a specific load.

SDP Speaker Drive Processor

The SDP circuit can be seen as the “brain” of the amplifier. By means of speaker-specific modules, that are located in 2 front-accessible slots, the characteristics

of the connected speaker are loaded into the amplifier. With this, the amplifier is “tailor-made” to the speaker, regardless of the power output specifications of the

amplifier.

Multiple processing functions are operating at the same time;

- protection: The speaker is protected against damage from over-excursion and power overload.

- dedicated filtering: The fixed cross-over settings cater for the best system performance.

- optimised power response: The SDP module adjusts the RMS and peak values to the speakers capacity, giving maximum system power output.

- system equalising: This circuit equalises the system response, with utilising the maximum component efficiency. This results in higher overall system sensitivity

and reduces the need for active filtering while offering efficient amplifier usage (passive system).

High efficient Class-G power stages

The ALC4 is equipped with two class-G power amplifiers for increased thermal efficiency, while also saving weight on the heat sinks and the power supply.

SIS Signal Integrity Sensing

SIS is a unique feature installed in all Alcons amplifiers that senses the signals arriving at the loudspeaker terminals, and so compensating for errors introduced

by cable resistance and self-induction. Doing so, SIS maintains low linear and non linear distortion, compensation of signal loss and high damping figures, thus

achieving high signal integrity, regardless of the cable length.

ALC4 User’s Manual. Rev. 0 5

1. Introduction___________________________________________________

ATCM Advanced Thermal and Clip Management

ATCM has a number of sensors within the amplifier, that constantly monitor both operating temperature, in and output signal. For the temperature section of

ATCM, the class-G stage is regulated when dangerous temperature increase is sensed. In this way, the amplifier stays in operation, instead of switching into

“heat protection”.

The clip limiter section reduces the signal input level to the safest maximum level, when continuous clipping is detected. In this way your high frequency drivers

are protected against damage from harmonics and also the amplifier remains cooler.

Variable speed DC fan

Heat sink and power supply sensing circuits control the intelligent variable speed DC fan. Fan speed increases only as required by the measured temperatures,

thus keeping fan noises to a minimum.

RF and ultrasonic protection

A RF sensing circuit is continuously monitoring the inputs of the ALC4 to detect ultrasonic energy. When RF energy is detected, the inputs of the ALC4 are

muted to prevent damaging your loudspeakers or the amplifier.

DC and subsonic protection

The ALC4 senses DC and very large subsonic waveforms at both amplifier outputs. When DC or subsonic energy is detected, the corresponding output relay will

be opened to protect any connected loudspeakers, and the related protect LED will illuminate.

Short circuit protection

The output sections of the ALC4 have a current limiter, protecting the output devices from loads lower than two ohms, or short circuits. Current limiting is

dynamic, which means that the amplifier does not shut down, but dynamically limits its current but keeps working.

Ground lift switch

If hum is audible, the cause may be a ground loop in your sound system. The ground lift switch ‘lifts’ the ground from your sound system from the AC mains

ground, thus ‘opening’ the ground loop.

ALC4 User’s Manual. Rev. 0 6

2. Important safety instructions ____________________________________

Warning: – To reduce the risk of fire or electric shock, do not expose this apparatus to rain or moisture.

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 dry cloth.

7. Do not block any ventilation openings. 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 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. If the provided plug does not fit into your

outlet, consult an electrician for replacement of the obsolete outlet.

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. Only use attachments/accessories specified by the manufacturer.

12. Use only with the cart, stand, tripod, bracket or table specified by the manufacturer, or sold with the apparatus. When 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, 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.

The lightning flash with arrowhead symbol within a triangle, is intended to alert the user to the presence of uninsulated dangerous voltage within the enclosure

that may be a risk of electric shock to humans.

The exclamation point within a triangle is intended to alert the user to the presence of important operating instructions in the literature accompanying the product.

ALC4 User’s Manual. Rev. 0 7

3. Precautions ___________________________________________________

- Save the packing material. Should you ever need to ship the amplifier, use only the original packing.

- Read this manual carefully before installing and operating your amplifier. Retain this documentation for future reference.

- Always operate the amplifier with a grounded AC mains supply. Ensure that the quality of the mains supply is good enough and that it can supply the

required peak currents. In addition, proper earthing is necessary to prevent hum and safety problems.

- Do not use the amplifier if there is visual damage to the enclosure or cables. Inspect the amplifier and wiring before use. When in doubt, have the

amplifier inspected by authorized technical personnel.

- Do not make connections to the amplifier while it is switched on. Always shut off the amplifier when making connections to

it, and mute the inputs when making connections to preceding equipment in the chain.

- Do not spill water or any other liquid to or into the amplifier. Do not operate the amplifier if suspected or standing in liquid.

- Do not block the air intake for the fan on the front, or the exhaust ports on the left side of the amplifier. The amplifier can run hot, or even go into

protect mode if there is insufficient cooling air.

- Do not remove the cover. There are no user serviceable parts inside the amplifier. Removing the cover exposes you to dangerous voltages inside the

amplifier.

- Refer servicing to qualified service personnel. Servicing is required when the amplifier has been damaged in any way, liquid has been spilled on or into the

amplifier, does not operate normally or has been dropped.

- Do not series or parallel connect an amplifier output with any other amplifier output. Connecting outputs together can cause damage to the amplifiers.

ALC4 User’s Manual. Rev. 0 8

4. Installation____________________________________________________

Unpacking

Carefully open the shipping carton and inspect the amplifier. Every Alcons amplifier is thoroughly tested and inspected before leaving the factory and should

arrive in perfect condition. If you find any damage, notify the shipping company immediately. Only you, the consignee, may initiate a claim for shipping damage.

Be sure to save all packing materials for the carrier’s inspection.

Please save the packing material. If you ever need to ship the amplifier back to your dealer or the factory, you should only use the original packing.

Mounting

The ALC amplifiers mount in standard 19-inch racks. Rear mounting ears give additional support. Rear support is highly recommended in all mobile and touring

systems. ALC4s may be stacked directly on top of each other. There is no need for spacing between units.

ALC4 User’s Manual. Rev. 0 9

4. Installation____________________________________________________

Cooling and ventilation

The ALC4 amplifier uses forced air cooling in order to maintain a low operating temperature. In the ALC4 the cooling air enters at the front and the hot air leaves

the amplifier at the left and right side. The reason for this is that the air outside the rack is usually cooler than inside, and therefore the amplifiers can run at

higher continuous power levels without thermal problems. Should the amplifier get too hot, the related channel will be protected. When the output devices of the

amplifier reach a temperature of 85 degrees centigrade (185° F), the ALC4 will prevent further temperature rise by shutting down the class-G amplifier stages.

This is indicated by the protect LED blinking. Usually this will reduce the amount of heat produced in the amplifier enough to stop it from overheating. If this is not

the case, when the amplifier reaches 90 degrees centigrade (194° F), the related channel will be muted, and the protect LED will be illuminated constantly.

When the amplifier cools down to a safe value, normal operation is resumed. Make sure that there is an adequate supply of fresh air in front of the amplifier, and

that there is sufficient space in the rack for the exhaust to escape. In order to let the warm air leave the rack unobstructed, the rack must have openings in it of at

least 150 cm2per ALC4.

Mains Power

The AC mains voltage for the ALC4 amplifier is stated at the rear of the amplifier near the PowerCon® input. Make sure your local power matches that of the

amplifier. Connecting the ALC4 to the wrong voltage is dangerous and may damage the amplifier. For safety reasons you also must ensure that the AC supply is

properly grounded. The AC current draw is measured according to the IEC 65 safety standard. The normal operating power is measured using pink noise, with

an average power equal to 1/8 of full power. This corresponds to normal music being played to the clip level of the amplifier. The table below shows the AC

current draw for different loudspeaker loads. Make sure your AC power distribution can handle the currents demanded by the amplifiers.

Peak output power per channel: AC power draw: Idle:

8 Ω1270 W 1000 VA 100 VA

4 Ω1960 W 1400 VA 100 VA

2 Ω2760 W 2200 VA 100 VA

The AC mains power may not deviate more than +/-10% from the nominal value.

ALC4 User’s Manual. Rev. 0 10

4. Installation____________________________________________________

Installation of SDP module cards.

If you are using SDP (Speaker Drive Processor) modules, you can install them behind the cover on the front panel. To do this, switch off the amplifier and

unscrew the cover on the front panel. Place the SDP modules with the component-side up in the SDP connectors. The upper connector is for channel 1 or mono

bridge mode operation, the lower one is for channel 2. The modules lock into position and do not need to be secured. The ALC4 automatically routes the signals

through the modules once they have been inserted. All SDP modules can be used in normal mode, or in bridge mode. The ALC4 automatically recalculates the