Introduction, Unpacking, Voltage Requirements

Operating Manual 6125A and 4200A Multi-Channel Power Amplifier

1.INTRODUCTION

The 6125A and 4200A power amplifiers combine the efficiency of a MOSFET high-speed switching output stage with the sophistication of modern microprocessor and DSP technology to produce a multi-channel amplifier with unprecedented versatility and power in a single 3RU pack- age.

Although similar to other amplifiers with class D output stages, the 6125A and 4200A amplifiers employ internal microprocessor and DSP algorithms to optimize output switching characteristics and eliminate the usual harshness associated with high-frequency audio in stan- dard class D amplifiers. This optimization results in a spread-spectrum switched output that varies with input amplitude and frequency, and minimizes radiated emissions by eliminating the single-frequency high-energy radiated interference normally associated with switching outputs. The use of a simple linear power supply removes another potential source of radio-frequency interference, an im- portant consideration as racks become more and more heavily populated with digital signal processing equipment. A small switching supply using flyback topology provides an efficient power source for logic, protection, pre-ampli- fier and indicator circuits.

To assure reliable operation, the usual protection from excessive high-frequency, DC offset, and thermal overload is supplemented by power supply undervoltage, power supply overvoltage, and output overcurrent detec- tion, all monitored and controlled by the latest in minia- turized microprocessor technology.

In sum, 6125A and 4200A amplifiers combine the best of the new digital technologies with the best of the traditional analog technologies to provide a product that will supply clean sound at full output from every channel while generating minimal heat, thus increasing the reli- ability of every other piece of equipment in a rack as well as preserving its own.

2.UNPACKING

As a part of our system of quality control, every Altec Lansing product is carefully inspected before leav- ing the factory to ensure flawless appearance. After un- packing, please inspect for any physical damage. Save the shipping carton and all packing materials, as they were carefully designed to reduce to minimum the possibility of transportation damage should the unit again require packing and shipping. In the event that damage has oc- curred, immediately notify your dealer so that a written claim to cover the damages can be initiated.

The right to any claim against a public carrier can be forfeited if the carrier is not notified promptly and if the shipping carton and packing materials are not avail- able for inspection by the carrier. Save all packing mate- rials until the claim has been settled.

3.AC POWER REQUIREMENTS

3.1Voltage Requirements

The 6125A and 4200A amplifiers can be operated from nominal 120VAC or 240VAC, 50/60Hz mains. This is user-configurable by changing the insert in the AC Inlet (See section 7.9). The power connector on the amplifier accepts a standard IEC-320 receptacle.

For nominal 120VAC operation, the power cord should be three-conductor, rated for at least 13A (16AWG). The line fuse should be type MDA, 12A.

For nominal 240VAC operation, the power cord should be three-conductor, rated for at least 10A (18AWG). The line fuse should be type MDA, 10A.

3.2Current Requirements

1.)	Idle (no audio):
	6125A	4200A
	120V: 0.81A	120V: 0.9A
	240V: 0.42A	240V: 0.5A
2.)	With typical audio inputs:
8Ω loads on all channels
	120V: 4A	120V: 4.6A
	240V: 2A	240V: 2.3A
4Ω loads on all channels
	120V: 6.5A	120V: 7.0A
	240V: 3.3A	240V: 3.5A

6125A and 4200A amplifiers consume less than 12 amps when all channels operate at 1/8 power into rated (4 ohm) loads. This condition satisfies the UL, CSA and building electrical code requirements for a piece of audio equipment not to consume more than 80% of the current available when plugged into a grounded 15 amp outlet and operated at 1/8 of maximum power.

3.3AC Grounding and Earth Grounding To reduce the risk of ground loop hum, all system

ground references should originate at the same point in your AC power distribution. Do not remove the amplifier’s ground pin, as it creates a potential shock hazard.