Crown Audio ce 4000 Advanced Features and Options, CE 4000 Power Amplifier, page, Fault

CE 4000 Power Amplifier

5 Advanced Features and Options

Figure 5.1

Fault Indicator

NOTE: For detailed information about these Crown amplifier features, please consult the Crown Amplifier Application Guide, available on the Crown website at www.crownaudio.com.

5.1 Protection Systems

Your Crown amplifi er provides extensive pro- tection and diagnostic capabilities, including built-in anti-clip limiters, amplifi er fault protec- tion, and switchable high-pass fi lters.

5.1.1 Anti-Clip Limiters

Your Crown amplifi er has built-in Anti-Clip Limiters which offer a degree of protection to your loudspeakers. The Anti-Clip Limiters work by dynamically reducing the amplifi er gain if the output stage is driven into clip, thereby reducing potentially damaging distor- tion to moderate levels.

While some audio systems may already con- tain protective limiters preceeding the amplifi er in the system, the amplifi er’s Anti-Clip Limiters generally will not noticeably affect output qual- ity. For systems without additional protection, the Anti-Clip Limiters can enhance your sys- tem’s output quality and prevent catastrophic damage to your speakers.

Even with the Anti-Clip Limiters, your amplifi er should never be operated at a level which causes the front-panel Clip LEDs to illuminate constantly. While the Anti-Clip Limiters help to prevent damage due to signal distortion, your speakers can still be damaged by excess power dissipation.

5.1.2 Fault

The amplifi er will light the Fault LED (Figure 5.1) of an amplifi er channel under fi ve different conditions:

1.When the amplifi er is fi rst powered up, until the unit is ready for operation.

2.If the heatsinks reach a temperature above normal working limits.

3.If the transformer thermal protection cir- cuit is activated.

Figure 5.2

Fault Jack

Figure 5.3 High- Pass Filter Switch

4.If amplifi er output wires develop a short- circuit.

5.Should the amplifi er output stage become non-operational.

The Fault status of the amplifi er can also be monitored remotely by attaching a signaling device to the Fault jack (see Figure 5.2). For suggestions for external signaling circuits to use, see Section 1.5 of the Crown Amplifier Application Guide, available on the Crown website at www.crownaudio.com.

5.1.3 High-Pass Filters

Very low frequency signals contain no useful musical energy, waste valuable amplifi er power and headroom, and can be damaging to

your speakers. Your Crown amplifi er provides switchable high-pass fi lters to remove these signals from each channel’s output.

For each channel, a back-panel, three-position switch provides optional settings of Flat, 30 Hz, 40 Hz, or 50 Hz (left to right, see Figure 5.3). The 30 Hz setting is suitable for all full-range and low-frequency applications. The lower-frequency settings may be selected when the amplifi er is being used to drive a sub-bass program; use only with speakers that provide a useful frequency response below the frequency setting. The FLAT setting provides bypass of the high-pass fi lters, for use when subsonic protection is provided elsewhere in the system.

5.2 Circuit Designs

5.2.1 BCA

BCA (Balanced Current Amplifi er) is Crown’s patented, cutting-edge technology that gets more power out of an amplifi er with less waste than was ever before possible. A completely new adaptation of standard amplifi er design, Crown’s BCA “switching” amplifi er design pro- vides for high output, exceptional reliability and nearly twice the effi ciency of typical ampli- fi er designs.

Crown’s BCA “switching” technology is a com- pletely new adaptation of standard switching (PWM) amplifi er design. In fact, BCA is differ-

ent enough from other amplifi er classes that it received a patent and merits it’s own class designation, “class-I.”

BCA technology offers several key advantages. It provides unprecedented effi ciency, requiring less power from the AC supply than other designs, meaning signifi cant cost savings over the life of the amplifi er. BCA handles reactive speaker loads easily and gracefully, by reusing energy returned from the speaker rather than dissipating it as heat or forcing the amp into premature current-limiting. This ability makes BCA models extremely resilient—especially at low, 2-ohm impedances. It also makes them more reliable, since they are not constantly stressed to their limits or subjected to exces- sive heat. Best of all, as proud owners can attest, amps with BCA technology sound great, with a powerful low-end that stands out from the competition.

5.2.2Switching Power Supply with

PFC

Crown’s new Switching Power Supply with PFC provides a range of benefi ts over both non- switching and conventional switching power- supply designs.

Typical non-switching power supplies require large, heavy transformers in order to produce the required power at the output stage. These transformers must be large to absorb the sub- stantial waste that occurs when operating at 50 to 60 Hz (standard AC supplied by the power company).

By contrast, switching power supplies can operate with a much smaller (and lighter) transformer because they fi rst convert the AC up to a much higher frequency, thereby reduc- ing waste.

However, in both non-switching and conven- tional switching designs, phase differences occur within the power supply due to the inductance of the transformer. This phase dif- ference prevents much of the available power from the AC mains from making its way to the load.

Operation Manual page 13