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Cambridge Audio 540A CAP5 Five WAY Protection System, DC detection, Over temperature detection

Models: 640A 540A

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CAP5 - FIVE WAY PROTECTION SYSTEM

Cambridge Audio has developed a proprietary protection system to ensure reliability and a long life to its amplifiers. This protection system comprises of five main protection methods:

1. DC detection

Indicator - Unit has switched off during operation, protection LED constantly flashes in single bursts.

Description - CAP5 offers loudspeaker protection if the output of the amplifier goes to a high constant voltage (DC) because of some internal fault. This is a rare fault although detecting it could just save those expensive loudspeakers.

Remedy - Due to the necessary sensitivity of the DC protection circuit, hard clipping of the amplifier may cause DC protection to be triggered. If this fault occurs please switch the unit off, power up again and check operation with a reduced volume level. If the DC fault occurs again please contact your dealer for service.

2. Over temperature detection

Indicator - Unit has switched off during operation, protection LED constantly flashes in bursts of two.

Description - CAP5 includes temperature detection which constantly monitors the heat generated by the output transistors. If the monitored temperature reaches a high level (suitably within the limits of the output devices) the amplifier will automatically switch into a fault mode. The unit should ideally be left for 15 minutes in this state to cool down adequately. If the unit has not fully cooled down then the temperature may reach the limit soon after the amplifier is powered up. If the loudspeaker impedance is low the temperature of the amplifier may rise faster as the

14Azur integrated amplifier

amplifier is working harder. If the amplifier is mounted in a cabinet or the ventilation slots are obstructed the over temperature detection may activate/reactivate after a short listening time.

Remedy - User related fault. The internal temperature of the output transistors has reached the over temperature limit. The unit is not damaged, although it should be left for 15 minutes to cool down before being switched out of Standby.

3. Overvoltage/overcurrent detection

Indicator - The unit attempts to come out of Standby mode, the protection LED flashes in bursts of three.

Description - CAP5 offers V/I protection by constantly monitoring the output transistors to keep them working inside their Safe Operating Area (SOA). The SOA is a set of limits given by the output transistor manufacturer to ensure reliability. Many amplifier designers include V/I limiting in the signal path which can degrade the signal by compressing dynamics. The CAP5 system operates outside the signal path and when triggered shuts down the amp rather than limits the size of the signal passing through the amp (signal compression). V/I also protects the amplifier against short circuits on the speaker terminals during use.

Remedy - The resistance on the loudspeaker terminals is too low. Check to see if there is a short circuit between the loudspeaker terminals.

Note: If the indication remains the same and multiple loudspeakers are being used on each loudspeaker output then please remove a pair and retry. If too many loudspeakers are connected to any amplifier causing the load resistance to drop too low the amplifier will overheat. CAP5 will detect this situation. If the indication remains the same with only one set of loudspeakers connected, there may be a fault with one or both of the loudspeakers.

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Cambridge Audio 540A, 640A user manual CAP5 Five WAY Protection System, DC detection, Over temperature detection
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640A, 540A specifications

Cambridge Audio has established itself as a formidable force in the realm of high-fidelity audio equipment, and the 540A and 640A amplifiers exemplify the company's commitment to delivering exceptional sound quality at a competitive price point. These integrated amplifiers, known for their detailed sound reproduction and robust performance, cater to audiophiles who appreciate both quality and value.

The Cambridge Audio 540A is part of the company's entry-level range, designed for music enthusiasts seeking an affordable yet high-performance amplifier. The 540A boasts a powerful 50 watts per channel output, allowing it to drive a variety of speaker types with ease. The design emphasizes simplicity and user-friendliness, featuring straightforward controls and a sleek finish that fits well in any audio setup.

One of the standout features of the 540A is its dual-mono circuit design. This architecture minimizes crosstalk and signal interference, allowing for a cleaner, more precise sound. It also incorporates high-quality components, including a toroidal transformer, which contributes to improved efficiency and reduced distortion. Additionally, the amplifier features a range of inputs, including multiple line-level options, making it versatile enough to accommodate various audio sources such as CD players, turntables, and streaming devices.

On the other hand, the 640A is an upgrade that builds upon the strengths of the 540A. With a more powerful output of 75 watts per channel, the 640A is designed for users who demand more from their audio systems. This amplifier incorporates an improved power supply and enhanced components, further refining the sound quality. The 640A also introduces features such as a high-quality phono stage, enabling direct connection to turntables without the need for separate equipment.

Both amplifiers incorporate Cambridge Audio's dedication to quality with a focus on analog circuitry. This is particularly evident in the warm, rich sound signature that these amplifiers provide, making them ideal for a range of music genres. The build quality is robust, with a solid chassis designed to reduce vibration and resonance, ensuring a stable platform for audio performance.

In summary, the Cambridge Audio 540A and 640A amplifiers offer a compelling combination of sound quality, versatile connectivity options, and robust design. Whether you are an entry-level audiophile or a seasoned listener looking for an upgrade, these amplifiers provide an engaging listening experience that highlights the nuances and details of your favorite music. With Cambridge Audio's unwavering focus on high-fidelity sound, both models are captivating choices that continue to impress users worldwide.