540A/640A V2.0 Integrated amplifier

4. Short circuit detection

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

Description - During power up from Standby CAP5 performs a check on the loudspeaker terminals to see if a short across the terminals has been accidentally introduced. If the resistance measured across the loudspeaker terminals is too low the unit will stay in Standby mode until the fault has been removed and Power up is re-attempted.

Remedy - User related fault. There may be a short circuit between the loudspeaker terminals. Check all loudspeaker connections before attempting to switch the unit out of Standby.

5. Intelligent clipping detection

Indicator - Volume is nudged down automatically.

Description - CAP5 has the ability to detect when the amplifier starts to clip or overdrive at it’s output, which can damage loudspeakers, and degrade the sound. Clipping distortion is caused at high volume levels when the output signal briefly goes outside the maximum voltage that the amplifier can provide, causing the tops of the signal to flatten off. When CAP5 detects clipping the volume will be automatically nudged down until CAP5 detects an undistorted output.

Volume

Clipping

It is possible to disable the clipping detection feature by holding down the Standby/On button during power up (whilst plugging the unit into the mains power). The unit will indicate this by flashing the protection LED for several seconds.

Note: Disabling the clipping detection is not advised as this feature has been added deliberately to protect the amplifier and loudspeakers.

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Cambridge Audio 640A, 540A user manual Short circuit detection, Intelligent clipping 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.
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