CAP5 - Fiveway protection system

Cambridge Audio has developed a proprietary protection system to ensure reliability and a long life for its amplifiers and the speakers they are connected to. Note: Due to the required sensitivity of the CAP5 system, it is possible that mains power disturbances can falsely trigger CAP5 in extreme situations. This protection system comprises of five main protection methods:

1. DC detection

Indication - Unit has switched off during operation, display flashes “DC ERROR”. Press the INFO input select button for a brief on-screen description and remedy, or read below for more information.

Mode

Volume

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, extremely hard clipping of the amplifier may cause DC protection to be triggered. If this fault occurs press the RESET input select button, then press the Standby/On button to 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

Indication - Unit has switched off during operation, display flashes

Mode

Volume

“OVER TEMP”. Press the INFO input select button for a brief on-screen description and remedy, or read below for more information.

Description - Over temperature is caused by a combination of high listening levels and low impedance speakers. 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 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. Press the RESET input select button and leave the unit for 15 minutes to cool down before pressing the Standby button to resume normal operation.

3. Overvoltage/overcurrent detection

Description - CAP5 offers V/I (voltage/current) 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. The V/I protection has been incorporated within the amplifier circuitry to provide a fast response to temporary overload conditions. When the V/I protection is triggered the unit will continue to operate but distortion may be heard as the unit protects the output transistors.

Remedy - Reduce the volume. If distortion is still present, check the speaker connections and ratings.

4. Short circuit detection

Indication - Unit has not come out of Standby, display flashes “SPKR SHORT”. Press the INFO input select button for a brief on-screen description and remedy, or read below for more information.

Mode

Volume

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 (display flashes “SPKR CHECK”). 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 (display flashes “SPKR SHORT”).

Remedy - User related fault. There may be a short circuit between the loudspeaker terminals. Press the RESET input select button and check all loudspeaker connections before attempting to switch the unit out of Standby (display will flash “SPKR CHECK” then “SPKR OK” when short circuit fixed).

It is possible to disable the short circuit detection feature by pressing the SHORT DT button to off when in the 840A V2 System Configure menu, but it is not recommended. This would only be required if the loudspeakers have very low DC resistance.

5. Intelligent clipping detection

Indication - Volume is reduced automatically, “CLIPPING” appears on the front panel display.

Mode

Volume

Description - CAP5 has the ability to detect when the amplifier starts to

clip or overdrive at its output, which can damage loudspeakers, and

degrade the sound. Clipping distortion

 

 

 

is caused at high volume levels when

 

 

 

the output signal attempts to go

 

 

 

outside the maximum voltage that the

 

Clipping

amplifier can provide, causing the tops

 

 

 

 

of the signal to flatten off. When CAP5

 

 

 

detects clipping the volume will be

 

 

 

automatically reduced down until CAP5

 

 

 

 

 

 

 

 

 

detects an undistorted output.

 

 

 

It is possible to disable the clipping detection feature by pressing the CLIP DT button to off when in the 840A V2 System Configure menu.

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 840A V2 user manual CAP5 Fiveway protection system
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840A V2 specifications

The Cambridge Audio 840A V2 is a high-end integrated amplifier that stands out in the realm of audio equipment, delivering both exceptional sound quality and sophisticated design. This amplifier embodies the brand's philosophy of providing a genuine listening experience that captures the essence of music.

One of the key features of the 840A V2 is its Class XD amplification technology. This unique design combines the best aspects of Class A and Class AB amplification, allowing for low distortion while maintaining high efficiency. This ensures that the amplifier can deliver potent power to drive a wide range of speakers without compromising on audio fidelity. The Class XD design allows the amplifier to operate in Class A mode at low power levels, delivering warmth and detail, while switching to Class AB at higher power levels for greater efficiency and headroom.

The 840A V2 boasts a robust construction that not only enhances durability but also minimizes resonance and vibration, contributing to cleaner sound reproduction. With a meticulous attention to detail, the amplifier features a symmetrical layout, which aids in reducing unwanted noise and crosstalk. The use of premium components throughout the signal path ensures that the audio remains true to the source.

One of the most appealing aspects of the 840A V2 is its extensive connectivity options. It includes multiple RCA inputs, a dedicated phono stage for vinyl enthusiasts, and balanced XLR inputs, making it versatile enough to accommodate various audio sources. The headphone output is powered by a dedicated circuit, ensuring that headphone listening experiences are equally exquisite.

Additionally, the 840A V2 incorporates a high-quality remote control that allows users to conveniently adjust volume levels and switch between sources from a distance. The front panel features a clear display and intuitive controls which makes operating the amplifier straightforward, even for those who might be new to high-fidelity audio equipment.

In summary, the Cambridge Audio 840A V2 integrated amplifier is an exemplary piece of audio engineering. With its Class XD technology, premium build quality, versatile connectivity, and user-friendly design, it offers audiophiles and casual listeners alike the opportunity to experience their music in an immersive and dynamic way. Whether paired with high-end speakers or used in a modest setup, the 840A V2 delivers a performance that reflects Cambridge Audio’s commitment to sound excellence.
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