Question about Cambridge Audio Azur 640A Amplifier

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Loss of sound Azur 640A

When my amp is not used for a while (24 - 48 hours or more), output is zero or very soft at first. The volume control has no effect. The sound then fades in with some crackling noises within 2 to 3 minutes.

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Re: Loss of sound Azur 640A

This is a classic dry joint,,,,,,,,When a box of electronics is assembled thousands of soldered connections are made, to connect all the components together correctly.

During this soldering process a special FLUX is used to ensure the components are electrically connected correctly and reliably....sometime this FLUX creates an air bubble and over time this bubble causes the outside air to corrode the electrical connection and thus the minute electrical voltages cannot pass though this connection correctly....

When you turn on... electricity and heat are generated just enough to allow the voltages to get through the faulty joint...
thats why the sound is weak and changing in intensity...

This fault needs to be located and resoldered. Its not an easy task to locate it... but the resoldering takes only 5 seconds,,,,but as you can imagine searching for it can be time consuming....
You will need a circuit diagram of the amp and some nowledge of the audio path from input to output to search effectively...
But please check your speaker wires very carefully as maybe the simplest thing is causing this problem!!!!!

Cheers From YUBEUT

Posted on Nov 16, 2007

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Cambridge audio 640a problem, olume goes to zero, I hear a little bang on speakers, light starts blinking!

This sounds like there's an overload in the main amp section. Often caused by a short-circuited device.

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You are overloading your amp. IMO 640A cannot handle heavy loads.

Better change the speaker combo and connect something that puts right load on the 640A. Else, get a meaty amp from CA.

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Volume goes to zero and protection light comes on, any idea what the problem is?

Check the speaker wires for a short. Try operating the amp without the speaker wires hooked up.

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HI, Can the Cambridge Audio 640a integrated amp be used as a preamp if I buy a separate power amp.

Of course, just run an audio RCA pair out from the Pre Out to your next amp and any input. All control for volume, tone, etc will remain with the 640A.

Jan 26, 2011 | Cambridge Audio Azur 640A Amplifier

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I have a Cambridge Azur 640A amp, every time I turn the volume up to over 12 oclock the amp shuts down. Can this be changed? I presume this is a safety mode on the amp. Can you help?

Yes, you are right. That's a protection feature to prevent burnouts. Typically it appears when your speakers are sucking up a lot of load from the amp. Please check your speaker impedance and the amps' output impedance and ensure the wiring are properly done. Some amps are soo sensitive that they may cut-off after certain level due to overload.

Jan 06, 2011 | Cambridge Audio Azur 640A Amplifier

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Red light flashes - will not work - could it be dust in the amp?

its not because of dust. AZUR 640A 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.
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 switch the unit off, power up again and check
operation with a reduced volume level. If the DC fault occurs again contact your dealer for service.

Dec 29, 2010 | Cambridge Audio Azur 640A Amplifier

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Hello, I am trying to plug my Mixer into my amp but only one speaker has sound..I am using a Rane ttm57sl mixer with technics turntables & cambridge audio azur 640a amp...I've gone from the Aux out on...

Why don't you try using the main outputs (the 2 XLR connectors). With 2 cables connect these two (left - right) outputs at your amplifier's aux in. In that case take care that the "output level" of the mixer works like master volume controlfor the signal that the mixer sends to the amplifier.

In case of a problem or clarification, don't hesitate to post.

Thanks and regards
Please kindly rate this solution

Feb 04, 2010 | Cambridge Audio Azur 640A Amplifier

1 Answer

Protection snaps into action intermittently

I don't think the pin or third prong on your power cord would be the problem, but I would make sure that all of your speaker wires and connections going to your amp are not shorting out against eachother.

I hope this helps you out.

Apr 01, 2008 | Cambridge Audio Azur 640A Amplifier

1 Answer

Using a tube pre amp with my CA Azur 640A?

There are many answers to your questions but Ill have a go with the basics...
Audio connections should be matched.... its called Frequency impedance,.... to get a signal along wires or cables (or Fibre) the Impedance of the cables and wires must be matched to the device they are connected to transfer the signal along the cables without distortion...

Manufacturers provide many sockets on the input side of amplifiers and preamplifiers to allow the consumer to connect various devices of different impedance.

They label these inputs like CD, or Tuner, or PHONO etc etc,

That means if you have a CD player it must be plugged into the CD input socket then the impedance will be correct and the sound will transfer along the CD cables correctly, without distortion..same with the Phono input etc...
You will find on the sound output to the speakers terminals are also labelled 4-6ohm, or 8-10ohm, these are the impedance expected for the coil ratings of the speakers them selves and its important to get the correct speakers to the correct out put terminals...

In your case all you have to do is follow these simple rules and all will be say you have a squeeze box well there probably isnt a port labelled squeeze box so you need to experiment and try out each input port for the squeeze box to see what input gives you the correct sound output...Watch the Phono inputs as these are very sensative to input sound levels and must be treated very carefully as they have a double stage of sound amplification and as such you need to have the volume right down when connecting up the Phono inputs then increase the volume carefully after the cable connections are completed.

If you follow these rules then all will be well,,,,there is no difference if the Pre amp or Power amp is valve or transistor or FET or has IC outputs to the speaker the same impedance rules apply..just treat it as a box with input and output terminals and all the impedance will be taken care of for you...if you read the lables...

You need to connect you signal source to the Preamp inputs the out put from the Preamp connects to the power amp input then the power amp output goes to the speakers. this is a basic configuration for sound systems, there are other variations but are outside this discussion.

Cheers From YUBEUT

Nov 12, 2007 | Cambridge Audio Azur 640A Amplifier

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