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  1. #1
    AR Newbie Registered Member
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    Cambridge Audio 640A v2

    I have the Cambridge Audio 640A v2 amp paired with the 640C CD player and a pair of pretty good Monitor Audio gold speakers. The problem is, the amp's protection circuit trips whenver I turn the volume up over half (12 o'clock). Now, the Cambridge website says the amp is going pretty hard at half but I would like to have the option of having it REALLY LOUD at times. But the protection circuit won't let me go over even for a little while. The shop where I bought the amp says there is nothing wrong with it but I am not convinced. I think it should have at least some leeway with regard to volume.
    Anyone else have this experience with the 640A v2 (75 watts)?

  2. #2
    Retro Modernist 02audionoob's Avatar
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    I've never had that amp nor that experience, but I see their point. Some of those speakers aren't the easiest to drive. And it really isn't about where the knob is, anyway.

  3. #3
    Vinyl Fundamentalist Forums Moderator poppachubby's Avatar
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    You bought a nice set up, but at the end of the day it's too polite for where you want to go. Get your self some speakers that are more efficient, and "half way" will make your ears bleed.

  4. #4
    Forum Regular audio amateur's Avatar
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    Half way should be pretty loud, depending on the recording.
    My parents own a 340A Cambridge (40 watts per channel) and I've been past the half way mark running Kef iQ5 speakers with no problems. It could be that your Golds have a lower overall impedance which could mean the amp has trouble delivering the goods at higher levels. If the speakers are already distorting when you're at the half mark, and you want it louder than that, my guess is you need more efficient speakers and/or a different amp.

  5. #5
    Forum Regular blackraven's Avatar
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    The 640A should play fairly loud. The specs show that the 640A puts out 120wpc at 4ohm's.
    Which model MA golds do you have?

    Have you tried a different Cd player or DVD player to see if it is the ouput of the 640c?

    Have you double checked all the settings and connections?

    Also, what gauge speaker wire are you using? If it is 18 or higher, I would suggest dropping down to 10-14g which are larger wires and will offer less resistance. When I got my MMG speakers and hooked them up to my old JVC 120wpc AVR I was using a very small gauge speaker wire and the amp would shut down at very loud volumes. When I switched to 10g wire I no longer had that problem.

    Also, check the voltage switch in the back and make sure its set to 115 and not 230.

    Have you checked to see if the CAP5 protection LED is going off?
    Last edited by blackraven; 03-24-2010 at 09:35 AM.
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  6. #6
    AR Newbie Registered Member
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    Thanks to all for the responses. I should have been more specific: the problem with the 640A is indeed that the CAPS circuit is tripping and shutting down the amp when the volume is turned up. I am happy with the punch of the MA GS10 speakers and for the most part the problem with the 640A is an irritant.
    Interesting new development: I got a new Cambridge Audio 650A to take home as a test, as the guys at the shop where I bought my gear said there was nothing wrong with the 640A. After a weekend of music of many types and volumes, the entire system performed brilliantly. I am convinced there is a fault in the 640A that causes the CAPS protection to trip at high volumes. Incidentally, the 650 is a fantastic machine.

  7. #7
    Forum Regular audio amateur's Avatar
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    The 650 looks like a nice machine indeed.

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