Boom of death!!

[bay24]

Hi all,

My Cambridge audio 740a has started to make a very loud boom/thudd noise through the speakers quite often when it is powered up. This seems to trip my amp and the readout says possible internal amplifyer failure. I sent it off to Cambridge audio and they did a factory reset and ran it for a couple of days and said there was no problem. it came back home and seemed okay for a couple of days but it has started again. Anyone have any ideas what it might be? I am planing to send it back to Cambridge audio but I am worried it may be something else in my system causing it or they will just tell me it is fine.

Any ideas would be great.

 

[nopiano]

I suspect it isn't fine at all, and they just failed to spot the fault as it is intermittent.

You risk damaging your speakers so don't use it any more. I cannot think what else would cause it, particularly from other system components, as long as all the basics about sound connections are OK. Some amps are sensitive to items like fridges switching on, but you'd have noticed that originally.

They maybe need to test it for more than a couple of days, and not just leave it on but cycle it every hour. Nothing very advanced, just common sense.

Fingers crossed it's second time lucky!

 

[churchill1963]

Hi,

I have a similar thud on my Cambridge Audio A5 amp. It's not that loud and it happens on power up and when it is turned off (I always turn the volume down first). I can't remember when it started but it was not there when I first brought it. I thought it might be something to do with the power supply, on/off switch or shielding, but I'm no expert. I would also like to know what the cause is as I have replaced my old Rogers with LS50s. I am looking to buy a new amp soon, has anybody had this problem with any other make?

 

[Blackdawn]

A small thud can be quite normal when you switch on the amp. For example, my dads NAD 3020A has been doing this for 25 + years with no harm to the Mission speakers as they haven't been changed and work just as well now as in the past. The volume is always on zero anyway when I turn on the amp just to make sure. With my Denon PMA 250SE there is no thud, just a click of the relay and the same for my new Pioneer A30 (no thud). I guess it depends on make/model and age. If the thud/ boom is very loud I would insist on getting the amp serviced or replaced by dealer.

 

[bay24]

Thanks very much for your responses. It is a loud thud. I didnt think it would be something else in my system but thought i should ask. I have turned it off so it does not ruin my speakers. I need to send it back to them and get them to test it for longer and do lots of turning it on and off. Glad I took out the 5 year richer sounds warranty!

 

[abacus]

All amps and AV Receivers produce this voltage spike, which is why they have relays (Or similar) in the output section that delays connection to the speakers, thus giving time for the spike to pass and subside.

On switch off the relay acts immediately to disconnect the speakers so as to prevent any voltage spike reaching them.

It sounds like yours (Or the control circuit) has become faulty and needs replacing.

Hope this help

Bill

 

[BigH]

My old NAD amp used to do this when switching off, no harm done I don't think, do you have a mute button on your amp, if so I would put that on at switch on.

 

[bay24]

I dont think I can mute it as it happens at power on before I can control the amp. I am going to take it back in to richer sounds asap.

 

[bay24]

All amps and AV Receivers produce this voltage spike, which is why they have relays (Or similar) in the output section that delays connection to the speakers, thus giving time for the spike to pass and subside.

On switch off the relay acts immediately to disconnect the speakers so as to prevent any voltage spike reaching them.

It sounds like yours (Or the control circuit) has become faulty and needs replacing.

Hope this help

Bill

Thanks for this I will sugest this to them when I take it back.

 

[BigH]

I dont think I can mute it as it happens at power on before I can control the amp. I am going to take it back in to richer sounds asap.

Yes best to take it back if you think there is a problem.