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Cambridge audio A5i with blown speakers.
Cambridge audio A5i with blown speakers.
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Old 25th January 2008, 12:24 PM   #1
elaar is offline elaar  United Kingdom
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Join Date: Oct 2005
Default Cambridge audio A5i with blown speakers.

Hi all,

I had a bit of a party in my small flat, my cambridge audio A5i (the same as an A5 but with large transformer and copper shielding) amp's volume was sitting about half way for what must have been about 4 hours. I estimate this to be about 30watts.

All of a sudden all bass in the music went and we were left with a very quiet tinny treble sound. I immediately thought something in the amp had gone as it wasn't on particularly loud and the bass went in both channels at exactly the same time. The speakers were fairly cheap, being Gale mini monitors but are supposed to be rated 60W+.

I have since found out that the amp is working correctly (tested with other speakers), but was concerned that the amp had malfunctioned in some way and perhaps sent a considerable DC voltage to the speakers etc. causing both of the bass speakers to go at the same time. I just wanted to get people's thoughts on this before I go out and spend some money on some nice new speakers

Many thanks,
Andy
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Old 25th January 2008, 04:31 PM   #2
jaycee is offline jaycee  United Kingdom
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Join Date: Apr 2004
Location: Norwich, UK
If you were driving the system into clipping then this could have blown the speakers even at "only" 30W of power.

You might want to check the DC offset on the speaker outputs with a multimeter, but to be honest i would expect the A5i to have a protection circuit that'd be tripped if the DC was excessive.

I'd say it's just party syndrome - volume turned up to the point where the signal distorted (but not noticeable in a party environment), and the DC from the clipping killed the speakers.

Check the speakers themselves by gently depressing the bass cone. If the motion feels smooth, the drive units are probably OK (and there could be some fuse/parts in the crossover blown instead). If the motion feels rough or you can hear grating, then the voice coils are fried.
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Old 25th January 2008, 04:58 PM   #3
elaar is offline elaar  United Kingdom
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Join Date: Oct 2005
It was a party, but i'm very careful with the my audio equipment and always conscious of the neighbours so it really wasn't that loud, certainly not loud enough to clip, also I never let anyone touch my tone controls

I removed the rear speaker posts from the back of the speakers, the crossover components look fine externally, there are no fuses.
I've had bass speakers blow in the past and when the voice coil was fried you could tell from the muffled sound coming from them. At present, absolutely no sound is emiited from the bass speakers which I thought was wierd.

Thank you for your reply and I will check the DC offset when I get a mo.

Cheers,
Andy
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Old 25th January 2008, 05:36 PM   #4
Nigel Goodwin is offline Nigel Goodwin  England
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Join Date: Jul 2005
Location: North Derbyshire
It sounds like the voice coils have gone O/C, either due to the amp failing (DC on the outputs) or just too much power and blown them. However, if the amp had failed, you wouldn't be getting the tweeters still working - so I would suspect too much power.

The position of the volume control doesn't really matter, even at half way you might have been over driving them - party conditions aren't good for small domestic speakers.

If you have a multimeter, put it on the lowest ohms range, and measure directly across the voice coils of the bass units - it should read about 6 ohms or so. If it does?, there may be a fuse somewhere inside the crossover (but this would be rare for the bass units).
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