Hi-fi problem

Okay, I have a weird failure symptom of my audio gear. We upgraded our TV and speakers a few months ago, but still have the same DVD player and amplifier. A few nights ago we popped in a Dr Who DVD, planning to watch the Eccleston season again from the beginning. At a point in the first episode where there should have been an explosion (judging by the video), the amplifier spontaneously switched itself off. I switched the amp back on, rewound the DVD, and tried playing through the explosion again, 3 or 4 times, and the amp switched itself off at the same point each time.

Each time when I turned the amp back on, the front panel displayed an error message “CHK SPKR WIRES”, which I’ve never seen before, for a couple of seconds, before returning to normal working order. There’s no problem with the speaker connections as far as I’m aware – all speakers seem to be working fine. We watched the remainder of the episode, which also contained several more explosions, but the amp didn’t glitch at those.

We then watched a second episode on the same DVD, and it worked fine, until one point in the episode where the amp switched itself off again. There was no visual explosion on screen this time, and rewinding and playing through again caused the amp to switch off again at the same point, so I don’t know if there was a loud sound in the soundtrack at that point or not. Once past that point, the amp didn’t glitch again.

Last night we watched a DVD movie, without incident.

Just now, I put on the third Dr Who episode from the same DVD, and the amp is now turning itself off multiple times during the opening music/credits sequence. So annoying that we gave up and put the DVD away.

So now I’m wondering if it’s something to do with the audio levels on this Dr Who DVD, which might be overloading my new speakers and causing the amp to switch off in self-preservation, or if the amp is actually breaking down. We’ve watched this DVD before, with the same amp, but with older speakers, with no incident. I may have to do more experiments, but does anybody out there have any insights?

3 Responses to “Hi-fi problem”

  1. Stephan says:

    A quick google shows that other people have experienced the same problem with their amps. This blog entry is actually the 6th hit. Looks like there’s many possible causes. Since you got new speakers, I’d look at those first.

  2. Stephan says:

    Oh, by the way, I googled “amp switches off by itself during loud sounds”.

  3. Paul says:

    There’s an intermittent short somewhere. It could be as simple as one stray filament of speaker wire brushing the opposite terminal on the speakers or the amp connection, or the back panel of the amp itself. It’s not until there’s a significant demand on the amp that the impedance drops low enough to cause it to go into protection mode. I’d start by unhooking and reconnecting the new speakers, taking care to ensure the stripped ends of the wire are not too long, and neatly twisted with no stray copper filaments. If that doesn’t fix things, try hooking up the old speakers again to rule out a fault inside the new ones. If the old speakers give you the same results, move to the amp end and check the wires there next. Last possibility in the chain is a fault in the amp has developed.

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