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Thread: Turn on Thump ! |
    
New member Username: Delirium
Post Number: 7
Registered: Jun-04
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| Posted on Thursday, June 24, 2004 - 04:41 pm: |
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I have a refurbished Harman Kardon AVR 430 and I have a KLH subwoofer plugged into it. (for power & preout). When I turn on the receiver, the subwoofer gives a loud THUMP! Then it is fine. I noticed that this sub does not have the standby delay like some other subs do, this one just turns on with the receiver... Any ideas of what this can be? Is it the sub? The wiring? Hopefully its not the HK receiver~! I just received it & it is newly refurbished from Harman Kardon... There is no Turn off thump though.. please help! |
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New member Username: Delirium
Post Number: 8
Registered: Jun-04
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| Posted on Thursday, June 24, 2004 - 04:57 pm: |
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Strangely, If I turn on the receiver quickly right after I turn it off, there is no thump... could it be its the subwoofer amp that is causing the problem? |
Silver Member Username: Project6
Post Number: 921
Registered: Dec-03
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| Posted on Thursday, June 24, 2004 - 08:34 pm: |
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it is the sub and its components. |
J. Vigne Unregistered guest |
| Posted on Friday, June 25, 2004 - 12:06 pm: |
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Thumps during powering up and down are common. They used to be a problem up to about twenty years ago when manufacturers began using muting/protection circuits that delayed the power up until voltages in the power supply settled and this helped eliminate thumps. The problem you are experiencing may be related to a faulty muting/protection circuit in the HK. I'd give them a call to ask. But, without trying to offend you, the problem is more likely a cheaper subwoofer that doesn't have a standby system. To get around this problem you should follow the turn on/off sequence that was normal operating procedure a few years ago. When you power up you go up the chain of amplification. You turn on the sources first, wait a few seconds and then turn on the next level of amplification, in this case the reciever. Let the power supply settle and then turn on the sub. When you power off you go in the reverse order. This will eliminate the thump. The other two solutions are to live with the thump if you don't think it will harm the sub. Or if it is a cracking type thump you can wait till the sub destroys itself and then go buy a sub with a decent standby circuit. I'd call HK first just to ask if they think there might be problem. |
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