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andrew Ivimey
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#16

Post by andrew Ivimey »

Those are the swtiches I too use in my home builds Philip.
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Mike H
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#17

Post by Mike H »

There's no rule that sez you can't have mains suppressors on every amp. Think I have, just about.
 
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andrew Ivimey
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#18

Post by andrew Ivimey »

Who abides by rules anyway!
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Paul Barker
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#19

Post by Paul Barker »

"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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andrew Ivimey
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#20

Post by andrew Ivimey »

So I should short the speakers before switching off?
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Nick
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#21

Post by Nick »

That is a STARTUP mute.

You are opening a world of work if you want the output relay to operate before the mains goes away. And if you are going to do that, you may as well just use a zero crossing switch. Assuming that is the actual problem. Its just as likely the falling HT is the cause of the problem instead of spikes on switch off.
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andrew Ivimey
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#22

Post by andrew Ivimey »

Exactly - I don't see the point of Paul's posting so my comment was not at all serious.
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Nick
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#23

Post by Nick »

Though, while that won't save you from the switching transient, it would be fast enough if its the B+ dying.

You need to be more specific about the noise in question :-)
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#24

Post by Mike H »

Just FYI, never had abrupt noises caused by dying HT. :?: Guess it depends how fast? From which you may gather mine is not that fast :D
 
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#25

Post by Nick »

Mike H wrote:Just FYI, never had abrupt noises caused by dying HT. :?: Guess it depends how fast? From which you may gather mine is not that fast :D
Yep, if the heaters go before the + then all is generally well.
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andrew Ivimey
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#26

Post by andrew Ivimey »

my problem is ... what is the sound a 'spike' makes? an electronic 'click', something that affects only the tweeters (because they are 'fast' enough). I can imagine an instantaneous arc making this sort of noise.

But why should it happen?

It doesn't happen with my GM70 SE amp, for example, and the HT always goes off before the heaters for an obviou reason.
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#27

Post by Mike H »

You still haven't said what amp it's happening to. Must be something particular about that amp.

Like I said it's an arc or mains transformer being switched off halfway through a half cycle as Nick said, it induces a pulse type signal into the amp, no amount of delayed HT decay or what supply goes off first will make any difference, it's a radio pulse that's picked up and amplified by the amplifer.

Best demonstration is an AM radio and turn on and off your room light switch. :D

Isn't necessarily confined to treble, you can get quite a powerful click noise.

HTH
 
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#28

Post by Mike H »

 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
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