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  #1  
Old 14th September 2013, 03:09 PM
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Default Pre3 problem.

My Pre3 has a problem.

I have a noise on one channel, it's regular, but intermittent. I say intermittent but the gaps between are very small. A bit like motorboating but not.

When the noise appears (seems to need a little while to start) the volume control (shunted alps) and selector switch have no effect, even mute.

I did change the two 0.1uf coupling caps but that made no difference.

Help.
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Old 14th September 2013, 05:05 PM
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Default Re: Pre3 problem.

Hi Philip,

Sounds like a noisy valve, have you swapped them over to check or popped in a new one?

Pre3 runs them quite hard compared with a lot of other gear (several whole mA!) and Gerry B and I have both had noisy ECC82, the supplied JJs in particular.

I think they would be fine in gentler applications but perhaps the extra heat gets to them. We made up a good pair between ours and that was fine and I use some nos Mazda/Thorn which are good and have been in 2 or 3 years now
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  #3  
Old 14th September 2013, 07:54 PM
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Default Re: Pre3 problem.

I did try swapping the two valves around but the noise stayed put.

I'll see if I can find the original valves and try them again.
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Old 14th September 2013, 09:09 PM
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Default Re: Pre3 problem.

I found the two ECC82 and plugged them in, and the noisy channel was noisy as soon as I switched on.

I wiggled the valve a bit and it's gone quiet for now. Will see how it responds after 30 mins or so.

I was using GE 5814wa up till today.
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  #5  
Old 16th September 2013, 05:39 PM
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Default Re: Pre3 problem.

Touch wood ( puts finger on bonce ) the pre3 is still noise free.
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  #6  
Old 16th September 2013, 05:46 PM
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Default Re: Pre3 problem.

Great stuff, what do you think it was, noisy valve, dusty socket, or is it worth resoldering the bases to the pcb do you reckon?
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Old 16th September 2013, 05:53 PM
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Default Re: Pre3 problem.

I'm more inclined to blame the socket.

I re-soldered the valve bases a while ago when the problem first occurred.

Perhaps I will re-try the 5814wa at a later date.
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Old 16th September 2013, 10:19 PM
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Default Re: Pre3 problem.

Glad you've got it sorted, our Philip
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  #9  
Old 17th September 2013, 11:14 AM
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Default Re: Pre3 problem.

Quote:
Originally Posted by Greg. View Post
Glad you've got it sorted, our Philip
Cheers Greg.

I've tried several times to build a better pre-amp than pre3 but although I have had successes I always end up coming back to pre3.
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  #10  
Old 17th September 2013, 06:15 PM
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Default Re: Pre3 problem.

The Aikido not better then!
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