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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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28th Mar 2017, 10:12 pm | #1 |
Hexode
Join Date: Apr 2016
Location: Yeadon, West Yorkshire, UK.
Posts: 251
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Clicking tapping noise possibly coming from valves after turning off.
I'm not sure if it's normal or not but I have recently realised after switching off my valve amplified record player after the valves have fully heated up (>20mins) there is an irregular clicking/tapping noise coming from the amplifier somewhere, most likely the valves and persists for about a minute after turning off.
My best guess is that it's the sound of the metal and glass contracting as the valve cools although you don't hear those noises when you turn a hot incandescent light bulb off. Should be noted that the amplifier still works absolutely fine. Is it an early sign that the valves will need replacing soon? any help is appreciated. The amplifier consists of 2 UF89 valves and 2 UL84 valves. 1 of each on 2 separate circuits. Thanks Peter |
28th Mar 2017, 10:32 pm | #2 |
Banned
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
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Re: Clicking tapping noise possibly coming from valves after turning off.
Turn it off and go and do something else away from it. Stop worrying, its normal when things cool down.
0.1A heater valves are cheap and easy to find anyway. Its likely to be a metal part cooling anyway, valves are quiet beasties. |
28th Mar 2017, 10:54 pm | #3 |
Dekatron
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,087
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Re: Clicking tapping noise possibly coming from valves after turning off.
Definitely! I've heard the same. Nothing to worry about.
Unusual valve line-up, is it a stereo record player or a fairly powerful mono one with push-pull output? The UF89 is a variable-mu pentode so would introduce a bit of distortion. |
28th Mar 2017, 10:57 pm | #4 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,554
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Re: Clicking tapping noise possibly coming from valves after turning off.
They mount the chassis on rubber feet of one kind or another on posh sets to stop the heat expansion noises being heard. They are normal on things with metal frames in wooden cabinets.
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29th Mar 2017, 5:35 am | #5 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 7,667
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Re: Clicking tapping noise possibly coming from valves after turning off.
The amp I'm working on at the minute sound's like it's ripping itself apart when it cool's down, the normal pop's and clicks are amplified by the chassis. It can sound like something is wrong but is just normal contraction as you say.
Still our senses are there for a reason, maybe you've picked up on something. If your UL84's are running hot due to leaky coupling cap's or a similar fault, it will sound louder. Are they blackened? Check the cathode current to be on the safe side. Andy.
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29th Mar 2017, 9:29 am | #6 | |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,335
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Re: Clicking tapping noise possibly coming from valves after turning off.
Quote:
Yes, it used an IF valve for the AF function.
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Edward. |
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29th Mar 2017, 10:50 pm | #7 |
Hexode
Join Date: Apr 2016
Location: Yeadon, West Yorkshire, UK.
Posts: 251
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Re: Clicking tapping noise possibly coming from valves after turning off.
It's a stereo record player made by EMI/Capitol but badged as HMV in 1958/9 as Edward said. I was told that the amplifier uses U series valves simply because they were cheaper for the manufacturer to buy.
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30th Mar 2017, 12:15 am | #8 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,554
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Re: Clicking tapping noise possibly coming from valves after turning off.
I would be prepared to say that the U series valves were used for their low heaters at 100ma in series so that they could get away without using a transformer.
The valves cost the same as any others. |
30th Mar 2017, 12:21 am | #9 |
Nonode
Join Date: Jun 2014
Location: Bristol, UK.
Posts: 2,074
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Re: Clicking tapping noise possibly coming from valves after turning off.
Probably not the problem but I did get a couple of 'ticking' 6V6G Russian equivalents from a nice guy in Ukraine a few years ago. He eventually found a couple of good ones for me but he had a whole batch that ticked! Mind you - that was when the amp was running.
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