Manley Compact 160w noise problem -please help - diyAudio
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Old 7th February 2009, 08:09 AM   #1
alexIG is offline alexIG  Canada
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Default Manley Compact 160w noise problem -please help

Hi,
I have a pair of Manley Reference Compact 160 W monos. One of them developed constant crackling/sputtering noise mixed with periodic noise that sounds like a static discharge. It does not look like a tube or a plate resistor problem. As soon as I install one output tube in any of 4 sockets the amp starts producing this noise. The same tube is dead quiet if I install it in my other amp. I donít think that itís a failing cap in the power supply either because I donít hear any hum/buzz. Suggestions are welcome with many thanks.
Alex
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Old 7th February 2009, 12:43 PM   #2
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Solder joint, loose pin in socket, and coupling cap would be the first three places I'd look, assuming you've truly eliminated the tube as a possibility.
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Old 7th February 2009, 12:46 PM   #3
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Pull the input tubes and see if it still does it.
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Old 7th February 2009, 03:27 PM   #4
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Solder joint, loose pin in socket, and coupling cap would be the first three places I'd look, assuming you've truly eliminated the tube as a possibility.

Itís very unlikely that its a socket or capacitor since the amp makes noise when I put one tube in any of 4 sockets. One or two sockets can fail at a time but not all of them and the same with coupling capacitors. I also forgot to mention that from time the amp blows B-fuse and yesterday it blew main fuse. However it still working after I replace blown fuses.
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Old 7th February 2009, 03:27 PM   #5
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Default Pull the input tubes and see if it still does it.

It makes the same noise when I pull the input tubes.
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Old 7th February 2009, 04:57 PM   #6
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I'm starting to think bad electrolytic in the B+ HV or bad electrolytic in the B- bias supply.

Do you have a schematic you can post?
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Old 7th February 2009, 09:26 PM   #7
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I isolated one problem- a faulty output tube. I replaced it. Now when I pull input tubes the crackling noise is gone but I can hear some buzz which it s not as loud (I can hear it only 1-1.5 ft from a speaker) as was the noise from the faulty output tube. When I put input tubes back the noise is the same as it was with bad output tube. It does not look like input tubes are bad. When I put them in my second amp they are pretty quite there.

I isolated one problem- a faulty output tube. I replaced it. Now when I pull input tubes the crackling noise is gone but I can hear some buzz which it s not as loud (I can hear it only 1-1.5 ft from a speaker) as was the noise from the faulty output tube. When I put input tubes back the noise is the same as it was with the bad output tube. It does not look like input tubes are bad. When I put them in my second amp they are pretty quite there.

Unfortunately I donít have schematics.
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Old 7th February 2009, 09:26 PM   #8
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I just realized that I made a mistake. When I said that I pulled input tubes indeed I pulled both input tube and driver tube. When I pull only input tube the noise get louder. Crackling noise is gone only when both input and driver tubes are pulled.
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