Chinaski
331 posts
Sep 09, 2016
2:36 AM
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I have an otherwise great sounding small amp, which is producing noticeable tube rattle at certain frequencies. Usually on the lower notes of lower pitched harps.
I've tried rubber damper rings on the power tubes, but to no avail.
Anybody else have a cure for this before I fork out for a new set of tubes, which possibly won't fix it either!
Last Edited by Chinaski on Sep 09, 2016 2:37 AM
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SuperBee
4097 posts
Sep 09, 2016
3:35 AM
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why do you believe it is tube rattle? rather than speaker voice coil rub or cone cry for instance?
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Chinaski
332 posts
Sep 09, 2016
4:27 AM
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I know it's tube rattle - it is a very specific kind of noise that I'm already aware of.
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SuperBee
4098 posts
Sep 09, 2016
5:43 AM
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External cab
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tmf714
2884 posts
Sep 09, 2016
6:35 AM
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Tube dampers are ok-but if its filament rattle,you'll hear it when the amp is on tapping with a pencil.
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1847
3678 posts
Sep 09, 2016
7:16 AM
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i just spent a month of sundays tracking down a tube rattle. to confirm it was a tube
i took the chassis out, i had just enough lead wire to the speaker to test it. it was indeed the power tube.
it seems the magnet in my case was affecting the electrons somehow. i tried several ways to get the tube further away
from the speaker. so finally just this week, the holes on the chassis were enlarged just enough to slide it far enough away
from the speaker and that seemed to do the trick. now i just need to shim the back plate somehow to get it attached to the back before i electrocute myself.
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barbequebob
3291 posts
Sep 09, 2016
9:03 AM
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Sometimes this can be caused by a tube getting loose in the socket and that usually is remedied by just pushing the tube further into the socket (make sure you do it gently) and newer production tubes tend to be more prone to having this happen.
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Sincerely,
Barbeque Bob Maglinte
Boston, MA
http://www.barbequebob.com
CD available at http://www.cdbaby.com/cd/bbmaglinte
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Chinaski
333 posts
Sep 09, 2016
1:31 PM
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Thanks for the replies, guys.
Bob - not a tube that has worked loose from socket, have been through the whole amp nipping and tightening!
Interesting what you say about newer production tubes, though. I may see if I can track down some older ones.
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Barley Nectar
1256 posts
Sep 09, 2016
4:48 PM
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It's usually just one tube. You may find the culprit by using the tap test or substitution. I have had this happen with tubes of all vintage. Used, NOS, New Production. Can happen to any of them.
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Bugfan
52 posts
Sep 09, 2016
7:27 PM
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Had the same thing. Amazing how loud the rattle was. The inside guts if the tube restyled against the glass at certain frequencies. I couldn't work it out with harp what it was... Tried the cage, the amp chassis, all the screws, valve base ... but using a guitar it was easy to track and identify. The only cure is different tubes that have different clearances inside the valve itself.
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