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Blackstar Amp Rattling Noise


LPguitarman

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So it's definitely one of the power tubes. While Bryan was playing, I held a rag and slightly pushed up on the tube... the rattle stopped. I'm thinking it's the white plug that the tube plugs into. Maybe it's loose, or maybe the plug holes for the tube pins are just not holding the tube tight enough. It was only on one of the tubes. We also took the retainer clip off (metal ring with two small screws) to see if it was the tube vibrating against the clip. The rattle was still there without the retainer clip.

 

Is the plug for the tube easy to replace?

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So it's definitely one of the power tubes. While Bryan was playing, I held a rag and slightly pushed up on the tube... the rattle stopped. I'm thinking it's the white plug that the tube plugs into. Maybe it's loose, or maybe the plug holes for the tube pins are just not holding the tube tight enough. It was only on one of the tubes. We also took the retainer clip off (metal ring with two small screws) to see if it was the tube vibrating against the clip. The rattle was still there without the retainer clip.

 

Is the plug for the tube easy to replace?

Try swapping the tubes and check if the noise wanders with the tube or stays with the mounting position.

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Try swapping the tubes and check if the noise wanders with the tube or stays with the mounting position.

Ok, but I would hope it's not the tube. They are brand new, just installed last week, and the rattle was happening before he replaced the tubes too.

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Guest Farnsbarns

We've covered that it's not coming through the speaker and since a revalve didn't fix it we now know it's the tube socket. Cheap nylon tube sockets are often held down with a thin pressed steel mounting allowing for movement some times. Undo the little metal bracket which holds the socket to the chassis, bend it a little so the oposing screw holes are a little further away from the chassis but being sure to bend the part that goes around the socket edge. When you retighten it it'll all be pre-tentioned which should stop the rattle.

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We've covered that it's not coming through the speaker and since a revalve didn't fix it we now know it's the tube socket. Cheap nylon tube sockets are often held down with a thin pressed steel mounting allowing for movement some times. Undo the little metal bracket which holds the socket to the chassis, bend it a little so the opposing screw holes are a little further away from the chassis but being sure to bend the part that goes around the socket edge. When you retighten it it'll all be pre-tentioned which should stop the rattle.

Thanks Farnsbarn. I assume we will have to take the chassis apart, or open it somehow, to get to the tube socket. Is there any danger in opening up the chassis? Do we need a trained technician?

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... I assume we will have to take the chassis apart, or open it somehow, to get to the tube socket. Is there any danger in opening up the chassis? Do we need a trained technician?

Be very careful! Valve/tube amps operate at potentially lethal voltages that might be present even some time after switching off and interrupting the power line, even considering that recent amp designs include bleeder resistors. The power amp of your son's Blackstar likely has 450...500 volts plate voltage.

 

After waiting ten minutes it is still very recommendable to bleed off the filter capacitors manually, again very carefully. If you're not skilled and knowledgeable enough, it is better to have it done by an expert.

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Guest Farnsbarns

It's true that the caps in there could potentially deliver a deadly shock although it would be DC (unless powered up) to which the human body has huge resistance.

 

If you're unsure a tech might be advisable, while it pains me to say it because the fix here is so simple as to stop a captive, but loose, socket from rattling. I do get it though. There is a danger and it's life at stake. At least you've pretty much isolated it to a single valve socket.

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