Rattling on Fender Red Knob Twin! What could be the cause?

[jalexquijano]

My 1991 Fender Red Knob Twin rattles whenever i play the bass notes after volume 3 on either channels. I already checked all the preamp and power tubes and everything ssems ok. I also tightened the chassis screws. Could the rattling be attributable to the Speakers? Could one of both 12 inch speaker be damaged?

[Jazz P Bass]

Damaged or the screws are loose.

[Mick Bailey]

I've repaired a few Fenders with rattles that sounded like speaker or mechanical problems, but where it's turned out to be fractured solder joints on the preamp electrolytics. Even If the amp is connected to an extension cab to disconnect the internal speakers, the caps become sensitive enough to cause the sound of a speaker rattle.

[Alex R]

spent a long time chasing a rattle round a Twin once. It was the handle.

[Jazz P Bass]

I had a rattle on a Hot Rod Deluxe.
It was the indicator lamp holder.

[Mick Bailey]

Just had a Kustom 100w combo (should that be Kombo?) with a freaky loud rattle on the E and A strings. It was the spring inside one of the 'tilt-back' bayonet-action legs. Sounded exactly like speaker rattle. Even pressing one side of one of the speakers stopped it.

[jalexquijano]

Just to let all of you know that i solved the rattling. It was a preamp tube in V1 position which controls the overdrive channel. I swapped the Sovtek 12ax7Wa tube with a Marshall ECC83 red labeled i used to have in my 1959 Marshall Hand Wired plexi and viola the rattling is gone. I wish i could figure out who manufactures this low microphonic preamp tubes for hi gain amps?

[g1]

Did that also fix the squealing problem you had with channel 2? Or did something else fix the squealing?

[jalexquijano]

various things helped fixed the squealing:

1. Be sure to solder correctly all the filter capacitors and there is enough solder on their terminal so the circuit is not interrupted.

2. Double check all of the small cables that run from the preamp tube sockets to the central preamp pc board

3. Use a low microphonic preamp tube such as Marshall labeled ECC83 for V1 and V7 position.

[Jquijano]

I'm back again with this same issue as 2013. Had my amp fixed by an experienced tech but still chasing a mechanical rattling sound. I really dont know where it comes from. I took some pictures of the preamp tubes in V7 and V1 for ready reference and comments. Should i get better quality preamp tubes? More sturdy and less microphonic?