Monsta-Tone
New member
I have a Blues Deluxe Re-Issue in my shop that is driving me crazy! I've worked on thousands of amps over the last 13 years and I've never had one make me as angry as this one......
It came in sounding like a blown speaker. The sound was farty and an open low E string made the entire amp buzz like a table saw with the blade stuck in a piece of ironwood.
I was tired (burned out on repairing amps....) and didn't try a different cabinet.
I swapped the speaker without trying tubes or any other standard troubleshooting.......My bad!
I changed the junk stock speaker (which looked very new) for an old Celestion/Mesa Black Shadow that I had laying around.
I also tightened up all of the baffle screws and chassis screws.
I checked the bias just to make sure the amp was running the way it was supposed to. Bias was correct in both power tubes.
The sound was still there, but not nearly as prevalent. Back to the drawing board.....
I started swapping tubes.
The PI was bad, when it was replaced with a new JJ, the amp suddenly had twice the volume!
Unfortunately, this did not remove all of the buzz, but it did help.
I swapped the other preamp tubes, one at a time. This did nothing for the noise.
I swapped in a new set of power tubes and biased the amp up again. This did nothing for the noise.
I ran the amp through an external cabinet and the blown speaker noise is still there! Not nearly as bad, but I couldn't believe my ears.
I placed my hand on top of the amp cabinet (right above the power transformer) and noticed that it was vibrating like crazy.
Then, I noticed that the power transformer is dead silent when the amp is in Standby. When I turn the amp off of Standby, the transformer starts vibrating like one of those beds you put a quarter in at a cheap motel.
Or....like the way an airplane feels the second before it starts taking off, when the engine is revved up and the brakes are still on.
I have never seen this type of problem before. I try very hard not to work on modern Fender or Marshall amps though. Nothing personal, but I would much rather have my hands in a Mesa or Rivera or Vintage Fender.
I don't fix amps for a living anymore, it's more of a make ends meet type of thing when my contracting business is slow.
Basically, what I think is happening is that the power transformer is inducing vibrations into the signal path. Maybe a cheap filter cap or something is a little loose inside.
I wanted to see if anyone else has had this issue, and how it was resolved.
Days like this make me very happy that the contracting business is picking up again......
It came in sounding like a blown speaker. The sound was farty and an open low E string made the entire amp buzz like a table saw with the blade stuck in a piece of ironwood.
I was tired (burned out on repairing amps....) and didn't try a different cabinet.
I swapped the speaker without trying tubes or any other standard troubleshooting.......My bad!
I changed the junk stock speaker (which looked very new) for an old Celestion/Mesa Black Shadow that I had laying around.
I also tightened up all of the baffle screws and chassis screws.
I checked the bias just to make sure the amp was running the way it was supposed to. Bias was correct in both power tubes.
The sound was still there, but not nearly as prevalent. Back to the drawing board.....
I started swapping tubes.
The PI was bad, when it was replaced with a new JJ, the amp suddenly had twice the volume!
Unfortunately, this did not remove all of the buzz, but it did help.
I swapped the other preamp tubes, one at a time. This did nothing for the noise.
I swapped in a new set of power tubes and biased the amp up again. This did nothing for the noise.
I ran the amp through an external cabinet and the blown speaker noise is still there! Not nearly as bad, but I couldn't believe my ears.
I placed my hand on top of the amp cabinet (right above the power transformer) and noticed that it was vibrating like crazy.
Then, I noticed that the power transformer is dead silent when the amp is in Standby. When I turn the amp off of Standby, the transformer starts vibrating like one of those beds you put a quarter in at a cheap motel.
Or....like the way an airplane feels the second before it starts taking off, when the engine is revved up and the brakes are still on.
I have never seen this type of problem before. I try very hard not to work on modern Fender or Marshall amps though. Nothing personal, but I would much rather have my hands in a Mesa or Rivera or Vintage Fender.
I don't fix amps for a living anymore, it's more of a make ends meet type of thing when my contracting business is slow.
Basically, what I think is happening is that the power transformer is inducing vibrations into the signal path. Maybe a cheap filter cap or something is a little loose inside.
I wanted to see if anyone else has had this issue, and how it was resolved.
Days like this make me very happy that the contracting business is picking up again......
