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Hello folks,
I imagine there are a bunch of fixes for this issue. I'm just sharing an experience I had with a 70's SF Super Reverb. I think it was a Rain Drip edge, but someone changed the Grill cloth & I think they removed the edge.
This particular amp would make the thumping trem noise and was particularly loud when the reverb was turned up. I found that moving the wire from the trem Oscillator tube V5 p2 away from the rivet board, the thumping got louder. Against the board it was quieter, but still too loud.
Moving it closer to the neon drive side of the bug made it louder, so that seemed to be the source.
Regardless, my aim is to remedy the issue w/o trying to redesign it. I replaced the wire from p-2 to the rivet board with a shielded cable and grounded the one end at the tube to the ground lug of the Vibrato pedal (the closest ground availabe),
The trem is absolutely quiet with reverb up or down AND the shape of the trem pulse is wider with a much smoother affect, as opposed to the kind of on-off effect it had previously.
Since p-2 is the grid of the oscillator section of V-5 and the bug side is the plate, I have to think the pulse of the bug was affecting the shape of the oscillator.
I know there are a ton of these amps out there and this symptom might be unique to this particular one, so who knows if I or anyone will ever experience this issue.
Still, if there's any place to post this info, this is it!
Thanx, Glen
I imagine there are a bunch of fixes for this issue. I'm just sharing an experience I had with a 70's SF Super Reverb. I think it was a Rain Drip edge, but someone changed the Grill cloth & I think they removed the edge.
This particular amp would make the thumping trem noise and was particularly loud when the reverb was turned up. I found that moving the wire from the trem Oscillator tube V5 p2 away from the rivet board, the thumping got louder. Against the board it was quieter, but still too loud.
Moving it closer to the neon drive side of the bug made it louder, so that seemed to be the source.
Regardless, my aim is to remedy the issue w/o trying to redesign it. I replaced the wire from p-2 to the rivet board with a shielded cable and grounded the one end at the tube to the ground lug of the Vibrato pedal (the closest ground availabe),
The trem is absolutely quiet with reverb up or down AND the shape of the trem pulse is wider with a much smoother affect, as opposed to the kind of on-off effect it had previously.
Since p-2 is the grid of the oscillator section of V-5 and the bug side is the plate, I have to think the pulse of the bug was affecting the shape of the oscillator.
I know there are a ton of these amps out there and this symptom might be unique to this particular one, so who knows if I or anyone will ever experience this issue.
Still, if there's any place to post this info, this is it!
Thanx, Glen
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