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Hello everyone.
I have an old Acoustic 370 that is developing "issues". Last week at a gig I plugged 2 cabs into the output and it sounded very distorted. When I unplugged one of the cabs the signal came back nice and strong so I left it that way for the rest of the gig.
Some things I noticed: When I had both cabs plugged in (around 2 ohms) the output became "dirty". It also became extremely bright. It was almost impossible to cut enough of the treble out of the signal - I had to turn ALL of the treble knobs to 0. When I went back to one cab (4 ohm) everything returned to normal.
I've replaced a couple of things over the last few years, namely the big power cap and the 3900uf cap where it's coupled to the output. I also replaced the bridge, which was shorted, but I don't think that would have any affect on the output, but it did quit blowing fuses.
The output cap was new old stock. Do these things degrade with age? Should I start looking at the high power output transistors (2n3055)? After all, they've been in there since the early '70s.
I'm not a tech and I don't have anything more sophisticated than a Fluke multimeter. But if it's something simple like replacing the output transistors, I can probably handle that. I do have a schematic and I've got good at stopping before I let the smoke out of anything. Like Abe Lincoln said: "Good judgement comes from experience, and experience comes from bad judgement".
I appreciate the help.
I have an old Acoustic 370 that is developing "issues". Last week at a gig I plugged 2 cabs into the output and it sounded very distorted. When I unplugged one of the cabs the signal came back nice and strong so I left it that way for the rest of the gig.
Some things I noticed: When I had both cabs plugged in (around 2 ohms) the output became "dirty". It also became extremely bright. It was almost impossible to cut enough of the treble out of the signal - I had to turn ALL of the treble knobs to 0. When I went back to one cab (4 ohm) everything returned to normal.
I've replaced a couple of things over the last few years, namely the big power cap and the 3900uf cap where it's coupled to the output. I also replaced the bridge, which was shorted, but I don't think that would have any affect on the output, but it did quit blowing fuses.
The output cap was new old stock. Do these things degrade with age? Should I start looking at the high power output transistors (2n3055)? After all, they've been in there since the early '70s.
I'm not a tech and I don't have anything more sophisticated than a Fluke multimeter. But if it's something simple like replacing the output transistors, I can probably handle that. I do have a schematic and I've got good at stopping before I let the smoke out of anything. Like Abe Lincoln said: "Good judgement comes from experience, and experience comes from bad judgement".
I appreciate the help.
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