No gain lotta pain

  • Thread starter Thread starter Dougtech
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Dougtech

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I am new to amps. I have a 1978 jmp 50 watt that has no gain. Do the big capacitors have anything to do with it? I replaced the preamp tubes to no avail.

Thanks for all the recommendations guys. Please don't laugh too hard, but as l said, l have 0 amp repair experience. I cleaned the pre amp and master volume pots with contact cleaner and the grit is back and has not gone away since (so far). For the record, l am replacing the caps. Also, some of you are correct, it is not a ton of grit, but I really like that tone. Thanks again, everyone.
 
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By "no gain"...what exactly do you mean? Can you post a short clip?
 
sorry, the pre-amp knob just seems to act as a volume knob, the sound is great. Crystal clear but no grit at all. I have it apart right now or I'd add a clip. I see one of the big blue capacitors has some blistering so I assume it is bad, but will that affect the gain?
 
What does the volume knob do ? LOL I want this to be a legitimate thread !!! LOL!!
 
Dougtech said:
sorry, the pre-amp knob just seems to act as a volume knob, the sound is great. Crystal clear but no grit at all. I have it apart right now or I'd add a clip. I see one of the big blue capacitors has some blistering so I assume it is bad, but will that affect the gain?
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So if you turn the master volume all the way down, and the preamp gain all the way up, and slowly turn up the master....it is crystal clear? What preamp tubes do you have in in the slots?
 
Jmp will not give you modern high gain . I think he’s expecting modern gain tones out of the wrong amp
 
What’s a tone you are trying to achieve with this amp ? Name a song that has the sound you’re going for ? That will help
 
It`s hard to do any "remote diagnosis". Someones gained out is a crunch or break up for another one. Just post a video where you have different settings on the amp.
 
Techdeth said:
Jmp will not give you modern high gain . I think he’s expecting modern gain tones out of the wrong amp
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Thanks for the response, but the gain l speak of comes and goes. It is great when it works. It is a gain this amp can do that it once had but no more.
 
BesaMoogie said:
It`s hard to do any "remote diagnosis". Someones gained out is a crunch or break up for another one. Just post a video where you have different settings on the amp.
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Thanks, but it is not settings. The amp had the gain but it is now gone.
 
BesaMoogie said:
It`s hard to do any "remote diagnosis". Someones gained out is a crunch or break up for another one. Just post a video where you have different settings on the amp.
Click to expand...
This amp had what I wanted but it is now gone.
 
japetus said:
So if you turn the master volume all the way down, and the preamp gain all the way up, and slowly turn up the master....it is crystal clear? What preamp tubes do you have in in the slots?
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Yes, turn master all the way down, crank pre amp all the way up. Then add master. No gain, crystal clear like beach boys.
 
Panhead5 said:
What does the volume knob do ? LOL I want this to be a legitimate thread !!! LOL!!
Click to expand...
The volume knob works fine and the pre amp knob acts basically like another volume knob. There is no grit to the sound at all. It had the grit I want intermittently but is now gone for good.
 
The big capacitors shouldn't have anything to do with it. If you swapped the preamp tubes with no success then it's something else in the circuit.
 
You're going to need to take it to a tech unfortunately to go over the preamp.
 
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