Hello all,
This is my first post on your forum. Im new to the tube amp scene.
I found your site while researching an amp that I have: McMartin MA-20 (20 watt tube PA amp). I am having some issues with the amp, and Im hoping that someone can help...
Anyway, the amp essentially works as it should. All tone and volume knobs are fully functional. However, there is a consistant 'crackle' that is occuring. It is very similar to the sound that a dirty pot/tone knob would make when being turned. I have cleaned everthing, replaced all of the tubes, and the 'crackle' still occurs. I dont know what else to try, any ideas?
Another problem is that there used to be a bad buzzing noise coming from the amp. I learned that when I turned down the volumn knob, the buzzing would die down as well. I assumed that one of the two pre-amp tubes were bad, so I replaced them. However, I was only able to solve the problem when I removed one of the two preamp tubes from the circuit entirely. So now, Im just running the amp with one 12ax7a tube and there is no more buzzing. This cant be normal/good for the amp. Any idea what this means??
BTW I noticed that a member by the name of 'Porkchop61' has one of these same amps and supposedly did some guitar mods to his. Would love to see what he did.
If anyone has any ideas or suggestions to these problems, please let me know. thanks, tf
This is my first post on your forum. Im new to the tube amp scene.
I found your site while researching an amp that I have: McMartin MA-20 (20 watt tube PA amp). I am having some issues with the amp, and Im hoping that someone can help...
Anyway, the amp essentially works as it should. All tone and volume knobs are fully functional. However, there is a consistant 'crackle' that is occuring. It is very similar to the sound that a dirty pot/tone knob would make when being turned. I have cleaned everthing, replaced all of the tubes, and the 'crackle' still occurs. I dont know what else to try, any ideas?
Another problem is that there used to be a bad buzzing noise coming from the amp. I learned that when I turned down the volumn knob, the buzzing would die down as well. I assumed that one of the two pre-amp tubes were bad, so I replaced them. However, I was only able to solve the problem when I removed one of the two preamp tubes from the circuit entirely. So now, Im just running the amp with one 12ax7a tube and there is no more buzzing. This cant be normal/good for the amp. Any idea what this means??
BTW I noticed that a member by the name of 'Porkchop61' has one of these same amps and supposedly did some guitar mods to his. Would love to see what he did.
If anyone has any ideas or suggestions to these problems, please let me know. thanks, tf
