Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: slash1986 on February 26, 2015, 04:54:29 am
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Hi, I write here because I have a problem with my tube amp for guitar.
the amplifier is this model:
JET CITY JCA20H.
The problem is that it emits a bad noise like a buzz when I raise the gain and volume.
When I lower the master volume buzz disappears, when I raise the master buzz reappears, obviously all with the selector of the gain to 7/8.
if I lower the gain noise is reduced obviously.
I thought that might be the preamp tubes, and I changed v1 and v2, but the result does not change.
What could it be? a problem of ground?
I live in an old house and I do not have ground.
Can this be the problem?
I am attaching the recording of the noise:
The gain is set at 7, I raise the volume gradually a couple of times, and with the volume up increasing the presence control.
it is normal for a 20w amplifier make this noise?
what kind of trick that noise is?
I hope you can help me
Thank You.
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Has the amp always made this buzz? Does it buzz if no guitar plugged in? That's not uncommon for a high gain amp to buzz like that. Fluorescent lights or lamp dimmers in the area can cause that buzz. Having a good grounding system in your house may help. Take the amp to another location and see if you still have the buzz.
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Hello. Yes, the amplifier does even if the guitar and the cable are not connected.
I tried to change the room, but he does it anyway.
I should try another house.
if it continued what would be the solution?
could be the power supply section?
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Has the amp always made this buzz? There may not be a solution.
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Yes, I think it has always done. has always been in the same position and the same outlet. I realized why when I turned up the volume to make recordings, and with the high gain, making noise. I do not know if it's just my amp.