Lightning Hands
New member
Just got a Bugera 333 XL Infinium and a Blackstar 2x12. Is makes a crackling sound when I turn it off. Any idea why?
Need a little help
- Thread starter Lightning Hands
- Start date
glassman
Electron Herder
Re: Need a little help
Simple answer: It's normal behavior and nothing to worry about.
More complex answer: The cause is a mixture of the design of the power supply, component quality, the output tubes in the amp and how they are set up. When you power down, the bias supply for the power tubes discharges causing the current to increase in the power tubes. If the amp was in standby for some time prior to shutdown, there still is a couple of volts on the power rail. High gain amps have a considerable amount of reserve in the filter caps, even at only a couple of volts. What voltage is left bleeds off pretty quickly when the bias supply bleeds down and depletes the reserve in all of the filter caps from the screen supply back to the preamp node...and through any dropping resistors that are in the circuit. That's where the noise comes from...the current running through the dropping resistors. Some resistors hiss, some crackle; with most amps, it fades in rather quickly and then fades out at a similar rate.
Simple answer: It's normal behavior and nothing to worry about.
More complex answer: The cause is a mixture of the design of the power supply, component quality, the output tubes in the amp and how they are set up. When you power down, the bias supply for the power tubes discharges causing the current to increase in the power tubes. If the amp was in standby for some time prior to shutdown, there still is a couple of volts on the power rail. High gain amps have a considerable amount of reserve in the filter caps, even at only a couple of volts. What voltage is left bleeds off pretty quickly when the bias supply bleeds down and depletes the reserve in all of the filter caps from the screen supply back to the preamp node...and through any dropping resistors that are in the circuit. That's where the noise comes from...the current running through the dropping resistors. Some resistors hiss, some crackle; with most amps, it fades in rather quickly and then fades out at a similar rate.
Lightning Hands
New member
Re: Need a little help
Thanks so so much. I thought I was gonna have to get it checked or get a new one. I really appreciate your help.
Thanks so so much. I thought I was gonna have to get it checked or get a new one. I really appreciate your help.
