Mesa Boogie Fifty / Fifty

[Metal_Man13]

Hey guys, I just got a Fifty Fifty in the mail (used) and it sounds great! Just one little problem... I have a hum in channel B. I made sure it was only coming from that channel. I just changed the Power tubes too. Not sure what's up. If somebody could help me out, that would be great! Thanks

 

[soundguruman]

Hey guys, I just got a Fifty Fifty in the mail (used) and it sounds great! Just one little problem... I have a hum in channel B. I made sure it was only coming from that channel. I just changed the Power tubes too. Not sure what's up. If somebody could help me out, that would be great! Thanks

Once again, the hum usually comes from AC filament noise entering the audio path.
However it can be modified with DC heaters.

Another cause of HUM is oscillation in the preamp or power amp.
This oscillation is typically high frequency, and cannot be detected without an oscilloscope.

In older amp, the hum can be caused by stale capacitors.