12-24-2016, 02:14 PM
Not sure why but my model 84 has recently developed a hum in the audio. It is present all of the time and stays the same in that it does not get louder with volume. At first I thought it was interference hum on the A/C line, but I plugged my model 80 in the same outlet with no issues. I also swapped out tubes in the 84 one at a time but no help. Paralleled a new electrolytic cap on the 8 mfd section and then the 4 mfd section with no change. All caps were replaced and it was working great until just recently. Also no difference if it is just turned on (cold) or on for an hour. Any ideas?
