6B4G noise
Posted: Thu Jan 06, 2011 10:17 am
I finished up my switchable 6B4G/2A3/300B GSG last august and since then have noticed a burst-noise (digital noise?) like sound increasing whenever I have the 6B4G selected as the output tube. At first it's nice and quiet and not much of a problem, but as I listen longer I hear it more and more and slowly to go insane. It sounds exactly like the noise that computers always pump out of their on-the-motherboard sound card. The 2A3 has nothing of the sort (though has a different filament supply), and the 300B are also silent (and share all but a paralleled 1.5R resistor).
What was strange is that I happened to swap the left and right 6B4G and the noise followed. Further tests confirm the noise follows the 6B4G. (at least I can stop tinkering with the wiring beneath ).
Anyone know of why this could happen? Is it a sign of the tube's imminent death? I could try to get another few 6B4G tubes, but with a 2A3 and 300B a switch throw away, it's not high on my priority list. Maybe I'll just mark it with a big scarlet 'N' to indicate it's propensity towards noise
What was strange is that I happened to swap the left and right 6B4G and the noise followed. Further tests confirm the noise follows the 6B4G. (at least I can stop tinkering with the wiring beneath ).
Anyone know of why this could happen? Is it a sign of the tube's imminent death? I could try to get another few 6B4G tubes, but with a 2A3 and 300B a switch throw away, it's not high on my priority list. Maybe I'll just mark it with a big scarlet 'N' to indicate it's propensity towards noise