@ebm I compliment you on adding punctuation to your posts. It’s an improvement. Spelling will be your next great challenge. Perhaps in time, your posts will actually be helpful or informative.
tube noise - 2 questions
Q1: Three months ago, I installed two matching NOS 6DJ8’s in my preamp. Sounded great up until a week ago. Barely audible tube rush on startup - and then totally quiet. Three months later, one started making crackling noises. Only intermittently. It will crackle for a few minutes - then all is well again for days. But, this repeats every so often. Does this intermittent problem mean that tube is soon to be history?
Q2: With a different preamp, a NOS 12AU7 had crackling & popping noises from the get-go. The noise never went away - even after 100 hours of burn-in. I tried the same tube in my DAC, zero noise - ever. Why might that be?
Q2: With a different preamp, a NOS 12AU7 had crackling & popping noises from the get-go. The noise never went away - even after 100 hours of burn-in. I tried the same tube in my DAC, zero noise - ever. Why might that be?
8 responses Add your response
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@steakster You can count on it coming back again... Its giving you plenty of warning that you need to find another tube. |
Q1: the tube has an intermittant problem. Giving it a good whack on the side might shut it up for a while. Eventually that will get old- just change it out. Q2: This depends on the gain of the circuit. In a DAC, the gain is relatively low, but if you use that same tube in the front end of a phono section it might be quite noisy. If its not a problem further upstream or in the DAC, that's probably where it should stay. |
I've experienced similar sounds with tubes. If it goes away, or is intermittent, you should be ok. The tube rush sound will only get worse over time, but usually takes a long time to get there. If you can hear the tube rush from say, 2 to 3 feet from the speaker, not much of a problem. If you start hearing it at the listener's position, it might be time for replacements. IMO |