Bottlehead Forum
Bottlehead Kits => S.E.X. Kit => Topic started by: StivVid on October 02, 2017, 08:06:07 AM
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Hi, all. Just finished my first S.E.X. 3.0 build. Had a listen last night before the C4S upgrade and everything sounded great. I heard a short hum through headphones when powering up. Assumed that was the transformers? Anyway... as soon as everything warmed up it was nice and quiet and sounded great. Today, I installed the C4S upgrade and am experiencing an issue. I hear a constant buzz through headphones when the power is turned off. As soon as the power is turned on, I hear the hum of the transformers then the tubes warming up, then it's nice and quiet and seems to behave normally. I'm guessing there's some kind of grounding issue if I hear buzzing before the amp is even turned on. Any thoughts?
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How were your voltage checks?
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All checked out. C4S voltages were 66 at both terminals.
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I have seen that happen from electro/magnetic fields - it can be from electric fiends (lights, dimmers, etc) or from magnetic fields (nearby transformers, electric heaters, etc.)
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You may be right. Just checked it again and no buzzing. Certainly appears to be intermittent. I'll have to do some trouble-shooting. Thanks, Paul.
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No problem. I had that with my first 300B amp - my speakers are efficient (101dB) and I heard a buzzy hum when the amps were off; I even pulled the power cord and input cables, made no difference. As you have found, once the amp is on, it greatly reduces. I have a theory why, but it's too long for a post. :^)
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i get some noise when i have the fluorescent tube lights on in my room from time to time, But i hardly use them anymore since i added a lamp at my desk.
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Well... I haven't heard the buzzing again since my original post. We'll consider the issue solved.for.now. Thanks as always for your help and suggestions.