I recently purchased an Xduoo TA-26s OTL tube amp to use with my HD 600s, and I've encountered what seems to be a reasonably common issue with tube amps: I'm hearing some noise/buzzing in the headphones when I use them with the amp. I've read some other threads on Head-Fi and elsewhere discussing similar problems, but I'm looking for some additional help in diagnosing the problem beyond what I've been able to glean from those threads.
Some more detail about what I'm noticing:
The noise is only audible when the volume is at zero; when I turn the volume up a little bit, it goes away and so doesn't really affect music playback. That said, the noise is quite noticeable when the volume is at zero. The noise in question is actually two different sounds. First, there's a white noise-like, whooshing sound that is softer but occasionally also involves the tubes picking up a radio signal. Second, there is a buzzing or humming sound that is somewhat louder; it is more or less prominent depending on where the headphones and headphone cable are positioned relative to the amp. To be clear, all of this is noise I'm hearing in my headphones when they are plugged into the amp (i.e., "within" the audio chain); there is no unusual mechanical humming or buzzing coming "externally" from the amp itself.
I switched out the power tube and preamp tube for replacement ones I have. Initially I thought that changing the preamp tube made a difference, but with more testing I no longer think this is the case. In other words, the problem appears to be independent of what tubes I'm using, though I haven't done a ton of testing and my ability to do so is limited by the small number of tubes I have. I've also previously had the chance to try out a TA-26 that was entirely silent in terms of noise in the headphones when the volume knob was placed at zero, so I'm confident in saying that this doesn't always occur with TA-26 units. I'm not clear, however, on whether people often accept at least a little bit of noise from tube amps with the volume at zero, so long as it isn't affecting one's listening experience. Maybe the "dead silent" unit I tested was an outlier. Some online searching suggests that this issue could sort itself out with time; I've only had the unit for a week or so and used it a few times.
Does anyone have any thoughts re: what might be causing the issues I've described here and to what extent you would regard them as a problem that might call for replacing the amp? Any idea, in particular, what might be causing the humming/buzzing sound I described to vary in intensity when I move the headphones/headphone cable relative to the amp (i.e., literally when I walk around with the headphones on and cable in hand)? I'm still quite new to tube amps, so any suggestions or thoughts would be appreciated.
EDIT: It sounds like the problem I'm describing may be a grounding issue, because disconnecting the RCA cables linking the amp to the DAC eliminates the noise. If anyone else has further thoughts on what could be going on or suggestions for how best to continue troubleshooting it (or when to give up and just return the amp), I'd be grateful for your advice!
Some more detail about what I'm noticing:
The noise is only audible when the volume is at zero; when I turn the volume up a little bit, it goes away and so doesn't really affect music playback. That said, the noise is quite noticeable when the volume is at zero. The noise in question is actually two different sounds. First, there's a white noise-like, whooshing sound that is softer but occasionally also involves the tubes picking up a radio signal. Second, there is a buzzing or humming sound that is somewhat louder; it is more or less prominent depending on where the headphones and headphone cable are positioned relative to the amp. To be clear, all of this is noise I'm hearing in my headphones when they are plugged into the amp (i.e., "within" the audio chain); there is no unusual mechanical humming or buzzing coming "externally" from the amp itself.
I switched out the power tube and preamp tube for replacement ones I have. Initially I thought that changing the preamp tube made a difference, but with more testing I no longer think this is the case. In other words, the problem appears to be independent of what tubes I'm using, though I haven't done a ton of testing and my ability to do so is limited by the small number of tubes I have. I've also previously had the chance to try out a TA-26 that was entirely silent in terms of noise in the headphones when the volume knob was placed at zero, so I'm confident in saying that this doesn't always occur with TA-26 units. I'm not clear, however, on whether people often accept at least a little bit of noise from tube amps with the volume at zero, so long as it isn't affecting one's listening experience. Maybe the "dead silent" unit I tested was an outlier. Some online searching suggests that this issue could sort itself out with time; I've only had the unit for a week or so and used it a few times.
Does anyone have any thoughts re: what might be causing the issues I've described here and to what extent you would regard them as a problem that might call for replacing the amp? Any idea, in particular, what might be causing the humming/buzzing sound I described to vary in intensity when I move the headphones/headphone cable relative to the amp (i.e., literally when I walk around with the headphones on and cable in hand)? I'm still quite new to tube amps, so any suggestions or thoughts would be appreciated.
EDIT: It sounds like the problem I'm describing may be a grounding issue, because disconnecting the RCA cables linking the amp to the DAC eliminates the noise. If anyone else has further thoughts on what could be going on or suggestions for how best to continue troubleshooting it (or when to give up and just return the amp), I'd be grateful for your advice!
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