systemtruck
Well-known member
One of the multiple HV test clip leads of mine that I was using on the amp was causing some kind of audio issue that was all of the distortion you heard in that recent video. It had worsened just by chance yesterday, or the JJ EL84’s exacerbated it ten fold. If also was causing a swirling audio phase sound which I never heard before. At some point I went into chop sticking mode and found this. I have had this lead clipped on one of the rails for a long time now, for much of this project, to monitor the rail as I bring up the Variac.
Just one of those things you never think of. The other leads are fine.
So the new JJ’s are stable and sound as good as they can. Not quite the same round vintage Mullard sound but close enough for now.
I’m going to pursue the Paul Ruby Zener+Diode idea in 18watt article linked a few posts back, to see if I can get the crossover distortion reduced. I think it is part of rhe EL84 sound that some people don’t like, such as myself.
But now that the random test lead distortion is gone, and the tubes are working well and stable, I can tell that the design and build is just fine and that the crossover distortion is almost just a taste thing. It was much worse with both sets of older tubes. But now I can at least live with it and gradually resolve that.
This thread went way way out of its original point, and I thank everyone for the help. In the end there were multiple real issues that were basically bad luck. Bad luck with original tubes red plating and collapsing the B+, bad luck with replacement “matched pair” also red plating and collapsing B+ and still sounding pretty bad during higher levels, and bad luck with a test lead behaving horribly just when I install brand new tubes, a lead that I never would have questioned before this.
The amp is enjoyable enough to play at full volume now and like I said I will investigate the crossover distortion modification attempts. I’m not at all interested in all of the various timbre adjustment mods that people pose, like the Snubber idea and the Smoothing/Enhance cap across first PI rail resistor, or other EQ/cap type adjustments. The crossover distortion seems to be an inherent part of the EL84 tube breakup and id like to try working that out a bit. I think the point of the mod is to limit the “unused” polarity of the waveform coming out of each PI side, so that the whole waveform doesn’t end up getting “auto” biased by the EL84 into a territory where the “wanted” polarity of the waveform is now clipping worse than it would have had the “unused” portion not been so strong. The diodes attempt to reduce that “unused” reach. That’s my understanding.
We’ll see how it goes.
But I think my transformers are probably fine which is the best news of all.
Cheers and thanks for everyone’s amazing patience and help. I have learned more from GroupDIY in the past year than I would have ever thought possible. My other tube builds, some preamps for a console, are going great due to this and sound amazing. Thank you!
Just one of those things you never think of. The other leads are fine.
So the new JJ’s are stable and sound as good as they can. Not quite the same round vintage Mullard sound but close enough for now.
I’m going to pursue the Paul Ruby Zener+Diode idea in 18watt article linked a few posts back, to see if I can get the crossover distortion reduced. I think it is part of rhe EL84 sound that some people don’t like, such as myself.
But now that the random test lead distortion is gone, and the tubes are working well and stable, I can tell that the design and build is just fine and that the crossover distortion is almost just a taste thing. It was much worse with both sets of older tubes. But now I can at least live with it and gradually resolve that.
This thread went way way out of its original point, and I thank everyone for the help. In the end there were multiple real issues that were basically bad luck. Bad luck with original tubes red plating and collapsing the B+, bad luck with replacement “matched pair” also red plating and collapsing B+ and still sounding pretty bad during higher levels, and bad luck with a test lead behaving horribly just when I install brand new tubes, a lead that I never would have questioned before this.
The amp is enjoyable enough to play at full volume now and like I said I will investigate the crossover distortion modification attempts. I’m not at all interested in all of the various timbre adjustment mods that people pose, like the Snubber idea and the Smoothing/Enhance cap across first PI rail resistor, or other EQ/cap type adjustments. The crossover distortion seems to be an inherent part of the EL84 tube breakup and id like to try working that out a bit. I think the point of the mod is to limit the “unused” polarity of the waveform coming out of each PI side, so that the whole waveform doesn’t end up getting “auto” biased by the EL84 into a territory where the “wanted” polarity of the waveform is now clipping worse than it would have had the “unused” portion not been so strong. The diodes attempt to reduce that “unused” reach. That’s my understanding.
We’ll see how it goes.
But I think my transformers are probably fine which is the best news of all.
Cheers and thanks for everyone’s amazing patience and help. I have learned more from GroupDIY in the past year than I would have ever thought possible. My other tube builds, some preamps for a console, are going great due to this and sound amazing. Thank you!
