I think I have finally sorted out my distortion issue.
After losing one of my Electro Harmonix GL tubes I pondered a replacement. After much reading I decided on JJ 300B matched pair from Tube Depot.
After comparing them to the remaining EH tube and the LinLai, and Psvane tubes, I have come to the conclusion that (1) I wasn't biasing the tubes hot enough, and (2) I just had lousy luck on the previous tubes.
The JJ are capable of under 0.5% THD at one watt when pushed to 36W dissipation. The rest are near 1% (or over, LinLai) except the remaining EH tube.
After losing one of my Electro Harmonix GL tubes I pondered a replacement. After much reading I decided on JJ 300B matched pair from Tube Depot.
After comparing them to the remaining EH tube and the LinLai, and Psvane tubes, I have come to the conclusion that (1) I wasn't biasing the tubes hot enough, and (2) I just had lousy luck on the previous tubes.
The JJ are capable of under 0.5% THD at one watt when pushed to 36W dissipation. The rest are near 1% (or over, LinLai) except the remaining EH tube.
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I found a problem with my regulator for the driver tube. Ok, I blew it up by pulling a "TubeLab" and had been cranking B+ up to 500V+ on 450V caps.
Once I rebuilt everything, I find my distortion at one watt is running well below 0.3% with the JJ tubes.
Once I rebuilt everything, I find my distortion at one watt is running well below 0.3% with the JJ tubes.