Tubes Asylum

Posted by JazzDude (A) on January 30, 2016 at 10:36:52

In Reply to: RE: 6NIP & 6H30Interpretation of tube test results. posted by mondial on January 29, 2016 at 21:41:09

Hi Mondial. TC Tubes is one of the best online sources for vacuum tubes. They use a variety of methods and instruments to test tubes including an Amplitrex AT1000 tube tester. Do examine their webpage/white paper titled "Interpreting Amplitrex AT1000 tube tester results."

This paper details and compares the differences between the AT1000's Fixed Bias and Auto Bias test modes. In summary, their concluding statement is "It is my opinion that Fixed Bias mode should be the default mode for evaluating a tube's condition because it provides mA and gm scores at fixed operating voltages for plate, screen, and grid bias."

You mentioned your test results were derived from Auto Bias testing. Per the TC Tubes description of the 2 test modes, re-doing your tests using the AT1000's Fixed Bias mode would provide more a meaningful understanding of the condition of each tube. The results will also be easier to interpret as they will indicate plate current and GM as percentages of what a new tube would measure when tested at DATASHEET PARAMETERS. Do let us know what results!

• Interpreting Amplitrex AT1000 results white paper   (Open in New Window)