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In Reply to: 12AU7 Reviled posted by pictureguy on July 1, 2021 at 19:45:03:
"bad stuff"I'm not certain what you mean by "bad stuff" but different tube types have inherent characteristics such as their operating points and distortion profiles. It is simply a function of their technical design. Some tubes have lower distortion than others as a result.
It turns out, based upon distortion tests done by respected engineers over many decades, that the distortion characteristics of a 12AU7 are inferior to many other triodes that are similar in operating conditions. For instance the 37, 76, 6P5G, 2C22, 7119, 5687, 6CG7, 6F8G, and the venerable 6SN7 all have lower second and third harmonic distortion when compared to a 12AU7. For more information you can read Morgan Jones, 'Valve Amplifiers' for the most comprehensive evaluation and "Distortion In Audio Phase Inverter And Driver Systems," W. B. Bernard, IRE National Convention Record, 1958, Part 7, E 87. For a less comprehensive review see the VTV article below.
It seems clear that contemporary consumer gear uses the 12AU7 simply because it is readily available as a result of the guitar amp market where distortion is of no concern.
Edits: 07/02/21 07/02/21
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Follow Ups
- RE: 12AU7 Reviled - Palustris 11:06:00 07/02/21 (10)
- "the venerable 6SN7" - 1973shovel 12:42:06 07/02/21 (9)
- RE: "the venerable 6SN7" - Triode_Kingdom 15:54:31 07/02/21 (8)
- "Is the 6SN7 version...?" - 1973shovel 18:34:55 07/02/21 (5)
- VTA Amplifiers - Triode_Kingdom 21:50:16 07/02/21 (4)
- RE: VTA Amplifiers - pictureguy 00:53:29 07/04/21 (1)
- RE: VTA Amplifiers - Palustris 07:51:27 07/05/21 (0)
- I agree 100% - 1973shovel 05:24:20 07/03/21 (1)
- RE: I agree 100% - pictureguy 16:02:03 07/07/21 (0)
- RE: "the venerable 6SN7" - airtime 16:02:59 07/02/21 (1)
- Schematic (I think) - Triode_Kingdom 20:52:44 07/02/21 (0)