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In Reply to: RE: Less guess and more psychology... posted by Michael Samra on February 1, 2015 at 15:53:28:
Your tagline is relevant to your observations.
Do you know or have an idea what causes various tubes to sound different? Emissivity is obvious; the higher the emissivity the lower the impedance. Interelectrode capacitance could affect highs, but really shouldn't be much of a factor in tetrodes and pentodes, especially at audio frequencies. An English guy measured the harmonic distortion of a bunch of tubes and determined that statistically black plate tubes have lower harmonic distortion than other tubes (but no explanation).
One thing you wrote I suspect is most of it: That different tubes sound better/worse in different amps. That suggests interaction between the tube and the circuit. Reactance, feedback, and power supply impedance (perhaps even as a function of frequency) come to mind.
So what's left? What are the physical reasons that tubes in good condition sound substantially different from each other?
I think that a perhaps a study of gain linearity and distortion as a function of signal level and complex load might be revealing. A good study would probably be at least a Masters thesis.
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Follow Ups
- Your subject and your tagline - Lee of Omaha 08:24:24 02/02/15 (5)
- Do you know or have an idea what causes various tubes to sound different? - Michael Samra 12:59:17 02/02/15 (0)
- One factor may be precision of mechanical construction.... - Steve O 09:33:37 02/02/15 (3)
- RE: One factor may be precision of mechanical construction.... - Michael Samra 13:17:18 02/02/15 (0)
- RE: One factor may be precision of mechanical construction.... - Nunki 10:35:08 02/02/15 (1)
- RE: One factor may be precision of mechanical construction.... - Michael Samra 13:07:05 02/02/15 (0)