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When I asked Coffman why he opted for vacuum tubes over solid-state, he said, "That's a good question; tubes are inherently linear devices, but solid-state electronics require feedback to become sufficiently linear."
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Many is the claim that "valves are linear, but transistors are not". This is bollocks! Valves are not linear, and the simple proof of this is a glance at any plate voltage vs. current characteristic chart. If the valve were in fact linear, there would be a series of straight lines on the chart, not the curved lines we always see.
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http://sound.westhost.com/valves/myths.html#s22
 
I am no expert, but I suspect that the term 'linear' here based on a different definition. It is true that the most common definition is "a straight line," but it also can be taken to mean "having or being a response or output that is directly proportional to the input," which I think it more appropriate when talking about amplifiers.

http://www.merriam-webster.com/dictionary/linear

As to whether a tube is 'more linear' in any sense than a transistor, I do not know and have no opinion. I like them both, but my ears are notoriously unrefined, to my vast pleasure.
 
Wigwam Jones said:
As to whether a tube is 'more linear' in any sense than a transistor, I do not know and have no opinion. I like them both, but my ears are notoriously unrefined, to my vast pleasure.
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Not a matter of opinion, but of measurable and well-documented fact. Transistors and tubes are both inherently non-linear devices, meaning that the transfer curve of input current/voltage vs output current/voltage is not a straight line. They can be biased to operate within the most linear portion of the transfer curve, and feedback is virtually always used (despite marketing claims) to dramatically improve linearity. Transistor amplifiers can be designed to remain stable with much more feedback than tube amps, and are therefore capable of orders of magnitude better linearity (hence lower distortion).
 
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chicks said:
Not a matter of opinion, but of measurable and well-documented fact. Transistors and tubes are both inherently non-linear devices, meaning that the transfer curve of input current/voltage vs output current/voltage is not a straight line. They can be biased to operate within the most linear portion of the transfer curve, and feedback is virtually always used (despite marketing claims) to dramatically improve linearity. Transistor amplifiers can be designed to remain stable with much more feedback than tube amps, and are therefore capable of orders of magnitude better linearity (hence lower distortion).
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I was speaking of the definition of the word 'linear', and I'll take exception to any attempt to pretend it isn't as valid a definition as "a straight line." I can't and won't claim that tubes are or are not any more of a 'straight line' than transistors, but you utterly ignored my point about the actual meaning of the word. I do not know in what sense the word was being used, but it doesn't only mean "a straight line," which could easily explain the nature of the disagreement. I can't argue the science with you. I can and will argue English.
 
No offense meant, Wiggy. Just common usage to us geeks who enjoy reading technical design books. ;)
 
'Honey, Steve Guttenberg just wrote another "Wow ! This thing rocks !" piece at CNET !"

"That's nice, dear. I havent seen him in a movie for years."

"Ah, I think thats a different Steve Guttenberg. The actor seems to spend most of his time in recent years helping people who have suffered through no fault of their own"

"Like audiophiles' partners ?"

"Sure. Hey, do we have any beer in the fridge ?"
 
Wigwam Jones said:
I am no expert, but I suspect that the term 'linear' here based on a different definition.
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Both your definitions are the same. The response is proportional to the change in x, thus the slope of the signal is constant (y = mx + b) represented by a straight line. When the line becomes curved (exponential) its response no longer follows that course
 
chicks said:
Not a matter of opinion, but of measurable and well-documented fact. Transistors and tubes are both inherently non-linear devices, meaning that the transfer curve of input current/voltage vs output current/voltage is not a straight line. They can be biased to operate within the most linear portion of the transfer curve, and feedback is virtually always used (despite marketing claims) to dramatically improve linearity. Transistor amplifiers can be designed to remain stable with much more feedback than tube amps, and are therefore capable of orders of magnitude better linearity (hence lower distortion).
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All of this is true, as far as I know. If I remember correctly, one major difference -regarding the characteristics,i.e., relation between current and voltage- on these devices is that tubes naturally amplify voltages whereas bipolar transistors amplify currents. Input and output impedances are also quite different, again IIRC.
 
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