[Arny Krueger]

"Ian Thompson-Bell" wrote in
message
Arny Krueger wrote:
"Ian Thompson-Bell" wrote in
message
wrote:
"In a word: YES...

"The answer is rooted in the harmonic content that the
device can pass or generate..."

Continued: http://easyurl.net/TubesTubes

There is a lot missing from this article. First, it is
triodes alone that generate pleasing 2nd harmonic
distortion. Pentodes generate odd harmonics just as much
as transistors do.

It is a myth that triodes generate only even harmonics.
In fact, tubes have basically exponential response,
which leads to the generation of a wide variety of
orders of distortion, both odd and even.

No, pentodes have an exponential transfer function like
BJTs do, but triodes have a simpler ^3/2 transfer
function which produces a different harmonic content.

In my book, what you call ^3/2 transfer function is just another flavor of
exponential.

A ^3/2 transfer function can be read as the square root of cubed, which is
nothing like pure even order or pure second order.

[Ian Thompson-Bell]

Arny Krueger wrote:
"Ian Thompson-Bell" wrote in
message
Arny Krueger wrote:
"Ian Thompson-Bell" wrote in
message
wrote:
"In a word: YES...

"The answer is rooted in the harmonic content that the
device can pass or generate..."

Continued: http://easyurl.net/TubesTubes
There is a lot missing from this article. First, it is
triodes alone that generate pleasing 2nd harmonic
distortion. Pentodes generate odd harmonics just as much
as transistors do.
It is a myth that triodes generate only even harmonics.
In fact, tubes have basically exponential response,
which leads to the generation of a wide variety of
orders of distortion, both odd and even.

No, pentodes have an exponential transfer function like
BJTs do, but triodes have a simpler ^3/2 transfer
function which produces a different harmonic content.

In my book, what you call ^3/2 transfer function is just another flavor of
exponential.


I sujggest you get a better book.

A ^3/2 transfer function can be read as the square root of cubed, which is
nothing like pure even order or pure second order.


A simple expansion shows that the even order terms dominate. See any
book on tubes for details.

Cheers

Ian

[Arny Krueger]

"Ian Thompson-Bell" wrote in
message
Arny Krueger wrote:
"Ian Thompson-Bell" wrote in
message
Arny Krueger wrote:
"Ian Thompson-Bell" wrote in
message
wrote:
"In a word: YES...

"The answer is rooted in the harmonic content that
the device can pass or generate..."

Continued: http://easyurl.net/TubesTubes
There is a lot missing from this article. First, it is
triodes alone that generate pleasing 2nd harmonic
distortion. Pentodes generate odd harmonics just as
much as transistors do.

It is a myth that triodes generate only even harmonics.
In fact, tubes have basically exponential response,
which leads to the generation of a wide variety of
orders of distortion, both odd and even.

No, pentodes have an exponential transfer function like
BJTs do, but triodes have a simpler ^3/2 transfer
function which produces a different harmonic content.

In my book, what you call ^3/2 transfer function is
just another flavor of exponential.

I sujggest you get a better book.

Sue me for having a better general knowlege of math.

I also suggest you stop confusing "less odd harmonic" with "no odd
harmonic".

A ^3/2 transfer function can be read as the square root
of cubed, which is nothing like pure even order or pure
second order.

A simple expansion shows that the even order terms
dominate. See any book on tubes for details.

The same book says that there are significant odd-order terms. Maybe not
quite as big, but still there and audibly significant.

Furthermore, running tubes in either a balanced configuration (often done in
line level tubes amps used for audio production) or push-pull configuration
(done in any decent power amp) cancels out the even ordered terms very
nicely. Thus, the remaining odd-order terms are far more significant.

Bottom line is that most real-world tubed amps put out plenty of odd-order
distortion, no matter what kind of word games that the tubed amp bigots try
to play.