tube nonlinearity

[Eric Barbour]

>>I am under the impression that the "tube sound" is in part
>>caused by their nonlinearity.
>>I guess I am wrong or confused or both :-)

No, the situation is far more complex than that. The problem is with
the poor quality of engineering talent nowadays, and with ignorant
statements made by marketing people.

See the upcoming August issue of IEEE SPECTRUM
magazine for more information.

>hope the book idea regarding tubes
>(as noted on the Engineering Musician site)
>happens, I could use it.

There are a few books on the subject already. Let me recommend:

THE ULTIMATE TONE vols. 1 and 2 by Kevin O"Connor (guitar-amp and preamp design)
PRINCIPLES OF POWER by Kevin O'Connor (guitar-amp and high-end audio)
BEGINNER'S GUIDE TO TUBE AUDIO DESIGN by Bruce Rozenblit (high-end design)

All these books are available from Antique Electronic Supply
at (602) 820-5411 or via their website http://www.tubesandmore.com.


> In fact, some small-signal triodes are MORE LINEAR THAN ANY
> AVAILABLE TRANSISTOR.
> The tubes used in these VCOs are nonlinear, which makes them
> useful for unique FM behavior. A low-distortion tube VCO IS possible.......

>>so the nonlinear nature is in the type of tube, but not tubes in general.
>>That is, one can design for degrees of non linearity?

Yes. There is a VAST range of distortion products possible with tubes;
from extremely low (as in the case of triodes such as antique types
27, 56 and 76, and the later 6CG7, 12BH7 and 12SX7), to the very high
(as in "remote-cutoff" tubes such as the 6SK7 pentode). Take your pick.

And bear in mind, I haven't said ANYTHING
about using negative feedback yet...all this
is achieved WITHOUT feedback......