Hi all,
I would like to know if there are any studies on harmonic distortion
spectrum analysis vs heavy plate current for tubes such as 12AX7, 6V6,
6L6, EL84, EL34?

thanks,
thomas

In message , Thomas Alkire
writes
Hi all,
I would like to know if there are any studies on harmonic distortion
spectrum analysis vs heavy plate current for tubes such as 12AX7, 6V6,
6L6, EL84, EL34?

thanks,
thomas


Are you talking about the anode curves outside the normal operating
region? I would have though not as most published curves extend beyond
the acceptable dissipation.

Otherwise it's simply drawing the load line and working out the
non-linearity.

And why a poor weedy 12AX7 in the list?
--
Chris Morriss

Chris,

What I'm interested in is how the various harmonics of a tube color the
sound. There was an article in Glass Audio in 1997 vol 9, number 4 titled
"Sound of the Machine: The Hidden Harmonics Behind THD" by Lynn Olson and
Matt Kamna which described the various even and odd harmonics for various
biasing circuits. Understanding how much contribution of distortion each
harmonic is for various loadings would give an understanding of the tonal
coloring that would be added to the output.

In guitar amps the overload harmonic distortion coloration is vastly
different for preamp and output stages. Since the 12AX7 is common in guitar
preamp stages, I added that to the list. For output there are often
descriptions of the 6L6 having glassy highs and the EL34 having tight bass.
I suspect that the various spectral weighting of the harmonics are probably
creating this characteristic sound.

Anyway, that's the general idea of what I had in mind.

Regards,
thomas


"Chris Morriss" wrote in message
...
In message , Thomas Alkire
writes
Hi all,
I would like to know if there are any studies on harmonic distortion
spectrum analysis vs heavy plate current for tubes such as 12AX7, 6V6,
6L6, EL84, EL34?

thanks,
thomas


Are you talking about the anode curves outside the normal operating
region? I would have though not as most published curves extend beyond
the acceptable dissipation.

Otherwise it's simply drawing the load line and working out the
non-linearity.

And why a poor weedy 12AX7 in the list?
--
Chris Morriss