F6 Amplifier

[Zen Mod]

what ?

you didn't tried IGBT ?

[dimkasta]

Does it still beat vanila F5 though? I guess it should because of the better symmetry between the push pull fets?

[Zen Mod]

if you're going to differentiate them by your ears/brain combo , there is no other way than to try them both

for me - F6 , even with IRF outputs , will beat F5

[buzzforb]

Not vanilla F5 fan.

[lhquam]

How much of the better THD with the SS Jfets is due to less degeneration (near zero) and higher transconductance resulting in more overall global feedback?

Originally Posted by Nelson Pass

The F6 with IR parts works fine - you need to degenerate the parts with
0.47 ohms or so (maybe a little more) for thermal stability, and you will
find that there is higher harmonic distortion. Typically an IRFP240 will come
in with about twice the THD figure, but as the overall amplifier also has a
distortion contribution from the transformer, you will not see a doubling of
distortion in the overall amplifier.

The primary value of the SS Jfets are less thd and thermal drift, but you can
get along fine with other parts.

[generg]

Look at the F2J, degeneration, no feedback...... One third of the distortion of the F2 with IRF.

So I think most of the better distortion values is really due to the SS.

[buzzforb]

Dog!,beat me to it Generg

[Dzius]

Will the PLH amp work also better on R100 transistors then ?
(I've got PCB done for PLH but no will to do it).

[buzzforb]

I think it would make a very nice amp.

[Zen Mod]

what's up , Dodos ?

except few residents , it seems somewhat silent here ......

I'm thinkin' of F6 lookalike with 2SK60 and 2SJ18 ( so having complementary pair of VFets) , using 600:1200s ( meaning 150+150:300+300) repeater .

logically ,connected as 150:300+300 , having some 3db in xformer phase splitter itself

but , that's on loooong rope , having at least 3 projects tied on same line