EL34s and 6L6s working together in perfect harmony

[Enzo]

Like a race car is just a car if you obey the speed limits and just drive to the store.

[jmaf]

This has been debated to death before. I like to make the distinction between design class and operating class.

That's a nice synthesis of an otherwise hard to explain topic. I'll use that next time the subject is brought up.

[Alan0354]

you're wrong.

Changing the voltage bias don't change the amp class to A, AB1, B or D.
Because it depends of the construction and project of the amp in itself.

You better study up the meaning of the different class of amp. definition of class A in tube means the tube is conducting in 100% of the cycle. class B means tube is conducting in 50% of the cycle both at the maximum input. Nothing more.

Say if your power tube cuts off at control grid at -51V with a given +B, Say if your expect max input is 20V peak. If you adjust the control grid to -30V, This is class A for the given input signal. Even the input signal is at the most negative, it is -20V, together with the grid bias at -30V, the tube just at the verge of not conducting but still have a little current. So the tube is conducting in 100% of the cycle and THIS IS CLASS A.!!!!!


BTW, this has nothing to do with single tube or two tubes in push pull mode. You can have single end class A or you can have a pair of tubes bias in class A push-pull. Just follow the definition of what I said in the beginning.

[Ramsay]

Today I bought a brand new pair of Groove Tubes 6L6 Red.
So I will pull out the four EL34 tubes to put the 6L6's.

To play at home, I don't need more than 50W and for my taste my amp sounds better with 6L6's instead of EL34's.

How I use a resistive power attenuator, I will rebias the amp to use 50% of the rated dissipation plate of each 6L6.

With that I think I will be satisfied with the amp working at AB class.