tmidgett wrote:Watch current draw on 6550s.
They draw more current than the others.
Do you mean plate current, or heater current?
The EL34 is a heater current hog, at 1.5 or 1.6A per tube! Much more than the others which are only 0.9A. The Winged's C 6550C is also 1.6A according to this
Going from EL34 or 6550 to 7027 is a safe bet... but not necessarily so the other way around.
And yeah, switching tubes is gonna likely require a rebias, and some of these tubes will require much more current than others.
In terms of power, the 6550 is rated at 35W plate dissipation, making it the beefiest of the bunch. 6L6GC's are 30W, and EL34's are 25W.
And Rodabod, the 6CA7 is roughly equivalent in specs to the EL34, the exception being that the EL34 has a suppressor grid (a true pentode) and the 6CA7 is a beam forming pentode/tetrode (depending on who you're asking, it's considered a pentode or a tetrode). The beam vs suppressor is the difference.