Alternatives to the Dynaco ST-70

[percy]

yes I did compare the Mullard sheets for both. I just linked that page for ease.

Mullard EL34 Datasheet
Mullard EL84 Datasheet

and I don't know if I am missing something but any way I look at it - PP,SE,UL, Pentode, Triode, it seems that EL34 has less total distortion than EL84. Or atleast more power for a given amount of distortion (in other words less distortion for the same amount of power).

about Zout - yes I did interpret that as R(a-a) and what I was trying to say is that lower R(a-a) could possibly relax the output transformer design requirement(?)

 

[SY]

Yes, the EL34 is a bigger tube, higher power. But at full swing, the linearity is no better than the EL84 and of course there's requirements for more drive voltage, more heater current, and higher B+ to achieve that power. A pair of EL84 in parallel will give a similar power output and distortion as a single pair of EL34, but need half the drive voltage- this means that the driver stage will show about 6dB less distortion. Trade-offs, trade-offs- that's why Mullard made both.

 

[guitaristz]

Has there been a a St-70 type amp built but single ended and cathode biased? I've been really thinking that would be very versatile.

Also thinking of just a 6BM8, with the 2'nd triode as a cathode follower direct coupled into the grid of the output tube. 30 watts should be enough for most people. Man, I could even play next to a drummer with it!

kind of hyped about this...