Power amp output newbie question

[gjo]

I plan to scratch build a pair of push pull monos based loosely on the Dynaco Mk III, each mono using either two EL 34s/6550s/ or KT 88s. Could anyone tell me what kind of output power one could expect with these options, assuming that the OPT can handle upto 60 watts?

Thanks in advance.

George

 

[audiousername]

Depends on a lot of things, especially the maximum allowable supply voltage, load impedance and acceptable distortion (especially of the nasty crossover type).

Philips gives data for a pair of EL34s in class B producing 100W. The KT88 may be able to produce somewhat more power.

You could easily meet or even exceed the OPT's 60W rating - but more power does not mean it will sound good.

 

[Brett]

Ditto what a-u-n said, but another factor to take into consideration is class of operation and the way the tube is connected. Class A will give you less than the 60W that the Mk3 will in AB1 UL; class A triode maybe 15 - 20W, etc.

If you have none of the components and are starting from scratch, work out how much power you want and work from there to find a configuration, PS voltage, OPT turns ratio etc that gets it for you. For example, if 15W will do it, then B+ = 400V, Ia = 85mA/tube and 7ka-a for the OPT gets you there (from memory) in Class A triode.

The tube manufacturer datasheets will often have example operating points for different configurations too.