Little Help with Mark IV Wattage

[MereImage]

Hey all.

I need a little assistance with calculating the wattage in a Mark IV using two EL34s and two Yellow Jacket EL84s.

From the Mark IV manual, in class A mode, the EL34s run at about 30 watts triode and 50 watts pentode. It also says that running in simul-class boosts the wattage to 70 watts triode and 85 watts pentode. So it looks like simul-class adds 35 to 40 watts to class A mode.

The YJ documentation says that the YJs bring down two tube 50 watts to about 20 watts and 4 tube 100 watts down to about 40 watts.

So, with two EL34s and two YJ EL84s, I should be looking at about 46 watts triode and about 64 watts pentode.

If I'm running 4 YJ EL84s, class A mode would be about 12 watts triode and 20 watts pentode. Simul-class would be about 28 watts triode and about 34 watts pentode.

Does this seem to be in ballpark?

The whole reason for this little exercise is that I want to replace the C90 speaker with a 50 watt speaker and want to make sure that my tube compliment will work with the speaker. From the above, it looks like I can run the two EL34s and two EL84s triode or I can run four EL84s either triode or pentode.

Thanks.

 

[Shep]

i find the amp sounds it's best at the 70 watt setting on simlu class tridoe and pentode is best at Aclass.. if you don't click your amp any higher than the triode simlu class then you should be fine putting a 50 watts speaker in.. also don't forget switch to tweed and thats even less power...