Guitar AMP: Please check my calculation

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Hi!
I'm building Marshall-style 50W PP guitar amp with EL34 power tubes in class AB1.
I already have OT with Primary-to-Secondary_8ohm ratio = 23.13, which means Raa=4280 ohms.
In other words the OPT is 4.2K : 8 and this is a starting point for power amp calculation.
Having read this nice article (loadmatch4-pp-beamtetrodes) I made the calculation.
Here it is.
Please check it, because I'm confused with such small Ea=400V for 50W of output power.
An externally hosted image should be here but it was not working when we last tested it.


I would be very appreciate for any help to understand my miscalculations.
 

PRR

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Joined 2003
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It is very near the book value.
 

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Yes, it seems correct. At full power, the voltage swings from 355V of push to 355V of pull, and the current swings from 330mA push to 330mA pull.

For a sine wave, the rms voltage is 355/sqrt(2), and the rms current (in amps) is 0.33/sqrt(2).

Power output (for a sine wave) is 355/sqrt(2) x 0.33/sqrt(2)= 355 x 0.33 / 2 = 58.6 watts
 
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