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Has anyone tried doubling the wattage of a Lightning by running 4 el84's. I have done the following:

The output transformer is beefy enough to handle the additional powe so I have no worries as far as that is concerned. I have not changed the design at all, aside from running 4 el84’s (compared to 2 in the original design).
What I did:

1. All I did was run both R20and R22 in series with the additional tube. So R20 went to tube 1 then in series to the grid (pin 2) of tube 2 and R22 went to the Grid of tube 3 then in series to tube 4.

2. C12 is run in series with the cathode (pin 3) of all 4 tubes

3. The plates are run in series with…similar to what I describer with the plates I described above.

4. And finally I have all 4 grids(pin 9) running parallel off the 33uf 450 v capacitor. – I think this might be my error.

I cranked it on and no real sound but some odd squeals. I didn’t really look at it much. But I wanted to see if this made sense to anyone - I do suspect I might way offbase.

Thanks

It's beefy, but not really enough for double the current draw. And also there's the PT to consider.


The tubes should be operated in parallel pairs. Nothing in series.


Yes, that will kill all your drive signal. Where did you get the idea of putting a huge cap like that on the grids??

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