6550 to 6L6

I have a Krank Krankenstein plus that runs 6550's stock. Can I switch to 6L6's? The plate voltage was measuring at about 420V when using a Eurotubes bias probe.

Thanks!

You'll likely need to modify the bias circuit to supply the correct grid voltage to bias 6L6 tubes correctly. It may not be able to swing enough negative voltage to simply plug and play swap.

The plate impedances are different for both tubes so the OT primary likely isn't matched correctly for the same given speaker impedances. This will mean the power tubes will demand greater or less current flow for a given plate voltage. Nothing you can do about it - but it's worth noting. It's not all about just the plate voltage FWIW.

Thanks!

You’re welcome!