57 DELUXE REISSUE W/NOS 5Y3: CAN I SAFELY SUB 6K6GT's FOR 6V6's WITHOUT SERIOUS MODS?

[Mango Moon]

Greetings All,

There's been a fair bit of discussion here on MEF and elsewhere over the years about taming the power output/volume on a 5E3 by swapping-out the stock (12w) 6V6's for NOS 6K6's (8-10w), and I'd REALLY like to make this change to a '57 Deluxe Reissue equipped with 5Y3 rectifier, if possible, but its not particularly clear to me whether I can safely do so without making other modifications to the amp. In particular, its not clear to me what the plate voltage (B+) is likely to be on this Deluxe Reissue (with 5Y3) or whether I may need to change the PT or other components to reduce that voltage below the maximum specified for a 6K6GT (i.e., <315V).

Can anyone provide me with some sound guidance on this topic? Are 6K6's directly swappable with 6V6's in such an amp (plug-n-play), without the need for other mods? Or is the plate voltage likely to be too high (>315V), even with NOS 5Y3 rectifier installed? If so, is a complete replacement tranny the only approach?

Many thanks!

[MWJB]

I wouldn't go the 6K6 route, the amp will need rebiasing cooler at the least, this will push up plate voltage even further.

A simple power reduction mod for the 5E3 would be to find pin 5 of the 6V6 power tube that sits next to the rectifier, run a wire from pin 5 to ground. AC signal to pin 5 is now turned off, only the 6V6 next to the speaker jacks is now functioning no & rebiasing or PT mods are necessary, the amp is now running single ended like a Champ (<6W). Disconnect the grounded wire from pin 5 and the amp is back to stock.

DO NOT try this trick with a fixed bias amp as you will kill the negative voltage supply to pin 5 of the power tubes & fry them, probably the OT too.