When was Mesa rebranding Winged Cs?

[CoG]

I just acquired a minty-mint MkIII green stripe that still had the original "MESA ECC83" preamp tubes in it (see other thread.)

However, it also had some Svetlana Winged Cs in the outboard EL34 sockets, with Mesa identifiers screened onto them so badly I can't even read what the STR number is. I didn't know Mesa rebranded these tubes... when might they be from?

Based on the fun I had tonight, if you are ever looking for a slightly less aggressive tone in your Simul-Class Mark, WInged Cs + 5881s=

 

[ANIMATED SUSPENSION]

They are STR454's, they were sold as an upgrade tube about 4-5 years ago ?when they were using STR430's as standard fit. I have a brand new pair actually that I may try with EL34's in my MKIV when the STR440's need replacing. Great tubes, really well made and heavy too !!

 

[ANIMATED SUSPENSION]

OOPS !! Sorry, wrong ref there !!! The EL34 's are STR442's, the 6L6's are STR454's !!