[sdiy] sort of OT tube rectifier question

[anthony]

What is the point of connecting an indirectly heated cathode directly to the 
filament eg in the GZ34?

I can understand using the filament as the the cathode connection with, say, 
a 5Y3GT and having them totally separate like in, say, a 6AX5GT or EZ80 
etc...

Is it to make the GZ34 reverse compatible with upgraded older circuits that 
used something like a 5Y3GT, but needed more current? Seems like it'd be 
just as easy to use 2 5Y3GT's in parallel.


cheers,
aa