[Hammarlund] nuvistaplug mod for sp600?

[Eugene Hertz]

Hello all,

I've been reading up on the nuvistaplug mod for the sp600. I'm not sure of one thing. Does one buy a product called a nuvistaplug that contains two 6DS4's plus 3 resistors and 2 caps? 

Or does one simply purchase 2 6DS4's and construct the circuit in the article on some kind of tube plug in connector?

Seems if I had a tube connector to plug into the socket, I could construct this circuit. 6DS4s seem plentiful on ebay, but I don't know if one can actually acquire the whole thing built.

Does anyone know if this same circuit can be built with 6CW4's?

Anyone done this mod? Is it a noticeable improvement?
thanks
Eugene