interesting article

[stusnyder]

Just found a interesting article on how to convert 01a tubes to solid state. Only drawback is "plate voltage" is 18 volts compared to 90 volts originally supplied. So all tubes in a set would have to be done, and feed it 18 volts instead of the normal 90.
My question: is there a small solid state component that will take 90 volts and drop it to 18? Or a component that could be tied in under the tube socket to drop the voltage?
http://www.greenhillsgf.com/Project_SS-Tubes.htm