Replacing 5U4G with 274B's - Which 274B's are best?

[iaxel]

A bit OT, can anyone recommend a good source for a NOS GEC U52?

 

[ketcham]

Infonosaudiotubes@gmail.com
Umar Shaikh - Mumbai, India.
I purchased 50 units some years ago.
All tested strong
Highly recommended. They have many.

 

[NaimYourTubes]

Mullard Blackburn GZ33 are a 5AR4 on steroids and are compatible with the majority of 5U4G circuits. Fantastic rectifier tube. Also labeled CV5475 IIRC for military issue tubes.