WAD 300B PP Rectifier

[Richard]

Hi Tony,

I was on hols so have come to this a bit late, but yes, I've tried 4 types here,

Mullard GZ37
Mullard GZ34
Russian 5U3 (coke bottle 5U4)
National 5U4GB (Philips USA straight tube)

All work fine though the direct heated ones will turn on HT more quickly.

All sound quite different. GZ37 was the best imo and I immediately ordered a couple of spares. 5U3 was pretty good. I didn't like GZ34 somehow harsh sounding, and 5U4GB was very dark and I felt something was missing.

All very subjective I know but do try a few types and you'll hear the differences quite clearly.

It may be a construction thing and impedance/voltage drop as Ian says seems possible too.

Rich