[sleepysurf]

I'm a tube neophyte, still learning since Dan upgraded my SWL 9.0SE to the tube-rectifier.  For those advocating rolling to the Mullard NOS 5AR4 tube... what's the key sonic difference (if any) between those with serrated vs. smooth edged plates?  On eBay I've seen NOS Mullard tubes (date codes f3 Bx) with either smooth or serrated (3 or 7 notched) plates.  If these are all of the same vintage, why the different design?  Also, some ads mention "double-D" getters, and others make no mention.  Are *ALL* Mullard f3 Bx vintage tubes sonically equivalent?

[rpf]

I've been told by someone with an extensive knowledge of all things audio that the smooth plates are best, followed by the tubes with fewer serrations (3 as opposed to 7). When I asked Andy Bowman about this he laughed and said the no. of serrations made no difference, that the quality of the individual tube was paramount.

[sleepysurf]

Well, I scored a NOS RCA branded Mullard (F32 Bx date) on eBay, and agree that vintage offers up significant sonic improvement over the Sovtek.  Bass is deeper, tighter, midrange has incredible presence and bloom, with imaging to die for!  It's really a shame that sonic signature can't be found in new stock tubes.

BTW, from the eBay picture it looked like the rectifier plates were smooth, but turns out they are serrated (three notches).  At this point, I have NO further desire for tube-rolling... just gonna sit down and fall into the music.