[Philistine]

For all the seasoned tube rollers out there, what has the biggest impact:
The manufacturer or the design?

For example would switching from a Mullard 5AR4 to a Chinese/Russian 5AR4 have a bigger sonic change than say switching from a 5AR4 to a 5U4G (or any other equivalent)?

NB
I'm running the Sovtek 6N1P's in my TP, and they are very very good.  My former reference was a pair of Bendix 6900's in a Sony 999ES. At the price difference I can change them out every month for the next 3 1/2 years to reach break even!  A Mullard 5AR4 in the 999ES was a great combination with the 6900's. 

[AB]

The bigger change is in design. But I have heard pretty substantial differences between manufacturers too.
Hows that for definitive? 

The differences in design you hear can/may be real electrical differences. Different voltage drop characteristics is one thing you can hear in different rectifier designs.
Or so I've been told.

[robinje]

I bought a NOS Matsushita 5AR4 from Andy.  It works great in my SWP9.0SE and was a bit cheaper than a Mullard.  Great service and advice from Andy...   

[sleepysurf]

FYI... another apparent Sovtek 5AR4 tube failure.  A couple weeks ago I turned on my SWL 9.0, saw sparks around the rectifier tube socket, then the fuse blew.  I was afraid I blew out the power supply, so sent the unit back to Dan to check.  After testing, turns out everything is intact, and it was apparently just the tube that blew.  My units on it's way back, and Dan included a Ruby 5AR4.  Kudos to Dan (yet again) for stellar service!  For those of you still running Sovtek 5AR4's, watch out! 

[rpf]

I switched the Sovteks out of my Modwright pieces early on but I second the warning. I was using them in a pair of Quad II Classics and their instability blew a few power tubes until I found out what was going on.

[modwright]

Sorry about the Sovtek 5AR4 mess guys.  I have since learned of other failures from other manufacturers.  Don't get me wrong, Sovtek is not a bad tube manufacturer, but for some reason, I have NOT had good success with their 5AR4's and do not recommend them in any of our product applications.

Thanks,

Dan