I feel like the 4 volt rectifiers deserve their own thread at that point, rather than hijacking the Sophia Electric discussion.

I'm a newcomer to the world of 4 volt rectifiers. Will has mentioned them in the past and I was was intrigued, but not enough to do anything about it. And I have a lot of rectifiers already. Then a friend on another website, who really likes the tubes in his headphone amps (I forget now which ones) was thinning his herd and I bought 2 pairs of 30's TFK AZ1. One long mesh plate and the other long solid plate. FWIW my sources prefer the 30's globe version to the later one. I also got a pair of AZ12s and the appropriate adapters from my favorite ebay source: xulingmrs.

A note on the adapters. My sources claim they include a resistor to drop the filament voltage from 5 to 4 volts. And certainly they test fine as a 5V rectifier (on my tester the test is essentially the same for most 5 volt rectifiers).

I got them with the idea of using them on my UFO25s, which I hope to be getting soonish. But I tried them in my pre/headphone amp and was very pleased with the results. Very similar to my prized GEC U52. The should have plenty of juice for most Decware amps, with the exception of Sarah.