What's your best 5U4GB rectifier tube and why?

I'm surprised no one has mentioned the EML (Emission Labs) 5U4g mesh. In my Modwright Transporter, and in my Woo headphone amp that rectifier was wonderful, and topped my list when rolling in both applications. YMMV according to the application/circuit that you are using it in though, but the EML is most definitely a contender for top billing.

I acquired a pair of NOS Tung-Sols to sample first. Frankly I'd be surprised to hear if swapping rectifier tubes will make a noticeable difference but I'm open minded.

Thanks to all who chimed in w/ suggestions!

they made a huge difference in my 300B SET

good luck

is you amp by chance grant fidelity?

I agree with the NOS recommendations above. It's worth trying a few. The coke bottle RCA black plate and GE 5-rib skinny 5u4g have been exceptional in my Melody Pure Black 101 pre, in Quad amps and in my guitar amps where appropriate.

But I wanted to mention one current production inexpensive tube. Tubestore.com has a private-labeled and highly-tested version of the Shuguang 274B. It is available as a Shuguang tube, too, I think, but with Tubestore you can be sure. It is a heavy glass, large plate 274B with a lighter 5ar4-like filament current draw, and has much harder vacuum than the basic Shuguang tube. These are under $30 each, and have sounded very fine in anything I've tried them in. They feel robust, haven't flashbulbed like so many other current production cheap rectifiers. Absolute longevity is TBD. It's borderline for some amps, like a Mesa Mark V, that are aggressive with voltage, but it seems copasetic with most hifi amps stocked with 5u4 rectifiers.

Phil