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


I recently acquired a 9 watt Class A design 300B tube integrated that came with a 40's NOS Japan 5u4gb rectifier that I wanted to compare to some of the best that's available. I'm new to tubes so I'm asking for your expertise.

It would be helpful to know why you're high on your particular tube recommendations and what differences one could anticipate with those you're suggesting to sample. Acquisition cost for same would be very helpful as well.

My amp is currently running with a pair of Shuguang Black Treasure 300B's and a pair of Black Treasures 6CA7's, in conjunction with a pair of Psvane 12AX7's all combined with the 'rec mentioned above.

Thanks in advance to all for the assist!

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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!
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