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I recently did a rectifier tube test on my Priceton reverb, I was surprised to find the EHX 5u4gb to had the lowest voltage output. That was only reason I have stayed away from them, even though they are made at the same factory as the tung-sol's.
My slightly scientific test (copy/paste from different forum):
So I got in all my tube rectifiers, and finally have a decent matching pair of power tubes to test them with (In a Princeton Blacface clone).
I have an Amprex (made in Holland) GZ34/5AR4, a WU4GB Weber copper rectifier, 5V4GA Airline, Phillips-miniwatt 5U4GB, and a new EH 5U4GB. All tubes test NOS. Running them through VT107 JAN 6V6-GT's (RCA).
By the list above, you can see how overly-anal I am in the tube selection!
I baselined the 6V6 tube match with the Copper weber since it is solid state. I got 408volts with .024 on tube 1, and .0237 on tube 2 (like I said, close match!)
Here are the results:
Tube / Voltage / Bias at 9.8 watts
GZ34 - 412 - .0237
Weber WU4GB - 408 - .024
5V4GB - 403 - .0243
PW 5U4GB - 399 - .0245
EH 5u4GB - 396 - .0247
I have looked up references on the web, showing much more drastic voltage losses for some of these tubes. I do see that the 5U4GB's are current hungry and really have earlier breakup and loss of bass at higher volumes.
As for the winner in my combo? No contest; the Amprex GZ34...it was the cleanest, most bass, best sounding distortion.
Second place...5V4GB
Third....Weber
Fourth...the Phillips 5U4GB (this was a close to a tie with the Weber)
Fifth was the new EH 5U4GB, wow did this thing make the amp sound like crap!
This wasn't the most scientific test, but at least I was able to hear quite a difference with such a subtle difference in voltage.
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