Elrog 300B vs Takatsuki 300B tubes

While I'm hesitant to question George's recommendations, FWIW I don't understand some of them. According to my documentation and my understanding, the 5AR4 (which he advises against) is two-way interchangeable with, and therefore very similar to, the GZ34 and the GZ37 (which he suggests trying). Also, the filament current drawn by the 5AR4, at least in its vintage incarnations, is 1.9 amps, not 4 amps as stated. 1.9 amps being substantially LESS than the draw of the EML versions of the 5U4 and 274B that are supplied by Lampi according to its website, as well as the filament draw of the vintage versions of those tubes. It is also slightly less than the 2.0 amp filament draw of the 5Z4 and 5R4.

Although if the filament current drawn by the tube is too low, as well as too high, problems can result. If it is significantly too low relative to what was anticipated in the design it could conceivably result in the filament voltage that is applied to the tube being high enough to shorten its life.

If it were me, without an ok from Lampi, either directly or via some indication on its website, I would be hesitant to use a rectifier whose filament current is significantly outside of the range of 2.4 to 3.0 amps, those being the ratings of the EML tubes the Lampi site indicates they supply. Are 1.9 and 2.0 amps "significantly outside" of that range? Not having knowledge of the specifics of the design, I don't know.

Good luck. Regards,
-- Al

I'm so happy! I found the problem.

Thanks Al, for the detailed explanation. Can you point out where on the lampizator site it states the rectifier filament current needs to between 2.4 to 3.0 amps? I'm currently using the Psvane 274B replica tube. Does this tube have filament current in the correct specified range?

10-27-15: Dracule1
Thanks Al, for the detailed explanation. Can you point out where on the lampizator site it states the rectifier filament current needs to between 2.4 to 3.0 amps? I'm currently using the Psvane 274B replica tube. Does this tube have filament current in the correct specified range?

You're welcome, Dracule. But I didn't say that the site specifies 2.4 to 3 amps. What I said is that the site indicates that the GG is supplied with either the EML 5U4 or the EML 274B. And I said that since those tubes have filament current ratings of 3 amps and 2.4 amps respectively, as can be seen at the emissionlabs.com site, without an ok from Lampi I would be hesitant to substitute a tube having a filament current rating significantly outside of that range. As I see it, doing so would amount to incorporating a design change into the DAC, without any means of knowing what its ramifications may be, in terms of long-term reliability as well as sonics.

I couldn't find a datasheet on the Psvane 274B. FWIW, though, the original Western Electric tube that it is intended to emulate was rated at 2.0 amps, although I wouldn't necessarily assume that the Psvane version is the same.

Regards,
-- Al

Correction. Apparently George at TubeUSA misheard me when I asked him about the 5AR4. He thought I said 5AU4, which draws 4 amps. As Al has pointed out, the 5AR4 draws 2 amps.