Elrog 300B vs Takatsuki 300B tubes

As a point of information, the Big 7 is indicated at the Lampi site as being supplied with one of the following rectifiers. I've determined the filament currents listed for each tube from datasheets that can be found elsewhere on the web:

5C3S (filament current 3 amps +/- 10%)
Shuguang 274B (filament current 3 amps)
(Optional) EML 5U4G (filament current 3 amps)

Other tubes mentioned in Wyan's post just above:

5Z4 (filament current 2 amps)
Cossor 53KU (filament current apparently 2.8 to 3 amps)
WE 422a (filament current 3 amps)
WE 274A/B (filament current 2 amps)
Takatsuki 274B (filament current 2 amps)

Hope that helps. Regards,
-- Al

Wyan, thanks for reminding me. I forgot it was you in the other forum.

Charles1dad, for awhile I thought I had a bad set. I've gone direct to amp before with mixed results, but mostly positive. The Elrogs seem to be very sensitive tubes on many levels. But Elrogs in the GG DAC seem to have one of the most dramatic change in sound going direct to amp.

Thanks Al. I got the distinct impression from George at TubesUSA to stay away from rectifier tubes that draws more than 2 amps. The list of rectifiers recommended by George for the Elrog 300Bs I think draw no more than around 2 amps (5R4, 5R4GY, GZ34 and GZ37). I'm afraid to try my EML 5U4 (3 amps) with my Elrogs.

Dracule and Al Here we go again! I pasted in below a comment from page 6 of this thread from Matthias regarding AC voltage and Elrog life. Now, I am hearing that there is another issue, i.e. filament current. The 5U4, 5U4GB, CV387 tubes recommended for the Frankensteins, in addition to my beloved VU-71s, all have a filament current of 3A. The communication from Matthias below indicates that what is required is selecting Elrogs that are appropriate for the operating requirements of a given amp. I have such a pair. In addition, I am regulating the incoming voltage at 115 V using a PS audio P10. I have detected no erosion of sound quality vs regulating at 120 V. I assumed that given all of this, I should be in good shape with my Elrogs. Comments?

07-07-15: Mk_
Hello,

Thanks to snopro for his efforts on this topic...I received the results a day earlier ;-)

By my oppinion a variac is not needed. As can be seen all the measured tubes are having a little bit different operating conditions. All they are 300B fitting the WE300B datasheet (more or less) wthin the tolerances...The Takasuki's running a little "hotter" and the Psvanes a little "cooler". This is the effect of the deviations of real tube data...(against the design center values/plate curves in datasheet)
So the task is very simple. We have to select the "right" pairs of ER300B fitting to the operating conditions of the Franks (or any other amp whose conditions are known) in all cases(+10% or -10% main voltage) with a small safty margin.
A smart dealer like Gorge should be able to affairs which.
No variac is needed nor any changes in the amp...We only need to know the type of amplifier, so we can deliver the fitting tubes. (This way will improve the sound quality too.)

Regards, Matthias
Mk_ (Answers | This Thread)