Elrog 300B vs Takatsuki 300B tubes

Thanks Al. Got it.

Hello Al,
A directly heated triode requires it's own dedicated filament winding unlike an indirectly heated triode. If you look at the bottom of a power transformer(not a plate transformer mind you)you will see individual windings for the output, signal & rectifier tubes. Indirectly heated driver tubes such as the 6sn7,6sl7 etc can share a 6,3v/2 amp winding. Of course the rectifier tube has it's own winding as well. It's typically 5v/3a.

You can use a 5v/2a tube on a 3 amp winding, but you can't use a 5u4g on a 5v/2a winding. Since this thread is largely about the "Franks", lets try to keep in mind that these two circuits are completely different from one another, and that we don't have a "one size fits all" situation here. Hope this sheds some light up here.

Best,

George

Hi George thanks for chiming in. So as far as Elrog 300B in Lampizator Golden Gate DAC is concerned, a rectifier that draws 2A/5V is fine (assuming GG DAC has a separate 3A winding for rectifier tube)?

Yes, thanks for chiming in, George. After thinking about your comment I agree -- the 5 volt winding for the directly heated 300B and the 5 volt winding for the rectifier must be separate, or the circuits wouldn't work properly. Thanks for pointing that out.

I'm still a bit uncertain, though, that it would necessarily/always be appropriate, with respect to long-term reliability, to use a 2 amp rectifier on a winding that is designed with the expectation that it would be used with a 3 amp rectifier. My concern, as I mentioned earlier, being that the filament voltage provided to the rectifier would increase to some unknown degree compared to the voltage that would be provided to a 3 amp tube, due to the lighter loading on the winding.

Thanks again. Best regards,
-- Al

Al,
If you have 200 amp service in your home, do you use all of the current that your electrical service box offers? Of course not. It's there to insure capacity. Also, many 5 volt filament transformers for output tubes provide in excess of the 1 1/4 amps that a traditional 300b tube will draw.

Right now I happen to be looking at a Hashimoto power transformer that has a 5 volt/3 amp winding for each channel of a 300b amplifier. The tube doesn't need that amount of current, but will function just fine connected to it. The output tube draws what it needs from the current reservoir. The same goes for a rectifier tube. With rectifier tubes, you control the amount of B+ you have in your circuit by deciding on your choice of rectifier tubes.

Many people talk about how one rectifier tube sounds over another, but the real reason for this is the amount of B+ that has been added(or reduced)into the equation. This causes the output tube to work at a higher or lower anode voltage and that of course will influence the sound of what is being heard. Hope this helps.

Best,

George