Q1, 300B S-Splot, 360V 60mA? Q2, James 6112HS or 6123HS?

[HighVividity]

Hello,

I am working on my first 300B project. I have two questions.

1. People talking about 300B sweet spot (for example, http://www.diyaudio.com/forums/tubes-valves/81581-max-300b-se-output-possible-james-6123hs.html) suggests 360V, 60mA。Does this 360V refer to B+ voltage, or voltage across tranformer+300B, or voltage across 300B only?

2. I am going to buy James transformer. 6112HS can handle 70mA, 10W. 6123HS can handle 90mA, 20W. Of course, price wise, 6112HS is less than 2/3 of 6123HS。Which sounds better for a pair of 300B working with 360V, 60mA?

I seems 6112HS can work well in this condition. but it seems people are using 6123HS for 300B and 6112HS for 2A3，and the transformers are advertised so too. This makes me wondering. Please share your experience with me. Thank you!

 

[tomchr]

I've seen numbers ranging from 50~60 mA @ 350 V to my preference 90 mA @ 400 V, 5 kOhm load. The voltage should be Vak not B+, though, in many circuits Vak is within a few volts of B+ and in those cases the figure could be either/or...

I would buy an OPT that allows for 100-ish mA. That allows you to experiment with the operating point and find what you like.

~Tom