417A-300B Plate Choke or Interstage Coupled?

[dsavitsk]

Originally posted by tubelab.com
He did tell me that the prices have gone up considerably in the last year, so your numbers may be more realistic.

I was afraid that might be the case. I am using some now in a spud amp to drive some low impedance headphones. They are really great sounding tubes -- a little sloppy in the the bass compared to a 6N6p or 5687 with the two sides in parallel, but a really nice midrange. For this quality of sound, and considering the custom wound electra print OPTs, I don't really consider $13 to be high. But, the WE version is getting up there, and I am torn whether that is worth the investment. I really want to try the 437a's, but that is too rich for my blood I am afraid.

Originally posted by tubelab.com
When I find it, a redesign of the board will be required.

How about using a daughter board to allow people to plug in different tubes? This is essentially how the above mentioned headphone amp works, and it is really great. You can make each board essentially have the grid stoppers, and perhaps the bias mechanism, and maybe even the CCS, which would allow easy experimentation with different tubes.

[massi68]

dear all, I am a new entry of this forum and I use a 5842 (Haltron)to drive a 300B Mesh palte (Fullmusic) on my 2 monoblocks power amps.

the 5842 work with Vg -2,2 V/Vp 175V and Ip 17/18 mA. It is load with a Rplate of 9 kohm.
The I have a 0,5 uF oil cap to grid og 300 B and it is load with a 3k OPT on plate. Besides the 300b has Iplate=70mA and Vg-69V. With this config. I can have 6,4 W on output on 8 ohm and 2,2% of 2°harm. distorsion.
Some people in Iatly told me that the 5842 doesn't want a Rplate when it has to drive a power tube like 300B. Which it is better to use on plate of 5842 (417 a)?
I think the others load: IT, choke, CCS, but I don't know the use of that and the + and - point of eash.
Please help me to understand better the best solutuion from your experience.

ciao, massimiliano.