I want to build a 3D21WB PP amp

[multi]

wicked1
thanks
I was only yesterday looking up Petes PP pcb and his mosfet driver for clas AB2 .
I made my 3D21Wa amp using Williamson; with Russian 6N6 and direct coupled cathode followers 6BL7's at 470 volts the 3D21's have not exploded so far.
Did you have problems with the 3D21's and bias {current} drift? i had 6550's in this amp before, no bias drift.
Phil

 

[wicked1]

I had a couple well used 3d21's that weren't stable, but tubes I believe are NOS/unused didn't drift. I might have played music through it for 10 or 15 hours before I took it apart and built my 829 amp w/ the driver PCB.

I'm probably going to build something w/ the 3d21's(or 7403's) this winter.

 

[multi]

wicked1
Please let me know how you go with your 3D21's and the circuit you use.
Phil

 

[multi]

3D21B

Does anyone have the DATA for the 3D21B?
I can find data sheets for 3D21A, 3D21WB but not B
Appears to have larger plates than A
Thanks
Phil

 

[tiger01]

These are great valves but information is limited. The WB is supposed to be a direct electrical replacement for the A, B and WA types. I have some WA types but they look like the WB data sheet version.... confusion reigns !! I tried a pair as pass tubes in a regulated supply with great success so I would think they could handle 40W. Research continues.....

 

[dowdylama]

PP UL op points?

Can anyone recommend 3D21WB PP UL voltage/bias points to begin experimentation?
Thanks.

 

[20to20]

UL? Has a proper UL tap point been established for this tube?

 

[multi]

I used 3k with 3D21 WA wired as triodes; but can be very hard to find 3D21Wa or WB that are not gassed had to use 3D21b has only 15 watt plate. Tubelab has done some testing I think he got 100 watts triode connected . Best to run them with just the heaters before applying HT. EPay Sellers want crazy prices for 3D21Wb or WA