Hiwatt: What's V3B?

[jeff]

Can anyone explain what V3B is for? I can't understand what it's actually doing, what it's purpose is.
Thanks
 Jeff

[sluckey]

V3B is a fancy way to develop a fixed bias voltage to be applied to the grids of V4, LTP PI. Notice V4 grids do not connect to the cathode tail resistor like a more familiar LTP PI?

[jeff]

Ahh, thanks. What's the advantage of doing it this way?

[sluckey]

None that I can think of. Hiwatt just likes to do things differently.

[HotBluePlates]

If they didn't do that, there'd be an unused triode hanging out.

In the same situation, Fender chose to leave an unused triode, while saving the couple extra resistors needed to rig that triode into a cathode follower with a d.c. voltage on its input grid.

[jeff]

If they didn't do that, there'd be an unused triode hanging out.

In the same situation, Fender chose to leave an unused triode, while saving the couple extra resistors needed to rig that triode into a cathode follower with a d.c. voltage on its input grid.

I don't know... If they didn't do it this way they could save $$ eliminating a whole tube and socket. It's not really using an unused triode, it creates the need for another tube vs Fender's PI because V2B, which is unused, could replace V3A and V3 wouldn't be needed.

If it is just used to supply a bias voltage couldn't a voltage divider be used? Like the one biasing the grid?

 

[sluckey]

If it is just used to supply a bias voltage couldn't a voltage divider be used? Like the one biasing the grid?

Sure, but that's just not like Hiwatt. They love to make things overly complex, almost insane. There is another recent thread about another Hiwatt oddity.