Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Stuff4bikes on January 02, 2022, 11:45:10 am

Title: Best method for 150v screen supply.
Post by: Stuff4bikes on January 02, 2022, 11:45:10 am

Like the title states.....
I need 150v for the screens of two output tubes.

0A2 or dedicated seperate transformer?
Or if even possible another node on the PT dropping it down to the needed voltage.

Title: Re: Best method for 150v screen supply.
Post by: PRR on January 02, 2022, 11:51:40 am

What is any available B+? How much current *and current swing* available/needed on main B+ and screen supply? Does your religion forbid Silicon?

What is "best"? Fastest? Cheapest? Coolest? Most stable? Best sound? Uses parts already in your shed?

Historically the answer was to use high-Mu(g2) tubes so that G2 could eat very nearly plates supply voltage, with maybe a slight filter between.

Title: Re: Best method for 150v screen supply.
Post by: Stuff4bikes on January 02, 2022, 12:07:07 pm

Sorry I am a novice hobbyist.

I have several nos 0A2 tubes and half a dozen 6BQ6gtb's just wanted to see if I can do something with them
Even if it was a ipod/CD/record player amp...

Title: Re: Best method for 150v screen supply.
Post by: sluckey on January 02, 2022, 12:19:41 pm

Connect a series resistor and 0A2 between B+ and ground. Take the 150V from the tube. Here's an example...

     https://el34world.com/charts/Schematics/files/Gibson/Gibson_mercury_i_ii.pdf