Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dwinstonwood on August 26, 2025, 10:06:41 am

Title: 12AZ7 as DC Cathode Follower?
Post by: dwinstonwood on August 26, 2025, 10:06:41 am

The datasheet for the 12AZ7 states a peak Heater-Cathode voltage of 200; the amplification factor is 60; and max dissipation is 2.5W.

Sort of looks like a good DC Cathode Follower candidate. And they're not pricey. What am I missing/overlooking?

Thanks!
David

Title: Re: 12AZ7 as DC Cathode Follower?
Post by: tubeswell on August 26, 2025, 10:45:00 am

Beware the Heater filament draws 450mA @ 6.3VAC


https://frank.pocnet.net/sheets/127/1/12AZ7.pdf (https://frank.pocnet.net/sheets/127/1/12AZ7.pdf)

Title: Re: 12AZ7 as DC Cathode Follower?
Post by: dwinstonwood on August 26, 2025, 10:57:55 am

Thanks tubeswell. OK, as compared to 300mA for 12AX7's. In a pinch I guess you could wire the 12AZ7 12.6V series for 225mA?

Title: Re: 12AZ7 as DC Cathode Follower?
Post by: tubeswell on August 26, 2025, 11:32:16 am

Quote from: dwinstonwood on August 26, 2025, 10:57:55 am

Thanks tubeswell. OK, as compared to 300mA for 12AX7's. In a pinch I guess you could wire the 12AZ7 12.6V series for 225mA?

If you have a 12.6VAC power supply…