Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Colas LeGrippa on December 11, 2011, 08:51:35 pm

Title: OT question
Post by: Colas LeGrippa on December 11, 2011, 08:51:35 pm

Hi again,

I just want to make sure I am right here. I want to choose the right OT for this project. A push-pull amp. both EL34 draw 50mA each = 100mA . Plate voltage is: 400V . reflected load is 100mA / 400V = 4K . So I need a 4k primary load tranny or do I have to multiply by 2 for 2 tubes which is 8K ?

Colas

Title: Re: OT question
Post by: PRR on December 11, 2011, 09:15:06 pm

If class-A (or self-bias), 8K is correct.

If fix-bias, and more than 100mA is available, you can load however you want, and suck more power; however 3K4 or 4K is a good limit for EL34.

Title: Re: OT question
Post by: Colas LeGrippa on December 12, 2011, 07:52:48 am

I see. I didn't know the rule was different from self bias to fixed bias. Thanks for the info.

Regards

Colas