OTL headphone amp question

[elkym]

http://gilmore2.chem.northwestern.ed...bender_prj.htm


I've asked about this before, but I think I'm better able to understand now.

I think I get the basic idea behind using a tube as a load-- in the 'white cathode follower' style, or sometimes it's called a totem-pole arrangement.

What I'm not sure I understand is why v2a has plate voltage on the grid? (sans the traditional coupling cap...) Does this arrangement absolutely require 3 triodes to function correctly-- or is there a way around that?

[schmidlin]

Notice how the grid is 3 volts less than the cathode? That's properly biased. Biasing is all about the grid voltage in relationship to the cathode voltage.

As for other designs, dunno. Snappy little circuit, tho.

[elkym]

Thanks... you just gave me an epiphany about this circuit-- it just 'clicked' in my head.