Why hybrid CCS?

leadbelly · 16th January 2006, 07:21 PM

Background: I am searching for my next input stage for my EL84M PP, which right now consists of paralleled 6922 triodes in a long tailed pair with a MOSFET CCS. So I was looking at things like a cascoded long tailed pair and various forms of CCS's as a "step up".

So in Morgan Jones' book I do see some hybrid CCS's, basically shown as SS CCS's on the cathode of a pentode such as and EF184, in which the combination of SS and tube is used as a CCS for the cathode of a driver tube. What does this improve over just using the SS portion alone?

EC8010 · 16th January 2006, 07:36 PM

Prettier and higher voltage compliance; an EF184 can dissipate 2.5W and operate with 250V across it.

ray_moth · 17th January 2006, 10:03 AM

Or, why not ust the pentode alone? If you look at the plate curves of a good small signal pontode, they're almost horizontal at low currents with a suitable screen voltage.

16th January 2006, 07:21 PM	#1
leadbelly diyAudio Member Join Date: Dec 2002 Location: Calgary, Alberta	Why hybrid CCS? Background: I am searching for my next input stage for my EL84M PP, which right now consists of paralleled 6922 triodes in a long tailed pair with a MOSFET CCS. So I was looking at things like a cascoded long tailed pair and various forms of CCS's as a "step up". So in Morgan Jones' book I do see some hybrid CCS's, basically shown as SS CCS's on the cathode of a pentode such as and EF184, in which the combination of SS and tube is used as a CCS for the cathode of a driver tube. What does this improve over just using the SS portion alone? __________________ Aerodynamics are for people who can't build engines. Enzo Ferrari

16th January 2006, 07:36 PM	#2
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Prettier and higher voltage compliance; an EF184 can dissipate 2.5W and operate with 250V across it. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

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17th January 2006, 10:03 AM	#3
ray_moth diyAudio Moderator Emeritus Join Date: Jan 2004 Location: Jakarta	Or, why not ust the pentode alone? If you look at the plate curves of a good small signal pontode, they're almost horizontal at low currents with a suitable screen voltage.

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