Or near 40W from an 845 ...

Posted by Naz (A) on January 8, 2010 at 21:46:24

In Reply to: What? 16 Watt! From a 300B! Betcha! posted by Thorsten on January 8, 2010 at 02:00:55:

I can't agree more! For many years now I've been using a White CF to (easily) drive a pair of parallel 845s in similar fashion to get around 75W or near 40W with a single tube. The WCF is DC coupled to the previous (somewhat unconventional) stage which provides gain and sets the overall bias for the 845s. Current through each 845 is individually fine tuned by adjusting a small cathode R. 845s may be hard to drive but done this way they have absolute authority and lose nothing in finesse. Anyone who thinks 845s have no top end should try driving them with a very low impedance!

I agree that you can have your cake and eat it. Similar power and efficiency to PP but all the benefits of SET ... biased in A1 where most of the music lives and only transitioning into A2 when called upon.

I've been trying to get around to modifying my conventional 300B / 2A3 SETs along similar lines but perhaps I'll try your simpler approach as they are somewhat easier to drive.

Naz

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Follow Ups Full Thread

Topic - What? 16 Watt! From a 300B! Betcha! - Thorsten 02:00:55 01/08/10 (16)

Or near 40W from an 845 ... - Naz 21:46:24 01/08/10 (2)

RE: Or near 40W from an 845 ... - SomeJoe 08:30:52 01/09/10 (1)

The operating points are not nearly as important as the implementation ... - Naz 03:35:28 01/10/10 (0)

RE: What? 16 Watt! From a 300B! Betcha! - SteveBrown 08:27:31 01/08/10 (5)

RE: What? 16 Watt! From a 300B! Betcha! - Thorsten 08:50:43 01/08/10 (4)

RE: What? 16 Watt! From a 300B! Betcha! - Eli Duttman 17:59:51 01/08/10 (1)

RE: What? 16 Watt! From a 300B! Betcha! - Thorsten 19:46:12 01/08/10 (0)

RE: What? 16 Watt! From a 300B! Betcha! - SteveBrown 11:42:10 01/08/10 (1)

RE: What? 16 Watt! From a 300B! Betcha! - Thorsten 19:50:49 01/08/10 (0)

RE: What? 16 Watt! From a 300B! Betcha! - Triode_Kingdom 08:14:47 01/08/10 (0)

Clarification please to the Lux reference - Frihed89 02:21:55 01/08/10 (5)

RE: Clarification please to the Lux reference - Thorsten 02:52:09 01/08/10 (4)

RE: Clarification please of the bias design - Neff 00:59:15 01/10/10 (1)

RE: Clarification please of the bias design - Thorsten 17:40:51 01/10/10 (0)

RE: Clarification please to the Lux reference - jeff mai 19:51:26 01/09/10 (1)

RE: Clarification please to the Lux reference - Thorsten 17:42:14 01/10/10 (0)

Follow Ups

Or near 40W from an 845 ... - Naz 21:46:24 01/08/10 (2)

RE: Or near 40W from an 845 ... - SomeJoe 08:30:52 01/09/10 (1)

The operating points are not nearly as important as the implementation ... - Naz 03:35:28 01/10/10 (0)

Or near 40W from an 845 ...

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