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New PP amp...
http://dcaudiodiy.com/phpBB3/viewtopic.php?f=4&t=488		 Page 4 of 4
Author:  Jetbat [ November 17th, 2014, 4:57 pm ]
Post subject:  Re: New PP amp...
Ok. That's where I was confused. :)

Thanks
Scott
Author:  FerdinandII [ November 17th, 2014, 6:49 pm ]
Post subject:  Re: New PP amp...
I think I know what Jetbat is referencing.....
Some people call this a Cathode Coupled circuit. They claim that the cathode of V1a is "driving" the cathode of V1b, which then makes the behavior of V1b look a lot like a grounded grid stage (AKA Common Grid). Not saying this is right....... :roll:


Roscoe Primrose wrote:
Jetbat wrote:
Isn't V1B a common grid stage? Or does that change with the grid tied to the R8-R9 junction?

Scott


No, it's a standard common cathode stage. Input is the grid, output from the plate. The connection of R2 to the junction of R4 & R7 just provides a DC feedback to keep the bias current in the output tubes more stable (as does the R1/R3/R6 combo).

Roscoe
Author:  Roscoe Primrose [ November 17th, 2014, 7:01 pm ]
Post subject:  Re: New PP amp...
FerdinandII wrote:
I think I know what Jetbat is referencing.....
Some people call this a Cathode Coupled circuit. They claim that the cathode of Via id "driving" the cathode of V1b, which then makes the behavior of V1b look a lot like a grounded grid stage (AKA Common Grid). Not saying this is right....... :roll:


I think 'cathode coupled' would refer to a phase splitter that has a shared, unbypassed, cathode resistor for both V1A & V1B, with the grid of V1B (at least AC) grounded. Also know as a Long Tailed phase inverter. That's NOT what's happening here at all...

Roscoe
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