PCF801 Suggestions

Juergen Knoop · 21st August 2009, 09:28 PM

Hi,
I have a bunch of PCF801 (combined pentode/triode w. common cathode) lying around and would like to build my first tube preamp with them.
Thought about a buffer+grounded grid circuit with heavy negative feedback.

Should I use the triode connected pentode as buffer or the triode?
The frame grid triode may be less affected by low anode voltages, so it may better be used as the grounded grid part.
I want as much open loop gain and less open loop distortion as possible.
Any suggestions?

AND would it work at all?

simplified schematic attached....

kavermei · 21st August 2009, 09:47 PM

You could get some inspiration here:
http://webpages.charter.net/dawill/t...Compound2.html

Juergen Knoop · 28th August 2009, 09:19 PM

thank you, I already hate this tube...connected cathode...grrrr
Regards

kavermei · 29th August 2009, 06:55 AM

Looks like that guy in the link is thinking in the same direction as you are with the GG configuration.

Just try it... you would have something unique...!

Boeing · 8th September 2009, 02:50 PM

It is great if you build it with Mu stage schem. Easy to drive the next power tube.
Try it so you will happy on it.
Good luck.

aardvarkash10 · 08:54 PM

swinging around a CCS tail, triode input side, pentode as anti-triode in a p-p VERY low output amp or a headphone amp?

jerluwoo · 9th September 2009, 12:33 AM

Here's a good starting point for ya. I based it on the standard operating points from the datasheet so it should work out fairly close.

8th September 2009, 08:41 PM	#6
aardvarkash10 diyAudio Member Join Date: Mar 2007 Location: Auckland, NZ	anti-triode, anyone? swinging around a CCS tail, triode input side, pentode as anti-triode in a p-p VERY low output amp or a headphone amp? __________________ "Folks, you can't prove truthiness with information. You prove truthiness with more truthiness. In a process known as truthinessiness." - Stephen Colbert, The Colbert Report Last edited by aardvarkash10; 8th September 2009 at 08:54 PM.

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21st August 2009, 09:47 PM	#2
kavermei diyAudio Member Join Date: Jan 2005 Location: Lokeren, Belgium	You could get some inspiration here: http://webpages.charter.net/dawill/t...Compound2.html

28th August 2009, 09:19 PM	#3
Juergen Knoop diyAudio Member Join Date: Jan 2007 Blog Entries: 3	thank you, I already hate this tube...connected cathode...grrrr Regards

29th August 2009, 06:55 AM	#4
kavermei diyAudio Member Join Date: Jan 2005 Location: Lokeren, Belgium	Looks like that guy in the link is thinking in the same direction as you are with the GG configuration. Just try it... you would have something unique...!

8th September 2009, 02:50 PM	#5
Boeing diyAudio Member Join Date: Apr 2007	It is great if you build it with Mu stage schem. Easy to drive the next power tube. Try it so you will happy on it. Good luck.