Posted new P-P power amp design

pmillett · 11:38 PM

Hello all & happy labor day -

I just posted the design of a new power amp that I've been working on for some time.

This is a push-pull amp pentode using sweep tubes. Not screen driven (sorry SY) but pentode mode, with plate-to-grid feedback. Using 6JN6 or 6JM6/6GV5 tubes it does about 18W. Works with no global feedback, or with 6dB of feedback.

Drivers are also pentodes. The amp is set up to cancel some distortion between the driver and output stages (yes, it really does work!)

My goal was a practical and affordable amp. The total BOM cost is about $325.

Details are here:

http://www.pmillett.com/DCPP.htm

Pete

whitelabrat · 5th September 2009, 11:44 PM

Happy day!

tubelab.com · 6th September 2009, 01:56 AM

6GV5's are still listed on the dollar menu at ESRC, so for a buck, I would be tempted to dial up a bit more B+, OK a lot more B+ but that is just my MO. I got a bunch of these when they first went on the dollar menu. I think that I have several hundred 6CB6's and a bunch of other IF tubes with the same pinout. If I ever get some time, I might put one together.

The Edcor power transformer looks like a good choice for the Simple P-P, so I may get one of these.

bigwill · 6th September 2009, 11:35 AM

Pentodes are SOOOOO in fashion right now

revintage · 11:56 AM

Nice use of Compactrons and 7-pins

.

Calculated the Zout of each output tube to ca 1k and Zin to ca 7k with inverse feedback applied.

This looks great!

Yvesm · 6th September 2009, 02:18 PM

Hi Pete,

No compactron this side of the ocean !

Who may disagree with such design ?
Pentodes LTP, local FB, stabilized G2, no

UL ! I love it.

Just a question, did you try to balance the driver (or even the pwr stage) by adjusting screen voltage ?
This affects transconductance and seems to be a way to match tubes "dynamically".
Not yet checked, work in progress ....

CUSOON, I hope.

Yves.

Mickeystan · 6th September 2009, 02:48 PM

Pete,

Great looking design and beautiful execution. I can tell by the design elements and the thoughtfull layout that your truly an engineer. Form clearly follows function and the use of these traditional TV tubes and the feedback scheme makes the design unique. Very cool. From one engineer to another, Job Well Done!

Doug S. (aka Mickeystan)

kmtang · 6th September 2009, 03:12 PM

Are those 12 pins tube sockets still available??

Johnny

vinylkid58 · 6th September 2009, 05:01 PM

Quote:

Originally Posted by kmtang

Are those 12 pins tube sockets still available??

Search our favorite auction site and you'll find the ceramic pcb version.

Jeff

SY · 6th September 2009, 11:33 PM

Nice one, Pete, despite the lack of screen drive.

Looks like you've got some new software to replace AudioTester- what is it?

5th September 2009, 11:32 PM	#1
pmillett diyAudio Member Join Date: May 2005 Location: Dallas (but I am not a Texan!)	Posted new P-P power amp design Hello all & happy labor day - I just posted the design of a new power amp that I've been working on for some time. This is a push-pull amp pentode using sweep tubes. Not screen driven (sorry SY) but pentode mode, with plate-to-grid feedback. Using 6JN6 or 6JM6/6GV5 tubes it does about 18W. Works with no global feedback, or with 6dB of feedback. Drivers are also pentodes. The amp is set up to cancel some distortion between the driver and output stages (yes, it really does work!) My goal was a practical and affordable amp. The total BOM cost is about $325. Details are here: http://www.pmillett.com/DCPP.htm Pete __________________ When life hands you a jeffery, stroke the furry wall. Last edited by pmillett; 5th September 2009 at 11:38 PM.

6th September 2009, 01:56 AM	#3
tubelab.com diyAudio Member Join Date: Jul 2005 Location: South Florida	6GV5's are still listed on the dollar menu at ESRC, so for a buck, I would be tempted to dial up a bit more B+, OK a lot more B+ but that is just my MO. I got a bunch of these when they first went on the dollar menu. I think that I have several hundred 6CB6's and a bunch of other IF tubes with the same pinout. If I ever get some time, I might put one together. The Edcor power transformer looks like a good choice for the Simple P-P, so I may get one of these. __________________ Too much power is almost enough! Turn it up till it explodes - then back up just a little.

6th September 2009, 11:53 AM	#5
revintage diyAudio Member Join Date: May 2007 Location: Eskilstuna, Sweden	Nice use of Compactrons and 7-pins. Calculated the Zout of each output tube to ca 1k and Zin to ca 7k with inverse feedback applied. This looks great! __________________ Brgds Lars Last edited by revintage; 6th September 2009 at 11:56 AM.

6th September 2009, 11:33 PM	#10
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	Nice one, Pete, despite the lack of screen drive. Looks like you've got some new software to replace AudioTester- what is it? __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

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5th September 2009, 11:44 PM	#2
whitelabrat diyAudio Member Join Date: Dec 2006 Location: Maryland	Happy day!

6th September 2009, 11:35 AM	#4
bigwill diyAudio Member Join Date: Dec 2004 Location: UK	Pentodes are SOOOOO in fashion right now

6th September 2009, 02:18 PM	#6
Yvesm diyAudio Member Join Date: Jul 2004 Location: Ardeche	Hi Pete, No compactron this side of the ocean ! Who may disagree with such design ? Pentodes LTP, local FB, stabilized G2, no UL ! I love it. Just a question, did you try to balance the driver (or even the pwr stage) by adjusting screen voltage ? This affects transconductance and seems to be a way to match tubes "dynamically". Not yet checked, work in progress .... CUSOON, I hope. Yves.

6th September 2009, 02:48 PM	#7
Mickeystan diyAudio Member Join Date: Jan 2008	Pete, Great looking design and beautiful execution. I can tell by the design elements and the thoughtfull layout that your truly an engineer. Form clearly follows function and the use of these traditional TV tubes and the feedback scheme makes the design unique. Very cool. From one engineer to another, Job Well Done! Doug S. (aka Mickeystan)

6th September 2009, 03:12 PM	#8
kmtang diyAudio Member Join Date: Nov 2004 Location: Vancouver	Are those 12 pins tube sockets still available?? Johnny

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