Output Transformer question

famousmockingbird · 12th December 2011, 06:02 PM

So I have a class AB push-pull 6v6 amp and the load impedence is 6.6k at 8 ohms. I want to try 6K6GT's for output tubes so I used a 5U4GB to lower the voltage but I believe the 6K6GT's want to see something like 12000 load resistance. My question is can I us a 16 ohm speaker on the 8 ohm tap to raise my effective load resistance?

Andrew Eckhardt · 12th December 2011, 06:29 PM

Yes.

HollowState · 12th December 2011, 06:32 PM

Yes, in essences you can do that. Actually a 6V6, according to the tube manual and all amps I've seen or worked on, prefers 8 to 10K ohms plate to plate. So 6.6K is a bit on the low side. And, in my opinion, 6K6's are not as "good" a 6v6's. But give it a try.

cerrem · 12th December 2011, 06:33 PM

The gm of the 6K6GT is much lower and requires a larger plate load for normal AB1 operation... If you go into AB2 operation, then you can probably use a much smaller plate load like 6.6K..... thats provided that the driver circuit is up to the task..

Chris

famousmockingbird · 12th December 2011, 06:57 PM

I found some literature on the OPT and I think the turns ratio is 50:1, just got to remember how to put that info to use.

And say there were two cathode followers one for each of the grids of the output tubes would that drive the tubes into AB2?

pieter t · 12th December 2011, 08:31 PM

Quote:

Originally Posted by famousmockingbird

I found some literature on the OPT and I think the turns ratio is 50:1, just got to remember how to put that info to use.

That does not seem to be correct: 50:1 is 20k to 8 ohms.

famousmockingbird · 12th December 2011, 09:43 PM

Quote:

Originally Posted by pieter t

That does not seem to be correct: 50:1 is 20k to 8 ohms.

Yeah your right, 50x50=2500

2500x8=20,000

pieter t · 12th December 2011, 10:16 PM

To be sure it is rather simple to calculate the impedance ratios by measuring the voltage (winding) ratios.

famousmockingbird · 12th December 2011, 11:05 PM

I think I figured it out the turns ratio, it is 29:1

I got it all hooked up and the 6k6gt's in and everything is fine. Thanks everyone for all your help.

12th December 2011, 06:02 PM	#1
famousmockingbird diyAudio Member Join Date: Dec 2010 Location: Amesbury, MA	Output Transformer question So I have a class AB push-pull 6v6 amp and the load impedence is 6.6k at 8 ohms. I want to try 6K6GT's for output tubes so I used a 5U4GB to lower the voltage but I believe the 6K6GT's want to see something like 12000 load resistance. My question is can I us a 16 ohm speaker on the 8 ohm tap to raise my effective load resistance?

12th December 2011, 06:32 PM	#3
HollowState diyAudio Member Join Date: Aug 2006 Location: Taxland, New Jersey	Yes, in essences you can do that. Actually a 6V6, according to the tube manual and all amps I've seen or worked on, prefers 8 to 10K ohms plate to plate. So 6.6K is a bit on the low side. And, in my opinion, 6K6's are not as "good" a 6v6's. But give it a try. __________________ "The supercomputer is technologically impossible. It would take all of the water that flows over Niagara Falls to cool the heat generated by the number of vacuum tubes required." ~ Professor of Electrical Engineering, New York University

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Output transformer question	woody	Tubes / Valves	4	19th November 2011 01:10 PM
Output transformer question	Doogie	Tubes / Valves	10	25th January 2011 08:57 PM
Output transformer Question	keithgreenhalgh	Tubes / Valves	14	3rd August 2008 02:42 PM
1:1 output transformer question	Tyimo	Solid State	31	16th January 2007 01:14 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read

12th December 2011, 06:29 PM	#2
Andrew Eckhardt diyAudio Member Join Date: Nov 2005 Location: PA	Yes.

12th December 2011, 06:33 PM	#4
cerrem diyAudio Member Join Date: Jun 2005 Location: San Diego, CA	The gm of the 6K6GT is much lower and requires a larger plate load for normal AB1 operation... If you go into AB2 operation, then you can probably use a much smaller plate load like 6.6K..... thats provided that the driver circuit is up to the task.. Chris

12th December 2011, 06:57 PM	#5
famousmockingbird diyAudio Member Join Date: Dec 2010 Location: Amesbury, MA	I found some literature on the OPT and I think the turns ratio is 50:1, just got to remember how to put that info to use. And say there were two cathode followers one for each of the grids of the output tubes would that drive the tubes into AB2?

12th December 2011, 10:16 PM	#8
pieter t diyAudio Member Join Date: Apr 2009	To be sure it is rather simple to calculate the impedance ratios by measuring the voltage (winding) ratios.

12th December 2011, 11:05 PM	#9
famousmockingbird diyAudio Member Join Date: Dec 2010 Location: Amesbury, MA	I think I figured it out the turns ratio, it is 29:1 I got it all hooked up and the 6k6gt's in and everything is fine. Thanks everyone for all your help.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)