Separate cathode resistors in push pull output

oldheathkitphil · 23rd May 2007, 03:26 PM

Hello

Many thanks to those who helped on my previous question.

Can anyone give me gneral guidance or direct me to a site that discusses replacing the single cathode resistor in a push pull out stage with separate ones and perhaps making them variable to match up as close as possible two unmatched output tubes.

I have both a heathkit and dynaco that are like that.

thank you much

oldheathkitphil

Ty_Bower · 23rd May 2007, 04:29 PM

Through some searching, I've found this thread which seems to discuss the topic to my satisfaction. Pay particular attention to the first dozen posts or so, after that it tends to wander off topic. Also remember the cathode bypass caps are essential to the circuit with separate cathode resistors, otherwise you are seriously screwing with the AC impedance of the outputs.

bias arrangements for P-P amps.

You might take a look at http://www.diytube.com/phpBB2/viewforum.php?f=1. They have an entire forum dedicated to a "build your own" Dynaco ST35 clone. One significant modification to the original Dynaco circuit is the replacement of the common cathode resistor with separate adjustable circuits. I think that is exactly what you are seeking.

23rd May 2007, 03:26 PM	#1
oldheathkitphil diyAudio Member Join Date: May 2007	Separate cathode resistors in push pull output Hello Many thanks to those who helped on my previous question. Can anyone give me gneral guidance or direct me to a site that discusses replacing the single cathode resistor in a push pull out stage with separate ones and perhaps making them variable to match up as close as possible two unmatched output tubes. I have both a heathkit and dynaco that are like that. thank you much oldheathkitphil __________________ oldheathkitphil

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
Difference between SE output transformer and push-pull output transformers	hilbert_mostert	Tubes / Valves	12	8th March 2009 05:10 PM
6T9 push pull with Cathode Coupled input	Brit01	Tubes / Valves	5	18th January 2009 11:58 AM
LED cathode biasing in push-pull input stage	exeric	Tubes / Valves	14	18th August 2008 01:35 AM
Push-Pull Cathode Bias Resistors	Kashmire	Tubes / Valves	5	6th January 2008 07:38 PM
The cathode FeedBack in Push-Pull amp	jmartins	Tubes / Valves	3	13th May 2005 03:17 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


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

23rd May 2007, 04:29 PM	#2
Ty_Bower diyAudio Member Join Date: Mar 2007 Location: Newark, DE	Through some searching, I've found this thread which seems to discuss the topic to my satisfaction. Pay particular attention to the first dozen posts or so, after that it tends to wander off topic. Also remember the cathode bypass caps are essential to the circuit with separate cathode resistors, otherwise you are seriously screwing with the AC impedance of the outputs. bias arrangements for P-P amps. You might take a look at http://www.diytube.com/phpBB2/viewforum.php?f=1. They have an entire forum dedicated to a "build your own" Dynaco ST35 clone. One significant modification to the original Dynaco circuit is the replacement of the common cathode resistor with separate adjustable circuits. I think that is exactly what you are seeking.