Separate supply for input/driver - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

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
Reply
 
Thread Tools Search this Thread
Old 16th July 2013, 09:13 PM   #1
diyAudio Member
 
Join Date: Sep 2004
Location: ---
Default Separate supply for input/driver

I am trying to finalise a design of a two stage P-P el84 amp. For a brief description, there's an input transformer with a center tapped secondary that performs the phase splitting that is then connected to the grids of the 12AT7 diff pair, whose plates are RC coupled to the grids of the output tubes. As I have it now, B+ is around 310V going to around 300V at the plates of the output tubes and dropping to about 270V (through the use of a dropping resistor) right before the drivers' plate load resistors.

So this is my question: Instead of using the dropping resistor to get to 270V, could I order a power transformer with a set of additional taps to get to this voltage point? Are there any other downsides besides the obvious complexity and additional cost to this scheme? I want to have separate power supplies for the two stages, but how much of the (potential) benefit will be negated by the sharing of the same transformer?
  Reply With Quote
Old 17th July 2013, 02:38 AM   #2
DUG is offline DUG  Canada
diyAudio Member
 
Join Date: Jan 2003
Location: mississauga ontario canada
What is your concern for the present arrangement?

Are you concerned about a shift in operating point?

That would be my concern...I would build a regulator for that supply.

But that is just me.

__________________
Doug We are all learning...we can all help
"You can't stop the signal, Mal. Everything goes somewhere..."
  Reply With Quote
Old 17th July 2013, 03:07 AM   #3
diyAudio Member
 
Join Date: Sep 2004
Location: ---
Not really a concern about the current arrangement, after all that's how most amps are set up when one supply feeds all stages. I am just thinking of ways to improve things, that's all. I am also not concerned about shift in the operating point with either arrangement, unless I should be concerned and am not seeing the whole picture - it's a possibility as well. Your idea about a regulator is not a bad one and I 'll perhaps revisit it in the future as another possible upgrade path.
  Reply With Quote
Old 17th July 2013, 07:26 AM   #4
ChrisA is offline ChrisA  United States
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by musical noise View Post
Not really a concern about the current arrangement, after all that's how most amps are set up when one supply feeds all stages. I am just thinking of ways to improve things, that's all. I am also not concerned about shift in the operating point with either arrangement, unless I should be concerned and am not seeing the whole picture - it's a possibility as well. Your idea about a regulator is not a bad one and I 'll perhaps revisit it in the future as another possible upgrade path.
I think the normal method where you use cascaded RC setions to drop the B+ voltage is actually the best design. The reason is that you end up with Good filtering after those multiple RC sections.

If you'd like to improve more replace the first resistor with a choke. Use a choke that has the same DCR as the resistor you are replacing
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Separate Power Supply Case nwboater Class D 5 27th June 2011 11:59 PM
Advantages of separate PS for input and output stages john dozier Tubes / Valves 9 16th May 2011 12:15 PM
Decoupling by separate supply or battery Elektor78 Solid State 2 16th December 2008 07:10 PM
UCD separate opamp supply? badman Class D 129 8th June 2006 07:48 AM
separate chassis power supply onixuser Class D 2 4th March 2005 08:42 PM


New To Site? Need Help?

All times are GMT. The time now is 06:24 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2