World-Designs-Forum  

Go Back   World-Designs-Forum > World Designs > WD Amplifiers
Register FAQ Members List Calendar Gallery Today's Posts Mark Forums Read

WD Amplifiers For discusson of World Designs Amplifiers

Reply
 
Thread Tools Display Modes
  #11  
Old 5th April 2008, 12:45 PM
Paul Barker's Avatar
Paul Barker Paul Barker is offline
Senior Member
 
Join Date: Dec 2005
Location: Scarborough
Posts: 1,609
Default Re: 845s or GM-70 amp.

I am struggling to get my head around this, but I think that you are saying this is a single ended output transformer, in which you must use two output valves with balanced current, one to pull current in one direction the other opposed.

To save my grey matter what happens to the secondaries?
Reply With Quote
  #12  
Old 6th April 2008, 08:58 AM
Polisois Polisois is offline
Junior Member
 
Join Date: Mar 2008
Posts: 11
Default Re: 845s or GM-70 amp.

Dear Paul,
Thanks for your interest.
The pair of primaries being in positive series (each pair), their secondaries should also be in positive series, in order to keep the same turns ratio.
But you can also put them in parallel, in which case the turns ratio doubles and the resulting impedance increases according to the known formula:-
Zp = N² x Zs where Zs is the load impedance.
As you can deduct from the connections of the primaries, they are opposed for the DC, hence the offset takes place, but, the ac in each pair being of opposed phase, the signals develop freely.
By the way, I am trying to send a file ( GIF ) totalling less that the accepted size (except the unreadable image that you see), and I get a refused access. This file contains some calculations confirming that, irrespective of the anode current of each valve, the offset takes place.
Can you help me please ? For instance, if I could post the original excel file as an attachment to a standard e-mail and you could take care of inserting it in the thread (sorry but I am unexperienced in this field).
Thank you and best regards,
Ari Polisois
Reply With Quote
  #13  
Old 7th April 2008, 03:37 PM
Polisois Polisois is offline
Junior Member
 
Join Date: Mar 2008
Posts: 11
Default Re: 845s or GM-70 amp.

Dear Paul,
A friend of mine helped me to convert the image into pdf format.
Here it is. I hope it works. Thank you very much for your help.
Attached Files
File Type: pdf 4x4 - when the dc offset takes place.pdf (22.7 KB, 36 views)
Reply With Quote
  #14  
Old 26th February 2009, 10:46 AM
audiodesignguide audiodesignguide is offline
Junior Member
 
Join Date: Feb 2009
Posts: 6
Default Re: 845s or GM-70 amp.

see this

http://www.audiodesignguide.com/Clau...st_result.html

or this

http://www.diyaudio.com/forums/attac...amp=1235224604
Reply With Quote
  #15  
Old 27th April 2009, 07:40 PM
audiodesignguide audiodesignguide is offline
Junior Member
 
Join Date: Feb 2009
Posts: 6
Default Re: 845s or GM-70 amp.

try this
http://www.audiodesignguide.com/Claudio845/GM70amp.html
Reply With Quote
Reply

Thread Tools
Display Modes

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
Forum Jump


All times are GMT +1. The time now is 02:15 AM.


Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright World Designs