6as7/6080 Se Otl - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 2nd December 2008, 12:10 PM   #11
diyAudio Member
 
Join Date: Mar 2003
Location: Zürich
Here is another one

6c19p se otl

Erik
__________________
my surname is indeed 'de Best': neither misspelling nor snobbism! Ask SY!
  Reply With Quote
Old 3rd December 2008, 12:49 AM   #12
diyAudio Member
 
Join Date: Dec 2004
Location: NE USA
here is the revised schematic showing how i plan to implement the cathode resistors in parallel. Again I stated earlier I have read that 6AS7's need to have separate resitors on each side of the triode to keep the current in check for the tube overall.

Any comments?

Thx
Attached Files
File Type: pdf otlserevised.pdf (95.4 KB, 344 views)
  Reply With Quote
Old 3rd December 2008, 03:44 AM   #13
poynton is offline poynton  United Kingdom
diyAudio Member
 
poynton's Avatar
 
Join Date: Mar 2005
Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)
Quote:
Originally posted by desperateaudio
here is the revised schematic showing how i plan to implement the cathode resistors in parallel. Again I stated earlier I have read that 6AS7's need to have separate resitors on each side of the triode to keep the current in check for the tube overall.

Any comments?

Thx
The large value of the cathode resistors chosen ( even though they are in parallel ) will severely reduce the output !!

Even if reduced to, say, 10ohms each, as in a previous post, the output would still be reduced.


Andy
Attached Images
File Type: png otl.png (87.0 KB, 865 views)
__________________
If it ain't broke, break it !! Then fix it again. It's called DIY !
  Reply With Quote
Old 3rd December 2008, 05:29 AM   #14
diyAudio Member
 
Join Date: Jan 2002
Location: Tyrone Ga. U.S.A.
Instead of using cathode resistors to equalize the current draw
could you use a plate resistor on each tube? I saw this done
in the RCA receiving tube manual where a 160 ohm pot was
used to ballence the current through both halves of a 6080?
  Reply With Quote
Old 3rd December 2008, 05:52 AM   #15
poynton is offline poynton  United Kingdom
diyAudio Member
 
poynton's Avatar
 
Join Date: Mar 2005
Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)
Quote:
Originally posted by desperateaudio
here is the revised schematic showing how i plan to implement the cathode resistors in parallel. Again I stated earlier I have read that 6AS7's need to have separate resitors on each side of the triode to keep the current in check for the tube overall.

Any comments?

Thx
The large value of the cathode resistors chosen ( even though they are in parallel ) will severely reduce the output !!

Even if reduced to, say, 10ohms each, as in a previous post, the output would still be reduced.


Andy
__________________
If it ain't broke, break it !! Then fix it again. It's called DIY !
  Reply With Quote
Old 3rd December 2008, 06:04 AM   #16
Klimon is offline Klimon  Belgium
diyAudio Member
 
Join Date: Apr 2005
Location: Leuven
Quote:
The large value of the cathode resistors chosen ( even though they are in parallel ) will severely reduce the output !!
?? Looks fine to me.

I think the implementation of a cathode choke should be worthwile (raising cost with about 60$ using Hammonds), requiring lower B+ and also (more importantly, or am I mistaken?) raising efficiency. Here's a similar circuit: http://vincent.brient.free.fr/otl7w_fr.htm

Regards - Simon
  Reply With Quote
Old 3rd December 2008, 06:04 AM   #17
diyAudio Member
 
Join Date: May 2007
To make this cicuit work you have to take out max currents through the 6080s which means their workingpoint should be Ia 125mA, Ua 100V.

You should also use a choke or a CCS from the cathodes to ground. A B+ of 130-170V will do.

Every triode has an theoretical (simplified 1/Gm)Rout of ca 140ohms, so adding a separate 10 ohm to each one will not make you loose so much. Without NFB Zout will be high anyway.

If going for a 8ohm load I would suggest using at least 5 but preferably 10 6080s/channel.
  Reply With Quote
Old 3rd December 2008, 06:36 AM   #18
diyAudio Member
 
Join Date: Jan 2002
Location: Tyrone Ga. U.S.A.
Here is an old circuite found on the web.
Attached Images
File Type: jpg otlse.jpg (39.0 KB, 856 views)
  Reply With Quote
Old 3rd December 2008, 06:41 AM   #19
poynton is offline poynton  United Kingdom
diyAudio Member
 
poynton's Avatar
 
Join Date: Mar 2005
Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)
Quote:
Originally posted by Klimon
?? Looks fine to me.

I think the implementation of a cathode choke should be worthwile (raising cost with about 60$ using Hammonds), requiring lower B+ and also (more importantly, or am I mistaken?) raising efficiency. Here's a similar circuit: http://vincent.brient.free.fr/otl7w_fr.htm

Regards - Simon
A cathode choke would improve efficiency.

Your circuit (see below) has the output taken via several caps from the cathode not from the junction of the resistors so the output power would be 'unaffected'.
Also the biasing is different.

I think what is needed is a combination of designs.

Andy
Attached Images
File Type: png otl2.png (11.7 KB, 846 views)
__________________
If it ain't broke, break it !! Then fix it again. It's called DIY !
  Reply With Quote
Old 3rd December 2008, 06:44 AM   #20
poynton is offline poynton  United Kingdom
diyAudio Member
 
poynton's Avatar
 
Join Date: Mar 2005
Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)
Quote:
Originally posted by woody
Here is an old circuite found on the web.

See post #8


Andy
__________________
If it ain't broke, break it !! Then fix it again. It's called DIY !
  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
Simplest 6080 or 6AS7 OTL Project? Michael Rothacher Tubes / Valves 29 26th August 2010 08:05 PM
WANTED - 6080/6AS7 Based Amplifier baileyler Swap Meet 1 26th March 2008 10:17 PM
Transformer coupled 6AS7/6080 dsavitsk Tubes / Valves 48 20th September 2007 06:16 AM
Set 6080/6as7 needtubes Tubes / Valves 34 28th August 2004 04:40 AM
6080/6AS7/6H13C/6H5C in SE? Colt45 Tubes / Valves 8 18th November 2002 05:56 PM


New To Site? Need Help?

All times are GMT. The time now is 05:28 PM.


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