6BQ5 as a Push Pull Output Stage. - 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 19th August 2001, 06:12 AM   #1
ppl is offline ppl  United States
diyAudio Member
 
ppl's Avatar
 
Join Date: Apr 2001
Location: Seattle, WA U.S.A.
Hi Folks,
Would a 6BQ5 be good as about 5 watt Push Pull Class AB or Willimson Circuit. and would operate on about +175 Volts?
  Reply With Quote
Old 21st August 2001, 01:03 AM   #2
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
ppl,
Purely as a rough guess, I'd think you'd be able to get something on the order of 7 watts out of a pair of 6BQ5s at 175V. Perhaps even a little more. If you're willing to give up a watt or two, you could bias the tubes slightly hotter and go a little more towards the class A side of things.

Grey
  Reply With Quote
Old 23rd August 2001, 06:43 AM   #3
ppl is offline ppl  United States
diyAudio Member
 
ppl's Avatar
 
Join Date: Apr 2001
Location: Seattle, WA U.S.A.
Thanks for that info. I have a bunch of NOS of assorted Brands of TV tubes and the 6BQ5 was used in alot of TV's. I have 5Y3's & 5U4GB's. I gess the 5Y3 would be good for a Stereo pair of 6BQ5 Amps?
  Reply With Quote
Old 18th September 2001, 02:31 AM   #4
hifiZen is offline hifiZen  Canada
diyAudio Member
 
hifiZen's Avatar
 
Join Date: May 2001
Location: Mountain View, CA
There are some nice EL84/6BQ5 designs up on Sheldon Stokes' website (which by the way has been recently updated!)

http://www.quadesl.com/

__________________
- Chad.
  Reply With Quote
Old 18th September 2001, 02:32 AM   #5
hifiZen is offline hifiZen  Canada
diyAudio Member
 
hifiZen's Avatar
 
Join Date: May 2001
Location: Mountain View, CA
Sheldon, BTW is one of the real pioneers of DIY audio online (perhaps THE pioneer?)
__________________
- Chad.
  Reply With Quote
Old 23rd December 2004, 05:03 PM   #6
Banned
 
Join Date: Dec 2004
Location: Zemun
Lightbulb 6BQ5 - EL84

I do not think that you can generalize that much with expected power -- running EL84s at that low a voltage as 175V B+ means you will get very very low power output, PP or otherwise!\\

Furthermore, running the tubes "hotter" does not give you any additional power! Actually, tubes will give you more power in one of the following cases>
a) higher B+ voltage
b) lower Ra (in SE) or Raa (in PP)
Running the tubes hotter (probably meaning "more current") only lowers the distortion, while reducing a little the bias and lowering the output power as well!

As I can read that some tube rectifiers are mentioned, I am inclined to understand that the main reason to try running a PP or whatever amp with a lower than usual B+ is lower voltage available when using tube rectifiers as compared to ss diodes. Furthermore, probably the power transformer at hand has relatively low HT on the secondary?

Well, if one or both of these reasons are involved, try using the secondary of the amp in a different way: i.e. do not connect the CT to ground, and use the rectifier in a hybrid graetz -- that way you will get way higher voltage output.

Post further questions, if you do not know how to do it...

Regards,
Aleksandar
  Reply With Quote
Old 23rd December 2004, 08:59 PM   #7
ppl is offline ppl  United States
diyAudio Member
 
ppl's Avatar
 
Join Date: Apr 2001
Location: Seattle, WA U.S.A.
Thanks this is exactly the situation howevr the application is for Headphones not loudspeakers so the lower power is not a problem however low distortion. can you post a schematic idea of the type of Power trans /Rect configuation you had in mind TIA
  Reply With Quote
Old 23rd December 2004, 09:32 PM   #8
Banned
 
Join Date: Dec 2004
Location: Zemun
Lightbulb Hybrid Graetz

Attached with this post you will find a graphical explanation of the difference in connecting a tube rectifier (double diode) in a classical manner, and in the hybrid graetz (or bridge) manner.

If the amp is for headphones, you do not need too much power (unless it's some 32 ohm Grado or similia). But, while you can always build it as OTL, I still think the transformer output option is the preferable solution, since there is no large cap in the signal path (electrolytic, that could leak...).

Still, a PP of EL84s seems a trifle too much... maybe SE EL84? Take a look at my site -- although the amps are for loudspeakers, they can drive headphones as well!
Attached Images
File Type: gif hybrid graetz.gif (6.1 KB, 299 views)
  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
Push-Pull Output Stage MOSFET Tester lineup Solid State 2 10th September 2008 11:00 PM
split push-pull output stage andrew_whitham Tubes / Valves 16 22nd March 2007 06:25 PM
Transformer coupled 6SN7 push-pull DAC output stage? cathode_leak Tubes / Valves 7 24th January 2005 07:26 PM
Push Pull Output Stage Question 316a Tubes / Valves 4 10th February 2003 01:04 AM
unity gain push pull output stage ergo Solid State 11 6th January 2003 10:32 AM


New To Site? Need Help?

All times are GMT. The time now is 03:34 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