PP OPT in SE mode operation? - 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 22nd April 2011, 03:50 PM   #1
diyAudio Member
 
Doug Kim's Avatar
 
Join Date: Apr 2008
Location: Maryland, USA
Default PP OPT in SE mode operation?

Hi there,

Please redirect me to the thread if this is already discussed. My search did not show one up.

So I just wanted to experiment this:
Mesa Boogie Patent for Switchable Single Ended, Push-Pull Guitar Amp

I have a couple of SE tube amps sitting and collecting dust, due to too much competetion between them to be chosen by me. I can use either phase splitter tranny or balanced output of a DAC to create two inverted signals, and use two SE tube output stage with one PP OPT.

Thoughts?

Doug
  Reply With Quote
Old 22nd April 2011, 04:31 PM   #2
diyAudio Member
 
smoking-amp's Avatar
 
Join Date: Dec 2001
Location: Hickory, NC
Patented in 2007!!! This is a very old technique. Some designer needs to be fired apparently. Perhaps the patent is limited to the dual switches only.

In any case it is easy to do a much better job. Just making one pentode into a CCS by grounding the grid is a relatively poor way to do the SE job, all it does is balance the DC current for the OT, but there is no power output from that tube.

What should be done is convert one pentode side to effective triode operation by local "Schade" plate feedback. (this will now require additional grid current drive to deal with the lower input Z of the Schaded pentode) The other pentode side can be left as is (although it is useful to increase the cathode degeneration resistance on the pentode there to make it into a better modulated current source, which would then require additional voltage drive). This way the trioded side controls the voltage output, while the pentode side remains high impedance, but still supplying complementary power (basically slaved). Then the bias of both tubes needs adjusting so that class A operation at least covers the first five or ten Watts or so. (some current/Wattage headroom required in the tubes and power supply to do this)

Finally there is the even better scheme called "anti-triode" which uses the above scheme (with a real power triode normally on the "triode" side) with a CCS tail added to the output stage, and the pentode side gets changed to a high gm device, either by using a Mosfet in its place or a gm booster circuit added to the pentode side. It is capable of equivalent sonics to true SE designs, with increased power and better speaker damping besides. Search on "anti-triode" to find a half dozen threads on the subject.
__________________
I want a Huvr-Board!!

Last edited by smoking-amp; 22nd April 2011 at 04:49 PM.
  Reply With Quote
Old 22nd April 2011, 04:59 PM   #3
diyAudio Member
 
Doug Kim's Avatar
 
Join Date: Apr 2008
Location: Maryland, USA
I think the patent is for "difference in sounds at your finger tip" rather than better sound or improvement.

Thank you for the suggestion and I found this thread which I can do some experiment from.
My version of the Simple EL84 or rise of the anti-triode.
  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
pentode in triode mode SE vs a DHT SE like 2a3/300b jarthel Tubes / Valves 67 8th July 2014 01:51 AM
Converting Simple SE to 230V operation bigjppop Tubelab 2 27th December 2010 05:14 AM
Yes, I've searched. Can I use a PP OPT in a SE amp ? Nihilist Tubes / Valves 13 10th March 2010 04:30 PM
What to do with this PP OPT? pwan Tubes / Valves 1 7th November 2008 02:36 AM
Calculating watt requirements for multi-mode/tri-mode operation? Datoyminaytah Solid State 1 14th August 2004 07:43 AM


New To Site? Need Help?

All times are GMT. The time now is 08:58 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