Why no CCS in PP 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 7th April 2005, 06:01 PM   #1
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Default Why no CCS in PP output stage?

Why is CCS so rarely used in PP output stages?

Planet10 gave me this reference:

EL84 at AA

I can't find much else that uses it. Is it a question of specific topology required to implement it that I can't discern, or builder opinion/preference?
__________________
Aerodynamics are for people who can't build engines. Enzo Ferrari
  Reply With Quote
Old 7th April 2005, 06:46 PM   #2
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Using a CCS output stage as its own phase splitter is fine as long as you don't mind the cost, inefficiency, and distortion. The RDH discusses this topology and pretty much dismisses it. And possibly for good reason.
__________________
And while they may not be as strong as apes, don't lock eyes with 'em, don't do it. Puts 'em on edge. They might go into berzerker mode; come at you like a whirling dervish, all fists and elbows.
  Reply With Quote
Old 7th April 2005, 07:19 PM   #3
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Also, a CCS in the output stage means that the stage folds catastrophically when asked to leave Class A.
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 7th April 2005, 09:41 PM   #4
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Quote:
Originally posted by SY
Using a CCS output stage as its own phase splitter is fine as long as you don't mind the cost, inefficiency, and distortion. The RDH discusses this topology and pretty much dismisses it. And possibly for good reason.
If you mean the section in Chapter 13.3.viii, I don't think that applies to the case where the input section is the phase splitter. Is there a more detailed reference somewhere else?

Oh, and I did find another example:

http://home.pacifier.com/~gpimm/1624.gif
__________________
Aerodynamics are for people who can't build engines. Enzo Ferrari
  Reply With Quote
Old 8th April 2005, 04:47 AM   #5
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Allen Wright claims to have been the 1st (he knows of) to use a CCS on the outputs -- he says so cautiously given how often something new is actually done. He does cite its use in a German atomic reactor.

It was at the last VSAC he started talking about it and showed his amp -- this amp set a few people on their ears. Since then the amp has won product of the year, 2 years in a row at enjoy the music.

It requires the amp run in class A (ie probably 4 watts max for your EL84s) and clipping is abrupt -- more like a SS amp.

The AA stuff is all spawned from that VSAC lecture, and has had active input from Allen.

I'm looking forward to his pending power Amplifier cookbook where he will discuss it in detail.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 8th April 2005, 05:19 AM   #6
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Thanks Dave!

BTW, my latest idea on how to build my power stage was to have a triode/UL switch, and in the UL position have partial feedback with a 100k resistor (don't want to use an OPT connection since the input stage is in a different box). I haven't yet figured out if the 70 mA/tube CCS setting in the AA amp jives with that. In Jones' book he glosses over how he biases the EL84, and that's what I need spelled out in crayon!
__________________
Aerodynamics are for people who can't build engines. Enzo Ferrari
  Reply With Quote
Old 8th April 2005, 05:26 AM   #7
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Quote:
Originally posted by leadbelly


If you mean the section in Chapter 13.3.viii, I don't think that applies to the case where the input section is the phase splitter. Is there a more detailed reference somewhere else?
In the linked John Swenson schematic, the input stage is not a phase splitter, it's a plain vanilla single-ended voltage amp.
__________________
And while they may not be as strong as apes, don't lock eyes with 'em, don't do it. Puts 'em on edge. They might go into berzerker mode; come at you like a whirling dervish, all fists and elbows.
  Reply With Quote
Old 8th April 2005, 05:44 AM   #8
diyAudio Member
 
Join Date: Feb 2004
Location: Hamilton, ON
Quote:
Originally posted by planet10
Allen Wright claims to have been the 1st (he knows of) to use a CCS on the outputs

Actually, it was Bill Beard who was first ( in his P30 power amp) to use a CCS in the output stage. I believe he used LM317's or 7812's (I'm not sure which) on the cathodes of each EL84.
By the way that was one fine sounding amp. The only bug was that if a tube went bad you had to replace the regulator as well almost every time.

Dan
P.S. I'm not trying to knock Allen
  Reply With Quote
Old 8th April 2005, 07:21 AM   #9
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
A lot of Allen's stuff use a cascode differential stage in them (which he pinched from HP test gear). His comment when i sent him a map from an early 50s mag that had a 7F7 cascode differential stage driving PP 807s (ie very similar to his PP1c) was that he well knew that very little we do with tubes is actually new.... hence his cautious statement :^)

Allen is at least responsible for the recent interest in this.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 8th April 2005, 07:22 AM   #10
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
PS: any references to the Bill Beard amp?

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  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
3C24 in a SE output stage - output transformer impedance recommendation !!! aldovan Tubes / Valves 15 6th September 2008 11:18 AM
preamp output stage resistor from output to V- ? ? Bernhard Solid State 4 19th October 2007 03:55 PM
Output stage biasing, with the driver stage andrew_whitham Tubes / Valves 0 19th May 2007 12:14 PM
Adding secondary of output transformer into cathodes of output stage ? Eico ST-70 freddymac406 Tubes / Valves 3 21st April 2007 07:15 PM
TV Horzontal Output Transistor for output stage..? ronybc Solid State 46 10th October 2005 03:26 AM


New To Site? Need Help?

All times are GMT. The time now is 02:09 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