New Class A, Super-A, Non-Switching : need a revival ? - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 9th April 2010, 10:23 PM   #21
diyAudio Member
 
tiefbassuebertr's Avatar
 
Join Date: Jul 2005
Location: D-55629 Schwarzerden
Quote:
Originally Posted by StevenOH View Post
The Sansui Tanaka patent is US4401951. It also has the discussion of a few other "nonswitching" patents.
The common mistake with this approach is to leave Power stage with the new type of distortions due to unpredictable nonlinearity of P. transistors currents at the small levels (and near the signal zero crossing!).

orig posted by Steph_tsF:
This the famous Nelson Pass patent, indeed. Thanks 1000 times for reminding us. It is panicking to see those japanese companies (Matsushita, JVC, Pioneer, Sansui) rushing around 1978-1979 for Non-Switching Class AB, while Nelson Pass had it done as soon as Feb 1975, with his US patent granted Nov 1976.
here the link therefore and some others in this case:
Patent US4401951
Patent US6429744
Patent US5019789
Patent US6297699

Steph_tsF: I also had the same thought many times.

Last edited by tiefbassuebertr; 9th April 2010 at 10:27 PM.
  Reply With Quote
Old 9th April 2010, 11:26 PM   #22
diyAudio Member
 
Join Date: Nov 2007
Location: Dallas
This was the simplified version of Pass' circuit from his patent.

At first glance, looks very similar to mine. But Pass' load isn't
forced to use only the diode path, so not sure how he keeps
a reactive load from sometimes depleting the emitter reserve?

Whatever else: even in simplest form, its more parts than I'd
ever throw at it. Still want to work up a sim of this one to see
if it might actually perform better in some subtle way I did not
expect???

I think crossing here is still shaped by the log law of emitters?
I'm not entirely sure yet if his quasi-complimetary diodes are
the primary shapers? I do see he sticks yet another diode into
parallel with some of his emitter resistance in Fig 5. Maybe to
do some shaping? Would have been redundant in my scheme...
Attached Images
File Type: gif Pass3995228.gif (17.2 KB, 841 views)

Last edited by kenpeter; 9th April 2010 at 11:39 PM.
  Reply With Quote
Old 10th April 2010, 04:15 PM   #23
diyAudio Member
 
steph_tsf's Avatar
 
Join Date: Mar 2008
let's try a summary about the class AB Non-Switching, or class B Non-Switching output stages for Audio Power Amplifiers. We are not including any class AA or class A+ here.

Patents :
Technics New Class A :
JVC Super-A : US4274059
Pioneer Non-Switching : US4215318 and US4254379
Sansui Non-Switching : US4401951
We need to add :
Hitachi Superlinear : US4345215
Pass Non-Switching: US3995228
Dodson Hyperbolic Class A :
Thornton Non-Switching : US4160216
Hawksford Non-Switching :
All patents are downloadable from Patent Searching and Inventing Resources

AES preprints and papers :
Technics New Class A :
JVC Super-A :
Pioneer Non-Switching : AES E-Library: Non-Switching Amplifier
Sansui Non-Switching : AES E-Library: New Biasing Circuit for Class-B Operation
Sansui Non-Switching : AES E-Library: New Biasing Circuit for Class B Operation
Hitachi Superlinear :
Pass Non-Switching:
Dodson Hyperbolic Class A : AES E-Library: Quasi-Class A/Improved Class AB Bias Loop
Thornton Non-Switching : AES E-Library: A Power Class A Technique with Open Loop Stability
Hawksford Non-Switching : AES E-Library: Error Correction and Non-Switching Power Amplifier Output Stages
All AES papers are downloadable (subscription needed) from AES E-Library

Commercial products :
Technics New Class A : SU-V5 SU-V7 SU-V8 SU-V9
JVC Super-A : AX1 AX2 AX3 AX4 AX7
Pioneer Non-Switching : SA7800 SA8800 SA9800 A5 A6 A8 A9 A60 A70 A80
Sansui Non-Switching : AU-D5
Hitachi Superlinear : HA-3700 / HA-4700 (BJTs) and HA-7500 MK2 (MOSFETs)
Pass Non-Switching:
Dodson Hyperbolic Class A :
Thornton Non-Switching :
Hawksford Non-Switching :
Many service manuals are downloadable from Free Manuals User / Service / Schematics for Download | HiFi Engine

Any omission ?
I have not included some techniques used inside opamps (Burr-Brown, Texas Instruments), barely applicable to Audio Power Amplifiers.

Cheers,
Steph

Last edited by steph_tsf; 10th April 2010 at 04:30 PM.
  Reply With Quote
Old 10th April 2010, 04:26 PM   #24
diyAudio Member
 
event horizon's Avatar
 
Join Date: Feb 2008
Location: East Midlands, England
Quote:
Originally Posted by steph_tsf View Post
Any omission ?

Cheers,
Steph
Yes, like i mentioned, the very early Technics "hi end" power amplifiers used a class B amplifier to drive a low voltage full current class A output stage Here is an example, the SE-A1, if i remember correctly these things cost many thousands of . Looks like they call it Class A+.

They don't make them like they used to
__________________
"Never let your morals prevent you from doing what is right!" Salvor Hardin
  Reply With Quote
Old 10th April 2010, 04:29 PM   #25
diyAudio Member
 
steph_tsf's Avatar
 
Join Date: Mar 2008
Quote:
Originally Posted by StevenOH View Post
I will show one "well forgotten" circuit from the '60s with the interesting properties. It is SRPP (in Cl. A bias), but is Non-Switching in Cl. AB bias. T11 will never switch off. The Non-switching condition for T12 is V(D5)≥0.5V + V(D6)max. D6 should be Schottky (to minimize power waste) with the appropriate current rating and in TO-220 or TO-3P case. Obviously, it is the voltage follower/power buffer and T1 provides the Error Correction function for Pushing and Pulling action of T11, T12. The bias with the shown values: T1, T12 ~0.4 mA, T11 ~10 mA, D6 is (may be) non conducting. D5 is generally not necessary (only for non-switching T12 and Cl. A bias) and can be shorted. C61 provides bootstrapping for R59.
Can somebody derive a stronger version, powered by +42V/-42V and able to deal with 5 amps ? How should we name this, if we succeed ?
Attached Images
File Type: jpg SRPP Bipolar Cl. B.JPG (5.2 KB, 983 views)
  Reply With Quote
Old 10th April 2010, 04:38 PM   #26
diyAudio Member
 
StevenOH's Avatar
 
Join Date: Jun 2004
Trio-Kenwood pat. US4342966.
__________________
The truth is out there. Who can handle the truth?
  Reply With Quote
Old 10th April 2010, 04:53 PM   #27
diyAudio Member
 
steph_tsf's Avatar
 
Join Date: Mar 2008
Quote:
Originally Posted by event horizon View Post
The very early Technics "hi end" power amplifiers used a class B amplifier to drive a low voltage full current class A output stage Here is an example, the SE-A1, if i remember correctly these things cost many thousands of . Looks like they call it Class A+. They don't make them like they used to
I know. Class A+ and class AA are expensive solutions, with two separate amplifiers for each channel. Over time, the class A+ got replaced by the class AA, where the second amplifier is a total feedback current buffer. You may consider the class AA as an upgraded Quad 405, still with a balancing bridge, but this time it is wideband (four resistors) and there is a total local feedback around the current dumper, which is a dedicated amp with a big open loop gain, instead of a dumb darlington. I think I'll open a few separate threads about Hitachi Dynharmony class G, Technics and Pioneer class A+, Technics class AA, QSC floating supply bridge. This present thread is about fiddling with the Vbe multiplier. Okay, the Thornton scheme is not what we may call a Vbe multiplier fidle, but as the Technics New Class A was already there, I found a nice parallelism between Technics New Class A, and Thornton scheme. They both displace the problem, using fast diodes. All classifications have limitations.

Cheers,
Steph
  Reply With Quote
Old 10th April 2010, 05:05 PM   #28
diyAudio Member
 
event horizon's Avatar
 
Join Date: Feb 2008
Location: East Midlands, England
No problem Steph I just thought i'd mention it for completeness & the fact that it had a true class A output stage.

Besides sooner or later (depending on how long it takes me to get stuff together) i'll be building a few of similar design 250W+ RMS 8ohm & 500W+ RMS 4ohm. There's plenty to go about
__________________
"Never let your morals prevent you from doing what is right!" Salvor Hardin
  Reply With Quote
Old 10th April 2010, 05:21 PM   #29
diyAudio Member
 
Join Date: Nov 2007
Location: Dallas
Will this do?
Attached Files
File Type: txt NoKlas21.asc.txt (12.0 KB, 104 views)
  Reply With Quote
Old 10th April 2010, 05:39 PM   #30
diyAudio Member
 
steph_tsf's Avatar
 
Join Date: Mar 2008
Quote:
Originally Posted by StevenOH View Post
Trio-Kenwood pat. US4342966.
Thanks for the info. Attached there is a .txt file containing the upgraded info.
Attached Files
File Type: txt Class AB & class B Non-Switching Power Amplifiers.txt (1.9 KB, 199 views)

Last edited by steph_tsf; 10th April 2010 at 05:44 PM.
  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
margan : non switching class B sreten Solid State 16 22nd May 2011 04:43 PM
Revival of incredible LM3886 design udailey Group Buys 82 3rd January 2009 12:03 AM
New class A biasing (with non-switching class AB overflow) Steven Solid State 34 24th March 2007 06:40 PM
switching class d amp steven344 Class D 10 20th November 2005 03:22 AM
Non-switching amp same as Class A? mjarve Solid State 2 26th June 2004 07:43 PM


New To Site? Need Help?

All times are GMT. The time now is 08:09 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