Crossover distortion - 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 1st December 2004, 01:53 AM   #1
diyAudio Moderator Emeritus
 
lumanauw's Avatar
 
Join Date: Oct 2002
Location: Bandung
Send a message via Yahoo to lumanauw
Default Crossover distortion

When I read about theories of output stages, they say that classB (and AB) power amp suffers a "Crossover distortion". With my limited knowledge, I accept it as happening when NPN and PNP output stages will be 1=on and the other =off. The transition between on and off causing this crossover distortion.

I assume this happens because each transistor will be off and on. If we can make all transistor never off (like classA), maybe this crossover distortion will dissappear. (Is this right?)

I'm looking for a way to always have both transistor on. Someone said there is a patent on "never turning off" in class (A)B, but I couldn't find it. Does anyone know where it is?

I think about this drawing that I attached. This is complementary EF output stage. If I put D1 and D2 after emitors, before output, and put 10mA CCS to rails, this way both T1 and T2 will never turn off, minimum will always have to pass 10mA in every condition.

I have question about this idea.

1. T1 and T2 will never turn off. But can this idea eliminate crossover distortion in class(A)B amp?

2. But it makes the D1 and D2 conducting/not conducting. Does diodes in this mode gives another kind of on/off distortion? If it gives "diode distortion" that is worse than "transistor distortion" then this idea is not good.

3. If this idea is working, what kind of diode is suitable for D1 and D2? Ordinary diode/Schottky/Fast recovery/Soft recovery?
Attached Images
File Type: jpg idea4.jpg (18.7 KB, 1272 views)
  Reply With Quote
Old 1st December 2004, 04:50 AM   #2
Eva is offline Eva  Spain
diyAudio Member
 
Eva's Avatar
 
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
Diode reverse recovery and turn-on delay, by themselves, are much worse than crossover distortion. Schottky diodes may be an interesting option
  Reply With Quote
Old 1st December 2004, 05:23 AM   #3
Steven is offline Steven  Netherlands
diyAudio Member
 
Steven's Avatar
 
Join Date: Oct 2003
Location: The Netherlands
Default Re: Crossover distortion

Quote:
Originally posted by lumanauw

I'm looking for a way to always have both transistor on. Someone said there is a patent on "never turning off" in class (A)B, but I couldn't find it. Does anyone know where it is?
http://www.diyaudio.com/forums/showt...339#post282339

S.Tanaka, "New Biasing Circuit for Class B Operation," JAES, 1981, Vol. 29, No 3, p. 148 (patented)

Nelson Pass: patent # 3,995,228


Steven
__________________
The Analog Art shows no sign of yielding to the Dodo's fate. The emergence and maturation of monolithic processing finesse has perhaps lagged a bit behind the growth of the Binary Business. But whereas digital precision is forever bounded by bits, there is no limit excepting Universal Hiss to the ultimate accuracy and functional variety of simple analog circuits. - Barry Gilbert, 1973
  Reply With Quote
Old 1st December 2004, 05:25 AM   #4
Steven is offline Steven  Netherlands
diyAudio Member
 
Steven's Avatar
 
Join Date: Oct 2003
Location: The Netherlands
Before I forget, also the Hawksford error correction circuit does not switch off the output transistors.

Steven
__________________
The Analog Art shows no sign of yielding to the Dodo's fate. The emergence and maturation of monolithic processing finesse has perhaps lagged a bit behind the growth of the Binary Business. But whereas digital precision is forever bounded by bits, there is no limit excepting Universal Hiss to the ultimate accuracy and functional variety of simple analog circuits. - Barry Gilbert, 1973
  Reply With Quote
Old 1st December 2004, 08:43 AM   #5
diyAudio Moderator Emeritus
 
lumanauw's Avatar
 
Join Date: Oct 2002
Location: Bandung
Send a message via Yahoo to lumanauw
Hi, Steven,

Thanks for the link. You also think the same too (but for classA?)
Quote:
Nelson Pass: patent # 3,995,228
Do you have a small JPG on this patent?
  Reply With Quote
Old 1st December 2004, 08:49 AM   #6
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
Quote:
Originally posted by Eva
Diode reverse recovery and turn-on delay, by themselves, are much worse than crossover distortion. Schottky diodes may be an interesting option
I have done similar experiments and I got real nasty crossover distortion => not a good idea
__________________
/Per-Anders (my first name) or P-A as my friends call me
Tube Buffered Gainclone in work |Thread || Diamond buffer |Thread for the group buy | Wiki
  Reply With Quote
Old 1st December 2004, 09:15 AM   #7
uli is offline uli  Austria
diyAudio Member
 
Join Date: Dec 2002
Location: Vienna, Austria
Quote:
Originally posted by lumanauw

Do you have a small JPG on this patent?

Source: www.passdiy.com
www.passlabs.com


Uli

__________________

'Jazz is not dead, it just smells funny' F.Zappa
  Reply With Quote
Old 1st December 2004, 01:20 PM   #8
diyAudio Moderator Emeritus
 
lumanauw's Avatar
 
Join Date: Oct 2002
Location: Bandung
Send a message via Yahoo to lumanauw
Quote:
=> not a good idea
Thanks for the input.
I see passdiy and passlab website, but couldn't find patents by Mr.Pass.
Where can I see all his audio patents?

Threshold series amps are marvelous in this area. Many kind of amp, with different cct, but same purpose. NP incorporated EC like cct, but he says its not for EC. Now I know what they was intended. To eliminate Xover distortion.
  Reply With Quote
Old 1st December 2004, 05:15 PM   #9
diyAudio Member
 
darkfenriz's Avatar
 
Join Date: Jun 2004
Location: Warsaw
What is so-called class AA?
I heard that Technics used it
  Reply With Quote
Old 1st December 2004, 05:42 PM   #10
Steven is offline Steven  Netherlands
diyAudio Member
 
Steven's Avatar
 
Join Date: Oct 2003
Location: The Netherlands
Quote:
Originally posted by lumanauw
Hi, Steven,

Thanks for the link. You also think the same too (but for classA?)

Do you have a small JPG on this patent?

Type the patent number in here: http://patft.uspto.gov/netahtml/srchnum.htm

or look here: http://l2.espacenet.com/espacenet/vi...b&LG=en&DB=EPD

Steven
__________________
The Analog Art shows no sign of yielding to the Dodo's fate. The emergence and maturation of monolithic processing finesse has perhaps lagged a bit behind the growth of the Binary Business. But whereas digital precision is forever bounded by bits, there is no limit excepting Universal Hiss to the ultimate accuracy and functional variety of simple analog circuits. - Barry Gilbert, 1973
  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
Crossover distortion - be gone! Circlotron Solid State 4 24th August 2009 12:09 PM
Help New TAC US 12A crossover distortion. spirod Solid State 1 9th February 2008 03:34 PM
So, what does crossover distortion sound like? beedlo Solid State 16 24th January 2005 12:29 PM
Crossover Distortion? Killjoy99 Multi-Way 8 30th March 2004 05:10 AM
Sensitivity to crossover distortion angel Everything Else 3 26th January 2004 02:33 AM


New To Site? Need Help?

All times are GMT. The time now is 07:10 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