Class i and siblings - Page 5 - 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 22nd December 2011, 05:56 PM   #41
diyAudio Member
 
Edmond Stuart's Avatar
 
Join Date: Nov 2003
Location: Amsterdam
Default push-pull drivers

Quote:
Originally Posted by dadod View Post
Hi Edmond,
Could you show the circuit?
Damir
Hi Damir,

Here it is. Red encircled are the PP-drivers and left to the 1X buffer the 2nd order LP filter. (btw, this amp is not complete).

With this synthetic 1x buffer you can push the amp to much higher slew rates. But, as said already, not without dangerous cross-conduction.

If you put the LP-filter in front of the pre-amp, it has to modified (of course).

Cheers,
E.

edit: The crux is the crosswise connection of R23 & R24.
Attached Images
File Type: jpg AB2-BJT-PP2.jpg (195.3 KB, 330 views)
__________________
Een volk dat voor tirannen zwicht, zal meer dan lijf en
goed verliezen dan dooft het licht…(H.M. van Randwijk)

Last edited by Edmond Stuart; 22nd December 2011 at 06:05 PM.
  Reply With Quote
Old 22nd December 2011, 07:51 PM   #42
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Quote:
Originally Posted by Edmond Stuart View Post
Hi Damir,

Here it is. Red encircled are the PP-drivers and left to the 1X buffer the 2nd order LP filter. (btw, this amp is not complete).

With this synthetic 1x buffer you can push the amp to much higher slew rates. But, as said already, not without dangerous cross-conduction.

If you put the LP-filter in front of the pre-amp, it has to modified (of course).

Cheers,
E.

edit: The crux is the crosswise connection of R23 & R24.
Hi Edmond,
It looks great, I will try it in my simulation soon.
Damir
  Reply With Quote
Old 22nd December 2011, 08:56 PM   #43
diyAudio Member
 
Edmond Stuart's Avatar
 
Join Date: Nov 2003
Location: Amsterdam
Default Filter

Hi Damir,

In case you incorporated also a front-end (with a gain of 28x), here's the modified LP-filter.
Hope it works; good luck. FYI, it's a Sallen-Key filter.

Cheers,
E.
Attached Images
File Type: png AB2-BJT-PP3.png (45.7 KB, 316 views)
__________________
Een volk dat voor tirannen zwicht, zal meer dan lijf en
goed verliezen dan dooft het licht…(H.M. van Randwijk)
  Reply With Quote
Old 22nd December 2011, 10:53 PM   #44
diyAudio Member
 
Edmond Stuart's Avatar
 
Join Date: Nov 2003
Location: Amsterdam
And for those with an adventurous mind or those who detest thermal NBF, here's another version that does away with thermal coupling of the PP-drivers and the bias spreaders.

edit: not recommended.

Cheers,
E.
Attached Images
File Type: png AB2-BJT-PP4.png (43.6 KB, 283 views)
__________________
Een volk dat voor tirannen zwicht, zal meer dan lijf en
goed verliezen dan dooft het licht…(H.M. van Randwijk)
  Reply With Quote
Old 23rd December 2011, 07:33 AM   #45
ontoaba is offline ontoaba  Indonesia
diyAudio Member
 
ontoaba's Avatar
 
Join Date: Nov 2009
Location: Kudus, Malang, Dieng
Yes. It (auto biased) work with 3906-3904.
Good slew rate but 9540 is just big gate caps charged with only 34mA.
Input is light error corrected and FFT around 0.004%THD all freq to 20k.
Attached Images
File Type: png Auto bias.PNG (38.6 KB, 271 views)

Last edited by ontoaba; 23rd December 2011 at 07:37 AM.
  Reply With Quote
Old 23rd December 2011, 08:06 AM   #46
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Quote:
Originally Posted by Edmond Stuart View Post
Hi Damir,

In case you incorporated also a front-end (with a gain of 28x), here's the modified LP-filter.
Hope it works; good luck. FYI, it's a Sallen-Key filter.

Cheers,
E.
Hi Edmond,
Thermal fluctuation of the PP drivers will not influence thermal stabillity of the output transistors, I suppose?
Damir
  Reply With Quote
Old 23rd December 2011, 09:57 AM   #47
ontoaba is offline ontoaba  Indonesia
diyAudio Member
 
ontoaba's Avatar
 
Join Date: Nov 2009
Location: Kudus, Malang, Dieng
May be I am doing wrong, I need pre EC to correct voltage gap and it work with 4148 too.

Hi, Damir.
Output stage is never turned off, up to 20kHz (my pict), looks like output transistor bias determined by AB circuit not heatsink temp.
Attached Images
File Type: png Auto bias 4148.PNG (32.5 KB, 259 views)
  Reply With Quote
Old 23rd December 2011, 10:55 AM   #48
diyAudio Member
 
Edmond Stuart's Avatar
 
Join Date: Nov 2003
Location: Amsterdam
Quote:
Originally Posted by ontoaba View Post
Yes. It (auto biased) work with 3906-3904.
Good slew rate but 9540 is just big gate caps charged with only 34mA.
Input is light error corrected and FFT around 0.004%THD all freq to 20k.
Hi ontoaba,

Amazing that even a minimalistic implementation, like yours, does work.
Nevertheless, I urge you to insert push-pull drivers between the bias circuit and MOSFETs (because of high Cgd and Cgs).

Cheers,
E.
__________________
Een volk dat voor tirannen zwicht, zal meer dan lijf en
goed verliezen dan dooft het licht…(H.M. van Randwijk)
  Reply With Quote
Old 23rd December 2011, 11:09 AM   #49
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Quote:
Originally Posted by ontoaba View Post
May be I am doing wrong, I need pre EC to correct voltage gap and it work with 4148 too.

Hi, Damir.
Output stage is never turned off, up to 20kHz (my pict), looks like output transistor bias determined by AB circuit not heatsink temp.
Hi ontoaba,
Nice implementation. I know how AB works from simulation Edmond AB2 and Kendall Class i.
Damir
  Reply With Quote
Old 23rd December 2011, 11:40 AM   #50
diyAudio Member
 
Edmond Stuart's Avatar
 
Join Date: Nov 2003
Location: Amsterdam
Quote:
Originally Posted by dadod View Post
Hi Edmond,
Thermal fluctuation of the PP drivers will not influence thermal stabillity of the output transistors, I suppose?
Damir
Hi Damir,

That's correct. Iq of the OPS is firmly stabilized by the high DC gain of the common mode NFB loop (51dB), see 1st pic.
The 2nd pic shows the differential loop gain and phase. This NFB loop determines to what extent the distortion is reduced.
The wild phase fluctuation at 100MHz worries me a bit, but I don't know (yet) how to tame it. Also, I don't know if it is really harmful.

Cheers,
E.
Attached Images
File Type: png AB2-BJT-Bias.png (13.0 KB, 130 views)
File Type: png AB2-BJT-FB.png (13.6 KB, 63 views)
__________________
Een volk dat voor tirannen zwicht, zal meer dan lijf en
goed verliezen dan dooft het licht…(H.M. van Randwijk)
  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
Class-AB meets Class-D: Yamaha's EEEngine Topology - where are this Diy Projects? tiefbassuebertr Solid State 29 14th April 2014 05:12 PM
Collection of Class B topologies <100mA Idle and Sound closest by Class A tiefbassuebertr Solid State 37 27th July 2012 09:04 AM
Can a Class AB PP amp be said to be operating in Class A at low signal levels? ray_moth Tubes / Valves 19 23rd January 2009 08:52 PM
How about a round-up of Class A kit power amps, or collectable vintage class A? Brisso57 Solid State 4 14th February 2007 11:30 AM


New To Site? Need Help?

All times are GMT. The time now is 12:24 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