ODNF or no GNFB power amp - Page 4 - 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 28th June 2013, 03:55 PM   #31
Shinja is offline Shinja  Japan
diyAudio Member
 
Join Date: Jul 2008
@pawel
I found the lower side mosfet is Nch.

@dadad
this is the feedforward distortion cancellation based on 80's DENON's circuit, he wrote.
http://www.ne.jp/asahi/evo/amp/Dnfb/edc.htm

I reserched it ago and found a patent US4447790.
Attached Images
File Type: gif aaaaaaaa.gif (192.1 KB, 234 views)

Last edited by Shinja; 28th June 2013 at 04:03 PM.
  Reply With Quote
Old 28th June 2013, 04:11 PM   #32
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Quote:
Originally Posted by Shinja View Post
@pawel
I found the lower side mosfet is Nch.

@dadad
this is the feedforward distortion cancellation based on 80's DENON's circuit, he wrote.
Distortion removal circuit

I reserched it ago and found a patent US4447790.
Thanks Shinja I will take a look at that.
  Reply With Quote
Old 28th June 2013, 05:19 PM   #33
diyAudio Member
 
Join Date: Mar 2004
Location: Krakow
Quote:
Originally Posted by Shinja View Post
@pawel
I found the lower side mosfet is Nch.
yes you are right again, this should be nmos too
this is cured circuit but not works as good as in post 27, the cancelation dost pot U3 not works... ODNF or no GNFB power amp
Attached Files
File Type: asc odnfb vlt source separ power suppl (1).asc (4.5 KB, 24 views)
__________________
regards, Pawel

Last edited by padamiecki; 28th June 2013 at 05:41 PM.
  Reply With Quote
Old 29th June 2013, 12:48 PM   #34
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Nobody commented my implementation of the HEC output stage, it's a bit different from Hawksford.
Distortion decrease at 1kHz is 42dB and at 20kHz is 25dB.
I simulated noise at full and at -40dB volume.
Next simulation is the gain.
As this amp is whitout GNFB output is not close enough to zero V, next step to add DC servo.
Attached Images
File Type: jpg GainWire-HEC-power-sch.jpg (108.8 KB, 216 views)
File Type: jpg GainWire-HEC-power-noise-maxvolume.jpg (209.1 KB, 200 views)
File Type: jpg GainWire-HEC-power-noise-volume-40dB.jpg (207.1 KB, 187 views)
File Type: jpg GainWire-HEC-power-gain.jpg (230.6 KB, 171 views)
  Reply With Quote
Old 29th June 2013, 03:31 PM   #35
diyAudio Member
 
Join Date: Mar 2004
Location: Krakow
Quote:
Originally Posted by dadod View Post
Nobody commented my implementation of the HEC output stage, it's a bit different from Hawksford.
Distortion decrease at 1kHz is 42dB and at 20kHz is 25dB.
I simulated noise at full and at -40dB volume.
Next simulation is the gain.
As this amp is whitout GNFB output is not close enough to zero V, next step to add DC servo.
Dear Dadod
you know I like your designs very much and I am very impressed of their performance but I cannot compliment every post
__________________
regards, Pawel
  Reply With Quote
Old 29th June 2013, 04:11 PM   #36
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Quote:
Originally Posted by padamiecki View Post
Dear Dadod
you know I like your designs very much and I am very impressed of their performance but I cannot compliment every post
No compliments, technical comments only.
  Reply With Quote
Old 29th June 2013, 04:41 PM   #37
diyAudio Member
 
bogdan_borko's Avatar
 
Join Date: Nov 2005
Location: serbia, zajecar
Dadod, that`s all nice in the simulation world but there`s a work ahead of you to therm. stabilize output stage and bias...
__________________
Svakog dana u svakom pogledu sve manje nazadujem.
  Reply With Quote
Old 29th June 2013, 05:20 PM   #38
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Quote:
Originally Posted by bogdan_borko View Post
Dadod, that`s all nice in the simulation world but there`s a work ahead of you to therm. stabilize output stage and bias...
Bogdan, yes there is more work to do. Q31 and Q32 should be thermaly connected with output transistors and P2 used for the bias adjustment. D1 and D2 should compensate for ambient change of temperature. Those days I am occupied with my grandsons and less time left for audio hobby.
  Reply With Quote
Old 30th June 2013, 05:01 PM   #39
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Here is HEC OPS with DC servo. This amp is now DC from the input to the output.
P1 is a volume control and P2 bias adjustment. Max gain is 45 or 33dB and in this case there is no need for preamplifier at all, just input switch.
Attached Images
File Type: jpg GainWire-HEC-power-DCservo-sch.jpg (92.3 KB, 123 views)
  Reply With Quote
Old 30th June 2013, 05:04 PM   #40
mcd99uk is offline mcd99uk  United Kingdom
diyAudio Member
 
Join Date: Mar 2008
Location: UK
Only thing I can add is that it is worth considering adding a low pass filter to the servo output. Another defence against high frequency nasties getting through the servo.
  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
Basic question re: gNFB around 3 stages rongon Tubes / Valves 7 21st May 2012 04:52 PM
LED bias with gNFB mashaffer Tubes / Valves 1 22nd December 2010 12:01 AM
Headphones amplifier with highish gnfb 00940 Tubes / Valves 9 12th October 2009 04:11 PM
Suitable jfet for an zero GNFB amp? roender Solid State 14 28th November 2008 05:08 PM
GNFB and distortion myhrrhleine Solid State 16 29th July 2008 06:55 PM


New To Site? Need Help?

All times are GMT. The time now is 02:29 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