a wonderfull sziklai - Page 22 - 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 7th October 2012, 02:56 PM   #211
Stee is offline Stee  Italy
diyAudio Member
 
Stee's Avatar
 
Join Date: Jul 2005
Location: milan
Default see also this LJM news L20 VER7

L20 VER7 Stero Audio power amplifier Kit DIY AMP | eBay
__________________
Please download my best audio idea https://www.facebook.com/DiyAudioHiEnd
  Reply With Quote
Old 20th October 2012, 08:31 PM   #212
catalin is offline catalin  Romania
diyAudio Member
 
Join Date: Jun 2007
Thank you Stee ,I don't want to buy any other amp.This one is really satisfying and I am listenning every day at him .At 1 W it has 0.005% thd at 20 khz and 100V/us minimum .Also the miller cap being so small (12 pF ) it does not add any noise or distortion .Also because the potentials on the miller cap are close to 0 we don't have noise comming from the capacitor currents .
And another thing which I like at him is that with the cfp output the idle current can be only 25 mA to obtain low thd ,in comparation with EF which need more power to disipate for the same thd .
So the final stage needs in total 25mA*80V*2 = 4 Watts total disipation in stereo mode for 0.005 %thd at 20khz .
So I am happy with this one .
__________________
"please try to listen to some music through the amplifier instead. Life is so short ..."

Last edited by catalin; 20th October 2012 at 08:36 PM.
  Reply With Quote
Old 21st October 2012, 08:07 AM   #213
Stee is offline Stee  Italy
diyAudio Member
 
Stee's Avatar
 
Join Date: Jul 2005
Location: milan
Default easy Sziklai

with very shorth NFB timing
only six devices for 3 stages
Attached Images
File Type: png CFP.PNG (110.9 KB, 435 views)
__________________
Please download my best audio idea https://www.facebook.com/DiyAudioHiEnd
  Reply With Quote
Old 21st October 2012, 10:36 AM   #214
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Stee's input is corrupted.
I don't know where it came from.
The LF filter is set to 200ms. That is very wideband.
The HF filter is not set to any fixed value.
At max volume the RF filter relies on the interconnect for some attenuation.
At mid volume the filter is set to 2.5us
At min volume the filter has no attenuation, but the impedance is near zero ohms and thus little interference will be able to get into the amplifier.

That nil attenuation to 2.5us is a silly arrangement.

Add 1k to 2k into the feed before the 100pF tapping point and replace the 100k attenuator with a 10k attenuator.
Personally, I would change C1 to somewhere in the range 1uF to 330nF.

I don't understand the 0r33 in the speaker connection to Audio Ground. Is this -ve output impedance?
__________________
regards Andrew T.
  Reply With Quote
Old 21st October 2012, 01:15 PM   #215
lohk is offline lohk  Europe
diyAudio Member
 
lohk's Avatar
 
Join Date: Apr 2001
Location: Northern Noricum, near the Limes
isn't it the current feedback point?
__________________
/lohk/
  Reply With Quote
Old 21st October 2012, 01:37 PM   #216
Stee is offline Stee  Italy
diyAudio Member
 
Stee's Avatar
 
Join Date: Jul 2005
Location: milan
The project is open to improvements
I am not skilled with the simulator
__________________
Please download my best audio idea https://www.facebook.com/DiyAudioHiEnd
  Reply With Quote
Old 21st October 2012, 01:41 PM   #217
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Stee,
you should not need a simulator to notice that some of the component values and some of the arrangement gives less than optimum results.
Like reduce pot value.
Add RF attenuating resistor.

These don't come from simulator.
These come from "looking" at the flawed schematic and understanding what is supposed to happen.
__________________
regards Andrew T.
  Reply With Quote
Old 21st October 2012, 06:27 PM   #218
catalin is offline catalin  Romania
diyAudio Member
 
Join Date: Jun 2007
Can we talk only about the Joy amp ? the working schematic which is present already from the first thread, from the beginning and updated with better performance in the past threads ?About the "Joy" amp ?
@Stee ,please if you want to present your ideas you are welcome to open a new thread .
Thank you very much!
__________________
"please try to listen to some music through the amplifier instead. Life is so short ..."
  Reply With Quote
Old 22nd October 2012, 08:06 AM   #219
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Good idea, you can request removing all my recent off topic posts along with Stee's off topic ramblings.
__________________
regards Andrew T.
  Reply With Quote
Old 1st November 2012, 02:38 PM   #220
catalin is offline catalin  Romania
diyAudio Member
 
Join Date: Jun 2007
Exclamation Why the sound is changing better ? The cfb or the low feedback ?

Hello ,I had the idea to limit the open loop gain by adding a single resistor to the amplifier and the sound has changed a lot .Now the music is played very natural and there are more details . The resistor is connected to have current feedback (about 60dB of feedback) which limit the open loop gain to less than 50 dB .Also the gain and phase from inputs to the collector's ltp are perfectly linear now.In simulation there are the same thd,imd and slew rate but the amp is sounding more enjoyable .The sound is warm compaired to the old version and very real .
All these on dynaudio contour 4 ohms speakers .
So overall we have firstly 60dB of current feedback and 20dB of voltage feedback .It is a vfb-cfb amp .It is possible also to decrease the feedback factor of the vfb by changing the R8 to 33 ohm and to decrease the R15(cfb resistor) to 33kohm .But I am extremely happy from what I hear in this topology .

Click the image to open in full size.
The gain and phase without R from inverting input to ltp collectors :
Click the image to open in full size.
The gain and phase with R from inverting input to ltp collectors :
Click the image to open in full size.

Thd at 1 watt ,20khz is 0.003%,slew rate about 150V/us and the "open loop" phase is linear with 50db gain .
For these conditions the final stage is biased at 20mA +10mA from the drivers .So on 0.22 emitter resistor we have 30mA ~almost 7-8mVolts .

I enjoy a lot this sound and I don't know if I should apply all these to do a perfect simetrical topology .
__________________
"please try to listen to some music through the amplifier instead. Life is so short ..."

Last edited by catalin; 1st November 2012 at 02:57 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
Sziklai output Moby Solid State 68 27th January 2011 10:39 AM
Hybrid Sziklai CFP Stee Solid State 0 27th December 2008 10:53 AM
ccs-loaded sziklai ionomolo Solid State 132 30th June 2008 06:39 AM
My DIY project - Wonderfull Loudspeakers ! Emeric Multi-Way 6 9th May 2008 02:38 AM


New To Site? Need Help?

All times are GMT. The time now is 09:53 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