QUASI is not that bad, really, (I post some proof here). - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

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 31st May 2010, 09:35 AM   #1
ontoaba is offline ontoaba  Indonesia
diyAudio Member
 
ontoaba's Avatar
 
Join Date: Nov 2009
Location: Kudus, Malang, Dieng
Default QUASI is not that bad, really, (I post some proof here).

Using ordinary component in simulation (not realized yet) like IRFZ44, it has some good result, not as good as some best amp out there, but it is more than enough for only IRFZ44.

I just leave it here for a moment, and this result proof something about quasi design.
Attached Files
File Type: pdf H6577L1.pdf (153.6 KB, 392 views)
  Reply With Quote
Old 31st May 2010, 10:07 AM   #2
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
The plot showing 100kHz @ 45Vpkwith time/div = 2u
I am looking at the zero crossing of the input signal and comparing the rising against the falling.
In the rising version I can see that the currents in the two devices are very similar as they hand over to each other.
In the falling version I can see that the currents in the two devices are not at all similar.

Is this a picture of crossover distortion or is it cross modulation?

How can the circuit be tweaked to make the device currents more equal at the zero crossing of the signal? Which characteristic will improve? Crossover distortion of some other?
__________________
regards Andrew T.
  Reply With Quote
Old 31st May 2010, 06:05 PM   #3
ontoaba is offline ontoaba  Indonesia
diyAudio Member
 
ontoaba's Avatar
 
Join Date: Nov 2009
Location: Kudus, Malang, Dieng
I have another advantage of using quasi, like the driver driving single mosfet instead of two, also it doesn't need to looking for match complementary (wide component choice), and more.
My pictures is proving that it could maintained well to not doing any dangerous collision even at high speed operation and using high(strong) error correction.
I post another picture (use mspaint to open so it could easily scroll up down and zoom large scale) contain simplified schematic and high frequency distortion simple picture.
Quote:
Originally Posted by AndrewT View Post
How can the circuit be tweaked to make the device currents more equal at the zero crossing of the signal? Which characteristic will improve? Crossover distortion of some other?
Actually it could be improved by more precise and speed at control stage, but it is not really necessary improving audio amplifier to work at 100KHz.
There is another advantage of using quasi with this setting, the output waveform error will repaired with both side instead of one if it reach specific timing and error not repaired yet.
Attached Images
File Type: png 100khzdist.PNG (30.6 KB, 480 views)
  Reply With Quote
Old 1st June 2010, 01:17 AM   #4
ontoaba is offline ontoaba  Indonesia
diyAudio Member
 
ontoaba's Avatar
 
Join Date: Nov 2009
Location: Kudus, Malang, Dieng
Quote:
Originally Posted by AndrewT View Post
The plot showing 100kHz @ 45Vpkwith time/div = 2u

In the falling version I can see that the currents in the two devices are not at all similar.

Is this a picture of crossover distortion or is it cross modulation?
yes it help to minimize crossover distortion for high voltage operation (fast fall time)
I do another test here, it showing the controller response in crossing maintenance.
The opposite mosfet start earlier at faster fall time (2us) than the slower (3us).
I cannot do this easily in non quasi. With non quasi design, I need to change its biasing voltage to do this.
Attached Images
File Type: png sinle pulse.PNG (20.6 KB, 442 views)
  Reply With Quote
Old 1st June 2010, 07:15 AM   #5
ontoaba is offline ontoaba  Indonesia
diyAudio Member
 
ontoaba's Avatar
 
Join Date: Nov 2009
Location: Kudus, Malang, Dieng
Default ???

I feel something wrong with this, I am trying some improvement but I think it going misled me.
Attached Images
File Type: png distortion improvement.PNG (37.4 KB, 428 views)
  Reply With Quote
Old 2nd June 2010, 04:24 AM   #6
ontoaba is offline ontoaba  Indonesia
diyAudio Member
 
ontoaba's Avatar
 
Join Date: Nov 2009
Location: Kudus, Malang, Dieng
Default Speed up capacitors make it twice faster.

I am trying to make better small signal delay with placing some capacitors and it did well. Good small signal delay will be very useful for my power gain project, so I am going to tweak it instead of tweaking the other.

quasi + old HEXFET is really good stuff ?
Attached Images
File Type: png speed up.PNG (41.1 KB, 391 views)
  Reply With Quote
Old 2nd June 2010, 04:35 AM   #7
ontoaba is offline ontoaba  Indonesia
diyAudio Member
 
ontoaba's Avatar
 
Join Date: Nov 2009
Location: Kudus, Malang, Dieng
Hi, another good news. This morning I am blowing a gecko many times until it death. It falling from the roof then trying to run but I catch it and kill it. Its big gecko.
The prophet says that blowing geckos and kill it, has great rewards. I am now kills 6 geckos total in my life.
  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
Quasi or not Quasi - that is the question x-pro Solid State 31 20th October 2013 04:25 PM
Which is Beter Quasi Or Non Quasi sekhar Solid State 87 22nd June 2010 08:12 PM


New To Site? Need Help?

All times are GMT. The time now is 11:20 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