FETZILLA - The Builders Place - 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 21st November 2012, 10:32 PM   #41
GregH2 is offline GregH2  Australia
diyAudio Member
 
GregH2's Avatar
 
Join Date: Oct 2009
Quote:
Originally Posted by meanman1964 View Post
Greg,Just do what you think is best.What do you mean with a long time?
Meanman,

By long time, I mean perhaps 15 minutes, but this is in no way damaging to the speaker. It just means the amp takes some time to reach optimal operating conditions. Actually the extra H2 distortion created by having some DC offset probably will sound nice!

I have no personal need for a 150-200W Fetzilla and I now prefer to make designs which use cheap and readily available parts (no lateral fets, depletion mode mosfets or JFETs). If you want a 150W fetzilla I am happy to advise you along the way and help you with all the details, but this time I will not be building the amp myself.

Let me know if you would like to proceed and I will post a schematic to try.

In the meantime, the 72W quasi amp I am designing should sound pretty good and provide reasonable power. Should be done in a few weeks.

Cheers,

Greg.
  Reply With Quote
Old 21st November 2012, 10:49 PM   #42
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
Quote:
Originally Posted by GregH2 View Post

In the meantime, the 72W .......

Greg.
  Reply With Quote
Old 21st November 2012, 11:14 PM   #43
GregH2 is offline GregH2  Australia
diyAudio Member
 
GregH2's Avatar
 
Join Date: Oct 2009
Quote:
Originally Posted by tinitus View Post
Wow, "Quasi" really seems to be a buzz word on these forums. The interest and number of personal messages this has generated is quite amazing. I hope the amp lives up to expectations.

I think the reason chip amps sound as good as they do is the quasi output. Couple that output to a simple single ended input stage and vas and you should have a good sound IMO. Anyway, this is getting off the feztilla topic so I will shut up now.
  Reply With Quote
Old 22nd November 2012, 12:57 AM   #44
AKSA is offline AKSA  Australia
diyAudio Member
 
Join Date: Sep 2001
Location: Melbourne, Australia
A quasi output stage mandates different loop gain for each half cycle. This promotes H2 and H4 output. THD overall is not as good as a complementary design, but many say that quasi amps sound better. This is a close paradigm that higher THD increase sound quality, but really is highly controversal.

Go for it, Greg!

Hugh
__________________
Aspen Amplifiers P/L (Australia)
www.aksaonline.com
  Reply With Quote
Old 22nd November 2012, 01:01 AM   #45
Jay is offline Jay  Indonesia
diyAudio Member
 
Join Date: Feb 2003
Location: Jakarta
Quote:
Originally Posted by GregH2 View Post
I think the reason chip amps sound as good as they do is the quasi output. Couple that output to a simple single ended input stage and vas and you should have a good sound IMO.
I think the opposite. The reason chip amps sound as mediocre as they do is the quasi output...

I don't think that a quasi amp can be "the best". We have LM overture series, we have Naim clones, etc. but I think "we" rely more on your capability than the dreadful quasi topology (yes, we have a LOT more NPN than PNP).

But please keep the original "spirit" of Lineup's circuit: current feedback. Visually I want to see no higher than 2k2 of feedback resistance, and I prefer the feedback applied to emitter/source.

BTW, since the beginning around almost 2 years ago, Hugh always wrote LINEOUT. Something I am missing?
  Reply With Quote
Old 22nd November 2012, 01:10 AM   #46
GregH2 is offline GregH2  Australia
diyAudio Member
 
GregH2's Avatar
 
Join Date: Oct 2009
Hugh: If you are chasing asymmetry in the output stage, does this mean that you would prefer a quasi output without the baxandall diode?

Jay: I think the thing that lets down the sound of the chip amps is the very complex circuit before the output, not the quasi itself. Be rest assured, my quasi amp will stick to the fetzilla topology with its single ended input and vas and current feedback.
  Reply With Quote
Old 22nd November 2012, 01:40 AM   #47
diyAudio Member
 
meanman1964's Avatar
 
Join Date: Oct 2006
Location: Belgium the land of chocolate
Quote:
Originally Posted by GregH2 View Post
Meanman,

By long time, I mean perhaps 15 minutes, but this is in no way damaging to the speaker. It just means the amp takes some time to reach optimal operating conditions. Actually the extra H2 distortion created by having some DC offset probably will sound nice!

I have no personal need for a 150-200W Fetzilla and I now prefer to make designs which use cheap and readily available parts (no lateral fets, depletion mode mosfets or JFETs). If you want a 150W fetzilla I am happy to advise you along the way and help you with all the details, but this time I will not be building the amp myself.

Let me know if you would like to proceed and I will post a schematic to try.

In the meantime, the 72W quasi amp I am designing should sound pretty good and provide reasonable power. Should be done in a few weeks.

Cheers,

Greg.
Greg,
I want to give it a try.As I said earlier it may be a real bass amp going to 200Hz top but if you can design a high power FetZilla be my quest.The FetZilla produces such a bass it's amazing strong ,tight and rocksteady fast that I want.
  Reply With Quote
Old 22nd November 2012, 10:17 PM   #48
GregH2 is offline GregH2  Australia
diyAudio Member
 
GregH2's Avatar
 
Join Date: Oct 2009
Quote:
Originally Posted by meanman1964 View Post
Greg,
I want to give it a try.As I said earlier it may be a real bass amp going to 200Hz top but if you can design a high power FetZilla be my quest.The FetZilla produces such a bass it's amazing strong ,tight and rocksteady fast that I want.
Ok, give me a few days and I'll cobble together a possible circuit for you to try.
  Reply With Quote
Old 4th December 2012, 07:48 PM   #49
diyAudio Member
 
meanman1964's Avatar
 
Join Date: Oct 2006
Location: Belgium the land of chocolate
Any update here?
  Reply With Quote
Old 5th December 2012, 12:29 PM   #50
GregH2 is offline GregH2  Australia
diyAudio Member
 
GregH2's Avatar
 
Join Date: Oct 2009
Sorry, been very busy with work and getting home late.

It's taking shape, haven't had a chance to simulate it or finalise the design yet. Will probably be something like this. Should get it finished on the weekend...
Attached Images
File Type: jpg Clipboard01.jpg (237.0 KB, 322 views)
  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
Swordfishy/ASPEN FETZILLA power amp AKSA AKSA 1167 2nd July 2014 09:29 AM
Group Buy #2 - FETZILLA AKSA AKSA 252 18th April 2014 03:09 AM
Fetzilla Build Documentation Woody1911a1 AKSA 234 23rd December 2013 04:37 PM
Group Buy #3 - FETZILLA, the amp... AKSA AKSA 44 28th September 2012 08:11 PM
Best place to place bleeder resistor in a power supply? G Tubes / Valves 13 4th August 2004 10:26 AM


New To Site? Need Help?

All times are GMT. The time now is 11:15 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