diyAB Amp - The "Honey Badger" - Page 16 - 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 23rd July 2011, 04:39 AM   #151
diyAudio Member
 
ostripper's Avatar
 
Join Date: May 2008
Location: Albany , NY (smallbany)
Default For this topology , this is Final.

#1 - between the layout and the circuit , the theoretical THD can not get any lower at this amps low to mid power levels (.38ppm !! 1k 1-2ppm @ 20k).
This is totally true at the VAS - running a class A Op stage , you would realistically get ppm performance.

#2 - The output stage WILL realistically add the most distortion depending on load + the quality of power supply. NFB +TMC will NOT cancel everything.
A triple OP or a well designed lateral might just better this amp.

#3 - the sound "quality" also might improve with the more advanced OP stage as well , but we want to keep this simple for the first time builders. A EF2 can be quite effective if designed right. The MJE15032/3 pair will form a colpitt's oscillator with the wrong base-stopper and a "crazy load" / abuse-clipping.
It is the driver that determines the OP stage's OLG and resulting stability.
Strange .... I found this out by accident by using my sanken 2sc3263/2sa1294 ...AS THE DRIVER PAIR.
Then I found this:
post #51 -
OPS

....which confirmed my suspicions on EF2 and 3 OP stage stability.

To generalize all this ,
You want the drivers to be faster than the OP's , as a few example's:
---- DRIVER / OUTPUT
2sc4793/2sa1837 /100mhz Ft -- njw0281/0302 /30mhz Ft (1-2 pair)
A+ - but low driver SOA.
----- DRIVER / OUTPUT
MJE15032/33 cob 200+ - 30mhz Ft --- njw0281/0302 /30mhz Ft
Durable , general purpose workhorse ... B+ (grade)
---- DRIVER / OUTPUT
2sc4793/2sa1837 /100mhz Ft --- 2sc3263/2sa1294/ cob 200 - 60mhz Ft
Better yet , this is the fastest EF2 for 8R loads , has the lowest THD. needs the lowest value "suckout" capacitor (.22- .47uF) and the lowest driver bias.
Click the image to open in full size.
Fast , cool , and the OEM's love it (cheap)

----- DRIVER / OUTPUT
2sc3263/2sa1294/ Cob 200 - 60mhz Ft --- 4-6 pair njw0281/0302 / 30mhz Ft
This actually would be the VERY BEST EF2 , highest gain and current .. fast , too.

My latest- greatest is ( bd139/140 / 2sc3263/2sa1294 / 3 X njw0281/0302 )
used in a triple (below).
This DIYA amp with the below output stage would indeed break ground. But , it might be too imposing for some constructors.

Device choices WILL affect stability , durability , and maybe... the final "sound".

OS
Attached Images
File Type: gif triple.gif (78.0 KB, 1548 views)
__________________
Mongrel website , always current and updated :
http://www.fidelityforce.com/ostripper
  Reply With Quote
Old 23rd July 2011, 09:33 AM   #152
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Sound_Buster, the time has come for you to start a Brazilian group to build OSs amps! His job deserves our efforts. I think that we could help develop this project if many of us built this beauty!
This project started out as a request from DIYaudio to Ost to design an amplifier for the Community and to make the PCB available through the DIYaudio shop.

Suggestions to organise pirate Group Buy seems to defeat the intent.
__________________
regards Andrew T.
  Reply With Quote
Old 23rd July 2011, 09:39 AM   #153
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
post151.
Can you explain 0r01 for R57&58
__________________
regards Andrew T.
  Reply With Quote
Old 23rd July 2011, 10:45 AM   #154
Bonsai is offline Bonsai  Taiwan
diyAudio Member
 
Bonsai's Avatar
 
Join Date: Jul 2003
Location: Taipei, Taiwan
Time to move to the execution bit. I doubt you can improve it any further. I think its just about pefect now spec wise.
__________________
bonsai
Amplifier Design and Construction for MUSIC! http://hifisonix.com/
  Reply With Quote
Old 23rd July 2011, 11:34 AM   #155
alex mm is offline alex mm  Europe
diyAudio Member
 
alex mm's Avatar
 
Join Date: Mar 2006
Location: ROMANIA ,
...... nice , well done OS , I will learn a lot , but too much layers
Alex.
  Reply With Quote
Old 23rd July 2011, 12:37 PM   #156
farjon is offline farjon  Brazil
diyAudio Member
 
farjon's Avatar
 
Join Date: Jul 2003
Location: Rio de Janeiro, RJ
Quote:
Originally Posted by ostripper View Post
It is the driver that determines the OP stage's OLG and resulting stability.
Strange ....
Although have built few amplifiers (only two... ), I had noticed these mutual influence between drivers and outputs on simulations.

What is the schedule for the boards appearing at DiyAudio Store?
  Reply With Quote
Old 23rd July 2011, 03:48 PM   #157
diyAudio Member
 
Join Date: Aug 2009
What min. Voltage does cap C9 has to be?
  Reply With Quote
Old 23rd July 2011, 04:29 PM   #158
loek is offline loek  Netherlands
diyAudio Member
 
Join Date: Feb 2005
Location: The Hague
Default input/output

Is the input cap (when you use a big one) not to close to the output rail?
Interesting project anyway.
Regards,
Loek
Attached Images
File Type: gif voltages.GIF (17.0 KB, 1406 views)
  Reply With Quote
Old 23rd July 2011, 04:49 PM   #159
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
Default sorry about commenting so late

the diff pair cascode resistive bias will compromise performance

a simple improvement is to use resistive bootstrap - add a R from the output to R19 in the ratio of the feedback resistors

I would still add a follower between the diff pair degen R and the cascode bias - the diff pair shouldn't be subject to resistive load or positive power supply noise injection at this point - check the psrr performance/look for ps ripple frequency sidebands - the filter for the front end is not that great for ps ripple frequencies


why no current clamp on the VAS - you already have the emitter degen R?


and I could (have) go on at some lenghth about TMC - a interesting criticism could be that the "single pole" "damped step response" of the global loop is in fact dangerous in a beginner's amp since the true stability margin is not reflected in the step response

Last edited by jcx; 23rd July 2011 at 04:56 PM.
  Reply With Quote
Old 23rd July 2011, 04:57 PM   #160
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
C9, the multiplier cap should never see more than 3Vpk, even in fault condition.
You could use 6V or 10V or 16V or 25V cap here.
__________________
regards Andrew T.
  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
diyAB Amp The "Honey Badger" build thread Variac Solid State 1187 24th August 2014 05:19 PM
Honey, I smoked the Weller 8200 jackinnj Equipment & Tools 5 25th April 2011 06:07 AM
Badger Badger Badger..... Mushroom !! 5th element Everything Else 15 20th September 2003 03:16 PM


New To Site? Need Help?

All times are GMT. The time now is 04:22 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