Discrete Opamp Open Design - Page 161 - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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 11th October 2012, 03:03 PM   #1601
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
Actually quite good as cascode.


Patrick
__________________
xen-audio.com
  Reply With Quote
Old 11th October 2012, 11:25 PM   #1602
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
I think this thread should get a gold star for lack of acrimony.
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."
  Reply With Quote
Old 12th October 2012, 12:12 AM   #1603
bcarso is offline bcarso  United States
diyAudio Member
 
Join Date: May 2005
Location: Canoga Park, California
Quote:
Originally Posted by scott wurcer View Post
I think this thread should get a gold star for lack of acrimony.
I agree. And statisticians needn't worry, the statistics are staying within long-term averages considering some exchanges over in the blowtorch thread.
  Reply With Quote
Old 12th October 2012, 02:46 AM   #1604
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
Quote:
Originally Posted by scott wurcer View Post
I think this thread should get a gold star for lack of acrimony.
indeed, probably this is due in part to the majority wanting to actually see something produced out of this exciting event; instead of degenerating into the usual squabble.

ssshhh geniuses at work
  Reply With Quote
Old 12th October 2012, 03:16 AM   #1605
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
:-) :-) :-)
  Reply With Quote
Old 12th October 2012, 04:13 AM   #1606
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 109
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Quote:
Originally Posted by EUVL View Post
If you refer to the PMBFJ620, then it has much higher noise and much lower Yfs than the BF862.
Idss is also way too high.
The part number and the specs strongly suggest this is two J310 die moulded into a single package. 6nV noise is quite far removed from the BF862 but fairly respectable for a JFET opamp input stage.
__________________
Seek not the favour of the multitude...rather the testimony of few. And number not voices, but weigh them. - Kant
The capacity for impartial observation is commonly called 'cynicism' by those who lack it.
  Reply With Quote
Old 12th October 2012, 04:13 AM   #1607
hhoyt is offline hhoyt  United States
diyAudio Member
 
hhoyt's Avatar
 
Join Date: Mar 2010
Location: Chapel Hill, NC
Default Acrimony

Quote:
Originally Posted by scott wurcer View Post
I think this thread should get a gold star for lack of acrimony.
Yeah, and as such is becoming quite un-entertaining on that level, in order to re-direct those who are here awaiting such antics: (with all credit to Monty Python):
_________________________________________________
Q: WHAT DO YOU WANT?
M: Well, I was told outside that...
Q: Don't give me that, you snotty-faced heap of parrot droppings!
M: What?
Q: Shut your festering gob, you tit! Your type really makes me puke, you vacuous, coffee-nosed, maloderous, pervert!!!
M: Look, I CAME HERE FOR AN ARGUMENT, I'm not going to just stand...!!
Q: OH, oh I'm sorry, but this is abuse.
M: Oh, I see, well, that explains it.
Q: Ah yes, you want room 12A, Just along the corridor.
M: Oh, Thank you very much. Sorry.
Q: Not at all.
M: Thank You.
(Under his breath) Stupid git!!
_________________________________________________
Indeed...I have read this on other DIYA threads, couched in slightly different prose...

Howie
  Reply With Quote
Old 12th October 2012, 04:19 AM   #1608
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 109
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Default Riiiiiight...

Acrimony? Acrimony? We used to dreeeeeeam of acrimony!
__________________
Seek not the favour of the multitude...rather the testimony of few. And number not voices, but weigh them. - Kant
The capacity for impartial observation is commonly called 'cynicism' by those who lack it.
  Reply With Quote
Old 12th October 2012, 06:24 AM   #1609
diyAudio Member
 
Join Date: Feb 2010
Location: Dallas Fort Worth area, Texas
Quote:
Originally Posted by scott wurcer View Post
I think this thread should get a gold star for lack of acrimony.
Absolutley agree, for being productive and instructive as well.
  Reply With Quote
Old 12th October 2012, 06:29 AM   #1610
diyAudio Member
 
Join Date: Nov 2011
Location: Cooktown, Oz
Quote:
Originally Posted by fas42 View Post
Hmmm ... in my sim I have very good agreement on the +ve PSRR figures, but the -ve PSRR is dramatically superior at lower frequencies for stinius.
Cgd of the input devices is one of the major paths for +ve PS noise into the i/ps. That's why the PSRR nulls with a particular source Z cos that's when the Zs presented by the feedback network & the source are equal and the CMRR of the amp ignores it. Cascoding the input helps make this effect innocuous.

Having separate CCS for both input devices re-introduces the problem from the -ve supply .. which then need extra cascodes.

But if we
Quote:
get rid of J1, Q11, 9 and tie the bases of Q15, 35 to emitter & collector of Q7 respectively
doesn't this eliminate the problem from the -ve rail?

Quote:
Originally Posted by GuruWurcer
Yes that could be, as long as the dynamic base current is captured it all works, time to Muntz away a little.

EDIT - It does not work out that easily, best left alone for now.
Scott, could you explain a little for us unwashed masses why we can't?

ricardo "wannabe a SPICE guru but failing" lee
  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
Discrete OPAMP audio-gd Vendor's Bazaar 27 20th September 2012 05:02 PM
discrete opamp help blackpowderaudio Parts 0 16th December 2009 04:46 PM
THAT transistor headphone amp (250ma discrete opamp) design sanity check. Russ White Headphone Systems 19 13th December 2007 01:52 PM


New To Site? Need Help?

All times are GMT. The time now is 12:42 PM.


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